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Should I completely discharge my laptop battery?

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  Should I completely discharge my laptop battery? andymhancock@gmail.com - 2014-12-30 11:53 -0800
    Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2014-12-31 13:35 +1300
      Re: Should I completely discharge my laptop battery? andymhancock@gmail.com - 2014-12-31 11:06 -0800
        Re: Should I completely discharge my laptop battery? andymhancock@gmail.com - 2014-12-31 11:54 -0800
          Re: Should I completely discharge my laptop battery? andymhancock@gmail.com - 2015-01-01 15:13 -0800
        Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-01-01 12:29 +1300
      Re: Should I completely discharge my laptop battery? mike <ham789@netzero.net> - 2014-12-31 12:05 -0800
        Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-01-01 12:55 +1300
          Re: Should I completely discharge my laptop battery? andymhancock@gmail.com - 2015-01-01 14:51 -0800
            Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-01-02 14:16 +1300
              Re: Should I completely discharge my laptop battery? andymhancock@gmail.com - 2015-01-01 18:11 -0800
                Re: Should I completely discharge my laptop battery? mike <ham789@netzero.net> - 2015-01-02 01:15 -0800
                  Re: Should I completely discharge my laptop battery? andymhancock@gmail.com - 2015-01-02 09:34 -0800
                    Re: Should I completely discharge my laptop battery? mike <ham789@netzero.net> - 2015-01-02 10:46 -0800
                      Re: Should I completely discharge my laptop battery? andymhancock@gmail.com - 2015-01-02 14:25 -0800
                        Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-01-04 12:28 +1300
                          Re: Should I completely discharge my laptop battery? andymhancock@gmail.com - 2015-01-03 16:48 -0800
                            Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-01-07 14:47 +1300
                              Re: Should I completely discharge my laptop battery? mike <ham789@netzero.net> - 2015-01-06 19:38 -0800
                                Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-01-09 13:36 +1300
                                  Re: Should I completely discharge my laptop battery? mike <ham789@netzero.net> - 2015-01-08 17:34 -0800
                                    Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-01-10 14:59 +1300
                                      Re: Should I completely discharge my laptop battery? mike <ham789@netzero.net> - 2015-01-09 20:22 -0800
                                        Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-01-13 12:18 +1300
                                          Re: Should I completely discharge my laptop battery? mike <ham789@netzero.net> - 2015-01-12 17:20 -0800
                                            Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-01-15 13:35 +1300
                                              Re: Should I completely discharge my laptop battery? mike <ham789@netzero.net> - 2015-01-14 17:37 -0800
                                                Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-01-16 12:33 +1300
                                            Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-02-08 14:24 +1300
                                              Re: Should I completely discharge my laptop battery? mike <ham789@netzero.net> - 2015-02-07 21:02 -0800
                                                Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-02-11 11:09 +1300
                      Re: Should I completely discharge my laptop battery? "~misfit~" <shaun.at.pukekohe@gmail.com> - 2015-01-03 11:47 +1300

Page 2 of 2 — ← Prev page 1 [2]

#2301

On 1/8/2015 4:36 PM, ~misfit~ wrote:
> Once upon a time on usenet mike wrote:
>> On 1/6/2015 5:47 PM, ~misfit~ wrote:
>>
>>>
>>> Anyway now I have another six 1st tier 18650 cells to play with.
>>> Learning their (remaining) capacity is the hardest part for me. If I
>>> wasn't so broke I'd buy a charger / analyser like the Maha Wizard
>>> One device that I bought ages ago for managing my Eneloops (I have a
>>> strong dislike of primary cells). However as it is I'm stuck with a
>>> 'dumb' charger that just charges until voltage is ~4.2v. Then I to
>>> do a timed discharge in a flashlight. :-/ Very crude.
>> But effective.
>>
>> I built a setup with programmable power supply and programmable load.
>> Makes nice graphs,but not clear that they have any value beyond
>> curiosity.
>
> I like to know cell capacity as I have some applications wher they run in
> parallel.

Try to use cells from the same pack and don't sweat it.  They're already
paralleled in pairs in many packs.  Unless a cell is shorted, it's not a 
huge risk.

The time you want 'em matched is when you run them in series.  If they're
not matched, the pack gets imbalanced and can overdischarge or overcharge
one.

I avoided all that hassle with my bike light.  I put 4 18650 cells
in a plastic pipe and brought out the wires of all cells to a DB-9
serial connector.  The light runs them in series.
The charger charges them in parallel.  I did put 4 1.5 ohm resistors
in the charger plug so that if something shorted, it would blow the
resistor instead of the battery.

>
>> I do have a suggestion.
>> use a variable power supply and a diode.
>> set the power supply so the output of the diode is at the low
>> limit discharge voltage. Set the current limit sufficiently high
>> to run the discharge load.

If you don't have an adjustable power supply, it doesn't matter.
The purpose of the diode and supply is to prevent overdischarge.
You set the power supply so that the diode is off and the supply
is completely disconnected during the whole test.
If you're gonna sit and watch a voltmeter during the whole test,
you don't need it.

When you do need it is when you aren't watching.  When the phone rings.
Or the wife gets freaky.
Or when the kid falls and hurts himself.
If you get distracted, the diode eventually turns on, supplies
all the load current and saves your
cell from overdischarging below whatever voltage you set minus the diode 
drop.

>
> That first thing sounds good but I'm a little challenged when it come to
> electronics. I know basics (enough to make audio crossovers etc.) and have
> some components around the place.
>
> Would you be so kind as to explain in a bit more detail? I'd be obliged.
>
> Cheers,
>
Bottom line is that it takes a lot of equipment to get any meaningful data.
I had fun doing it, but it's not clear that the data made any real 
difference in the
applications.

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#2302

Once upon a time on usenet mike wrote:
> On 1/8/2015 4:36 PM, ~misfit~ wrote:
>> Once upon a time on usenet mike wrote:
>>> On 1/6/2015 5:47 PM, ~misfit~ wrote:
>>>
>>>>
>>>> Anyway now I have another six 1st tier 18650 cells to play with.
>>>> Learning their (remaining) capacity is the hardest part for me. If
>>>> I wasn't so broke I'd buy a charger / analyser like the Maha Wizard
>>>> One device that I bought ages ago for managing my Eneloops (I have
>>>> a strong dislike of primary cells). However as it is I'm stuck
>>>> with a 'dumb' charger that just charges until voltage is ~4.2v.
>>>> Then I to do a timed discharge in a flashlight. :-/ Very crude.
>>> But effective.
>>>
>>> I built a setup with programmable power supply and programmable
>>> load. Makes nice graphs,but not clear that they have any value
>>> beyond curiosity.
>>
>> I like to know cell capacity as I have some applications wher they
>> run in parallel.
>
> Try to use cells from the same pack and don't sweat it.  They're
> already paralleled in pairs in many packs.  Unless a cell is shorted,
> it's not a huge risk.

When I charged the six cells from the Viao pack some took twica as long to 
charge as others.

> The time you want 'em matched is when you run them in series.  If
> they're not matched, the pack gets imbalanced and can overdischarge
> or overcharge one.

Been there done that with NiMH. Same deal.

> I avoided all that hassle with my bike light.  I put 4 18650 cells
> in a plastic pipe and brought out the wires of all cells to a DB-9
> serial connector.  The light runs them in series.
> The charger charges them in parallel.  I did put 4 1.5 ohm resistors
> in the charger plug so that if something shorted, it would blow the
> resistor instead of the battery.


Good solution. :)

>>> I do have a suggestion.
>>> use a variable power supply and a diode.
>>> set the power supply so the output of the diode is at the low
>>> limit discharge voltage. Set the current limit sufficiently high
>>> to run the discharge load.
>
> If you don't have an adjustable power supply, it doesn't matter.

Well, I have a few ~US$5 adjustable current / voltage LED drive / battery 
charge modules. I thought I might be able to re-purpose one of those?

> The purpose of the diode and supply is to prevent overdischarge.

Yep, that's what I want.

> You set the power supply so that the diode is off and the supply
> is completely disconnected during the whole test.

Can I do that with one of the modules mentioned above? I'm talking about 
these things;
http://www.dx.com/p/buck-constant-voltage-constant-current-module-blue-dc-dc-5a-239099#.VLCG0dKUcTs
I use them mainly for driving LEDs off old laptop adapters.

> If you're gonna sit and watch a voltmeter during the whole test,
> you don't need it.

Yeah - however....

> When you do need it is when you aren't watching.  When the phone
> rings. Or the wife gets freaky.
> Or when the kid falls and hurts himself.
> If you get distracted, the diode eventually turns on, supplies
> all the load current and saves your
> cell from overdischarging below whatever voltage you set minus the
> diode drop.

.... and that's why I'd like to set something up to protect the cells during 
discharge.

>> That first thing sounds good but I'm a little challenged when it
>> come to electronics. I know basics (enough to make audio crossovers
>> etc.) and have some components around the place.
>>
>> Would you be so kind as to explain in a bit more detail? I'd be
>> obliged. Cheers,
>>
> Bottom line is that it takes a lot of equipment to get any meaningful
> data. I had fun doing it, but it's not clear that the data made any
> real difference in the
> applications.

Understood. Still, if I can do something toward protecting the cells with 
what I already have then it'd be a big help.

Cheers,
-- 
Shaun.

"Humans will have advanced a long, long, way when religious belief has a 
cozy little classification in the DSM."
David Melville (in r.a.s.f1) 

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#2304

On 1/9/2015 5:59 PM, ~misfit~ wrote:
> Once upon a time on usenet mike wrote:
>> On 1/8/2015 4:36 PM, ~misfit~ wrote:
>>> Once upon a time on usenet mike wrote:
>>>> On 1/6/2015 5:47 PM, ~misfit~ wrote:
>>>>
>>>>>
>>>>> Anyway now I have another six 1st tier 18650 cells to play with.
>>>>> Learning their (remaining) capacity is the hardest part for me. If
>>>>> I wasn't so broke I'd buy a charger / analyser like the Maha Wizard
>>>>> One device that I bought ages ago for managing my Eneloops (I have
>>>>> a strong dislike of primary cells). However as it is I'm stuck
>>>>> with a 'dumb' charger that just charges until voltage is ~4.2v.
>>>>> Then I to do a timed discharge in a flashlight. :-/ Very crude.
>>>> But effective.
>>>>
>>>> I built a setup with programmable power supply and programmable
>>>> load. Makes nice graphs,but not clear that they have any value
>>>> beyond curiosity.
>>>
>>> I like to know cell capacity as I have some applications wher they
>>> run in parallel.
>>
>> Try to use cells from the same pack and don't sweat it.  They're
>> already paralleled in pairs in many packs.  Unless a cell is shorted,
>> it's not a huge risk.
>
> When I charged the six cells from the Viao pack some took twica as long to
> charge as others.

If the pack is decent, that shouldn't happen.  If it's been sittin' in a 
drawer for a decade, all bets are off.  Also, there are some laptops
that put the pack right up against the heatsink and can cause serious 
degradation
of those cells closest.

I'd charge 'em up to the design max, and measure it again.

Another cause I've seen is that you have two in parallel, but one of
them has popped it's internal breaker and you really only have one charging.
>
>> The time you want 'em matched is when you run them in series.  If
>> they're not matched, the pack gets imbalanced and can overdischarge
>> or overcharge one.
>
> Been there done that with NiMH. Same deal.
>
>> I avoided all that hassle with my bike light.  I put 4 18650 cells
>> in a plastic pipe and brought out the wires of all cells to a DB-9
>> serial connector.  The light runs them in series.
>> The charger charges them in parallel.  I did put 4 1.5 ohm resistors
>> in the charger plug so that if something shorted, it would blow the
>> resistor instead of the battery.
>
>
> Good solution. :)
>
>>>> I do have a suggestion.
>>>> use a variable power supply and a diode.
>>>> set the power supply so the output of the diode is at the low
>>>> limit discharge voltage. Set the current limit sufficiently high
>>>> to run the discharge load.
>>
>> If you don't have an adjustable power supply, it doesn't matter.
>
> Well, I have a few ~US$5 adjustable current / voltage LED drive / battery
> charge modules. I thought I might be able to re-purpose one of those?
>
>> The purpose of the diode and supply is to prevent overdischarge.
>
> Yep, that's what I want.
>
>> You set the power supply so that the diode is off and the supply
>> is completely disconnected during the whole test.
>
> Can I do that with one of the modules mentioned above? I'm talking about
> these things;
> http://www.dx.com/p/buck-constant-voltage-constant-current-module-blue-dc-dc-5a-239099#.VLCG0dKUcTs
> I use them mainly for driving LEDs off old laptop adapters.
>
>> If you're gonna sit and watch a voltmeter during the whole test,
>> you don't need it.
>
> Yeah - however....
>
>> When you do need it is when you aren't watching.  When the phone
>> rings. Or the wife gets freaky.
>> Or when the kid falls and hurts himself.
>> If you get distracted, the diode eventually turns on, supplies
>> all the load current and saves your
>> cell from overdischarging below whatever voltage you set minus the
>> diode drop.
>
> .... and that's why I'd like to set something up to protect the cells during
> discharge.
>
>>> That first thing sounds good but I'm a little challenged when it
>>> come to electronics. I know basics (enough to make audio crossovers
>>> etc.) and have some components around the place.
>>>
>>> Would you be so kind as to explain in a bit more detail? I'd be
>>> obliged. Cheers,
>>>
>> Bottom line is that it takes a lot of equipment to get any meaningful
>> data. I had fun doing it, but it's not clear that the data made any
>> real difference in the
>> applications.
>
> Understood. Still, if I can do something toward protecting the cells with
> what I already have then it'd be a big help.
>
> Cheers,
>
BIG FAT DISCLAIMER.
Don't do this unless you know exactly what you're doing and have the
test equipment to verify your assumptions.  YOU CAN SET YOURSELF ON FIRE
if the power supply fails or is set up wrong.

Based on the specs, that power supply will work fine.

But, you're putting two switchers in series. If either of them goes wonky,
you're in trouble.
Wonkiness often happens right at the threshold where current limiting 
starts.
Also happens if your current limit on the second supply causes the
first one to current limit.

The input to the second supply is a negative resistance.
If the voltage goes down, the current goes up.  If the first supply
goes into current limit, especially foldback, things can go bad quickly.

In a perfect world, this all works.  But I've seen some seriously
wonky power supply designs from people who's job was power supply design
working for a custom power supply design house.

I've seen the whole thing come crashing down when you disconnect the input
or short the input or have noise on the input...you name it.
Make sure that the open circuit voltage is what you set.
Some supplies require a minimum load to regulate.
If not, you need a load resistor so you don't overcharge your cells.
You also need to verify the voltage regulates to the proper voltage
when the supply heats up.
And if it overloads and shorts the switcher, you can smoke your cells
in a hurry.

Messing with lithium chargers is NOT SAFE.

Design worked fine in the intended application, but may not in yours.

I'm assuming that you know better than to try to solder directly onto the
cells.  People who claim it's safe just haven't hurt themselves YET.

So, here's one option.
Set your power supply to the max charge voltage, (maybe 4.2V depending
on the lithium technology).  Set your power supply current limit to the 
maximum charge current you want.
Put two diodes in series
supply -->|--->|-- to battery.
Pick a combination of regular silicon junction and Schottky diodes so 
that the output
of the diodes is the low voltage limit you choose.

Use a discharge test current that is LESS than the current limit set above.

Run your discharge test.
When done, disconnect the bottom end of the load resistor
and hook it to the power supply
across the diodes and it will charge back up.
You can even remove the load and short the diodes and charge at the max 
you set.
But you really must evaluate whether this all works with your
batteries and your power supplies.

Are we having fun yet?

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#2310

Once upon a time on usenet mike wrote:
[total snip]
> Are we having fun yet?

Thanks Mike. I've copied that to notepad and saved it for when I have a bit 
of time to play with.

I have a couple of these too 
http://www.dx.com/p/mp1405-5v-1a-lithium-battery-charging-board-blue-black-219454#.VLRT1MlZqUc 
and used one for re-powering a mini rotary tool I got cheap that used 3x 
small NiCad cells in shrink-wrap, the total size of which was similar to a 
single 18650 but had little 'power' and didn't hold much charge. I bought a 
new solder-tab Panasonic cell for that job as I didn't know how good my 
slavaged cells were and it's hard to open up the modded tool....

However it doesn't seem to like running a motor from the 'out' pads - maybe 
it's something to do with the brushes and how it works? I tried three of 
these PCBs for the job and they all didn't work right. In the end I had to 
wire a small momentary contact switch between the B+ and OUT+ pads to start 
the motor. Once it's started it runs fine from the 'OUT' contacts. <shrug>

As you can probably tell I only have basic knowledge (but try hard to not 
take risks - I'm very aware of the inherant dangers with Li-Ion tech and the 
potential for 'thermal runaway').

Cheers,
-- 
Shaun.

"Humans will have advanced a long, long, way when religious belief has a 
cozy little classification in the DSM."
David Melville (in r.a.s.f1) 

[toc] | [prev] | [next] | [standalone]

#2311

On 1/12/2015 3:18 PM, ~misfit~ wrote:
> Once upon a time on usenet mike wrote:
> [total snip]
>> Are we having fun yet?
>
> Thanks Mike. I've copied that to notepad and saved it for when I have a bit
> of time to play with.
>
> I have a couple of these too
> http://www.dx.com/p/mp1405-5v-1a-lithium-battery-charging-board-blue-black-219454#.VLRT1MlZqUc
> and used one for re-powering a mini rotary tool I got cheap that used 3x
> small NiCad cells in shrink-wrap, the total size of which was similar to a
> single 18650 but had little 'power' and didn't hold much charge. I bought a
> new solder-tab Panasonic cell for that job as I didn't know how good my
> slavaged cells were and it's hard to open up the modded tool....
>
> However it doesn't seem to like running a motor from the 'out' pads - maybe
> it's something to do with the brushes and how it works? I tried three of
> these PCBs for the job and they all didn't work right. In the end I had to
> wire a small momentary contact switch between the B+ and OUT+ pads to start
> the motor. Once it's started it runs fine from the 'OUT' contacts. <shrug>
>
> As you can probably tell I only have basic knowledge (but try hard to not
> take risks - I'm very aware of the inherant dangers with Li-Ion tech and the
> potential for 'thermal runaway').
>
> Cheers,
>
The website was translated into ChEnglish and doesn't make a lot of sense,
but if I were to guess...

How are you switching the power?

If you're switching between the battery and the board,
that may be your problem.  Sounds like the board has to be powered
up continuously.  I'd measure the drain from the battery in the
off state.  May be inconsequential...maybe not.

If you're switching between the board and the motor, the turn-on transient
from the motor may exceed the 3A current limit.  Maybe a big cap
across the out pads will help.

[toc] | [prev] | [next] | [standalone]

#2314

Once upon a time on usenet mike wrote:
> On 1/12/2015 3:18 PM, ~misfit~ wrote:
>> Once upon a time on usenet mike wrote:
>> [total snip]
>>> Are we having fun yet?
>>
>> Thanks Mike. I've copied that to notepad and saved it for when I
>> have a bit of time to play with.
>>
>> I have a couple of these too
>> http://www.dx.com/p/mp1405-5v-1a-lithium-battery-charging-board-blue-black-219454#.VLRT1MlZqUc
>> and used one for re-powering a mini rotary tool I got cheap that
>> used 3x small NiCad cells in shrink-wrap, the total size of which
>> was similar to a single 18650 but had little 'power' and didn't hold
>> much charge. I bought a new solder-tab Panasonic cell for that job
>> as I didn't know how good my slavaged cells were and it's hard to
>> open up the modded tool.... However it doesn't seem to like running a 
>> motor from the 'out' pads
>> - maybe it's something to do with the brushes and how it works? I
>> tried three of these PCBs for the job and they all didn't work
>> right. In the end I had to wire a small momentary contact switch
>> between the B+ and OUT+ pads to start the motor. Once it's started
>> it runs fine from the 'OUT' contacts. <shrug> As you can probably tell I 
>> only have basic knowledge (but try hard
>> to not take risks - I'm very aware of the inherant dangers with
>> Li-Ion tech and the potential for 'thermal runaway').
>>
> The website was translated into ChEnglish and doesn't make a lot of
> sense, but if I were to guess...

Sadly with that site you *have* to guess a lot (unless there are informed 
feedbacks).

> How are you switching the power?
>
> If you're switching between the battery and the board,
> that may be your problem.  Sounds like the board has to be powered
> up continuously.  I'd measure the drain from the battery in the
> off state.  May be inconsequential...maybe not.

I'm leaving the board and cell connected all the time. There doesn't seem to 
be much in the way of constant drain. I modded it a year ago and have only 
had to charge once in that time (it only gets light use).

> If you're switching between the board and the motor, the turn-on
> transient from the motor may exceed the 3A current limit.  Maybe a
> big cap across the out pads will help.

Hmmm, yes that might indeed be the problem - thanks. (I told you I have only 
basic knowledge of electronics. However I have a cheap rework station that I 
haven't unpacked yet which was delivered today so I better learn more!)

There's not much room in the enclosure for a 'big cap' - or anything else 
for that matter. I dismantled it several times, re-soldering and hot-gluing 
it all in place each time. The last time /was/ the last time - I taped it up 
good (as the plastic threads for the screws weren't made for repeated use 
and stripped quickly). I'll use it as-is now I think but it's good to know 
how to combat this issue if I use one of the other modules.

Silly me; Where it says "charge current 1,000mA max" I took that to mean 
what the board will put into the cell - not what the board would take. I was 
charging my 3,000 A/h cell from a 500mA source and it was taking hours so 
hooked it up to my 2,000mA plugpack. Well, I shouldn't have walked away for 
the ~30 minutes that I did! Seems it was dumping extra current as heat, 
there was hot glue running out of it! I thought that it would just 'take' 
what it could handle from the source? <shrug>

Cheers,
-- 
Shaun.

"Humans will have advanced a long, long, way when religious belief has a 
cozy little classification in the DSM."
David Melville (in r.a.s.f1) 

[toc] | [prev] | [next] | [standalone]

#2315

On 1/14/2015 4:35 PM, ~misfit~ wrote:
> Once upon a time on usenet mike wrote:
>> On 1/12/2015 3:18 PM, ~misfit~ wrote:
>>> Once upon a time on usenet mike wrote:
>>> [total snip]
>>>> Are we having fun yet?
>>>
>>> Thanks Mike. I've copied that to notepad and saved it for when I
>>> have a bit of time to play with.
>>>
>>> I have a couple of these too
>>> http://www.dx.com/p/mp1405-5v-1a-lithium-battery-charging-board-blue-black-219454#.VLRT1MlZqUc
>>> and used one for re-powering a mini rotary tool I got cheap that
>>> used 3x small NiCad cells in shrink-wrap, the total size of which
>>> was similar to a single 18650 but had little 'power' and didn't hold
>>> much charge. I bought a new solder-tab Panasonic cell for that job
>>> as I didn't know how good my slavaged cells were and it's hard to
>>> open up the modded tool.... However it doesn't seem to like running a
>>> motor from the 'out' pads
>>> - maybe it's something to do with the brushes and how it works? I
>>> tried three of these PCBs for the job and they all didn't work
>>> right. In the end I had to wire a small momentary contact switch
>>> between the B+ and OUT+ pads to start the motor. Once it's started
>>> it runs fine from the 'OUT' contacts. <shrug> As you can probably tell I
>>> only have basic knowledge (but try hard
>>> to not take risks - I'm very aware of the inherant dangers with
>>> Li-Ion tech and the potential for 'thermal runaway').
>>>
>> The website was translated into ChEnglish and doesn't make a lot of
>> sense, but if I were to guess...
>
> Sadly with that site you *have* to guess a lot (unless there are informed
> feedbacks).
>
>> How are you switching the power?
>>
>> If you're switching between the battery and the board,
>> that may be your problem.  Sounds like the board has to be powered
>> up continuously.  I'd measure the drain from the battery in the
>> off state.  May be inconsequential...maybe not.
>
> I'm leaving the board and cell connected all the time. There doesn't seem to
> be much in the way of constant drain. I modded it a year ago and have only
> had to charge once in that time (it only gets light use).
>
>> If you're switching between the board and the motor, the turn-on
>> transient from the motor may exceed the 3A current limit.  Maybe a
>> big cap across the out pads will help.
>
> Hmmm, yes that might indeed be the problem - thanks. (I told you I have only
> basic knowledge of electronics. However I have a cheap rework station that I
> haven't unpacked yet which was delivered today so I better learn more!)
>
> There's not much room in the enclosure for a 'big cap' - or anything else
> for that matter. I dismantled it several times, re-soldering and hot-gluing
> it all in place each time. The last time /was/ the last time - I taped it up
> good (as the plastic threads for the screws weren't made for repeated use
> and stripped quickly). I'll use it as-is now I think but it's good to know
> how to combat this issue if I use one of the other modules.
>
> Silly me; Where it says "charge current 1,000mA max" I took that to mean
> what the board will put into the cell - not what the board would take. I was
> charging my 3,000 A/h cell from a 500mA source and it was taking hours so
> hooked it up to my 2,000mA plugpack. Well, I shouldn't have walked away for
> the ~30 minutes that I did! Seems it was dumping extra current as heat,
> there was hot glue running out of it! I thought that it would just 'take'
> what it could handle from the source? <shrug>
>
> Cheers,
>
Not at all clear what happened.  Too many "it" and not enough specificity.

Lithium cells have a specification that defines the absolute maximum
charge termination voltage and the maximum safe charge current.
Also has a low-voltage cutout spec that tells you how far you can 
discharge it without damage.  Two problems with that.  You may not
be able to find a spec for the cell you have in your hand.
And if it's an EBAY cell, the capacity may be seriously exaggerated
and you can't rely on that to estimate what you should do.

Your charge board manages all that.
Typically, the voltage ramps up as the cell charges at the
set max current, but stops ramping
at the terminal voltage, typically 4.2V depending on the exact lithium 
technology.
The current max is set by the charge board and current starts to 
decrease when
the voltage hits 4.2V.  But it will charge until the current drops below
some point determined by the setup of the charge board.

The supply that powers the charge board MUST have enough voltage and current
capacity to run the charge board under all conditions.
Once the source current limits, the voltage to the charge board
drops and you have no idea what it will do.  DO NOT ASSUME
that it does anything safe.  It might, but DON'T trust that it does.

Here's an analogy.  Sit in your easy chair and breathe thru a straw.
It limits your supply.  You will lose control.  On second thought,
sit in the bathtub.  You may lose control of stuff you don't want
in your easy chair.

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#2316

Once upon a time on usenet mike wrote:
> On 1/14/2015 4:35 PM, ~misfit~ wrote:
>> Once upon a time on usenet mike wrote:
>>> On 1/12/2015 3:18 PM, ~misfit~ wrote:
>>>> Once upon a time on usenet mike wrote:
>>>> [total snip]
>>>>> Are we having fun yet?
>>>>
>>>> Thanks Mike. I've copied that to notepad and saved it for when I
>>>> have a bit of time to play with.
>>>>
>>>> I have a couple of these too
>>>> http://www.dx.com/p/mp1405-5v-1a-lithium-battery-charging-board-blue-black-219454#.VLRT1MlZqUc
>>>> and used one for re-powering a mini rotary tool I got cheap that
>>>> used 3x small NiCad cells in shrink-wrap, the total size of which
>>>> was similar to a single 18650 but had little 'power' and didn't
>>>> hold much charge. I bought a new solder-tab Panasonic cell for
>>>> that job as I didn't know how good my slavaged cells were and it's hard 
>>>> to
>>>> open up the modded tool.... However it doesn't seem to like
>>>> running a motor from the 'out' pads
>>>> - maybe it's something to do with the brushes and how it works? I
>>>> tried three of these PCBs for the job and they all didn't work
>>>> right. In the end I had to wire a small momentary contact switch
>>>> between the B+ and OUT+ pads to start the motor. Once it's started
>>>> it runs fine from the 'OUT' contacts. <shrug> As you can probably
>>>> tell I only have basic knowledge (but try hard
>>>> to not take risks - I'm very aware of the inherant dangers with
>>>> Li-Ion tech and the potential for 'thermal runaway').
>>>>
>>> The website was translated into ChEnglish and doesn't make a lot of
>>> sense, but if I were to guess...
>>
>> Sadly with that site you *have* to guess a lot (unless there are
>> informed feedbacks).
>>
>>> How are you switching the power?
>>>
>>> If you're switching between the battery and the board,
>>> that may be your problem.  Sounds like the board has to be powered
>>> up continuously.  I'd measure the drain from the battery in the
>>> off state.  May be inconsequential...maybe not.
>>
>> I'm leaving the board and cell connected all the time. There doesn't
>> seem to be much in the way of constant drain. I modded it a year ago
>> and have only had to charge once in that time (it only gets light
>> use).
>>> If you're switching between the board and the motor, the turn-on
>>> transient from the motor may exceed the 3A current limit.  Maybe a
>>> big cap across the out pads will help.
>>
>> Hmmm, yes that might indeed be the problem - thanks. (I told you I
>> have only basic knowledge of electronics. However I have a cheap
>> rework station that I haven't unpacked yet which was delivered today
>> so I better learn more!) There's not much room in the enclosure for a 
>> 'big cap' - or anything
>> else for that matter. I dismantled it several times, re-soldering
>> and hot-gluing it all in place each time. The last time /was/ the
>> last time - I taped it up good (as the plastic threads for the
>> screws weren't made for repeated use and stripped quickly). I'll use
>> it as-is now I think but it's good to know how to combat this issue
>> if I use one of the other modules. Silly me; Where it says "charge 
>> current 1,000mA max" I took that to
>> mean what the board will put into the cell - not what the board
>> would take. I was charging my 3,000 A/h cell from a 500mA source and
>> it was taking hours so hooked it up to my 2,000mA plugpack. Well, I
>> shouldn't have walked away for the ~30 minutes that I did! Seems it
>> was dumping extra current as heat, there was hot glue running out of
>> it! I thought that it would just 'take' what it could handle from
>> the source? <shrug> Cheers,
>>
> Not at all clear what happened.  Too many "it" and not enough
> specificity.

The "it" was referring to the charging module - you prompted me to check the 
specs when you mentioned 3 amps.

> Lithium cells have a specification that defines the absolute maximum
> charge termination voltage and the maximum safe charge current.
> Also has a low-voltage cutout spec that tells you how far you can
> discharge it without damage.  Two problems with that.  You may not
> be able to find a spec for the cell you have in your hand.
> And if it's an EBAY cell, the capacity may be seriously exaggerated
> and you can't rely on that to estimate what you should do.

This cell in question is from a legit seller local to me and is genuine 
Panasonic.

> Your charge board manages all that.
> Typically, the voltage ramps up as the cell charges at the
> set max current, but stops ramping
> at the terminal voltage, typically 4.2V depending on the exact lithium
> technology.
> The current max is set by the charge board and current starts to
> decrease when
> the voltage hits 4.2V.  But it will charge until the current drops
> below some point determined by the setup of the charge board.
>
> The supply that powers the charge board MUST have enough voltage and
> current capacity to run the charge board under all conditions.
> Once the source current limits, the voltage to the charge board
> drops and you have no idea what it will do.  DO NOT ASSUME
> that it does anything safe.  It might, but DON'T trust that it does.

This is my whole point. I was using a USB plug-pack PSU capable of 2A yet 
the specs for the charge board says, as above, "charge current 1,000mA max". 
That's when the thing got so hot it melted hot glue used to hold it in 
place. Very inelegant. I've used the same PSU for low-drain devices and they 
work fine, no excess heat anywhere so it wasn't the fault of the PSU.

> Here's an analogy.  Sit in your easy chair and breathe thru a straw.
> It limits your supply.  You will lose control.  On second thought,
> sit in the bathtub.  You may lose control of stuff you don't want
> in your easy chair.

I haven't been able to get into the bathtub for years (well, out of it 
actually), since my back got so much worse. I even need a plastic stool in 
the shower as I can't stand long enough to wash properly....

..... but I get your analogy. I said I'm a little challenged w/r/t 
electronics. I didn't say I had an IQ less than 80. (Actually I used to me a 
member of Mensa until I couldn't keep up the membership fees due to my 
injury and loss of income / life savings.)

Thanks,
-- 
Shaun.

"Humans will have advanced a long, long, way when religious belief has a 
cozy little classification in the DSM."
David Melville (in r.a.s.f1) 

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#2320

Once upon a time on usenet mike wrote:
> On 1/12/2015 3:18 PM, ~misfit~ wrote:
>> Once upon a time on usenet mike wrote:
>> [total snip]
>>> Are we having fun yet?
>>
>> Thanks Mike. I've copied that to notepad and saved it for when I
>> have a bit of time to play with.
>>
>> I have a couple of these too
>> http://www.dx.com/p/mp1405-5v-1a-lithium-battery-charging-board-blue-black-219454#.VLRT1MlZqUc
>> and used one for re-powering a mini rotary tool I got cheap that
>> used 3x small NiCad cells in shrink-wrap, the total size of which
>> was similar to a single 18650 but had little 'power' and didn't hold
>> much charge. I bought a new solder-tab Panasonic cell for that job
>> as I didn't know how good my slavaged cells were and it's hard to
>> open up the modded tool.... However it doesn't seem to like running a 
>> motor from the 'out' pads
>> - maybe it's something to do with the brushes and how it works? I
>> tried three of these PCBs for the job and they all didn't work
>> right. In the end I had to wire a small momentary contact switch
>> between the B+ and OUT+ pads to start the motor. Once it's started
>> it runs fine from the 'OUT' contacts. <shrug> As you can probably tell I 
>> only have basic knowledge (but try hard
>> to not take risks - I'm very aware of the inherant dangers with
>> Li-Ion tech and the potential for 'thermal runaway').
>>
>> Cheers,
>>
> The website was translated into ChEnglish and doesn't make a lot of
> sense, but if I were to guess...
>
> How are you switching the power?
>
> If you're switching between the battery and the board,
> that may be your problem.  Sounds like the board has to be powered
> up continuously.  I'd measure the drain from the battery in the
> off state.  May be inconsequential...maybe not.
>
> If you're switching between the board and the motor, the turn-on
> transient from the motor may exceed the 3A current limit.  Maybe a
> big cap across the out pads will help.

Mike, quick question as I'm going to use another of these modules for 
controlled discharge of Li-Ion cells using a motor as a load... What value 
do you mean when you say 'a big cap'?

Cheers,
-- 
Shaun.

"Humans will have advanced a long, long, way when religious belief has a 
cozy little classification in the DSM."
David Melville (in r.a.s.f1) 

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#2321

On 2/7/2015 5:24 PM, ~misfit~ wrote:
> Once upon a time on usenet mike wrote:
>> On 1/12/2015 3:18 PM, ~misfit~ wrote:
>>> Once upon a time on usenet mike wrote:
>>> [total snip]
>>>> Are we having fun yet?
>>>
>>> Thanks Mike. I've copied that to notepad and saved it for when I
>>> have a bit of time to play with.
>>>
>>> I have a couple of these too
>>> http://www.dx.com/p/mp1405-5v-1a-lithium-battery-charging-board-blue-black-219454#.VLRT1MlZqUc
>>> and used one for re-powering a mini rotary tool I got cheap that
>>> used 3x small NiCad cells in shrink-wrap, the total size of which
>>> was similar to a single 18650 but had little 'power' and didn't hold
>>> much charge. I bought a new solder-tab Panasonic cell for that job
>>> as I didn't know how good my slavaged cells were and it's hard to
>>> open up the modded tool.... However it doesn't seem to like running a
>>> motor from the 'out' pads
>>> - maybe it's something to do with the brushes and how it works? I
>>> tried three of these PCBs for the job and they all didn't work
>>> right. In the end I had to wire a small momentary contact switch
>>> between the B+ and OUT+ pads to start the motor. Once it's started
>>> it runs fine from the 'OUT' contacts. <shrug> As you can probably tell I
>>> only have basic knowledge (but try hard
>>> to not take risks - I'm very aware of the inherant dangers with
>>> Li-Ion tech and the potential for 'thermal runaway').
>>>
>>> Cheers,
>>>
>> The website was translated into ChEnglish and doesn't make a lot of
>> sense, but if I were to guess...
>>
>> How are you switching the power?
>>
>> If you're switching between the battery and the board,
>> that may be your problem.  Sounds like the board has to be powered
>> up continuously.  I'd measure the drain from the battery in the
>> off state.  May be inconsequential...maybe not.
>>
>> If you're switching between the board and the motor, the turn-on
>> transient from the motor may exceed the 3A current limit.  Maybe a
>> big cap across the out pads will help.
>
> Mike, quick question as I'm going to use another of these modules for
> controlled discharge of Li-Ion cells using a motor as a load... What value
> do you mean when you say 'a big cap'?
>
> Cheers,
>
That's not a simple question.  Motor load is complex. I have no idea
how the control board works.
The spec alludes to a 3 amp protection limit.  If your motor starting
current exceeds 3A, you need to limit that somehow.  A cap can help,
but it might take a very big one.  I'd start with 100uF and experiment 
from there.  But a cap won't help for a constant load like locked rotor.

The board says 3A Protection.  It's designed for a Maximum of 1A load.
You can be sure if it would survive much over that, the spec would be 
higher.  Monitor the FET temperature to see if it will melt off the board.

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#2322

Once upon a time on usenet mike wrote:
> On 2/7/2015 5:24 PM, ~misfit~ wrote:
>> Once upon a time on usenet mike wrote:
>>> On 1/12/2015 3:18 PM, ~misfit~ wrote:
>>>> Once upon a time on usenet mike wrote:
>>>> [total snip]
>>>>> Are we having fun yet?
>>>>
>>>> Thanks Mike. I've copied that to notepad and saved it for when I
>>>> have a bit of time to play with.
>>>>
>>>> I have a couple of these too
>>>> http://www.dx.com/p/mp1405-5v-1a-lithium-battery-charging-board-blue-black-219454#.VLRT1MlZqUc
>>>> and used one for re-powering a mini rotary tool I got cheap that
>>>> used 3x small NiCad cells in shrink-wrap, the total size of which
>>>> was similar to a single 18650 but had little 'power' and didn't
>>>> hold much charge. I bought a new solder-tab Panasonic cell for
>>>> that job as I didn't know how good my slavaged cells were and it's hard 
>>>> to
>>>> open up the modded tool.... However it doesn't seem to like
>>>> running a motor from the 'out' pads
>>>> - maybe it's something to do with the brushes and how it works? I
>>>> tried three of these PCBs for the job and they all didn't work
>>>> right. In the end I had to wire a small momentary contact switch
>>>> between the B+ and OUT+ pads to start the motor. Once it's started
>>>> it runs fine from the 'OUT' contacts. <shrug> As you can probably
>>>> tell I only have basic knowledge (but try hard
>>>> to not take risks - I'm very aware of the inherant dangers with
>>>> Li-Ion tech and the potential for 'thermal runaway').
>>>>
>>>> Cheers,
>>>>
>>> The website was translated into ChEnglish and doesn't make a lot of
>>> sense, but if I were to guess...
>>>
>>> How are you switching the power?
>>>
>>> If you're switching between the battery and the board,
>>> that may be your problem.  Sounds like the board has to be powered
>>> up continuously.  I'd measure the drain from the battery in the
>>> off state.  May be inconsequential...maybe not.
>>>
>>> If you're switching between the board and the motor, the turn-on
>>> transient from the motor may exceed the 3A current limit.  Maybe a
>>> big cap across the out pads will help.
>>
>> Mike, quick question as I'm going to use another of these modules for
>> controlled discharge of Li-Ion cells using a motor as a load... What
>> value do you mean when you say 'a big cap'?
>>
>> Cheers,
>>
> That's not a simple question.  Motor load is complex. I have no idea
> how the control board works.
> The spec alludes to a 3 amp protection limit.  If your motor starting
> current exceeds 3A, you need to limit that somehow.  A cap can help,
> but it might take a very big one.  I'd start with 100uF and experiment
> from there.  But a cap won't help for a constant load like locked
> rotor.

Thanks again. I really appreciate your input.

> The board says 3A Protection.  It's designed for a Maximum of 1A load.
> You can be sure if it would survive much over that, the spec would be
> higher.  Monitor the FET temperature to see if it will melt off the
> board.

That's what I have an infrared thermometer for. ;)  Well, that and to see if 
my LEDs are running at acceptable temps.

I just dismantled a completely dead Dell nine cell battery pack. It came 
with a laptop that I reburbished and sold on a couple of years ago. The 
laptop wouldn't have a bar of it, said battery dead and needs replacement. 
When dismantled I saw it was wired 3s/3p and three of the cells have 0.00v 
charge and simply won't take a charge no matter what I try - they just get 
hot.

However the other six (Samsung 18650-26 cells, 2,600 mA/h) seem great. They 
were sitting at 3.2v when the pack was dismantled and they came up really 
quickly in the charger. There's lots and lots of capacity left in all of 
them - a really good score. If I had to guess I'd say that the pack had been 
left in storage in a discharged state for some time and the pack contol 
circuitry took it's power from just that group of three cells. When it 
completely drained those it flagged the pack as dead.

Oh, I upgraded my charger to a Nitecore D2. Now I have a reasonable 
collection of usable Li-Ion cells it seemed like a good investment.

Cheers,
-- 
Shaun.

"Humans will have advanced a long, long, way when religious belief has a 
cozy little classification in the DSM."
David Melville (in r.a.s.f1) 

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#2295

Once upon a time on usenet mike wrote:
> On 1/2/2015 9:34 AM, andymhancock@gmail.com wrote:
>> Mike, your last post was entertaining.  As I said, though, I'm not
>> as passionate about it as to make it a hobby.  I'm OK with the gross
>> guidelines of discharging to 5% once a month.  I appreciate the
>> rationale behind those guidelines as much as I appreciate the
>> guidelines (which are not trustworthy without rationale).  Most of
>> the time, I'm on AC, and the battery is only a UPS.  If it goes,
>> I'll buy another (accepting the risk that it might have been on the
>> shelf since the turn of the century).  I'll just complain to the
>> vendor if it's crappy, and if they play hardball, I'll complain in
>> public.  I know it will not make it above noise level because so
>> many people do that anyway, but I am riding the technology
>> improvement trend that is driven by capitalism.  Batteries today are
>> heads and shoulders better than a decades ago...except to
>> enthusiasts who intend to crack them open to extend their lives. More 
>> power to you if you do, though.
> Consensus seems to be that you should take the battery out if using it
> on AC.
> Assuming the design of the charger stops charging when it gets to max,
> there's still the issue of heat.
> I use mine little, so just leave the battery in on AC all the time.
> If I used it a lot, I'd take out the battery.

The problem with that is there are some laptops that refuse to ramp the CPU 
up to full speed if there is no battery fitted - even on AC. The rationale 
being that it acts as an energy buffer, helping to supply high ampage bursts 
that would stress the power brick....

> I had more than one laptop where the battery sits two plastic
> thicknesses away from the processor heat sink.
> When you take the case off the battery, the ones closest to the
> heat are discolored...and much higher resistance than the others.
> Some designer oughtabeshot.

Or paid a bonus when sales of batteries increase. ;)

> It's been said that lithium cells degrade almost as fast on the shelf
> as if you use 'em sensibly.  A spare battery is great if you need to
> use it.  If it's sittin on the shelf justincase, it may not be a good
> investment.  Still might be better sittin' in your fridge than
> having it sittin' in that container
> in Arizona till you buy it. ;-)

That's my philosophy. I'm happy with my T60s (the last IBM designed 
ThinkPads) and can't see me needing to change for years to come <touch 
wood>. However as they get older battery packs will get harder to come by / 
more expensive so I grabbed a couple when I could and store them in ideal 
conditions / state of charge.

Incidently my T60s software will tell me a batterys date of manufacture, 
cell manufacturer (although I'm sure this can be fudged by after-market 
suppliers), date first used and number of cycles since new. Also it tells me 
the obvious things like design capacity and current capacity. (Battery 
currently fitted (my 'lazarus' battery); Manufacturer Sanyo. Manufacture 
Date 2008-12-04. First Used Date 2009-02. Design Capacity 56.16 W/h. 
Remaining Capacity 23.2 W/h.)

All after-market battery packs are rebuilt OEM units using original 
(reprogrammed) electronics - or at least they were last I heard.

Instead of stocking up on a couple batterys I was going to just re-pack them 
with panasonic 18650s but you pointed out some of the issues with that. With 
these batteries you can also include the fact that you need to supply the 
packs electronics with ~8v from a bench power supply while you have the 
cells disconnected. If you don't the battery CPU decides the pack has 
dropped below threshold and 'bricks' it (while running on a reserve 
capacitor). Then the laptop won't complete handshake with the battery pack 
CPU on boot up so will report no battery present.

Cheers,
-- 
Shaun.

"Humans will have advanced a long, long, way when religious belief has a 
cozy little classification in the DSM."
David Melville (in r.a.s.f1) 

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