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Charging Lithium Battery Pack without Charger

kageni

Feb 25, 2022
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Feb 25, 2022
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It is right for you to continue charging it, but reduce the current slightly for the pack to charge normally. continue charging untill the amps drop to 200mA. if you have a chargometer the percentage will be around 80-90% am currently using a TT bench voltage regulator on laptop batteries even my current smartphone untill i repair its charging port.
 

whiteoutage

Jul 20, 2017
101
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Jul 20, 2017
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101
It is right for you to continue charging it, but reduce the current slightly for the pack to charge normally. continue charging untill the amps drop to 200mA. if you have a chargometer the percentage will be around 80-90% am currently using a TT bench voltage regulator on laptop batteries even my current smartphone untill i repair its charging port.
Yes, I also recently read on BAT specs somewhere that amps should be no more than .5A. so will try to keep below. Without proper equipment I limit current with car lamp(s) {dome's bright/dim, series, etc.}. However, read elsewhere Max amperage can be 1A so go figure. If I recall my charging correctly, it started out at about 1A and after maybe 15 minutes was in .5A range. None of BATs ever even got warm. Still, do think maybe best to keep below .5A?
Also read somewhere to stop charging at 5% of capacity or about 100mA so from no on I will now stop charging earlier.
Thank you!
 

whiteoutage

Jul 20, 2017
101
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Update - cut a foot of 1/4" plywood. Fully charged pack of 20V dropped .5V. Not a real load test but good enough for now. Perfect cut and not as noisy as I thought it would be - will be good for small projects for sure.

Have not used BAT pack in 2 weeks and still has the same 19.4V. I did a better load test of pack today, cutting eight strips of 1x8 pine before the pack quit. What happened, I'm guessing is the pack's low voltage protection kicked in at 17.5V or 3.5V/bat average, the recommended low end of discharge, I think. Pack's voltage of 17.3 immediately after test may confirm this theory.
Still don't know what capacity the pack has, maybe 50% as a wild guess. Still, I am happy with the results, and glad to have found a cheap battery to power my old 14.4V ni/cd DC panel saw. Panel saws are maybe best for cutting 1/8-1/4 thick panels and I was cutting 1" thick pine and the saw never bogged down. Suspect a 2x4 would be a different story but may give it a try next time. Again, the carbide tipped blade that came with saw is very thin, at least compared to what I have used in the past on a table saw or an AC portable circular saw.
 
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whiteoutage

Jul 20, 2017
101
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Jul 20, 2017
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I did a better load test of pack today, cutting eight strips of 1x8 pine before the pack quit. What happened, I'm guessing is the pack's low voltage protection kicked in at 17.5V or 3.5V/bat average of five batteries, the recommended low end of discharge, I think. Pack's voltage of 17.3 immediately after test may confirm this theory.

While watching one of bigclivdotcom's youtube videos I heard that lithium batteries high end voltage is about 4V and low end is about 3V - so discharge protection should be kicking in at about 3V, but my batteries are quitting at about 3.5V average. Guessing the control circuit thinks there are ten cells not five, thus shutting down my pack prematurely. Can anyone think of a way to trick the pack into not cutting out at current 17.5V, but properly at 15V using current configuration of five cells?
 

whiteoutage

Jul 20, 2017
101
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Jul 20, 2017
Messages
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My previous question may not have been grammatically or logically clear. For those playing along, probably no one at this point, I have converted with some success, an 18V 10 battery pack to a 5 battery 18V pack while keeping the PAK's existing circuitry. Still getting full amperage/voltage output, but longevity is of course reduced. Pack's longevity is further hampered because the protection circuity, specifically low-voltage battery protection is incorrectly kicking in too early - when the PAK's total voltage is at 17.5, rather than at 15V (or 3V * 5 Bats) - probably because of 5 BAT mod.
My pea brain is thinking just to short or bypass the low voltage protection circuit, then just take battery pack voltage measurements once in awhile so batteries don't get too low. Here is a better picture of the circuit board. Unfortunately, the battery clips and large fuse hide most of the middle of the board including the 20 pin IC brain (which you can just barely see (10 pins protruding from under the large 30A fuse/red jumper). Also, as Edd previously mentioned, there are two heatsinked mosfets under the board. Of course, the circuity has other functions too, like balance charging each battery, and who know what else (certainly not me). So hacking or reverse engineering this board to prevent my PAK from dying so soon/charging so often, may not be the way to go, at least for me. Maybe an alternative solution would be to replace existing circuit with a simpler circuit that just balance charges the batteries - maybe something like Edd originally proposed to charge a battery(s)- penny for "The Gang's" thoughts?
Alternatives:
1.bypass low voltage protect circuity
2.modify low volt circuit to kick in at 15V, not 17.5V
3.start new - ommit low voltage circuit, replace charging circuit
4.?
 

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whiteoutage

Jul 20, 2017
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Oh well, the pack's mysterious cut-out voltage at 17.5V is now a feature I dub "SUPERMAX under-voltage protection".
 
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