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Small Cabin Forum / Off-Grid Living / LI tool battery recovery
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paulz
Member
# Posted: 7 Feb 2024 11:35 - Edited by: paulz
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The battery that powers both my chainsaw and leaf bower, my two most used stuff lately, went dead. Weird, don’t know why, been reliable for a few years. Put it on the charger, nothing, charger won’t even light the charge light or start the fan. No lights on battery, always stops the tool when it gets down to two lights.

Put a VOM on it, zero volts. Hmm, maybe it finally bit it. In desperation (I have a ton of branches to hack) I jumpered two car bats in series to it (it’s an 80v bat) for a few minutes, then shoved it in the charger. Vroom, charge light and fan! An hour later I was at full charge! That was last night, still full charge and tools running today. Yahoo, so far. Still clueless as to what happened. Maybe left it in a tool running? Would have heard that. Never under 40f here.
IMG_2159.jpeg
IMG_2159.jpeg


FishHog
Member
# Posted: 7 Feb 2024 11:40
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Some batteries can go into a sleep mode once charge gets too low and require a wake up charge to get them going. Glad you got them working again

Brettny
Member
# Posted: 7 Feb 2024 16:26
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I would take it appart and check the cells or for any type of fuse.

gcrank1
Member
# Posted: 7 Feb 2024 16:32
Reply 


Sounds like the BMS shut it down when the voltage dropped to the Low Voltage Cutoff.
Wonder how many folks just buy a new battery and junk the old one......

909
Member
# Posted: 7 Feb 2024 20:45 - Edited by: 909
Reply 


As cells age, they "get tired", slowly self discharge, and just won't hold as much charge.

Congrats on the jump start.

paulz
Member
# Posted: 8 Feb 2024 10:24 - Edited by: paulz
Reply 


Thanks guys. So yesterday I cut firewood, ran the bat down to when the saw stopped running, still 2 lights, charged back up and repeat. Seems to run and last as well as before. This morning it still has the two lights. I will monitor before charging again, no time to cut today. Maybe it is wearing down, had a lot of use. Not like buying new ones at the dollar store.

gcrank1
Member
# Posted: 8 Feb 2024 11:21
Reply 


That's the way I do it with cordless tools. Eventually they don't run more than a few min. or don't have enough beans to do their job, then its pay if ya wanna play.

paulz
Member
# Posted: 14 Feb 2024 17:16 - Edited by: paulz
Reply 


Well I got a few days chainsaw work, but finally bit the big one and bought a new battery. The old one, oddly, still shows 3 lights, measure close to 80v with a VOm, but will run the saw for about3 seconds and shuts off. Plug it in the charger and the red (fault) light goes on with a click, no charging.

So I did what any red blooded American man would do: took it apart. Surprised to see 18650s. I don’t see a ‘flip this switch’ sign anywhere and it looks kinda complicate. Oh well, it did me good for lots of work.
IMG_2192.jpeg
IMG_2192.jpeg


FishHog
Member
# Posted: 14 Feb 2024 18:26
Reply 


like Lead batteries, they can charge up to voltage, but fail load test very quickly. Likely one bad cell in that battery, usually the rest are fine.

909
Member
# Posted: 14 Feb 2024 20:07
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I agree. Usually just 1 bad cell. Manufacturers make it so hard to tear the pack apart, you basically have to destroy it to get access.

paulz
Member
# Posted: 15 Feb 2024 10:40
Reply 


Well the thought of just replacing one cell got me excited, would make a great spare battery, but you’re right, they are covered in special screw heads, glue, solder.. no plug and play access there.

909
Member
# Posted: 15 Feb 2024 10:49
Reply 


Yes. Just so they can overcharge us hundreds of dollars for cells that cost tens.

paulz
Member
# Posted: 18 Feb 2024 18:26 - Edited by: paulz
Reply 


On another note, I recently bought two new batteries for my old B&D saws. $25 a pair, brand new, delivered! They aren’t Li though, rather MIMH old tech. Much shorter on grunt but doing the job for me. I’m shorter on grunt myself these days anyway.
IMG_2211.jpeg
IMG_2211.jpeg


darz5150
Member
# Posted: 18 Feb 2024 20:11
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I recently bought one of those little 6 inch chainsaws, that I figured would be slightly better than useless. But it turns out, its really very handy. I used it for about an hour the other day clearing some face slapping branches off the trails and some other misc. crap laying around. Worked better than a recip saw. I cut a landscape timber in about 20/30 seconds no prob.
IMG_20240218_1858512.jpg
IMG_20240218_1858512.jpg


gcrank1
Member
# Posted: 18 Feb 2024 23:31
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I was looking at those with that style handle thinking it would work better for me than some of the other designs.

paulz
Member
# Posted: 19 Feb 2024 07:53
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Yeah that's a nice unit, especially for branches as mentioned.

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