Thread: Jupmstarting 18650's

I've got some rechargeable clippers that have a dead 18650 battery, I got some new cheap rechargeable batteries but they are so flat that they won't accept a charge. Is there any way to hotwire/jumpstart them so they will charge ?

would e time to upgrade house insurance before charging
just go get some decent new cells, lithium fires are fu..ing brutal

Originally Posted by gonetropo

would e time to upgrade house insurance before charging
just go get some decent new cells, lithium fires are fu..ing brutal

Second that comment.....Been there done that got the tee shirt ( and visit from the local fireys, new carpet , new drapes, painted the roof ....) And we were lucky we were home at the time....

@Night_Into_Day might have something suitable
https://www.piercingthedarkness.co.nz/

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I got 2 new cells but they won't start charging, my thought was that they are too flat to register (or something like that) so was thinking if I linked in the old 1 just to start the charging process. I was going to do that with an extension lead out on the driveway, sounds like I wasn't just been paranoid about the risk.

Thanks everyone, forewarned is forearmed

Yeah if they are the "protected" type of 18650 they have a circuit on the top that shuts the cell off over something like 4.25v or less than 3.3v from memory. Over the max, the cell will still discharge OK but will no longer charge. Under the voltage, the cell appears dead (0v on test) and the protection circuit for some reason isn't allowing the charge current to enter the cell like it should.

Jumpstarting refers to deliberately overvoltaging the cell (for an 18650 most often with a 12v battery across the 18650's terminals). What the theory is, is to get the voltage up over the lower cut off voltage to get the protection circuit to function and allow the cell to accept a charge as normal. With a 12v battery, doing the crash is not a huge time of contacting the battery - a few seconds is most likely all it will take to get the cell voltage up over the lower limit of the cell's protection circuit. Having said this, I've done this a few times as a pure experimental thing with cells out of second hand gear (I don't get that many second hand protected cells) and I've been successful only twice - every other time it has worked the cell has been way down in capacity after the 'crash'.

This idea about overvoltaging a defective cell is not applicable to cells that don't have a protection circuit, once they're dead they're dead. Also, as you aren't hooking a dead cell to a power supply (taping wires to the contacts of the 18650, putting a board of wood on the cell on concrete outside and then using the wires to contact the 12v battery for a few seconds at a time checking the voltage between is all it takes) the process is unlikely to create a boom. If you try it though you take your own risks haha. As I said I haven't found it to be worthwhile, once the protection circuits do that they do it for a reason...

Originally Posted by No good names left

I got 2 new cells but they won't start charging

What cells did you buy? I can't imagine any quality brand would have two arrive in that condition.

Only buy from well know brands otherwise you're risking your safety. Buy a DMM, they're handy to have on hand.

All cells can do it, I've had to Panasonic 3600mA protected cells arrive in the dead state never to be resurrected again. Replaced no questions asked, and on opening up they appeared fully legit just absolutely zero volts across the cell when measuring without the protection circuit on the bum in the way. The -ve casing was correctly marked and the inner poo and plate looked legit to me, but who knows?

Originally Posted by Night_Into_Day

What cells did you buy? I can't imagine any quality brand would have two arrive in that condition.

Only buy from well know brands otherwise you're risking your safety. Buy a DMM, they're handy to have on hand.

i use a dmm all day every day, nothing beats an analog meter for testing batteries and semi conductors
general use is klein/fluke but go to is the good old avo circa 1960ish and the jaycar $40 special

Originally Posted by No.3

All cells can do it, I've had to Panasonic 3600mA protected cells arrive in the dead state never to be resurrected again. Replaced no questions asked, and on opening up they appeared fully legit just absolutely zero volts across the cell when measuring without the protection circuit on the bum in the way. The casing was correctly marked and the inner poo and plate looked legit to me, but who knows?

Protected cells are entirely different because often the PCB is the cause with high parasitic drain. I've imported thousands of unprotected cells from Sony, LG, Panasonic, Sanyo, and Samsung over the years and never have I received a discharged cell. I have one of the best quality control checks in the world, everything is tested upon arrival and then again before shipping to a customer. I even purchased a professional Computerized Battery Analyzer to confirm authenticity of all cells I import. Customer safety is extremely important to me.

Originally Posted by Night_Into_Day

What cells did you buy? I can't imagine any quality brand would have two arrive in that condition.

Only buy from well know brands otherwise you're risking your safety. Buy a DMM, they're handy to have on hand.

They were just a cheap brand so I did end up having to buy something better, they held enough charge to work when I charged them.
Thanks to everyone that offered advice & possibly stopped me from blowing up myself

I have quite a few used 18650 LH 2100mA I won’t be using. They are all tested and charged for storage. I’m in Auckland this weekend happy to drop a few in the mailbox.

Thanks so much tibo.
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Originally Posted by Night_Into_Day

Protected cells are entirely different because often the PCB is the cause with high parasitic drain. I've imported thousands of unprotected cells from Sony, LG, Panasonic, Sanyo, and Samsung over the years and never have I received a discharged cell. I have one of the best quality control checks in the world, everything is tested upon arrival and then again before shipping to a customer. I even purchased a professional Computerized Battery Analyzer to confirm authenticity of all cells I import. Customer safety is extremely important to me.

Yep, correct - the unprotected cells (aka scavenged cells out of laptops etc) are not the usual culprits for the zero voltage gig unless they are coosed. Interesting how many packed battery units I've been into that the BMS is crook in, weak point in the system...