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-   -   18650 battery pack diagnosis. (https://www.diyaudio.com/forums/everything-else/338650-18650-battery-pack-diagnosis.html)

 redrooster 2nd June 2019 04:15 AM

18650 battery pack diagnosis.

I have a 7.40v, 18650 x 2 battery pack from an RC helicopter that has been laying around for a few years it reads 7.46v but only 0.03ma? Is there any hope of fixing this or is it a bin job? Whats the diagnosis Doc, is my little friend dead?:D

 thaumaturge 2nd June 2019 04:42 AM

Depends... sitting that long you may have to "prime it". No joke, this works if anything does. Need to get access to individual cells. Can probably just stick dressmakers pin through shrink wrapping to access center point. Then take a fully charged 18650 and hook it paralell to each cell for about 10 seconds. Each! Positive to positive, negative to negative. Do not hook up backwards! Do not leave hooked together for longer. Put on charger after priming. Then check it again. Report your results.

Doc (Thus I assumed you were asking me...).

 redrooster 2nd June 2019 08:48 AM

What do you mean by center point? Is that the positive and negative of the batteries?

 thaumaturge 2nd June 2019 09:42 AM

7,2v = 3.6 x 2 in series. That means cells are connected together in middle, the positive of one cell connected to negative of other. 7.2 volts will actually be a minimum voltage. Full chare on each cell is 4.3 volts making possible max voltage of 8.6 volts. So to prime cell that has negative connected to output wire, you must connect a positive lead where two celks are connected together. Like so

Minus wire of pack--------| |++++X--------| |++++++ plus wire of pack The X in middle is center point.

Doc

 Refugee1 2nd June 2019 01:27 PM

I had a flat pack single cell camera battery that went like that.
I set my bench power supply to about 4.5 volts and turned the current limit down to about 100ma and dabbed it on for a couple of seconds.
It then triggered the charger and took a full charge.
Good battery chargers test the battery before starting to charge it.

 redrooster 2nd June 2019 05:26 PM

Quote:
 Originally Posted by Refugee1 (https://www.diyaudio.com/forums/everything-else/338650-18650-battery-pack-diagnosis-post5810170.html#post5810170) I had a flat pack single cell camera battery that went like that. I set my bench power supply to about 4.5 volts and turned the current limit down to about 100ma and dabbed it on for a couple of seconds. It then triggered the charger and took a full charge. Good battery chargers test the battery before starting to charge it.
This battery has a 3 wire input, red, black and white. The output is 2 wires red and black. So I take it I will zap it through the input red and black wires to be sure?:D

 Refugee1 2nd June 2019 05:42 PM

Some cells even single ones have a FET inside them that shuts the output off if they become discharged that can also cut off the charging voltage at the end of charging like an electronic cigarette.

 redrooster 2nd June 2019 05:51 PM

Quote:
 Originally Posted by Refugee1 (https://www.diyaudio.com/forums/everything-else/338650-18650-battery-pack-diagnosis-post5810405.html#post5810405) Some cells even single ones have a FET inside them that shuts the output off if they become discharged that can also cut off the charging voltage at the end of charging like an electronic cigarette.
I've got it charging now, I zapped it through the inputs with a 9v battery for about 2 seconds then tried it in the charger and the red light flickered (it didn't do that before?) so I checked to see if it was charging with a DMM and it is charging at 8.46v. Thanks for the info fellas it saved this battery from a landfill. :D

 sq225917 2nd June 2019 06:43 PM

Same works for gopro batteries they're notorious for over discharging

 redrooster 5th October 2019 05:24 PM

1 Attachment(s)
Now I've got a vape that consists of 2 x 18650 batteries, it won't charge but I can't figure out how to kick start it? The anode is pushed down to make the connection when the top is screwed onto the batteries. I've pushed down with the positive probe of my Multimeter and grounded the black probe to the edge of the hole with no results? Any ideas on how would I get around this one?

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