Dead LI-ION Battery

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Andrew_Trayfoot

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I was given a 'dead' LI-ION battery by a friend.
It is 48v 2OAh.

It was reading about 12v

I worked out what the primary issue was pretty quickly:

Both the wires inside the charging lead had parted..
So I though, this easy: I shortened the charging lead re soldered the plug and stuck it on charge..
Two days later it was reading 15.7v, so was a bigger issue.

I then cut open the pack and pulled out the cells.

It has 12 sets of 9 cells
12 in series of 9 in parallel

Voltage readings are:


1. 2.85v
2. 2.68v
3. 2.66v
4. 2.56 v
5. 2.59v
6. 0.68v
7. 0.61v
8. 2.52v
9. 2.53v
10. 2.26v
11. 0.71v
12. 2.71v

So as luck would have it, I only actually want a 36v battery to power my DIY Electric outboard: Homemade Electric Outboard

My plan is to remove sets 6, 7, and 11 which should give me a 36v battery and then replace the 48v change controller with this 36v one that looks identical to the existing one:

https://www.amazon.co.uk/Battery-Pr...ocphy=1006680&hvtargid=pla-952000409935&psc=1

Any thoughts?

Andrew
 
It can work. Not uncommon for us modellers to remove / add cells in a pack. The problem usually though is the connecting of cells as they are 'hard soldered or Spot welded' ... soft solder often fails to 'take' ....

You will need to be extremely careful how you separate the cells and to retain as much of the connection as possible to allow you to solder.

When I sort cells ... I also check iR of each - because other cells that show good voltage can be near to failure as well and high iR will indicate which are likely.
 
Lithium batteries are causative to many fires consensus down my pub insurers will get tough on Lithium installation where DIY undertaken and to check with insurer,not only on boats but anything.
Mine wont touch DIY installation for my craft.
Would hate to think the reaction if I told them I had carried out a major op in opening up as advised and looking to rebuild.
Seriously check with your insurance provider you might have invalidated your insurance .
Remember its not just your own boat and life but others as a result of tinkering with a lithium bomb.
Madness and reckless come to mind.
Only positive your friend managed to play pass the parcel with his old battery and got it off his hands!
 
Osmosis said:
Lithium batteries are causative to many fires consensus down my pub insurers will get tough on Lithium installation where DIY undertaken and to check with insurer,not only on boats but anything.
Mine wont touch DIY installation for my craft.
Would hate to think the reaction if I told them I had carried out a major op in opening up as advised and looking to rebuild.
Seriously check with your insurance provider you might have invalidated your insurance .
Remember its not just your own boat and life but others as a result of tinkering with a lithium bomb.
Madness and reckless come to mind.
Only positive your friend managed to play pass the parcel with his old battery and got it off his hands!
Click to expand...
Depends on the type, the ones in small devices like cameras and phones are lithium-molybdenum-something and it's quite burny. Most marine leisure 'lithium ion' batteries are lithium-iron-phosphate (LFP). It's a different chemistry. Saying all lithium-ion batteries are dangerous is like saying sea salt is dangerous because it contains sodium and chlorine.
 
18650 describes the size of the cell. These are hugely common from electric tools to vapes to electric scooters. I do not know the chemical difference of different sorts but yes the type in scooters seem to be able to ignite with disastrous results. I think due to fast charging and being left on charge.
The charge controller in the link will probably be fine. However you may find that the current delivery control circuits are inadequate. 30 amps yes but I think Chinese have a different kind of amp to us. I got a 2 cell controller claimed 30 amp delivery capability but it would not deliver more than about 6 amps. No good for drill start up current. In this case I just dispensed with cut out circuits for load by connecting directly to battery.
I would go further and divide all the cells and check for performance. With 9 cells in parallel just one could kill the others or just make it look like that.
As Nigel says it is worth checking current delivery capability of each cell. Not sure but you should be able to get some amps out of each one momentarily.
I got one of these Battery Capacity Meter Discharge Tester 18650 li-ion lithium Lead-acid 1.2-12v | eBay
Current measurement was not accurate however device did show me that a lot of cheap 18650 (Ultrafire) had only about 10% or less of claimed AH capacity.
As said however be aware of possible fire danger but don't be too afraid. ol'will
 
William_H said:
Current measurement was not accurate however device did show me that a lot of cheap 18650 (Ultrafire) had only about 10% or less of claimed AH capacity.
Click to expand...
much quicker weighing the battery. Fakes will be around 35g where real ones will be more like 42g (ish)
Ultrafire are a highly regarded supplier which is why there are so many fakes around.
 
18650 are usually of LiIon format ... a basic Lithium battery and can be of 3.6 or 4.2V variety. Usually 4.2v. They are an excellent power source - but with regard to Lithium cells are actually one of the heavier forms due to the metal cylinder containment.

My comment about Internal Resistance ... it needs to be measured as Internal Resistance ... not as 'capacity or amp delivery'. Even a high iR cell will deliver high amps - but it will heat up due to the iR and have a short power time.... giving the appearance of low capacity. But in fact its purely that the amps die off due to the iR. Let the cell rest and you will read good voltage again ... etc.
 
Refueler said:
18650 are usually of LiIon format ... a basic Lithium battery and can be of 3.6 or 4.2V variety. Usually 4.2v. They are an excellent power source - but with regard to Lithium cells are actually one of the heavier forms due to the metal cylinder containment.

My comment about Internal Resistance ... it needs to be measured as Internal Resistance ... not as 'capacity or amp delivery'. Even a high iR cell will deliver high amps - but it will heat up due to the iR and have a short power time.... giving the appearance of low capacity. But in fact its purely that the amps die off due to the iR. Let the cell rest and you will read good voltage again ... etc.
Click to expand...
Hello Nigel. Can you explain this way to test internal resistance. I thought current supply capability ie short circuit current or high load would indicate internal resistance. (like you test zinc carbon dry cells). Do you have something else in mind. ol'will
 
It can be done two ways .... with a Wattmeter and taking readings while under load at different charge levels. It then becomes a bit of maths to arrive at the iR.

Or by using a dedicated iR meter ....

My point really was to illustrate that suggestions given by some actually don't do much to determining battery condition. The only way to do it without either of the two I mention - is to charge up the cell and then monitor amps / volts while under load and record time it provides. If it konks out after short time - then you know its not good.
 
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According to the MAIB Safety Digest 1/2023 which turned up here today....

"Put simply, a Li-ion battery should not be exposed to water or moisture..... A Li-ion battery that is found to be damaged or affected by water should not be used or charged."
 
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