LiFePO4 battery origins and quality

[davis]

greetings

I've just bought a 12ah 36v LifeP04 battery from a Chinese ebayer. The idea is to move on from a fading 2 year old Li-ion battery made by Phy-lion. It has worked well and is used mostly everyday.

I was concerned when the new battery arrived without any docs, instructions or guarantees. It looks identical to the advertised battery But then many cases are similar. How would I know that the battery is indeed a LifeP04 and not another Lithium chemistry when there are no markings to indicate? The unit weight 4.5 kilos and has battery like cells arranged 4 in a row for 12 rows, There is no marking inside the battery either.

I have been using the battery and it is indeed working well. there is not so much power on demand as the previous battery but it is long lasting.It is worrying not to be sure what it is as there is a big difference between it lasting up to 700 charges and 1000+

The impression I get is that the Chinese battery industry is a "wild west" of start ups, heavy demand, rebadging and variable quality. I would be interested to know if anyone can shed some light on the issue of source, chemistry and quality of Chinese lithium batteries

best, David

 

[Deleted member 4366]

To be fairly sure, you'd have to read what's written on the cells, but sounds to me like Lifepo4. Personally, I've found that most Chinese suppliers are honorable. Sure, there's one or two crooks, but that's always the risk you take. Regardless of how many charge cycles you can do, and what chemistry is in it, I'm sure it was good value anyway compared with alternatives.

 

[aseb]

my chinese 20Ah battery is only 12Ah. The cells are unmarked. A supplier can sell under several different names- my supplier uses Cammy_CC, VPower and some others I forget just now. Others have bought the same battery and get 15Ah. The cells are unmarked so no knowing the capacity, but if they are like chinese 18650 liPo's the claimed capacity can be 2 - 3 times the actual capacity. among the worst are the ulrafire batteries- some are only 30% of the claimed capacity.

Which supplier did you choose?

 

[Deleted member 4366]

my chinese 20Ah battery is only 12Ah. The cells are unmarked. A supplier can sell under several different names- my supplier uses Cammy_CC, VPower and some others I forget just now. Others have bought the same battery and get 15Ah. The cells are unmarked so no knowing the capacity, but if they are like chinese 18650 liPo's the claimed capacity can be 2 - 3 times the actual capacity. among the worst are the ulrafire batteries- some are only 30% of the claimed capacity.

Which supplier did you choose?

Is it possible that one of the spot-welds has broken? If it has, you can solder it back together. It only takes one weld to break and you can lose any amount of capacity depending where it is.
Personally, I wouldn't buy a battery with 18650 cells like this. You only have to go over a big bump and there will be a huge force on the welds if the battery isn't supported properly, which could rip it apart. The larger type cylindrical cells are better because the welds are stronger and the joining strips are stiffer, but they all depend on how well they're welded, which depends on in-process quality controls and expertise.

Edit: Sorry I just checked back and found that you had indeed had that problem and already identified it.

 

[aseb]

I've stripped the pack, checked, then rebuilt it replacing the balance cables. There's over 200 cells in the thing. I did find a few broken welds.