Vestwoods 7ah 12.8v lifepo4 battery teardown

I received my cheaper than market value (R426 ex vat) battery an proceeded to tear it open and see what cells and bms they use and the quality of construction.
22650 cells 2p4s, could not find any info on cells, bms seems like a future problem (no balancing circuitry)
the construction seems sturdy and well packed together for the max intended load of 7A I do not trust the single layer of Nickle strip they use from main pos and neg for anything more than 7A
The first charge it reached HVD at 13.6v
then I opened it up and soldered a 5 pin jxt lead on the cells.
pluged the JXT into a Battgo BG8s and it showed a pack voltage of 13.6v and a 260mV Delta.
cell 3 is the high cell, discharged it with a 4.7Ohm resistor until all cells were balanced at around 3.4V.
re connected the charger and HVD came at 13.8V (not a good sign)
keep in mind that without intervention this battery have no other way of self correcting the voltage imbalance.





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Strange, the pads for the balancing are there, the components are just not populated. That said, I have not seen any of those sot23-5 balancers rated for 3.2V cells, so I guess that is the reason. They probably just repurposed a Li-Ion PCB.

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Remarkable! The only thing I can assume is that all the chips for the LifePo4 cells have been bought up for the demand by battery pack manufacturers. This would then be a sign that these have replaced the LiPo cells…
But not having a balancing circuit is probably the reason for the cheaper price. I advise you to retrofit one when you can find…
I have a collection of the exact same battery pack config but with 18650 cells. These also didn’t have balancing and I’ve been retrofitting these.

26700 cells. :slightly_smiling_face:

Candidate for manufacturer possibly “O’Cell

On these 7Ah style batteries I will bet an element of planned obsolescence - like batteries for power tools. A less nefarious reason could be the assumed application for these batteries - how many alarms/gate motors will charge these batteries to a point where balancing will happen?

As far as unpopulated components go, the apparent absent NTC may mean that sticking these in a gate motor in a Bloemfontein winter is a bit iffy? Although I wonder whether any brand of these types batteries will prevent low temp charging.

The IC that is on the board is purely a protection IC.

SOT23-6 ?

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Agreed! The only reason we have the standard DC voltages that we do have (5, 12, 24 & 48V) is primarily due to the voltage of the lead acid cell.
On my router backup device I don’t worry about sticking to 12V since most electronic circuits regulate this voltage down to an even lower voltage.
PS: But I have found a particular WiFi that disconnects the supply if it isn’t exactly 12V :slightly_frowning_face:

Yes sir, like the round nokia router I have, 12v exactly, not 12.1v or 12.05V but 12V, it switches on when the voltage is higher but the light keep turning red and disconnects the fiber.