On Tuesday, June 26, 2018 at 12:37:55 PM UTC-4, wrote:
On Tuesday, June 26, 2018 at 11:01:35 AM UTC-4, OHM Ω http://aviation.derosaweb.net wrote:
A friend of mine was having an odd problem with his Bienno LiFePO4 battery that I had never seen before. He lent me his battery while I was working on his panel. https://www.bioennopower.com/collect...epo4-batteries
The next day I was surprised when the battery didn't power up the panel.. So I measured the output voltage of the battery. It was 2Vdc! That's not a typo, it was only two volts! Very strange. I put the battery onto the appropriate Bienno branded charger (which I assume is a dumb charger).
The next day the battery was back at an appropriate 13.5Vdc. Used it a bit to test the panel then disconnected it from any load. Next day the battery was back at ~2Vdc again! Repeating the charging cycle and same deal - OK at first then 2Vdc later. Something internal to the battery seemed to be draining the battery.
The friend contacted Bienno and they replied;
--------------------------------------
Please try the following:
1) Attach the charger to the battery. Connect the AC-to-DC charger to the AC outlet.
2) *Simultaneously* to the battery, please attached [sic] a load (12V load such as LED light, or GPS etc.). Turn on the load for 20 seconds.
3) This will force a reset of the battery.
--------------------------------------
The friend reports that this fixed his issue. I assume this resets the battery's internal power management system which must have been draining the battery.
Anyone else seen this issue? I own two of these same batteries and have not. Could this fault cause long term damage to the battery?
Thanks, John OHM Ω
Very strange. If the charger is attached at the same time as a modest load (such as a GPS) then how will the battery BMS "notice" the load? It's still a net charge, unless the battery is full and the charger "knows" that and is in a trickle-charge mode that persists while the load is attached.
BMS systems can be flaky. I've had two "power bank" type USB battery packs (3.7v lithium ion, not LiFePO4, and those also include a 3.7V to 5V conversion circuit) stop working (no output power) after just a few uses, and I "fixed" them by opening up the case (destructive, as they are not built to be opened), disconnecting the battery from the BMS (which allows the BMS to reset), then reconnecting and duct-taping the case.
Scientifically reproducible evidence that duct tape can, in fact, fix anything..