Phantom
Member
Hello All!
I'm hoping to salvage a battery. It's a 48V, 20Ah LiFePO4 battery that worked exactly once. It powered my bike for about 2-1/2 hours (35 miles), when the motor abruptly died. I pedaled home and plugged the battery into the charger (a cheap "dumb" charger [not a smart balancing charger] that came with the battery). The charger's light remained green, indicating a full charge.
This could not be. I'd ridden for over two hours. Even if the battery weren't fully drained, surely it must be depleted enough to receive a charge. Hmmm . . . .
Over time, I tried three different chargers, all of which work properly. The battery refused to charge. Always a green light, never red. Since the battery did work (once) I concluded that the cells themselves were probably good, but that the battery's BMS was probably faulty. I took a deep breath and opened the battery, and here's what I found (see pictures 1 thru 4):
Picture 1: the naked battery on left, stripped of its shrink-wrap covering on right. My hopes of finding 18650 cells were dashed as I believe these are "pouch" cells, no?
Picture 2: close up of the BMS (sorry for the blurry quality). I count 16 small charging leads connecting to the battery: 1 black, 1 red, and 14 white.
Picture 3: a 3/4 view showing the battery and BMS.
Picture 4: a close up of the top of the battery, showing all 16 leads soldered onto the cathodes/anodes. I took voltage readings at various points and the voltage progressed at each tab, indicating a series connection, no? Since I see no parallel connections anywhere, I conclude that the entire battery is wired in series only, as a 16S1P battery.
My questions for the forum:
Are my assessments/conclusions correct? If not, how so?
I'm willing to buy a new BMS since they're relatively inexpensive and I could get a working battery if it fixes the problem. It must work with a 16-cell, LiFePO4-chemistry battery with these specs:
Thanks in advance to all who can help!
I'm hoping to salvage a battery. It's a 48V, 20Ah LiFePO4 battery that worked exactly once. It powered my bike for about 2-1/2 hours (35 miles), when the motor abruptly died. I pedaled home and plugged the battery into the charger (a cheap "dumb" charger [not a smart balancing charger] that came with the battery). The charger's light remained green, indicating a full charge.
This could not be. I'd ridden for over two hours. Even if the battery weren't fully drained, surely it must be depleted enough to receive a charge. Hmmm . . . .
Over time, I tried three different chargers, all of which work properly. The battery refused to charge. Always a green light, never red. Since the battery did work (once) I concluded that the cells themselves were probably good, but that the battery's BMS was probably faulty. I took a deep breath and opened the battery, and here's what I found (see pictures 1 thru 4):
Picture 1: the naked battery on left, stripped of its shrink-wrap covering on right. My hopes of finding 18650 cells were dashed as I believe these are "pouch" cells, no?
Picture 2: close up of the BMS (sorry for the blurry quality). I count 16 small charging leads connecting to the battery: 1 black, 1 red, and 14 white.
Picture 3: a 3/4 view showing the battery and BMS.
Picture 4: a close up of the top of the battery, showing all 16 leads soldered onto the cathodes/anodes. I took voltage readings at various points and the voltage progressed at each tab, indicating a series connection, no? Since I see no parallel connections anywhere, I conclude that the entire battery is wired in series only, as a 16S1P battery.
My questions for the forum:
Are my assessments/conclusions correct? If not, how so?
I'm willing to buy a new BMS since they're relatively inexpensive and I could get a working battery if it fixes the problem. It must work with a 16-cell, LiFePO4-chemistry battery with these specs:
* Voltage : 48V
* Capacity: 20Ah
* Cut-off voltage: 40V
* Max. discharging current: 100Amp
* Max Continuous Discharging Amperage: 50 Amps
* Rated Discharging Amperage: 40 Amps
* Charging Current: <10 Amps
* Charging Voltage: 58.4 Volts
Thanks in advance to all who can help!