docw009
Minor legend
In August of 2015, I bought a 36V10AH Dolphin from elifebike on ebay. They later became pswpower. I also bought a 52V9AH Dolphin from Lunacycle. They had just started selling ebike packs that summer,
Both are still soldiering on. I did a discharge load test with a DLP 24 to measure the capacity, Due to power limits on the DLP. this is done at low currents, around 1 amp per cell. I run it til the BMS shuts off the battery and get a comparative number for AH., Both are on bikes I don't use that much, so running them flat by riding for a real life test takes too long,
The 36V pack checked in at 9.3AH, which is 93% of its rating. That sounds good, but it bounced back to 34.3 volt when I reset the BMS. That's 30% SOC and means voltage sag caused the BMS to trip. I measured the AC IR on each group and determined the individual cells were running about .090 ohms. which is high for an ebike use. The pack was a 10S-5P using 2000 mah chinese cells. They were all balanced by the way, but max charge was 41.3V instead of 42.0, indicating tired cells. Oh well. I can re-use the case for a 48V battery.
The Luna pack was a 14S-3P using Samsung 30Q cells. It shut off at 42V or 3V/cell, when the BMS tripped. Capacity was 8.28AH, over 90% of the rated 9AH. Cells were all close in blance too, Nothing wrong with that. I recall paying around $450 for this ten years ago. I got my use out of it, and I guess maybe I'll get some more.
Both are still soldiering on. I did a discharge load test with a DLP 24 to measure the capacity, Due to power limits on the DLP. this is done at low currents, around 1 amp per cell. I run it til the BMS shuts off the battery and get a comparative number for AH., Both are on bikes I don't use that much, so running them flat by riding for a real life test takes too long,
The 36V pack checked in at 9.3AH, which is 93% of its rating. That sounds good, but it bounced back to 34.3 volt when I reset the BMS. That's 30% SOC and means voltage sag caused the BMS to trip. I measured the AC IR on each group and determined the individual cells were running about .090 ohms. which is high for an ebike use. The pack was a 10S-5P using 2000 mah chinese cells. They were all balanced by the way, but max charge was 41.3V instead of 42.0, indicating tired cells. Oh well. I can re-use the case for a 48V battery.
The Luna pack was a 14S-3P using Samsung 30Q cells. It shut off at 42V or 3V/cell, when the BMS tripped. Capacity was 8.28AH, over 90% of the rated 9AH. Cells were all close in blance too, Nothing wrong with that. I recall paying around $450 for this ten years ago. I got my use out of it, and I guess maybe I'll get some more.
