nedfunnell
10 mW
- Joined
- Jun 30, 2009
- Messages
- 32
Hello all,
I bought a partly finished electric motorcycle for my second project. It has 24 CALB SE cells. It was in storage a long time before I bought it. After I bought it, life got in the way and I didn't do anything with it for 2.5 years- except take a test ride around the block and find out that the pack voltage sagged badly under moderate load. I'm ready to work on the bike again and need to figure out if the pack is merely in a coma it can be woken up from or if permanent damage has occurred. I've killed a motorcycle pack before (22s Nissan Leaf cells, let to sit with small load from the charger, dead as a doornail) at 6.3v).
The good news: pack voltage is well within a normal range at ~66v, 2.75v/cell. I haven't checked individual cell voltages yet. When I test rode it as-received 2 years ago, I assumed the bad voltage sag was from low SOC that I didn't understand because the voltage was OK- I've since been told that voltage is not at all a reliable indicator of SOC for LiFePO4. I recharged the pack with the algorithm the PO had on the DeltaQ- #53, or 87.6v final voltage. Probably too high for 24s LiFePO4. The bad news: There was still substantial voltage sag after that, and that's the last time I touched it in two years.
So, can I revive this pack, do you think? Maybe it will perk up after some gentle cycles? What's the best way to try and revive it (restore original power capacity), and what do you think my chances are?
[Note: My original post said the voltage after storage was 79v- this was wrong, I must've mis-read the multimeter in the dim garage light and with a preschooler 'helping'.]
I bought a partly finished electric motorcycle for my second project. It has 24 CALB SE cells. It was in storage a long time before I bought it. After I bought it, life got in the way and I didn't do anything with it for 2.5 years- except take a test ride around the block and find out that the pack voltage sagged badly under moderate load. I'm ready to work on the bike again and need to figure out if the pack is merely in a coma it can be woken up from or if permanent damage has occurred. I've killed a motorcycle pack before (22s Nissan Leaf cells, let to sit with small load from the charger, dead as a doornail) at 6.3v).
The good news: pack voltage is well within a normal range at ~66v, 2.75v/cell. I haven't checked individual cell voltages yet. When I test rode it as-received 2 years ago, I assumed the bad voltage sag was from low SOC that I didn't understand because the voltage was OK- I've since been told that voltage is not at all a reliable indicator of SOC for LiFePO4. I recharged the pack with the algorithm the PO had on the DeltaQ- #53, or 87.6v final voltage. Probably too high for 24s LiFePO4. The bad news: There was still substantial voltage sag after that, and that's the last time I touched it in two years.
So, can I revive this pack, do you think? Maybe it will perk up after some gentle cycles? What's the best way to try and revive it (restore original power capacity), and what do you think my chances are?
[Note: My original post said the voltage after storage was 79v- this was wrong, I must've mis-read the multimeter in the dim garage light and with a preschooler 'helping'.]