Marinepower
Solar Enthusiast
- Joined
- Apr 24, 2020
- Messages
- 220
Capt,
the REC BMS is as good as they get and a 2 amp balance current is huge, even for your big bank.
What cells are you using? If they are eve 280 or equivalent and aluminium terminals, my guess is that you have some resistance developing on your terminals and it's putting you whole system slowly out of balance.
Also, you have not connected you cells in a very balanced configuration ( as mentioned above) so that is making things worse. You have not said where your balance leads are attached - but they may also be unbalancing your parallel cells, if you don't have those property connected (and terminated) in the middle of pack.
I have a 4s pack and i have had to fully dissemble and clean the terminals twice in the 3 years I have run these cells (EVE 280K without welded studs). Otherwise imbalances start to show up in the system due to busbar connections resistance. Your system is way more complicated so will need a lot more care and attention to make sure there is no unbalanced resistance in the system. A marine environment is unforgiving in this regard.
I would write to REC and have them give you advice as to how to connect up your 4p4s pack ( both the balance leads and bussbars connections and main pos and neg.).
I would then disassemble the pack, and wet-sand every terminal, bus bar and balance lead with 75 - 100% alcohol and some 1000+ grit sand paper ( the black stuff, made for metal.)
Reassemble with some anti oxidant grease. Make sure balance leads are well terminated ( crimp connection) and attached directly to the bus bar (ie, busbar on terminal, then balance lead ring on busbar, then a washer, then the nut.)
I would also take this opportunity ,while its all apart to rebalance the cells.
MP
the REC BMS is as good as they get and a 2 amp balance current is huge, even for your big bank.
What cells are you using? If they are eve 280 or equivalent and aluminium terminals, my guess is that you have some resistance developing on your terminals and it's putting you whole system slowly out of balance.
Also, you have not connected you cells in a very balanced configuration ( as mentioned above) so that is making things worse. You have not said where your balance leads are attached - but they may also be unbalancing your parallel cells, if you don't have those property connected (and terminated) in the middle of pack.
I have a 4s pack and i have had to fully dissemble and clean the terminals twice in the 3 years I have run these cells (EVE 280K without welded studs). Otherwise imbalances start to show up in the system due to busbar connections resistance. Your system is way more complicated so will need a lot more care and attention to make sure there is no unbalanced resistance in the system. A marine environment is unforgiving in this regard.
I would write to REC and have them give you advice as to how to connect up your 4p4s pack ( both the balance leads and bussbars connections and main pos and neg.).
I would then disassemble the pack, and wet-sand every terminal, bus bar and balance lead with 75 - 100% alcohol and some 1000+ grit sand paper ( the black stuff, made for metal.)
Reassemble with some anti oxidant grease. Make sure balance leads are well terminated ( crimp connection) and attached directly to the bus bar (ie, busbar on terminal, then balance lead ring on busbar, then a washer, then the nut.)
I would also take this opportunity ,while its all apart to rebalance the cells.
MP