BigBrosMo
New Member
- Joined
- Feb 6, 2021
- Messages
- 93
Hi all, I've been lurking and learning for awhile and finally just built a new 24v, EVE 280ah LiFePO4 system. I am cost conscious so using components that have been recommended by the various well-known youtubers;
EPEVER 4210 SCC
TR16/AiLi Battery Monitor (350A shunt)
JK/Jikong 8s BMS K-B2A8S20P (spec sheet says it has an onboard coulomb counter)
I top balanced my batteries to 3.64v, current down to 0.1A, according to the charger used.
I temporarily connected up my system in series and attached the BM and BMS. Voltages measured were all about the same - or so close as that I assumed acceptable margin of error. I needed the power for the night so attached my inverter. The next day I set up the system in it's permanent home and connected the SCC.
I am on an in island in Thailand and conditions have not been perfect. It has basically been raining nonstop since I connected it all (today looks like it might get sunny/fingers crossed).
So here I am, roughly 2.5 days in with intermittent discharge of the battery, very little incoming charge. But now all of the units are reporting different voltages and SOC and so I have no idea which one to rely on! Here's a snapshot in time:
BMS is reporting:
26.35v system/Cells balanced each at 3.293v
69% of 280ah capacity
0.75A incoming charge (the SCC has minimally kicked in and the system is under small load)
Battery Monitor is reporting:
26.22v
43.9% of 280ah capacity
0.635A incoming charge
SCC is reporting:
26.4v
2.4A of charging current
The Volt Meter is reporting:
26.02V total/3.253V/cell at the Batteries themselves
26.07V and 2A output at the SCC
So my question is, since everything is reporting a different value, how do I trust that the SCC and BMS will do their jobs correctly or adhere to the settings I put in? How can they vary so much from the VM and how do I know what meter is correct for %SOC (BM or BMS)?
For the BMS, a 0.4v difference per cell is quite big and for the SCC my charging profile will be all out of whack won't it?
EPEVER 4210 SCC
TR16/AiLi Battery Monitor (350A shunt)
JK/Jikong 8s BMS K-B2A8S20P (spec sheet says it has an onboard coulomb counter)
I top balanced my batteries to 3.64v, current down to 0.1A, according to the charger used.
I temporarily connected up my system in series and attached the BM and BMS. Voltages measured were all about the same - or so close as that I assumed acceptable margin of error. I needed the power for the night so attached my inverter. The next day I set up the system in it's permanent home and connected the SCC.
I am on an in island in Thailand and conditions have not been perfect. It has basically been raining nonstop since I connected it all (today looks like it might get sunny/fingers crossed).
So here I am, roughly 2.5 days in with intermittent discharge of the battery, very little incoming charge. But now all of the units are reporting different voltages and SOC and so I have no idea which one to rely on! Here's a snapshot in time:
BMS is reporting:
26.35v system/Cells balanced each at 3.293v
69% of 280ah capacity
0.75A incoming charge (the SCC has minimally kicked in and the system is under small load)
Battery Monitor is reporting:
26.22v
43.9% of 280ah capacity
0.635A incoming charge
SCC is reporting:
26.4v
2.4A of charging current
The Volt Meter is reporting:
26.02V total/3.253V/cell at the Batteries themselves
26.07V and 2A output at the SCC
So my question is, since everything is reporting a different value, how do I trust that the SCC and BMS will do their jobs correctly or adhere to the settings I put in? How can they vary so much from the VM and how do I know what meter is correct for %SOC (BM or BMS)?
For the BMS, a 0.4v difference per cell is quite big and for the SCC my charging profile will be all out of whack won't it?