viccooper
New Member
- Joined
- Jul 7, 2021
- Messages
- 20
I have a 7 year old LifePO4 DIY battery that uses CALB 400ah cells. It is managed using an OrionJr BMS which was not setup to do any sort of active balancing. After years of daily cycling I noticed that the capacity was dropping quite a bit due to the cells being out of balance. So I purchased 6 new EG4 LL 100ah batteries and took the CALB battery off-line. Then I tested each cell using a ZKETech EBC-A40L tester, running a full charge, discharge, charge cycle. It took several weeks to run these tests. The results show that one cell, #14 only has 340ah. A few others are around 370. The rest are above 375ah.
My question to this forum is what to do next?
The options I see are:
Open to other ideas. Since the overall capacity of this battery would still be around 18kWh it seems like it would be worth investing some money to keep it going another few years. I will be adding a new BMS (Suart Pittaway DIYBMS) and a new active balancer to the battery once I get the low cells replaced.
Thanks!
Test results
Cell product parameters
My question to this forum is what to do next?
The options I see are:
- Replace the lower performing cells. I tried to find a few replacement CALB 400ah cells but after an extensive search including Alibaba I can't find them. My understanding is that they are no longer being made and the industry has settled on the smaller form factor 270 to ~320ah cells.
- Double up 200ah cells. They other option I am wondering if it will work would be to get two 200ah cells and parallel them together to create a 400ah cell. This has obvious problems in that I could no longer monitor each individual cell. Each double 400ah cell would have to be monitored as one cell. But 200ah cells are quite cheap so if they degrade faster in this configuration it doesn't seem like that big of a deal.
Open to other ideas. Since the overall capacity of this battery would still be around 18kWh it seems like it would be worth investing some money to keep it going another few years. I will be adding a new BMS (Suart Pittaway DIYBMS) and a new active balancer to the battery once I get the low cells replaced.
Thanks!
Test results
Cell number | C-CV-1 | D-CC | C-CV-2 |
14 | 369.8 | 339 | 356.3 |
10 | 374.6 | 368.7 | 370.8 |
5 | 371 | 370.6 | 374 |
3 | 379.2 | 372.5 | 375.7 |
2 | 373 | ||
13 | 379.8 | 374 | 376 |
4 | 377.7 | 374.2 | 374.1 |
15 | 378.6 | 375.6 | 377.8 |
7 | 376.3 | 377.6 | |
11 | 382.6 | 378.7 | 380 |
6 | 383.4 | 381.3 | 382.1 |
12 | 385.1 | 382.7 | 383.1 |
16 | 389.6 | 387.3 | |
9 | 387.4 | 388.2 | 390.3 |
8 | 386.5 | 390.9 | 390.7 |
1 | 327.1 |
Cell product parameters