doggy
New Member
- Joined
- Dec 11, 2021
- Messages
- 26
I'm an experienced electronics guy and wanted to replace my 11 year old and dying primary AGM battery bank on our yacht. It was 510AH 12V. Mainly based upon feedback in this forum, I chose to buy 12 LF280K cells from Docan and amy@docanpower.com. I'll configure a primary 4s2p 560AH bank to go aft and a 4s 280AH bank in the bow. I did not want to rely on the two JK BMSs alone to monitor and regulate charging. So I embarked on a plan to upgrade my two MPPT solar controllers for LFP as well as the engine alternator. Linked by RS485 bus. I'm also building a boost converter-charger to charge the bow bank from the main aft bank.
Amy was a delight to deal with and the first 8 cells arrived in Australia earlier than expected. 4 more are coming later. They were in pristine condition and perfectly packed. These are the cells with the welded studs. I have a suitable torque wrench for the nuts. I would like to see a little more surface area under the posts. However it will be sufficient and the connecting strips are good. I always use silver bearing conducting paste on cells and will do the same with the final assembly.
Rather than individually test and assemble cells and given I was ready to test the modified MPPTs, I put together a 560AH pack on the workbench with random selection of which cells to go where. I checked the QR codes and all cells were made on the same day (6 months ago) from the same factory line but with a range of serial numbers.
Anyway I have just finished a capacity test and after top balancing at 3.65V (for a short time) I was able to extract 560AH at an average of 12A (so .02C) with a termination voltage of 2.9V for the lowest cells. Therefore the worst pairing of cells is over 280AH as there will still be a few AH to go at 2.9V. My estimation is that there is a variation of a few AH between cells but given they are all over 280AH I am definitely happy. I look forward to the final 4 arriving in the next week or so. I might do some mixing and matching when I have 12. However given the BMS has a 2A balancer which is particularly effective in a 4s arrangement (more so than 8s or 16s) I'm not too bothered. I will end up with about 3 times the usable AH on the boat and the weight will be about a third.
So thanks to all the posters who have reported on Docan and EVE cells plus the excellent Amy Zheng. I hope Amy gets to have some sleep from time to time because she seems to be permanently online and is an excellent person with whom to deal. Docan also has an excellent reputation from everything I read and also based upon my own experiences so far.
Best Regards,
David
Amy was a delight to deal with and the first 8 cells arrived in Australia earlier than expected. 4 more are coming later. They were in pristine condition and perfectly packed. These are the cells with the welded studs. I have a suitable torque wrench for the nuts. I would like to see a little more surface area under the posts. However it will be sufficient and the connecting strips are good. I always use silver bearing conducting paste on cells and will do the same with the final assembly.
Rather than individually test and assemble cells and given I was ready to test the modified MPPTs, I put together a 560AH pack on the workbench with random selection of which cells to go where. I checked the QR codes and all cells were made on the same day (6 months ago) from the same factory line but with a range of serial numbers.
Anyway I have just finished a capacity test and after top balancing at 3.65V (for a short time) I was able to extract 560AH at an average of 12A (so .02C) with a termination voltage of 2.9V for the lowest cells. Therefore the worst pairing of cells is over 280AH as there will still be a few AH to go at 2.9V. My estimation is that there is a variation of a few AH between cells but given they are all over 280AH I am definitely happy. I look forward to the final 4 arriving in the next week or so. I might do some mixing and matching when I have 12. However given the BMS has a 2A balancer which is particularly effective in a 4s arrangement (more so than 8s or 16s) I'm not too bothered. I will end up with about 3 times the usable AH on the boat and the weight will be about a third.
So thanks to all the posters who have reported on Docan and EVE cells plus the excellent Amy Zheng. I hope Amy gets to have some sleep from time to time because she seems to be permanently online and is an excellent person with whom to deal. Docan also has an excellent reputation from everything I read and also based upon my own experiences so far.
Best Regards,
David
