New battery shelf as replacement for AGM

[Robbert]

Hi all,
I have not posted much on the forum, but have been reading a lot, learning a lot and now have decided to build a new Lifepo4 battery as a replacement for an AGM battery bank. Most of the parts are on their way, but expect everything to be here by the end of March. Since I live on the Caribbean, it does take some time to have everything here.

During the build I will share pictures and plans and hope that you provide me with feedback, so this project could be completed successfully.

Current setup:
2 x MPP Solar pip7248 max (not in parallel)
2 x AGM bank (8x Full River DC 400-6 per bank)
20x 415 Watt panels (10 panels per inverter).

In the new setup I will parallel the AGM banks to one inverter so the capacity of that bank is double the size. Since these battery degenerate pretty fast, I hope this new bank could be used for another 2 years until it has to be replaced.

The new battery will be a 280 lifepo4 bank connected to a single inverter.
For this battery I have ordered:
17 REPT 280 cells (one additional in case there is a bad cell and shipping takes ages here)
JK-BMS (with RS485 CAN module so it could connect to Solar Assistant)
A pre-charge button with resistor will be added, as well as a Class T-Fuse.
Everything will be in one enclosed shelf so it is possible to hook it directly to the inverter and the current installed breaker).

The build will go slowly but hoping to make some progress every week after parts are dripping in.

Attached the 'design' of the setup and the first pictures of the build.
Hope you can give me feedback and guidance along the way.

 

[Robbert]

There are so many builds on this forum and anywhere else on internet, that i think it is not very interesting to share an extensive thread on this topic.
I have received my cells (REPT 280amp from Nkon), completed the build and will share some of my experiences. Since, I actually am not a very technical person, I am kind of proud that I completed the build succesfully.
First of all, I learned a lot on the forum, especially with regards to a proper top-balance.
After receiving the cells I first connected the BMS (JK-BMS) and a bench power supply to do an initial charge, until BMS-cut-off. After that the batteries in parallel for the remaining top-balance.
A friend of mine bought a similar setup. They did not do a good top balance and the pack is all over the place. Mine is now installed and it is running exactly how it should be.
In the battery itself I installed a Class-T fuse. This bank will not be paralleled with an other bank so this is the only fuse I have for this bank (there are some breakers in the system, but no part of the battery)
Installed a button and resistor to do the pre-charge before turning the battery on. Also a couple of LED's showing the the current (BMS-on, Battery-on and Pre-charge).
Underneath a couple of pictures of the build. I do need to do some cleaning, but am finished for 99%.
The only thing I need to monitor the next couple of days is that one cell seems to be drifting a bit, at a high state of charge. The JK-BMS seems to be able to bring the difference back after some time absorbing. In order to be safe, I ordered an additional cell, so I could do a replacement if this cell keeps drifting.

 

[G.W. Mad Scientist]

Good job on your battery Bank build. Nice work on the rack. I did buy 16 built lipos for my battery bank but I think in the future I would love to try to build a bigger battery Bank from scratch... sometimes you surprise yourself with quality work ? there is a ton of good information on this site for sure.

 

[Robbert]

Good job on your battery Bank build. Nice work on the rack. I did buy 16 built lipos for my battery bank but I think in the future I would love to try to build a bigger battery Bank from scratch... sometimes you surprise yourself with quality work ? there is a ton of good information on this site for sure.

Ordered today 16 new cells for a second shelf. Will be indentical als the shelf above and is meant for the other inverter.

Also I discovered that I need to add 4 more panels on the roof (they are lying here already for a year now). Solar power is sufficient in order to provide power during the day and charge the battery after it was used during the night. Two weeks ago I installed an airco in my garage to keep the batteries and inverters cool. This one uses quite a lot of power and the battery is full just before sunset.
The current setup works, but is marginal. If I have guests over and they use an airco the whole day as well, I need more power.