Electrodacus SBMS0 with 2p4s or 2 JBD with 4s2p

[frthompson]

I am upgrading the battery in my RV to one built from 8 280 ah EVE cells. The rest of my system consists of a Victron multiplus 3000, mppt 100/50 SCC, BMV702 battery monitor, and Venus GX controller and 6 100w 12v solar panels. Its a 12 volt system. I think I've narrowed down the battery configuration and BMS to two options. Option 1 would use an single Electrodacus SBMS0 with the EVE cells configured as 2p4s. I would get rid of the victron venus GX and the SBMS0 would be able to turn the multiplus and mppt SCC on or off and I'd connect it to a victron battery protect to be able to disconnect the other 12v loads. Option 2 would use 2 JBD150a 4s bms and 2 4s batteries in parallel and would keep all my existing victron equipment as is. Option 1 only requires one bms and it directly controls the inverter/charger and scc, but uses paralleled cells within a battery. It might cost a little more up front but if I sell my Venus GX that would offset the added costs. Option 2 lets the victron venus gx control the charging with the JBD bmss acting as a failsafe and monitors every individual cell, but there are two batteries in parallel that might get out of balance over time. I'm interested in opinions on which is the better approach? There is one other confounding factor to consider, my existing battery is a 300 ah with internal bms. My plan was to remove it from the system. But If I wanted to include it that would steer me to option 2 with three batteries in parallel each with there own bms. Am I missing something to consider?

 

[frthompson]

@FilterGuy I was hoping you would have an opinion on this. Any others with Electrodacus and Victron knowledge have suggestions? Another couple of pieces of information, my max load would be 200a @ 12 volts but usually < 100a. I'm already set up for that load at 12 v with 4/0 cables on my inverter/charger and appropriate fuse.

 

[1 watt]

I am upgrading the battery in my RV to one built from 8 280 ah EVE cells. The rest of my system consists of a Victron multiplus 3000, mppt 100/50 SCC, BMV702 battery monitor, and Venus GX controller and 6 100w 12v solar panels. Its a 12 volt system. I think I've narrowed down the battery configuration and BMS to two options. Option 1 would use an single Electrodacus SBMS0 with the EVE cells configured as 2p4s. I would get rid of the victron venus GX and the SBMS0 would be able to turn the multiplus and mppt SCC on or off and I'd connect it to a victron battery protect to be able to disconnect the other 12v loads. Option 2 would use 2 JBD150a 4s bms and 2 4s batteries in parallel and would keep all my existing victron equipment as is. Option 1 only requires one bms and it directly controls the inverter/charger and scc, but uses paralleled cells within a battery. It might cost a little more up front but if I sell my Venus GX that would offset the added costs. Option 2 lets the victron venus gx control the charging with the JBD bmss acting as a failsafe and monitors every individual cell, but there are two batteries in parallel that might get out of balance over time. I'm interested in opinions on which is the better approach? There is one other confounding factor to consider, my existing battery is a 300 ah with internal bms. My plan was to remove it from the system. But If I wanted to include it that would steer me to option 2 with three batteries in parallel each with there own bms. Am I missing something to consider?

I’ve been using an SBMSO with 4 used 200ah cells in our old Sprinter van for a few years. It’s worked great and Dacian has patiently answered my many bone-headed questions.

2p4s diagrams B or C (4 fuses added) here https://nordkyndesign.com/assembling-a-lithium-iron-phosphate-marine-house-bank/ seems to be the best approach, using the SBMSO. Wire the tiny SBMSO wires same as you would 4s/12v. You don’t get individual cell monitoring/balancing like with only 4 cells, but each block of 2 should self equalize and you maintain under/over protection.

Since your existing 12v 300ah has an internal bms, I think you could parallel that with the other 12v “battery” (the 8 cells as wired) and you’d have a 860ah overall battery? Fuse the positive output of your single 12v battery. It’s BMS will be doing it’s own thing, but the SBMSO will be cycling the panel feed on and off based on the cell voltages from the 2p4s config as well as overall battery voltage. And if you wire up a temp sensor on the 2p4s rig that’ll trip charging (for the whole lot) if that setup gets towards freezing temps.

A year ago I put in an air conditioning system which draws about 40 amps, and last night I saw 4x200ah new cells on eBay for $212 and free shipping. I’m planning on doing the 2p4s wiring for this. Since my cells will be a mix of new and used, I’ll parallel used to used and new to new. And do a basic bottom balance with a resistor/voltmeter before hooking them up as one system.

Have fun!
Roy