Installing 3 12volts 310Ah (930Ah total) battery banks on a RV

[falco]

Afternoon gents,

I just acquired and RV that has a residential refrigerator, which runs at 120volts. After a long weekend with the generator starting almost every hour at night, I decided to switch to Lithium. Currently I have 6 6volts lead-acid T105, providing 675Ah. I would like to order 12 CATL 310Ah to build 3 12volt batteries (930Ah total).

Since this will be my first time building a lithium battery and have a few questions:
1- Do I need a BMC per battery? Any recommendations? (the battery compartment is partially expose underneath, so I didn't want a fan where the dirt will affect it)
2- Any enclosure recommended? (to fit 4 batteries each). Hopefully this will protect the cells from the elements (heat, cold, dust)
3- Besides the batteries, BMC and enclosure, do I need anything else?
4- Would I have a hard time charging the batteries with the generator? any gotchas? Currently I have a Magnum MS2812 (converter/ inverter/ charger) rated at 2500 watts.

thank you much for reading and any advice you can provide.

 

[snoobler]

Welcome to the forum.

1- yes. BMS typically limits your total current. 3 in parallel triple your current and offer redundancy if you have a problem with one.
2 - no recommendation.
3- Bus bars, beefy wiring to put them in parallel (see "Wiring" for best practices in link #2 of my signature).
4- check your inverter/charger charging voltage and current specs. The wattage is an inverter output specification. It likely has a lower charge power.

It's possible your inverter/charger settings don't properly utilize the available batteries and cycle excessively.

 

[vtx1029]

Afternoon gents,

I just acquired and RV that has a residential refrigerator, which runs at 120volts. After a long weekend with the generator starting almost every hour at night, I decided to switch to Lithium. Currently I have 6 6volts lead-acid T105, providing 675Ah. I would like to order 12 CATL 310Ah to build 3 12volt batteries (930Ah total).

Since this will be my first time building a lithium battery and have a few questions:
1- Do I need a BMC per battery? Any recommendations? (the battery compartment is partially expose underneath, so I didn't want a fan where the dirt will affect it)
2- Any enclosure recommended? (to fit 4 batteries each). Hopefully this will protect the cells from the elements (heat, cold, dust)
3- Besides the batteries, BMC and enclosure, do I need anything else?
4- Would I have a hard time charging the batteries with the generator? any gotchas? Currently I have a Magnum MS2812 (converter/ inverter/ charger) rated at 2500 watts.

thank you much for reading and any advice you can provide.

I have two 280ah 12v packs paralleled in my trailer. I run a seperate 4s 120amp BMS for each pack. I run a 2000 watt inverter from it. It works great for me. IMO the only other way to get around using only 1 BMS is to have one that controls a large contactor. The Eve 280ah cells fit nicely into a group 31 battery box with room for a BMS (not sure if CATL 310ah cells are close to the same dimensions)

 

[HRTKD]

2- Any enclosure recommended? (to fit 4 batteries each). Hopefully this will protect the cells from the elements (heat, cold, dust)

My recommendation is: Don't use an enclosure. Move the batteries inside the RV. Temperatures below 32° F are bad for charging LiFePO4 cells. The cells should be in a compression frame anyhow, which often won't fit into standard battery boxes.

3- Besides the batteries, BMC and enclosure, do I need anything else?

Consider a different AC-DC converter. More amps, with a LiFePO4 charge profile.
Consider a DC-DC charger so that the charge from the 7-pin circuit is giving your batteries a LiFePO4 charge profile. There's a lot more to this than just putting a DC-DC charger in the circuit. Could you get by without a DC-DC charger altogether? Maybe, but the safe answer is no. The other alternative is to disconnect the charge from the 7-pin circuit. But this works only if you have solar to charge the batteries.

4- Would I have a hard time charging the batteries with the generator? any gotchas? Currently I have a Magnum MS2812 (converter/ inverter/ charger) rated at 2500 watts.

If the charger is programmable (you can adjust the voltage settings) then it will work. The very last thing you want is a converter/charger that is four stage. The fourth stage is an equalization charge that can be 15v or more. Good for lead acid, very bad for LiFePO4.