Small 24V optimal Battery setup + BMS/Balancing questions

[fisherman]

Good Morning,

Looking at setting up a small ~1200w panel system with 100-200ah 24V battery capacity which I may scale larger down the road. Prefer to use BattleBorn or another LiFePo4 brand that has BMS and a good warranty. Looking to use Victron for the charge controller and inverter/charger.

This will be used for a small cabin likely 6 months a year. It gets very cold (-40c) here so I'd be removing the batteries for storage in the winter as I don't have a way to keep them warm.

I had a couple questions as I'm trying to figure out what would be the optimal configuration.

1. Cost aside, would it be better to use multiple 12v batteries in series to achieve 24V? Or use a single or dual 24v batteries in parallel?
2. How does BMS come into play in either config provided the batteries themselves have BMS?
3. Would I need to purchase a battery balancer for this config?
4. Is there anything else to consider with this type of setup?

I'd appreciate your feedback.

Thank you

 

[DThames]

Having one or more 24v batteries will make question 3 go away. If the batteries have BMS internal, your BMS needs are covered.

Anything else to consider.....the amp hour size of the battery needs to be the same as you build up to more capacity. Not required but needs to be. For example if you started with a 200ah battery and then wanted to add 200ah, great. If you started with 200ah and wanted to add 100ah, you would be better off to have 2x100ah to start with, then add the 100ah. Cable lengths should be considered and kept the same length. If you connect your first battery with a short cable, then are forced to a longer cable for the second battery, your power distrubution between the two will be a little less than ideal. Set your first battery far enough away to add another battery closer and size your cable length for the longer of the two locations

 

[fisherman]

Having one or more 24v batteries will make question 3 go away. If the batteries have BMS internal, your BMS needs are covered.

Anything else to consider.....the amp hour size of the battery needs to be the same as you build up to more capacity. Not required but needs to be. For example if you started with a 200ah battery and then wanted to add 200ah, great. If you started with 200ah and wanted to add 100ah, you would be better off to have 2x100ah to start with, then add the 100ah. Cable lengths should be considered and kept the same length. If you connect your first battery with a short cable, then are forced to a longer cable for the second battery, your power distrubution between the two will be a little less than ideal. Set your first battery far enough away to add another battery closer and size your cable length for the longer of the two locations

Thanks for your reply! So if I read this correctly, I'm better off using 24v batteries in parallel for capacity/reliability in a 24v system and my BMS will be covered by the internal ones?

 

[DThames]

Thanks for your reply! So if I read this correctly, I'm better off using 24v batteries in parallel for capacity/reliability in a 24v system and my BMS will be covered by the internal ones?

"Better off" would be determined by you. If it were me, the availability/cost of 24v batteries in the size range that I wanted to use would likely be the deciding factor. Have you looked at larger 24v batteries, not of the type that look like car batteries?

 

[fisherman]

Have you looked at larger 24v batteries, not of the type that look like car batteries?

I'm not familiar with those. Would you know of some brands that offer them?

 

[JK2369]

https://www.mobile-solarpower.com/lithium-batteries.html lists several batteries available for 24v with internal BMS, including Battle Born.

In the past, Will has also reviewed and recommended Kilovault for cold temperatures, as it’s available with internal heaters.

In Canada, you may find Lynac Lithium to be interesting.

 

[DThames]

I'm not familiar with those. Would you know of some brands that offer them?

Here are some examples. I am not familiar with the vendor.