Mixing SOK LiFePO4 batteries 48V, 4 or 8 12v 100aH with 2 server rack batteries 48V 100aH in one bank

cdrnorth

New Member
Joined
Apr 14, 2022
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7
Hello Everyone,

Brand new, and need advice for short-term and long-term solar setup. I am a total novice and will be hiring a professional installer. However, I need power now and I am looking at several months before they can help me. I would have an electrician wire up the short-term solution.

So, short-term...

We will be working off-grid. I am looking at 4500W (450W for 10hrs/day) consumption on my computers alone. Will be charging with a 4500W gas generator until I can get the Perkins 10kW installed.

I need batteries, now. So my plan was to purchase 4-8 SOK LiFePO4 batteries and wire them up for 48V (100 or 200Ah) and charge them with the generator. Pre-order 2-3 SOK server rack batteries (48V 100Ah). The question is can I mix them together in a single battery bank?

Regarding inverter and charge controllers...

High surge and general consumption items and some that are not:

  • Have a 120V well pump, don't know any other specifics.
  • Air fryer (my wife will not do without this)
  • Microwave (the same)
  • Gas refrigerator for now
  • Gas store
  • On-demand propane hot water heater
  • Wood heat with blower fan
  • Propane heat, no blower

I have so many questions. I will be meeting the installers, today, for a site visit.

Thanks in advance.
 

cdrnorth

New Member
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Apr 14, 2022
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7
Would like to buy once, cry once.

The installers use Schneider equipment but are willing to use what I want.
 

joanna_lannie

Maybe sleepwalking now
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Sep 14, 2021
Messages
190
Make sure your battery packs are all of the same chemistry (such as both LiFePO4) and the same voltage (such as your 48V) that can be mixed with batteries. But it seems that some people say that the capacity gap between battery packs should not be too large. You can also look at other people's opinions. At least on this issue, many people hold different views.
 

rmaddy

Full-time Solar-powered Trailer Life
Joined
Nov 16, 2019
Messages
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Location
USA
We will be working off-grid. I am looking at 4500W (450W for 10hrs/day) consumption on my computers alone. Will be charging with a 4500W gas generator
It's important to get the correct units here. 450W for 10 hours is 4500Wh, not 4500W. You don't need a 4500W generator to run a 450W computer. You only need a 450W generator running the same 10 hours per day. Obviously more loads would require the bigger generator.

A 48V 100Ah LiFePO₄ battery is 5120Wh so that is enough to run your 4500Wh each day assuming you can recharge the battery each day.

There's no reason why you can't parallel a 48V battery made from 4 12V batteries in series with an actual 48V battery, as long as they are the same chemistry. So your plan with the various SOK batteries will work. Putting 4 12V batteries in series will require a 12V LiFePO₄ friendly charger so you can properly balance the 12V batteries before you put them in series. Once in series you will need a 48V LiFePO₄ friendly charger. That charger can be used for the entire 48V battery bank as it grows.

What you should do first, before buying a single item, is to do a proper energy audit. This will help you figure out how much battery you need and what size inverter will work.

 

cdrnorth

New Member
Joined
Apr 14, 2022
Messages
7
Make sure your battery packs are all of the same chemistry (such as both LiFePO4) and the same voltage (such as your 48V) that can be mixed with batteries. But it seems that some people say that the capacity gap between battery packs should not be too large. You can also look at other people's opinions. At least on this issue, many people hold different views.
Thanks for the advice. They will have the same chemistry, capacity and voltage.
 

cdrnorth

New Member
Joined
Apr 14, 2022
Messages
7
It's important to get the correct units here. 450W for 10 hours is 4500Wh, not 4500W. You don't need a 4500W generator to run a 450W computer. You only need a 450W generator running the same 10 hours per day. Obviously more loads would require the bigger generator.

A 48V 100Ah LiFePO₄ battery is 5120Wh so that is enough to run your 4500Wh each day assuming you can recharge the battery each day.

There's no reason why you can't parallel a 48V battery made from 4 12V batteries in series with an actual 48V battery, as long as they are the same chemistry. So your plan with the various SOK batteries will work. Putting 4 12V batteries in series will require a 12V LiFePO₄ friendly charger so you can properly balance the 12V batteries before you put them in series. Once in series you will need a 48V LiFePO₄ friendly charger. That charger can be used for the entire 48V battery bank as it grows.

What you should do first, before buying a single item, is to do a proper energy audit. This will help you figure out how much battery you need and what size inverter will work.

Many thanks, Wh, got it!

Lots of good advice and will add it to my Roam Research graph.

Do you have a recommendation as to preferred charger?

You just saved me searching for or creating my own spreadsheet. I have been gathering that info, so now I can plug it in as I continue.

Once again, thanks for the great feedback.
 
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