charging different battery banks and different chemistries

skippsterr

New Member
Joined
Nov 10, 2019
Messages
15

charging different battery banks and different chemistries​

I have a shed and use it as my work from home office and radio shack. I have a few ideas/projects and it’s a bit of a mad scientist project. I have played with different chemistries, inherited some AGM batteries, and wanted to mostly learn, but now I would like to put into some functional, usable, modular practice. I would like to be able to quickly disconnect a bank and use for ham radio uses.



What I have:

  • (4) 135aH lifepo4 setup in series (in a milk crate)
  • (4) 280aH lifepo4 setup in series (in a milk crate)
  • (4)90ah AGM setup in parallel
  • victron mppt 100/30
  • (2) 260Watt solar panels
  • 2000 w inverter
  • Vitron lynx management
I was wondering if there was a way to charge the 3 separate banks? Would be interested in any thoughts, ideas to tie all these together. I will want to pull the 135aH for grab and go use cases.

Appreciate any feedback.
 

time2roll

Photon Sorcerer
Joined
Mar 20, 2021
Messages
3,611
The LFP can all be in parallel. The 135 could be connected with Anderson for grab and go.

The 4 AGM will be the trouble as it should be charged and probably discharged separately. I would probably skip all the headaches and sell/recycle the AGM with intention to eventually build a second 280 if needed.
 

joanna_lannie

Maybe sleepwalking now
Joined
Sep 14, 2021
Messages
190
You are in a mixed battery situation. If you want all batteries to be charged, then you should make sure that all battery packs have the same voltage. For example, it is 12V or 24V. The difference in capacity is not a big problem, the voltage is the main problem. But the problem is with your special AGM battery, lead-acid battery has different properties than LiFePO4 battery, such as float charge. This can cause problems if charged together. Some experienced people can handle this. If you have experience, it is possible to charge and discharge batteries of different chemistries together, but this will involve some more professional knowledge.
 

skippsterr

New Member
Joined
Nov 10, 2019
Messages
15
they are all 12v in the end, but sounds like im better off setting up 2 different setups. Was wondering if there was a "magical" device that would take care of this. I am a 100% novice at this, so will stay in my swimming lane.
 

Substrate

Solar Addict
Joined
Apr 28, 2021
Messages
880
Location
SoCal
You are in a mixed battery situation. If you want all batteries to be charged, then you should make sure that all battery packs have the same voltage. For example, it is 12V or 24V. The difference in capacity is not a big problem,

Actually a difference in capacity is a big problem. Those with lower capacity will be doing the most grunt-work and will wear out quicker than those with higher capacity.

As an amateur, you are wise enough to know that just slapping random things together is not only mad-scientist, but not even scientific. You are striving for good engineering, not just randomly throwing things at the wall to see what sticks - albeit that is a good way to sucker consumers from their money and time.

Study and take the time to do it right with good engineering. Avoid lego-land childish solutions.
 

joanna_lannie

Maybe sleepwalking now
Joined
Sep 14, 2021
Messages
190
Actually a difference in capacity is a big problem. Those with lower capacity will be doing the most grunt-work and will wear out quicker than those with higher capacity.

As an amateur, you are wise enough to know that just slapping random things together is not only mad-scientist, but not even scientific. You are striving for good engineering, not just randomly throwing things at the wall to see what sticks - albeit that is a good way to sucker consumers from their money and time.

Study and take the time to do it right with good engineering. Avoid lego-land childish solutions.
I once found in some blogs that some people likened battery packs of the same voltage but different capacities to large water tanks, one larger and the other smaller, and they were connected by water pipes. Under the same water pressure, they will be filled at the same time (connector principle). I'm in favor of this point of view, but based on your reply, I seem to be a little shaken... Can you tell me the reason?
 
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