Getting Started: lead-acid ==> LFP

[Gomez38]

A couple years ago--while laid off during COVID--we got interested in setting up a solar system here at home. I bought some SOK batteries, a 3000w Growatt all-in-one, and some used cheap Santan panels. AFter initially playing around and doing some learning, I got another job and let it languish.

After receiving an offer on our old mobile home/land, we are going to move! In the short term, we bought a 5tth wheel with old, dying lead-acid golf cart batteries (6v, 2S-2P), and I would like to switch them with the 12v SOKs, but that brings up questions:

1) is it ok/safe to just drop the SOKs in as a replacement, 4P vs. 2S-2P so that we have proper 12v power?
2) I know the current charger will not give the LFPs a full charge, due to a lower charge voltage. Does this damage them? Or can we just run on reduced capacity until later upgrading the controller?
3) Can any charger handle multiple LFPs in parallel, i.e. it just takes 2x as long to charge 2, or 4x as long to charge 4, or is there a limit for a given charger? If so, what spec would I be looking for?
4) Any recommendations on a good LFP charger to do this job?
5) would the Growatt be ok for this job? It is a 24v system, so I know it would also require a 24v/12v converter to power the RV DC system.

thank you all.

 

[0truck0]

1 yep. you really should just get the proper lithium charger to begin with, you will end up getting one anyway, just get it now.
2 just run it, you will never get to 100% charge, but you will not get to zero either... You are basicalyl giving it a float charge at higher amps/ lower volts than typical float.
3 as many as you can wire up, yes, and yes, takes longer. All the charger does is make voltage and the battery sucks it up... Can you fill a swimming pool with a garden hose or do you need a fire hose ?? Other factors will depend on the individual charger. SOme LA chargers will see the higher voltage of the lithium and stop charging long before full.
4 you want to start a fight?
Why not hook your solar panels up on the roof and charge that way?
Solar panels are all the same in that they put out voltage (until they dont), but until then they put out the same voltage, and a charge controller takes that voltage, changes it if needed and charges the batteries as needed.
5 sorry, I dont know this device to answer. No big deal to convert 24 to 12 for your system. Yes it will power your camper for a while, is not a huge power bank though for a 5th wheeler.

 

[Gomez38]

thank you, 0truck0! As far as roof panels: I live in the PNW, where we see rain, rain, rain, rain...I'm currently quite paranoid about penetrating the roof on the 5th wheel. I'm sure it can be done right, but not ready for that yet. I am hoping to take some panels along and set them out on the ground when camped, and when space allows. The Growatt is an all-in-one that takes PV input, so I'm hoping it would be the solution, but still needs a lot of figuring out.

 

[yodamota]

not knowing the growatt, i am not sure why it wouldn't give the batteries a full charge. Not sure why you need to change that. many people here have growatts with LFP batteries

 

[Gomez38]

not knowing the growatt, i am not sure why it wouldn't give the batteries a full charge. Not sure why you need to change that. many people here have growatts with LFP batteries

I wasn't clear...the Growatt indeed does the job. I haven't put it in the RV, and am leaning that way, but also thinking about simply changing the charger and batteries vs installing the Growatt in the RV. The installing guide wants it to have 20" above and below, and I think 12" left and right, which wouldn't fit in the RV underdeck. I might keep it as a standalone solar charger, not sure on my overall plans yet.

 

[yodamota]

I wasn't clear...the Growatt indeed does the job. I haven't put it in the RV, and am leaning that way, but also thinking about simply changing the charger and batteries vs installing the Growatt in the RV. The installing guide wants it to have 20" above and below, and I think 12" left and right, which wouldn't fit in the RV underdeck. I might keep it as a standalone solar charger, not sure on my overall plans yet.

much clearer, thanks