Your location is irrelevant. Chargers are programmed for suitable voltages.
Absorption: 28.8V
Absorption time: 30-60 minutes
Float: 27.0V
If temp sensor is installed, disconnect it.
You will need to get batteries that have their own internal low temp charge protection.
The exact model number is important for understanding if units can be paralleled and how they are programmed.
"big unit for a small output" is why they can handle high surge currents, and your AiO can't. They are made with high quality heavy duty components that include a large transformer.
YOU understand your own system, but you aren't familiar with its limitations OUTSIDE of your application. Pursuing your intended path may result in a system that no longer meets your friend's needs.
Outback manuals are complex because they have so many features and options well beyond your typical AiO. The basic settings are relatively simple to make.
Understanding your friends need's is important.
What problems is your friend having, i.e., how is the system not meeting his needs?
Biggest issue is low battery all the time he has a bank of 8, 6vdc 400ah sealed batteries at 24v..
the green light would drop to yellow in 1-2 hours with led lights on in the cabin and maybe a tv then red in another hour .
it never has managed to last through the day and night, they have to use a generator to charge at low amperage through the inverter.
online it looks like some units can do up to 80 amps charging from 120vac connection to inverter but I know his was way lower amp setting.
have to do some reading on it see if it can be changed.
needless to say for 10 years one fm60 charge controller had been set to 1 hour absorption and the other 1.5 hours at max there getting 22 amps x 2
.
not near enough time to charge them back up fully.
I would think the batteries never got a good full charge cycle for 10 years with standby power eating them back down.
I set them to 8 hours, the manufacture website said they can take 400amps for 4 hours. figured it would be fine.
he went back next week used air compressor for like 3 hours he said and everything was good green light never went yellow with just him there not 5 or 6 people.
that was when he closed the cabin up last year. not sure if he has made it back up yet.
last year I went up to help with his system.
He had a string on a array that had a bad connection and was producing nothing but 16-20vdc we got that taken care of and pretty sure was around 66-80-vdc on each string and both controllers.
So I see your point now batteries are the issue more than anything and absorption/charge time to keep batteries charged for night time.
Not having the knowledge you have, I would prefer to swap the charge controllers for Victron being so much simpler to understand and setup for the lifepo4.
I just sat here for 1 plus hour trying to understand the Mate & FM60's manuals and settings & there is just to much BS
and settings that is not needed it should be simpler for anyone to understand.. they have way to many setting to screw things up I want simple and more or less plug and play. .
grabbing 2x eg4, 200ah 24v lifepo4 batteries 2 Victron 150/45 or 150/35 charge controllers seems way easy vs the FM60 nightmare
.
this should make it much simpler for us on changing things over.
. this is 1 reason he wants a different unit & if I am helping I want a simpler solution as well.
