I just roughed in my solar
/ Lifepo4 battery
bank over the weekend. Nothing blew up and the batteries charged. Here are the details:
The batteries are (4) 3.2 volt HiPower 200 amp cells bought used. They were initially balanced to 3.7 volts each. I wired them together to get 13.? volts using battery
cable and lugs. The bank fits into a old plastic milk crate and drops into a locker in the boat. No BMS fitted. The existing 200 AH lead acid batteries stayed in place and are charged by the existing 120 volt charger
or the engine alternator
. The 1, 2 both switch picks which system is used.
is mounted on the bimini
. Solar is (2) 175 watt, 35 volt panels
going through a Morningstar TriStar 45 MPPT
controller with a separate output screen
so I can read the battery state of charge. I programed it to charge at 13.8 and float at 13.6 to the LifePo4
. The MPPT
has a battery sense wire so the battery voltage is very accurate. Solar does not charge the LA yet.
The system charged the bank quickly with no problems. It was interesting to watch the amps quickly drop off as the bank reached 13.8. I shut it off when I left the boat just in case I screwed up in the installtion. I'll look it over next weekend before I go live 24/7.
Here are things I learned:
cost a lot to ship. Cheaper high voltage panels require an expensive MPPT charger
to get the useable amps down to 12 volts. Higher priced panels and a cheaper controller may have worked as well. It is a pain to program the MPPT charger but that is the only way to not cook the batteries. All of this requires fuses
and disconnect switches on every wire to make sure nothing gets fried. This is not an install it and forget it system like we treat lead acid batteries. It costs a lot but I have doubled my battery capacity in a small space. Momentarily combining both batteries seems to do nothing. The 13.8 volts does not seem to have enough voltage difference to push power to the charged lead acids.
Costs to do this:
Batteries used $600
(2) 175 watt solar cells $500 + $200 for shipping
MPPT controller and remote
Wires, disconnects, fuses
Total about $2,041
What do I get for that? A system I can pull two days of 60 to 70 amp hours out of with no sun before I switch over to engine
What I plan to run on the system when we leave the dock
small Engel fridge 22 AH
16 to 20 AH
TV up to 12 AH
Everything else 10 to 20 AH, all LED lights
, no radar
, no SSB
, no electric windlass
on a 34 Pearson
I thought I'd post this summary for those after me. Thanks to all on this forum for talking about Lifpo4 and solar.
Your mileage may vary, I am not an expert, this may be dangerous, don't try this at home, use at your own risk.