Horsefly
Solar Wizard
Greetings. I'm hoping to get some review and pointers from experts here on an LFP house battery upgrade for a sailboat.
I've been posting here for a bit about off-grid systems. I've got one in a cabin in the mountains of Colorado, and am moving from AGM to LFP. I'm also a retired Electrical Engineer and have a fairly good knowledge of most things electrical. I feel that I'm pretty well versed in off-grid systems, and am now comfortable with LiFePO4.
My sister and her husband have a 42-ft sailboat, and my brother-in-law (BIL) has been bugging me to help him with the house electrical on the boat for a couple of years. Now the house batteries are almost shot and he's decided that he wants to switch his house system to LFP. He has asked me to do most of the engineering and purchasing of parts. I have very little knowledge about sailboats (I get sea sick thinking about it) and their electrical except for what I've learned by visiting the boat in FL and documenting what is there.
The current system includes:
I'd appreciate any thoughts on what we have, what we are planning, and alternatives. Thanks in advance!
I've been posting here for a bit about off-grid systems. I've got one in a cabin in the mountains of Colorado, and am moving from AGM to LFP. I'm also a retired Electrical Engineer and have a fairly good knowledge of most things electrical. I feel that I'm pretty well versed in off-grid systems, and am now comfortable with LiFePO4.
My sister and her husband have a 42-ft sailboat, and my brother-in-law (BIL) has been bugging me to help him with the house electrical on the boat for a couple of years. Now the house batteries are almost shot and he's decided that he wants to switch his house system to LFP. He has asked me to do most of the engineering and purchasing of parts. I have very little knowledge about sailboats (I get sea sick thinking about it) and their electrical except for what I've learned by visiting the boat in FL and documenting what is there.
The current system includes:
- Three separate DC (12V) systems: 5 x 100Ah AGM house, 1 x 100Ah AGM starter/engine, and 1 x 100Ah bow thruster (Note: I only know stuff about the house system, as that is what he asked me to look at. I'm unsure how the bow thruster AGM gets charged.)
- Solar - 2 x Kyocera KC130TM 130W panels ("12V", with a Vmp of 17V), and a Blue Sky 3000i MPPT Solar Charge Controller
- A Mastervolt 12/80 battery charnger, connected via a transfer switch to either shore power or a Mastervolt 3.2kW diesel generator.
- A 100A engine alternator with a Balmar ARS-5 "regulator" which I think today we would call a DC-to-DC charger
- A currently non-functional wind turbine and an old Xantrex C40 charge controller and diversion/dump load.
- A 1800W (unknown brand) inverter that is off most of the time. The navigation/GPS, radar, fridge, and all lights are 12VDC. The inverter is turned on if they need to run the microwave or charge up the laptop.
- As far as I can tell, the nav / radar and refrigerator are the biggest loads on the house battery now, and they are not all that big. (He told me their 12VDC current draw, but I can't find it in my notes). He doesn't think the instantaneous draw will ever be over 20-30A.
- Replace the 5 x 100Ah AGM house battery with 4s2p 280Ah LFP (I guess this is more than "leaning" since he has already had me order the 8 280Ah EVE cells from Amy @ Shenzhen Luyaun, and 2 100A JBD BMSs).
- Replace the two small panels with larger panels, and add two bifacial panels over the davits on the back of the boat. Not sure which panels in either case. This still will not be enough to actually keep the batteries charged, but will help. The SCC will obviously have to be replaced, and maybe with two new MPPTs if the two sets are not well matched (almost certain they won't be).
- Replace the current wind turbine with one that works.
- Probably have to replace some items just to be able to handle LFP charge profiles: DC-to-DC charger, SCC(s), AC-to-DC charger (or inverter / charger) and wind charge controller.
I'd appreciate any thoughts on what we have, what we are planning, and alternatives. Thanks in advance!