diy solar

diy solar

New to Forum, looking for supplier suggestions for DIY build

airmon

New Member
Joined
Jan 29, 2021
Messages
4
Hi all,
I'm new to the forum, but not new to Lithium batteries, solar or off grid projects. I've done solar and lithium conversions to several RV's and have lived off the grid as a full time RVer for the last 6 years. We spend probably 80% of our nights not on shore power and have spent months without plugging in or even firing up the generator for anything more than the exercise it needs to stay ready to go. Our current RV has a 400Ah@12v LiFePO4 battery bank, Magnum 3kVA inverter/charger, 100A Magnum SCC, and 780W of panels on a roof rack. I'm fairly new to building LiFePO4 batteries, but not a complete electrical noob.

I'm here because I'm looking to upgrade the battery bank and some of the electrical gear on our trawler. Right now it's got 660Ah of flooded GC2's, a 60A charger, 100A alternator ( which charges both house and starting bank ) and an 1800W inverter that powers outlets throughout the vessel. There's a DIY solar bimini on the aft deck with 640W of solar charging the batteries with a Victron 100/50 controller. The single diesel engine has two group 31 flooded batteries for starting.


DJI_0006 (1).JPG

My goal is to replace the house pack with DIY lithium batteries of about 280-300Ah in a bank of 4S4P to give us 1120-1200Ah@12v total for the house systems, and upgrade the Inverter to a 3kVA inverter/charger to allow us to run the aft cabin A/C overnight. I'm planning on leaving the starting batteries, but moving engine alternator output to the house batteries alone ( so I can adjust the output for the LiFePO4's ) and use a 30A DC to DC charger to keep the starting batteries topped up.
When under way we should be able to charge at 60A or so and when running the generator at anchor we should be able to achieve about a 160A charge rate ( 110A from the inverter/charger, 50A from the old charger ) plus whatever the solar puts out. At anchor we normally need to run the genny for 45minutes to an hour to heat water in the water heater, so that charge rate should mean we don't have to run it much other than that.

I've considered a higher voltage house bank which would be good for extended high energy discharges, but there would be significant additional costs to charge a higher voltage bank ( a 48V alternator, controller and pulleys would be in the neighborhood of $2k ) and I need to be able to power a 12v bow thruster and the 12v anchor puller, which draw pretty major amps, so I've decided to stay with a 12v house bank, at least for now.

I've been looking at AliExpress for supplying the LiFePO4 cells and BMS, but I'm not sure which store to buy from. I'd like to buy 16 cells and 4 Daly 200A ( maybe 250A) BMS. I thought there might be a resource or a thread with folks experiences and suggested stores, but if there is I haven't found it yet. I might just be looking in the wrong place.

So if anyone has a suggestion about where to shop, or if you see any issues with my plan, I'd like to hear about it.

Thanks!

Eric Udell
M/V Terrapin
 
Back
Top