36v/12v boat/camper LiFePo4 charging

Tom Morrissette

New Member
Joined
Jul 10, 2021
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4
I had a similar post before, but here's where I'm at...
I've done a bit of research, and I've worked plenty with electrical (and all other DIY things); but this will be my first battery/solar build.
I'm expecting 20, EVE 280AH LiFePo 3.2V cells to be delivered in the next month or so.
Around the same time our new Lance 850 truck camper should (finally) be ready.
Also, I have a 23' center console World Cat boat that I'll be adding a 36v trolling motor to. It also currently has 3 AGM 12v batteries (one house, two cranking for twin outboards) that charge off the alternators and a Noco Genius 3 bank on board charger.

My plan so far is:

-Build 5, 12v batteries (4 cells each, top balanced)
-Wire two parallel that will live in the camper
-Wire the other three in series for my 36v trolling motor bank that will be in a custom box in the console of the boat
-Buy the Renogy 400 Watt 12 Volt Solar RV Kit (or other recomendation) and either mount all 4 panels to the roof of the camper (if there's room) or keep two of the panels portable
-Buy either a Yandina Trollbridge 36 or the Power-Pole Charge (much pricier/more options) to charge the 36v trolling motor bank and/or the 12v house/starting batteries from the engines alternators

Questions:

-What's the best BMS's to get?
-What's the best/simplest way to keep all cells balanced/protected?
-I'm I correct that the two groups of 4 cells wired parallel for the camper's 12v can just each have their own 4s BMS, or would one 8s make more sense and be simpler?
-Similarly with the boat's 36v bank: 3 separate 4s BMS's vs 1, 12s BMS? I'm assuming with 3, 12v groups wired in series it's important to keep all 12 cells in balanced with each other?
-What would be the best/most efficient method to top balance each bank?
-What would be the best/simplest way to use the camper's solar panels to charge the boats batteries (instead of ac shore power and for maintenance charging)?
-Would the Power-Pole Charge be able to get charge to all the boats batteries from the alternators and give me the option to plug into the camper's solar (as well as ac)?
-Could I use the solar charge controller with the 400w Renogy RV kit to charge/maintain all my boat's and campers batteries at the same time, or is there another way to do that?

I welcome any and all advice, and am not wedded to any of these plans. I'll be sure to post what I end up doing, and hopefully this project and any advice I get will help other's wade through their own DIY projects! Thanks for reading and any responses!
 
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