Ultimate Bed Build and Custom Dual Battery System

[sixshooter_45]

The reason I mentioned I wanted to be able to swap out my AGM in the system instead of 'hard installing it' in is because I used it for 4 years on my offroad camping trailer. It still tests well, so I figured I'd run it for another year, maybe 2 before retiring it.

Lithium is good. I have one in my adventure bike - it holds a charge crazy well, starts faster, and is much lighter. Since I don't use the bike in freezing temps, I don't need to worry about trying to push a charge into it under freezing temps. My truck however, is in freezing temps so if I go Lithium, I know I can draw it down when it's freezing, but I can't push a charge into it without hurting it. The 'cold weather' lithiums have a BMS that senses temp and it will shunt the input power into a warming circuit until it reaches the minimum battery temp, then switch over to accepting charge. This delays the recharge of the battery, but protects it.


When I am travelling in the winter, I am not using much, if any cooler power. But I am using more lighting since it gets dark earlier. I could have little solar input due to cloud/rain, then if only driving an hour from place to place, all the alternator battery power would go into warming the Aux battery but not be long enough to actually recharge it. I don't think it is a huge issue because lights and cell etc. don't take much power compared to the fridge cooler.

The Bluetti looks great. The long charge time plugged into the truck is a consideration. The solar charge time is always an idealized situation. Maybe if you live in an area with reliable sun, closer to reality. Often reality is about half. Check to see if it can be charged in freezing temsps if that is part of your needs. I made a conscious decision to go with no AC --- all DC in my system. No conversion loss. If I need to plug something small in, I can use the trucks AC outlet. I do have a 2000W inverter I can bring and easily hook up, but that's more of an emergency use case run my fridge or freeze in the house in a power outtage.

Hope this helps.

I think some lithium batteries have a heater built in to allow them to charge in freezing temperatures.

 

[DINOZR]

I do have a 2000W inverter I can bring and easily hook up, but that's more of an emergency use case run my fridge or freeze in the house in a power outtage.

What is your setup for the inverter? How does it connect to the AUX batt? An inverter is probably the one useful thing my system is lacking.

 

[amREADY]

I keep all my 'travel' energy needs 12v, so I use those outlets.

The inverter has two leads and I just connect it to either my main battery or Aux battery for emergency use. The Aux battery is in a trolling battery box with fused posts so it is easy enough to connect.

 

[amREADY]

I should add:

The inverter has two leads and I just connect it to either my main battery or Aux battery for emergency use. The Aux battery is in a trolling battery box with fused posts so it is easy enough to connect.

The reason I said I might connect it to my main battery is the 1500W load of a fridge or freezer pulls about 75Amps and that would either overload my little 25A DCDC charger and system. So in those situations I'd connect to my main battery to get juice straight from the alternator/battery. I mounted the inverter to a board (reduce risk of shorts) and idle the truck or car to cycle the fridge or freezer for a while. This is only an emergency use case bcs I wouldn't normally idle my truck for an extended period. Would tide me over to setting up my genset.