Charging House Battery

[TeCKis300]

Here's my strategy to charge a secondary / house battery that is installed onboard. I have a 100Ah lithium battery installed in the trunk of my rig. Generally, an installed 12A Victron DC-DC charger will keep the battery topped off and onboard fridge running indefinitely with regular driving. When loading the fridge with tons of room temperature groceries or water, I want to make sure I'm topped off when setting out.

Here's how I go about charging or maintaining the house battery

1) Anderson power ports are great as they are are bi-direction power ports. Good for drawing or charging. Having at least a couple Andersons is good to charge and run things (fridge) at the same time.

2) NOCO Car charger which is multi-battery chemistry compatible. I have the Genius5 5Amp charger good for standard lead acid, AGM, or lithium (and LiFePO4). I keep this charger on board and it's good to use as a float charger for my main starter lead acid battery, or to charge and run anything in the house battery. I clip the battery terminals and terminate with Andersons.

The charger wires are thin enough route between closed hatch and tailgate.

 

[daneo]

That Noco charger should activate the Victron assuming the Victron is voltage controlled. I just clip a Noco to my starter battery and a BCDC turns on and charges my secondary battery. Your Anderson plugs are much more attractive though

 

[tbisaacs]

That Noco charger should activate the Victron assuming the Victron is voltage controlled. I just clip a Noco to my starter battery and a BCDC turns on and charges my secondary battery. Your Anderson plugs are much more attractive though

Never thought of this

 

[rlynch356]

The NoCo probably does not have the amps to charge both batteries, if you are using 12/12-18 DC-DC charger you are going to pull at least 12 amps out of the main battery when it senses the voltage rise, 18 amps at max.

if the NoCo puts out less you are basically pulling down the main to compensate, until the house battery goes into float mode.. then the main battery can charge fully...

The NoCo genius 10 for example only puts out 10amps...

I would disconnect and charge separately.
But YMMV..

 

[daneo]

You’re correct that the voltage will dip as charge moves from the starter positive node to the house battery if the charger current is smaller than the house battery charger current. But even a small 2A charger will eventually top off both batteries.

 

[TeCKis300]

Not a bad strategy for the right setup, but my setup isn't balanced to charge in that manner to @rylinch356. point. The external NOCO @5amp won't keep up with the Victron at @12amp. My house battery is also much larger capacity in the sense that it's 100Ah usable, whereas the starter flooded lead acid battery is 70Ah, but ~60% or 40Ah usable. It could work, but would deep cycle and wear the starting battery unnecessarily if done frequently.

If one were to get a larger external charger and find a space to carry it, it could be a great solution.

 

[daneo]

The house battery charger will turn off when the positive starter battery node dips to the normal “alternator off” voltage, so the starter battery doesn’t deep cycle. The starter battery will only ever dip to the same voltage that it dips to when you turn off the vehicle.

 

[Mrtwooooo]

The Orion should have the Input Voltage Lockout setting. That should make the Orion turn off when the main battery falls below a set voltage and turn back on when the voltage gets above a set voltage.

 

[Mrtwooooo]

Also once the lithium house battery gets more and more charged the 5amp Noco charger will be able to keep up better with the main battery better since the charging rate of the lithium will accept less amps the closer to 100% it gets.

 

[Valgrind]

@TeCKis300 how did you run the wires from the main battery to the trunk? Under the carpet or under the car? I’m mounting an air compressor in the trunk. Figuring i need about 20ft with 2 gauge for the 100amps.