The Electrical Layout
The following describes Spotto’s electrical system as far as I know. I’m sure there are aspects of the system that I missed or don’t know about so please cut me some slack. Thanks.
Spotto has two 12 volt batteries. The first is a regular car-starting lead acid battery that lives under the driver seat. This battery is sealed so I don’t need to add water – thank goodness. The second battery (house battery) is an AGM Deep Cycle battery. It’s also sealed and is an Exide MSDC24 92Ah 20hr. The starter battery – does just that – it starts Spotto. The house battery powers all the lights, the inverter, the USB port, the water pump and the refrigerator. There are two banks of three switches, there is a volt meter to check battery level, a USB port and an outlet powered by the inverter. The inverter is a 300 watt pure sign wave inverter that lives behind the head of the driver seat.
The first bank of three switches (left side) control the following from top switch going down:
- 1. Dome light close to cab
- 2. Dome light above bed
- 3. Refrigerator.
The second bank of three switches (right side) control the following from top switch going down:
- 1. Inverter
- 2. USB Outlet
- 3. Not used – until now!
I converted one of the unused switches so that I could cut power to the refrigerator at night right before we go to bed. Previously I had to get up, open the slider and go out to the back of the van, open the rear door and push the off button on the fridge itself. The fridge isn’t accessible from the inside of the van. A real hassle when you are about to fall asleep. We have to turn the fridge off at night because unfortunately the house battery does not produce enough Amp Hours (without being charged) to keep the fridge running that long.
The Charging System
As normal, the van’s starter battery is charged by the alternator. The house battery is connected to the starter battery via a Dual Battery Isolator. It is also charged when the van runs – same as the starter battery. I also purchased a portable 120 watt solar charger that I hook up when it’s sunny and we are not moving. I connect it directly to the house battery so only that battery gets charged. The portable unit comes with a built in PWM solar charge controller as opposed to an MPPT controller. A PWM controller is usually better for small systems. Finally, we have a voltmeter with a toggle switch to check the current voltage of each battery.
In this photo: the house battery and, in the back, the Isolator. This battery lives on the floor below our cabinets directly behind the drivers seat. Notice our spare 25 liter water tank to the right.