Camper Van Electrical – Add Inverter

Introduction

This section covers adding a 1500 watt pure sine wave inverter to the basic electrical system.

This will allow you to use 120 VAC home appliances, even when you don’t have shore power to plug into – as long as they don’t exceed the 1500 watt capacity.

GoWISE 1500 watt sine wave inverter

The electrical system flavors described on this site include this one that has a standalone inverter and can be paired (if desired) with separate shore power charger, OR a version in which the inverter and shore power charger are combined in a single unit. You want to pick one of these (not both!) – this page gives some of the pros and cons of each.

I chose this GoWise inverter because I think it is a good value. Its not a high end brand like Victron or Samlex, but it gets good reviews, and it has a US support contingent. The testing I did on it, which included running it right at the top end of its wattage range for significant periods, using it to run sensitive devices like microwaves, and running it with high loads at low supply voltage all turned out very good. If you have negative experience with this inverter, please let me know. There are, of course, many other inverters out there to choose from, so lots of alternatives if you don’t like green:)

One thing I should mention is that if you use this inverter to power large loads (eg a small microwave) with the two golf cart batteries, you are living near the maximum capability of the golf cart batteries. You should start with fully charged batteries, and you may find that for extended runs that you have to run the engine at the same time. The two LiFePo4 batteries run these kinds of loads with more margin.

Wiring Diagram

This is the Base System wiring diagram with the inverter added – its green!

Inverter (green) added to base wiring diagram
Hook the 12 volt terminals on the inverter to the Safety Hub

Wiring

There are only three wires to hookup 🙂

Connect an AWG #2 cable from the positive (red) terminal of the inverter to one of the 4 high amperage fused terminals on the Hub. This cable has 5/16 th inch (or M8) lugs on both ends. If you have a torque wrench, use 180 in-lb. The fuse at this position on the Hub should be a 200 amp AMI fuse (don’t forget to have a spare).

Connect the negative (black) cable of the same size in the same way as the positive lead. Any of the larger negative terminals on the Hub can be used, and you can double it up with another load if needed.

Try to keep these supply lines from the Hub to the inverter as short as possible – the longer they are, the larger the voltage drop in these very high current wires.

Connect a wire from the grounding lug on the inverter either to one of the negative lugs on the Hub, or to a carefully prepared chassis ground. Use at least AWG 6 for this ground wire – note that the one shown in the picture is too small and has been replaced.

Use the pictures for guidance, and leave a comment if you have a problem or question.

Showing inverter with power outlet strips.

As the picture above shows, the AC side wiring for our system is no wiring – all you do is plug cords in. To keep things simple, separate power strips are used when on inverter power and when on shore power. When on inverter power, you plug into one strip, and when on shore power plug into the other strip. There is no AC distribution panel and no AC circuit breakers (except inside the inverter) and I don’t have AC outlets spread out all over the van. I had all these on the first version of the van and, in truth, they were a total waste of time an money. The only outlet we ever used was the one by the galley. So, this time we simplified it down to what we actually use, and the result was no wiring to do. Just plug one power strip into the inverter outlet and another into the shore power outlet. The van only has 60 sqft of floor area – one outlet is fine for us.

They do sell transfer switches that will change over from getting AC power from your inverter or from shore power automatically. But, the two plug strips is satisfyingly simple to me.

If you decide to DIY one of these transfer switches, be sure to read up on how they work. At the same time you switch from shore power to inverter power, the point at which the neutral is bonded the ground must be changed – if you are not sure what this means, then don’t DIY it until you do.

Battery Imposed Limits

For two golf cart batteries that are charged and in descent condition, I believe an inverter output wattage of about 1150 watts is sustainable. This is enough to run a so called 700 watt microwave (700 watt microwaves actually use about 1100 watts – the 700 watts is “cooking power”). This corresponds to about 120 amps input to the inverter with the voltage dropping down just below 12 volt. I would like to hear what other peoples actual experience has been.

For the two SOK batteries, the usable output is higher. My testing indicates it will run the 1500 watt GoWise inverter at full power sustainably, and with less battery voltage drop than the golf cart batteries.

So, this is one area that favors the SOK LiFePo4 batteries. If you want to run sustained higher wattage inverter loads you will be better off with the Li batteries.

Larger Inverters

The Bluesea Safety Hub 150 can handle inverters up to about 1800 watts hooked directly to it as we show for the GoWise above. Inverters larger than this cannot be hooked to the Hub and should be handled like this…

Please let me know in the comments if see any errors or misleading info here, or if more info should be added, or if you had any problems.

Gary 7/16/22

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