I bought a chevy express van which came with a battery isolator and 2nd battery. I recently bought a small 200w space heater and when I plug it in, it turns on and off every second. Any idea what it could be causing this issue?

 

Have you tried something with less draw, like a phone charger? Or try the heater in the regular circuit (to make sure the heater isn't the issue). Then maybe have the battery checked. I don't know about the heater, but low voltage might cause it to do that.

I'd be interested in knowing more on the heater. A buddy of mine has a charter boat, and needs something substantial to defog the windshield. If it moves enough air, and isn't too tall, it might do the trick.

 

The inverter has to be big enough to feed the heater. Do you know what Wattage is the iverter capable of doing?

 

Well, lets take a moment to correct the terminology. A 'Battery Isolator' will not power anything. All an isolator does is electrically separates one battery from another, so that they are electrically isolated. You might have an isolator on your truck, but you must mean you have an inverter as well. An inverter takes 12 volts Direct Current and changes it to 120v Alternating Current. Seeing that electric heaters are typically very large current consuming hogs, I would tend to lean on the idea that is mentioned. Your inverter cannot supply enough current. You need to check the amperage ratings of both. The amperage of the heater and the amperage of the inverter.

In case you do not have an inverter and you are using a DC heater, same thing, check the amp draw of the device. Maybe the battery is shot. Perhaps that is even likely as there is a good chance it was constantly run down and never maintained.

 

You didn't say if the heater runs on 12Vdc or 120Vac. I'm assuming it's 120V, since a 12V would require a very chunky connection, so that means you're probably plugging it into an inverter. The factory inverter GM puts in is only rated for 150W. Not enough. For inductive loads (spinamathings like motors) you need some extra margin too. It was intended for little accessories. Phone/laptop chargers and whatnot. If you want to run bigger appliances (fridge, microwave etc.) you'll need a much bigger inverter. You can get 2,000W models.

 

What both gentlemen said. I didnt know these vans came with inverter. The one I have I think was part of the conversion. Its somewhere there, doesnt work anymore as it cant fire not even a small lamp.

 

From 2015 on, GM includes an Inverter. The outlet is in the dash, second slot to the left of the passenger cigarette lighter, among those little blank plates. I believe it is 150W. My 2015 had it, my 2014 doesn't.

 

 

To add another tidbit. Some inverters that have higher power ratings also come with more than one connection option. Mine has a 12v outlet/cigarette lighter plug for using up to 150 watts, and battery terminal clamps for getting its full potential.
To run a 200 watt heater, you most likely need to connect your inverter direct to the battery.