Inverter for Cargo Van

Greeneyes · Sep 28, 2011

Hi All,

I'm looking to get an inverter for my van and I'm confused as to the number of Watts, Amps, Volts, Etc. I need. I did read some of the old posts and I only got more confused

The items I will use it for are a Coffee Maker, a mini cube fridge, and a few small items like my electronics and a lamp. Any advice would be great.

Turtle · Sep 28, 2011

First piece of advice would be to dismiss any thoughts you may have about running all that crap off an inverter connected to your starting battery. Can't be done, so don't even think about it anymore.

You'll need a separate auxiliary battery bank. A 1500 Watt inverter will be plenty to run all that stuff. The real questions are how many amp hours should the battery bank have, and how will you recharge the bank. The answers depend on how many Watts (and amp hours) the appliances will draw from the battery bank, and for how long. Without knowing your power requirements, you cannot determine what kind and how many batteries you're gonna need.

Do a search on the forums for "inverter" and read all the results. There will be a test on Friday.

Greeneyes · Sep 28, 2011

Turtle said:
First piece of advice would be to dismiss any thoughts you may have about running all that crap off an inverter connected to your starting battery. Can't be done, so don't even think about it anymore.

You'll need a separate auxiliary battery bank. A 1500 Watt inverter will be plenty to run all that stuff. The real questions are how many amp hours should the battery bank have, and how will you recharge the bank. The answers depend on how many Watts (and amp hours) the appliances will draw from the battery bank, and for how long. Without knowing your power requirements, you cannot determine what kind and how many batteries you're gonna need.

Do a search on the forums for "inverter" and read all the results. There will be a test on Friday.

I'm glad I asked. The need for an auxiliary battery never occurred to me. Yeah, as much as I know about mechanics, I know very little about electrical systems(sad, I know).

OK, so another question this answer raised is if I know how many watts my appliances draw(per the label in the back), how do I convert that to amp hours.

Please forgive me if I end up asking too many questions on this topic, as I probably will...

LisaLouHoo · Sep 28, 2011

Turtle said:
First piece of advice would be to dismiss any thoughts you may have about running all that crap off an inverter connected to your starting battery. Can't be done, so don't even think about it anymore.

You'll need a separate auxiliary battery bank. A 1500 Watt inverter will be plenty to run all that stuff. The real questions are how many amp hours should the battery bank have, and how will you recharge the bank. The answers depend on how many Watts (and amp hours) the appliances will draw from the battery bank, and for how long. Without knowing your power requirements, you cannot determine what kind and how many batteries you're gonna need.

Do a search on the forums for "inverter" and read all the results. There will be a test on Friday.

Jeffman runs a 1000-2000W inverter with 2 6vs wired in. The 6vs are also wired into the main battery with a switch to allow them to charge simultaneously off the main while the van is running...also, a safety breaker is wired in between the charge switch and the main battery.

With this inverter and total 12v fully charged, we can run a box fan in the summer, the laptop, and charge our cell phones overnight. It isn't enough to run an electric space heater for very long. That's where heavy insulation, thermal underwear and 7 lbs. of blankets come in handy.

One note: make a conscious effort to make certain the charging switch is "off" when you shut the van off, otherwise you could be stuck on a side street in Miami Beach on a Sunday evening waiting for your road club to come jump the main battery. Just sayin'....

"Bruises fade and bones will mend-but a psyche can be ruined FOREVER" : LisaLouHoo, c. 2008

Turtle · Sep 28, 2011

Do read all the previous posts about inverters and batteries, as most any question you have will already be answered there. But the Watts on the on the label is how many Watts the appliance draws. Watts divided by volts = amps. A 900 Watt coffee maker divided by 120 volts is 7.5 amps. But since you'll be running it off a 12-volt inverter, it would be 900 divided by 12 = 75 amps from the batteries. If you run the coffee maker for one hour, that's 75 amp hours. If you run it for 15 minutes, it's 18.75 amp hours. If you run it for 8 hours, then it's 600 amp hours.

It's how many amps the appliance draws, and for how many hours it'll draw it between fully recharging the battery. If you have an 8 Watt lamp, that's 0.66 amps from the battery, and if you run it for 6 hours a day, that's 6 hrs X .66 = 4 amp hours.

Once you figure out how many amp hours you'll draw in a, say, 24 hour period, then you'd double that figure to get the minimum size of the battery bank amp hour capacity. A small cube fridge that draws 1.3 amps at 120 volts AC (156 Watts) will draw 13 amps as 12 volts DC. Over a 24 hour period the fridge alone will draw 312 amp hours. Of course, the fridge won't be running 24/7 and it'll actually draw between 150 and 200 amps, but you get the idea.

The reason you need twice as many amps hours of capacity in the battery bank as the amps you'll draw is, you don't want to ever draw the battery bank down below 50% Depth of Discharge, because every time you do it will dramatically shorten the life of the battery.

One note: make a conscious effort to make certain the charging switch is "off" when you shut the van off, otherwise you could be stuck on a side street in Miami Beach on a Sunday evening waiting for your road club to come jump the main battery. Just sayin'....

That's why wiring the aux batteries into the main battery without using a battery isolator is a really bad idea.

LisaLouHoo · Sep 28, 2011

And the isolators were installed on his fleet vans...his personal van was done by someone else, and as a rule he was good about flipping the switch. Obviously, it was forgotten this time. When he and I did the other vans ourselves, we did install the isolators on them. He didn't want to risk his drivers being stranded.

"Bruises fade and bones will mend-but a psyche can be ruined FOREVER" : LisaLouHoo, c. 2008

davekc · Sep 30, 2011

Greeneyes said:
Hi All,

I'm looking to get an inverter for my van and I'm confused as to the number of Watts, Amps, Volts, Etc. I need. I did read some of the old posts and I only got more confused The items I will use it for are a Coffee Maker, a mini cube fridge, and a few small items like my electronics and a lamp. Any advice would be great.

You may want to ask Camper.