Adding Inverter

Tal/IL wrote:
I recently read an article about cooking on the go, using a crock pot via an inverter. The gist of it was when traveling to a destination where you will arrive late, you put dinner in the crock pot, set the crock pot in the sink to secure it and it cooks on the road so you have a hot dinner ready when you arrive. Seems like a good plan.

The crock pot would draw 850 - 1,000 watts, but I like to have excess capacity. And I'll be able to locate the inverter close to the battery bay.

We have 484 AH of battery, a Xantrex Prosine 2.0 inverter connected with less than three feet of 4/0 (0000) cable. Our inverter will draw the batteries down to less than 12 Volts when run for more than a minute. Short fat battery cables are critical.

We have also used a crock pot as you plan but it is a small one and draws less current. Note that a 1000 Watt load will draw over 80 amps at 12.0 volts and a 850 Watt load will draw about 70 amps. Note also that vehicle alternators are not designed to provide high current for sustained periods.

We now have a trimetric with shunt that shows the true battery output or input current. We haven't used the crock pot since but we do run the fridge on electric which draws about 40 amps from the battery. With the engine running and the sun shining (we also have 420 Watts of solar panels) there is a net gain of a few amps to the battery when the fridge element is drawing power.

I think you plan may be doable but keep an eye on battery voltage.

One caution... I hard wired a surge protector last year. I added an inverter this year. The inverter has terminals for + an - and a ground post. I connected the ground to the chassis. The surge protector didn't like it when I turned the inverter on. Turns out that connecting bothe the - to the batteries and the ground to the chassis created a ground loop which caused the surge protector to do it's thing. I disconnected the chassis ground and it works fine.

One caution... I hard wired a surge protector last year. I added an inverter this year. The inverter has terminals for + an - and a ground post. I connected the ground to the chassis. The surge protector didn't like it when I turned the inverter on. Turns out that connecting bothe the - to the batteries and the ground to the chassis created a ground loop which caused the surge protector to do it's thing. I disconnected the chassis ground and it works fine.

BFL13 wrote:
If the big wattage inverter is at a low price or even free, grab it. The number of batteries and how fat the wiring and fuse size has to be depends on what you are actually running with the inverter; not on what the inverter "could do."

This is BAD advice. What if another family member or the next owner plugs in some high current device ?? The first thing to fail will be the part that is the most under-rated; in this case the sub-standard wire.

N7GLD wrote:
One caution... I hard wired a surge protector last year. I added an inverter this year. The inverter has terminals for + an - and a ground post. I connected the ground to the chassis. The surge protector didn't like it when I turned the inverter on. Turns out that connecting bothe the - to the batteries and the ground to the chassis created a ground loop which caused the surge protector to do it's thing. I disconnected the chassis ground and it works fine.

Although you haven't told us just which "surge protector" you have Progressive Industries' warning in the EMS-PT30C Owner's Manual is sage advice -

"Warnings

Never plug the EMS into an inverter."

Just because it seems to "work" doesn't mean it's a good idea. :R Back when I first wired my own inverter to feed the trailer "whole house" I heeded this warning and removed the EMS from the circuit, only using it when on shore power ... yet another reason it's far simpler to wire dedicated receptacles in the trailer directly to the inverter's output so the inverter's 120 vac output isn't connected in any way to the trailer's electrical system.

Sam Spade wrote:

BFL13 wrote:
If the big wattage inverter is at a low price or even free, grab it. The number of batteries and how fat the wiring and fuse size has to be depends on what you are actually running with the inverter; not on what the inverter "could do."

This is BAD advice. What if another family member or the next owner plugs in some high current device ?? The first thing to fail will be the part that is the most under-rated; in this case the sub-standard wire.

No, the first thing to go would be the fuse correctly sized to protect that wire. Also running the bigger load with the thinner (but properly fused) wire would cause the inverter to shut down at low voltage from the big voltage sag.

pianotuna wrote:
Hi,

Use #12 wire (or #10) from the inverter to the outlet you wish to install. Look for a 20 amp outlet at Home Depot.

#12 is overkill for a 2000 watt inverter. 14/2 Romex is fine.

theoldwizard1 wrote:

pianotuna wrote:
Hi,

Use #12 wire (or #10) from the inverter to the outlet you wish to install. Look for a 20 amp outlet at Home Depot.

#12 is overkill for a 2000 watt inverter. 14/2 Romex is fine.

If you would believe the NEC and best residential wiring practices, 12 AWG is the size of wire for that load. The load can be greater than 15 amps at 120V. Pianotuna is correct.

Are you sure your crock pot is 850-1000 watts? Most slow cookers are actually around 300 watts or so at most. If it's a dual-use sort of appliance it may have a much larger heating element and some sort of thermostatic control, in which case the higher wattage could well be correct, but very likely if it's a slow cooker with a crockery insert it is relatively low powered. Examine the label on the cooker to find out for sure.

If your crock pot does not have digital controls there is absolutely no reason to need a pure sine wave inverter for it.

Tal/IL wrote:
I'm thinking "extra capacity" in terms of inverter capability. I only expect to use it when traveling and my assumption is the alternator would keep the batteries from being depleted.

I have no idea how your house batteries are wired, but I would NOT assume that the engine will charge them. You need to verify.