Adding Inverter

[Tal_IL]

I am thinking of adding a basic inverter to my class A rig. I just want to make a single outlet available in the kitchen. My layout will very easily allow me to connect a basic inverter to my house batteries.

I had an opportunity to pick up a 2000/4000 watt inverter, which would easily meet my needs. In reviewing the specs and installation instructions, I found the expected warning to only connect to 12V systems. But, I also found this: "use only 12 v batteries with this item". The installation instructions show diagrams for wiring both 2 battery and 3 battery banks using 12 v batteries in parallel only.

My 12V system is a pair of 6 volt batteries in series. Anyone know why an inverter can't be connected to a pair of 6 volt batteries in series?

[BFL13]

Sam Spade wrote:

BFL13 wrote:

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.

If you are going to give advice, you need to make it complete.
You said nothing about adding a fuse or changing fuse sizes.

And the voltage drop would occur at the load end of the thin wire.
The inverter end would be just fine.

Agreed. Although I did mention the fuse. You make a good point.

[Sam_Spade]

BFL13 wrote:

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.

If you are going to give advice, you need to make it complete.
You said nothing about adding a fuse or changing fuse sizes.

And the voltage drop would occur at the load end of the thin wire.
The inverter end would be just fine.

[DrewE]

Tal/IL wrote:
Thanks for all the info. This isn't gonna happen before she goes into winter storage, so I'll have some time to scope things out further.

Cables to batteries can easily be short and heavy. As for outlet wiring, I grew up in the residential construction business and was always told 14-2 was OK for lights, but 12-2 w/ground for outlets.

It's a little different, actually. Either one could be used for outlets or for lights. 14 gauge wire can't be used for circuits greater than 15A (as determined by the breaker or fuse), and 12 gauge wire may not be used for circuits over 20A. The code does generally allow 15A outlets (i.e. standard ones with parallel flat prongs) on a 20A circuit provided there is more than one socket. Since virtually all receptacles are duplex receptacles, this is not a hard restriction to meet. All circuits these days should have a ground. (These are the general rules; there are some exceptions in esoteric circumstances that one is not likely to find in residential wiring.)

It is perhaps more common to find 15A circuits on lighting circuits than on circuits for outlets, if indeed the two are separated that way. At least around here, it's probably more common to have lights and outlets mixed together on 20A circuits in whatever manner is convenient and sensible.

[Tal_IL]

Thanks for all the info. This isn't gonna happen before she goes into winter storage, so I'll have some time to scope things out further.

Cables to batteries can easily be short and heavy. As for outlet wiring, I grew up in the residential construction business and was always told 14-2 was OK for lights, but 12-2 w/ground for outlets.

[theoldwizard1]

westend wrote:

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.

Then the OP should be sure to buy a 20A rate outlet (5-20R).

[theoldwizard1]

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

While that statement is correct, I would still recommend a pure sine wave inverter just so that the OP can run electronic devices without issues.

Microwave ovens struggle on modified sine wave inverters but run fine on a pure sine wave inverter.

[2oldman]

theoldwizard1 wrote:
I have no idea how your house batteries are wired, but I would NOT assume that the engine will charge them.

x2, or very quickly.

[theoldwizard1]

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.

[DrewE]

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.

[westend]

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.

[theoldwizard1]

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.

[BFL13]

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.

[SoundGuy]

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]

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.