Let's talk about RV Inverters

The short answer to your question is YES,

But there is a much longer answer:

Inverters come in 2x2xMANY types and sizes

First split: True sine wave v/s MSW (Modified sine/square wave) Go for TSW, I used to think the MSW units were more efficient and thus would last longer on a given battery charge.... Till I did the research and found they are very nearly identical in effiency, might make 10 minutes difference on my batteyr bank, if that.

MSW has a list of "Things that may not work well" This includes all sorts of electroincs, Night Lights, electric blankets, anything with a digital timer, among other things.. Even one coffee pot I used to have.

TSW the list is much shorter: (Anything needing too much power).

The next split: Stand alone/Inline.
Inline units work like a UPS, they replace your converter as well There are advantages to both these intergrated converter/charger/inverters and to separate units, I can make no recommendation,, I have both an intergrated Inverter/charger (Prosine 2.0) and Converter (Intella-Power 9180 with wizard).

BOTH are top end converter/chargers.

The MANY is the size, 300 watt, 600, 1000, 1500, 2000, 5000 10000, you pick the size.

How much do you wish to power?

Modern TV's with support electronics can often get buy with a Samulex 300 Watt TSW, Add in a good size HOME THEATER and you may wish to upgrade to 600 watts, add a Microwave, couple computers and such, 1500-2000 watt,

Air conditioners need around 3000-4000 watt (each) but read on,, Residential fridges need a few hundred watts.

Batteries: General recommendation is at least one pair of GC-2 six volt batteries (The two together make about a 8D or 4D battery 220-230 amp hours at 12 volt, but at half the weight of the larger 12 volt are easier to wrangle, they are DEEP CYCLE (not MARINE/deep cycle) and thus you can take them down to half full safely if you re-charge promptly)

One pair per Kilowatt, so a 2,000 watt inverter needs 2 pair, a 5KW inverter needs 10 pair. That is over 1,000 pounds of batteries.

Each pair holds about 1KWH of usable power at the overnight rate.. Perhaps a bit less.. Your A/C burns more than on KW every our so again, overnight is 10 pair.

Hope this helps.

Most RV's are wired like this.

Shore/Generator--Main Breaker box---Inverter---Sub panel

Main box --> Inverter, Fridge, Water heater, Some outlets, Air conditioner(s) and cut the lead to the converter (or in my case unplug it, or not as you wish, depends on the convrter).

Sub panel--Televisions, radios, entertainment stuff, computers, Microwave and GFCI chain.

On many RV's the "Sub panel" is built into the inverter, Mine it is not.

Normal operation (I do not do it this way) If I have shore power the Inverter/Charger senses that, passes shore power (up to 30 amps) to the sub panel loads, and charges the batteries (Normally disabled in my RV), should shore power be lost, it instantly switches to inverter mode, sucking power out of the batteries so my dinner continues to heat, the TV does not even blink. Wen shore power is restored it instantly switches back.

(In my case I use a different charger, but this is a matter of choice, in truth I rate the 3-stage + converter in the Prosine I have equal to the 9180 I use, but,,, For other reaons (Matter of personal preference) i like the 9180.

pianotuna wrote:
Hi,
Allowing for inverter inefficiency means that a 1000 watt device may consume more nearly 100 amps, not 83.

As usual you are correct. As I said, it was an oversimplified example. :)

Thanks to ALL for your insight on Inverters... That pretty much explains how they work in a nut shell... For the amount of time we go off grid... and the amount DW would like to run,,, my only solution will be the twin Generators...

Thanks Again to AlL !!

My 2000 watt inverter use 2 amps with out powering anything. As stated you have the efficiency (or lack of) factor to figure in.

I can last 5-7 days on 2 12v batteries without a inverter. This means staying outside around the campfire until bedtime and very minimal light usage and no furnace. True boondockers are switching to LED lights to relieve the load. I have a 12v television in the bedroom but it's only been used a couple of times in 2 yrs.

You'll have to figure out what you WANT to use and then what you NEED to use and for how long. These are very different answers for each of us.

ScottG wrote:
People that are new to this stuff often think they can run an inverter and use everything (like a microwave or even AC) in the RV as usual. It often comes as a surpise how quickly the batteries run down. For instance a microwave can deplete a set of 6 volt batteries in as little as 7~10 minutes.

Exactly right. I've been testing, actually using the Samlex PST-UL 2000 since its now hard wire capable (1500 too I think) and its the best I've seen for the money. I think they have an inverter/charger coming out soon too but don't need the charger side. Great units. Regardless, you can't expect an inverter to cool your coach or cook thanksgiving dinner on a pair of batteries.

Hi,

Allowing for inverter inefficiency means that a 1000 watt device may consume more nearly 100 amps, not 83.

Gene&Ginny wrote:
Lets try an over simplified example.

Watts = Volts times Amps.

If you want to run a 1000 watt microvave on 120 volts AC verses running it on a 12 volt inverter.

1000 watts = 120 volts times 8.33 amps

or

1000 watts = 12 volts times 83.3 amps

Continuous use on a 12 volt inverter would require 83 amps, that is a lit of current and requires a BIG piece of wire to handle that amount of current.

Lets try an over simplified example.

Watts = Volts times Amps.

If you want to run a 1000 watt microvave on 120 volts AC verses running it on a 12 volt inverter.

1000 watts = 120 volts times 8.33 amps

or

1000 watts = 12 volts times 83.3 amps

Continuous use on a 12 volt inverter would require 83 amps, that is a lit of current and requires a BIG piece of wire to handle that amount of current.

People that are new to this stuff often think they can run an inverter and use everything (like a microwave or even AC) in the RV as usual. It often comes as a surpise how quickly the batteries run down. For instance a microwave can deplete a set of 6 volt batteries in as little as 7~10 minutes.

Inverters.

Is yor rig 30 or 50 amps?
You can easily find inverters big enough or either size RV however... And this is a BIG however.

For each kilowatt of inverter power you need the equivalent of one pair of GC-2 Batteries (just over 100 pounds of lead) and that gives you about 1kW of usable power. An RV air conditioner needs more than this every hour.

So the problem is not finding a big enough inverter, its lugging enough batteries.

Recommendation, go with an inverter in the 2,000 or 3,000 watt range and power SELECTED systems only

Entainerment systems (Radio TV, Sat Receiver Recorders and such) Microwave, And selected outlets (GFCI CHAIN) make sure the converter is NOT powered, also do not power A/Cs Fridge or Water heater off the inverter. This should work best.

(Power outlets beside bed if you can.. on my coach that is the Fridge circuit so it is optional, Normally the Fridge is connected before the inverter, but If Im boondocking I can manually lock it on GAS and then switch the outlets over to a different circuit)

Inverter is easy... just be careful with what you expect to run and for how long as the batteries needed can stack up fast.

For extended self containment you may also need to think about 200+ watts of solar power to keep the battery up.