Community Forums

StansCustoms · 05-25-2011, 08:34 AM

I wa sjust browsing another thread that Monty mentioned the alternator not holding up on his Apex when using the inverter.

I'm curious how the inverter is supposed to be used ...since I have never had one, and never used it that I know of.

...and what you can expect from it in regard accessories it will safely power.

BryanL · 05-25-2011, 09:59 AM

A 2kw inverter provides about the same power as a single typical household circuit and should power anything with a 15 amp 120 VAC plug on it.

The inverter runs off batteries. It needs to be properly wired, especially when loads get above a couple hundred watts. A 2kw inverter should have at least 200 pounds of battery powering it.

Most engine alternators can't handle normal loads plus a large inverter load. For the short term that shouldn't be a problem because the batteries should pick it up but if they can't, the alternator will be asked for more than it can provide.

Note that, like a household circuit, you generally don't run at full loads all the time. When using an inverter, it is usually a good idea to keep large loads on for only a short time. Think microwave for a few minutes or a coffee maker doing a pot or a hair drier for a few minutes. The smaller the load, the longer a 'reasonable' duty cycle might be.

Also keep in mind that 200# of battery only has about 2.4 kWh of available energy (12 watt hours per pound). That rating is at at about 200 watts, which means about 12 hours runtime. Higher power draws than this will reduce the available battery energy quite a bit.

Another factor is inverter efficiency. They often run 85% to 95% efficient and will provide that over a range of about a quarter to three quarters the inverters rated load. The inverter will also tend to use several watts of power in standby as well and that can add up.

An inverter can be quite handy for running standard AC appliances off your battery when the battery energy limitations are properly considered. Things like the microwave or other such conveniences can be run without having to fire up a genset all the time. With a good solar system, you can even run a standard household fridge rather than the typical RV absorption type.

but you can also get by without one - choose your lifestyle!

**JohnRR** · 05-25-2011, 10:11 AM

Thank you Bryan for the answer to one of the questions I had not thought about yet.

RJay · 05-25-2011, 10:32 AM

Judging from your rig I would guess your alternator is rated at about 140 or 160 amp. At 160 amp the alternator would produce about 2000 watts. Given the normal 12 volt load of the chassis while underway plus whatever load the inverter requires would put a hefty demand on the alternator. Not knowing what load your inverter is powering I would suggest limiting AC loads or run the generator while underway.

Wanabee FTer · 05-25-2011, 11:02 AM

I have found that my 600w Prosine inverter will run most anything I need within reason. If I need to use the microwave or toaster I fire up the genny for a few minutes then go back to inverter power. I don't have the room necessary for a large battery bank, but happy with my setup the way it is.

DrDaveMA · 05-25-2011, 12:46 PM

Stan,

Someone with a 2001 can repond more accurately, however Alpine typically put about half the 120 volt outlets on the inverter. The lights over the couch (the puck lights) are 12 V halogen and will draw a lot of power. Search for the thread on LED lights, you can convert from halogen to LED and cut your power consumption to 10% of what the halogens run

.

There are several threads on boondocking (running on the battery bank/inverter) that have some good hints on extending your non generator time.

We have a residential refrigerator so I leave our inverter on whenever we are in the coach, shore power or boondocking it. Whenever we need to run the microwave if we are not on shore power I run the generator.

StansCustoms · 05-25-2011, 04:29 PM

I don't know diddly about the invertor...I guess, including how to determine if the thing even works right.

My dash air needs to be charged..and since I haven't fond the refigerant leak yet I don't want to waste the refrigerant on this upcomming weekend trip.

Sooo ..i was wondering if I could run a roof air while traveling on the inverter. At a gallon an hour on the gen set ...it kinda puts a dent the fuel consumption. Of course...that may be too much of a load for the batteries/alternator. Or may not even work that way at all.

Another thing that I have and don't have any information/manuals on is solar panels. I have two mounted on the coach...but don't know if they are functioning...or anything else about them?

JLMunsil · 05-25-2011, 04:42 PM

It's only needed when you want to use something that runs on 120V when you are not plug in to shore power or running the generator. Most of the lights and 120V plugs will work on the inverter. Some will not. They don't work unless you are using shore power or the generator. I leave the inverter all the time when I am using the coach so I don't have to reset the clocks when we stop for the night. I turn it off when it is parked not being used. This reduces the draw on the batteries.

RJay · 05-25-2011, 04:43 PM

There is no way the roof airs will run on the inverter. You don't say what size your generator is but judging from your rig I would guess you have no more than a 7.5 Kw Onan, in which case you would use no more than 1/2 gallons of fuel per hour running the front A/C.

JLMunsil · 05-25-2011, 04:45 PM

The a/c will not run using the inverter. You have to start the generator and run it while going down the road to use the a/c.

Dale777 · 05-25-2011, 05:10 PM

To clarify a bit on the inverter versus the engine alternator:

What folks sometimes call the inverter on an Alpine Coach is actually a combination unit - both an inverter and a charger, sometimes called an inverter/charger.

1. The inverter function of the combined unit INVERTS the house battery bank 12V DC current to 120V AC current.
2. The charger function of the combined unit CHARGES the 12V DC house battery bank by using 120V AC current from the shore power connection. If the house battery bank becomes fully charged, then the large relay in the battery compartment connects the house battery bank and the starter (chassis) battery bank together so that they both charge.

When the inverter provides 120V AC current on an Alpine Coach only a small sub-set of the 120V AC outlets are provided this current. You will need to test each outlet to determine which is which, since some models are different and WRV changed the build over the years.

The engine alternator primarily charges the starter (chassis) battery bank, but when that battery bank is fully charged, then the large relay in the battery compartment connects the house battery bank and the starter (chassis) battery bank together so that they both charge. So, you can see there is no relationship between the engine alternator and the inverter/charger.

On an Alpine Coach, the inverter function with the house battery bank does not have sufficient capacity to run either one or both of the roof air conditioner units.

Old Scout · 05-25-2011, 05:15 PM

You couldnt run your A/C units thru the inverter even if you wanted to--yr roof A/Cs are wired thru the shore power/genset side of yr electrical system not thru the inverter. Fact is, on a really hot Texas day, yr dash air wont keep the front of the coach cool [thought some hang a curtain behind the drive/pass seats] so the genset and roof a/c is needed anyway. I am not trying to be critical but if 3/4 of a gal of fuel per hour for your genset is too much impact on your fuel mileage, you may have bought the wrong vehicle.

wa8yxm · 05-25-2011, 05:16 PM

As with so many things it depends

There are basically two "Depends" on this

One: how it is wired
Two: Make & Model (Actually the type which we can determine from make and mdoel)

For example. I have several inverters lying about all but one collecting dust.. That one is a Xantrex Prosine 2.0.. It is basically 3 things.

1: Interupptable power supply, though I have a light that does indeed blink when power transfers to the inverter, neither my computer no my televisions seem to notice. In this case I leave the inverter on full time and the presence of SHORE POWER overrides and puts it in "Standby" It powers Televisions, Microwve and the GFCI loop (All the GFCI protected outlets in the house,, I modified so it can optionally power the bedrrom (Which are NOT GFCi, and fridge/ice maker. I do not use it to power the fridge,, Just the ice maker (I manually lock the fridge on Gas when driving)

Others may need to be turned off, or manually switched over, All depends on the installation.

StansCustoms · 05-25-2011, 05:33 PM

Quote:

Originally Posted by RJay

There is no way the roof airs will run on the inverter. You don't say what size your generator is but judging from your rig I would guess you have no more than a 7.5 Kw Onan, in which case you would use no more than 1/2 gallons of fuel per hour running the front A/C.

Well that is a surprise..I thought it was considerably more. And yes this rig does have a 7.5 Kw Onan.

..my old 6.5 Kw gas generator is considerably more expensive to run than the diesel in that case.

We boon dock a lot and some times that meant I would have to uproot and go buy gasoline in my old coach....