Inverter Use

[joesolo]

Ok, folks, here goes....we started RV'ing last May or so and came from a boating background where we ran our generator almost nonstop while out on the water. The new RV has a 2000 watt inverter and 7500 watt genie. I don't mind running the genie but hate I am not taking advantage of the inverter. Should I run the inverter instead of the genie if the power consumption is less than the 2000 watts? Also, I assume while driving the inverter is continually charging the batteries so I can't drain them. This kinda puzzles me and I still consider myself quite green still. If someone is interested in helping in detail let me know. I'll give you my email address and/or phone number.  Thanks yall.

Joe

 

[Tom]

Hi Joe,

A number of us here also come from the boating world, so you're in good company.

Should I run the inverter instead of the genie if the power consumption is less than the 2000 watts?

Your neighbors will appreciate the quiet, but remember that the batteries powering the inverter will need to be recharged at some point, probably a few hours of recharging a day.

Also, I assume while driving the inverter is continually charging the batteries so I can't drain them.

Not so. The inverter batteries will be recharged from the generator, as mentioned above. On many, but not all, motorhmes the inverter batteries are also recharged from the alternator on the engine. But of course that's only true if the engine is running (typically, when you're driving down the road).

Let me know if I need to clarify this.

 

[joesolo]

Tom,

Thank you. To keep it simple, I will only use the inverter while driving. So, as you said, the alternator would charge my inverter batteries. With that in mind, is the effect the same to me for powering my AC units (one roof A/C, TV, in motion satellite) from the inverter rather than the genie? The only time I run the generator is on the road or at a Flying J for a quick overnite.

I apologize for sounding so ignorant  here but my fear is draining batteries and getting stuck. The plus side is quiet power without the wear and tear on the expensive generator (I think).

FWIW, we have had more fun RV'ing than anything we have ever done together, including boating. And if you boated, then you know how much trouble a pump out was/is. I'd have to have a nip or two and watch the wind before making the 100 yard, 45 minute escapade to the pump out station!

Thanks

 

[Tom]

LOL Joe, yes we're very familiar with marine pump-outs.

With that in mind, is the effect the same to me for powering my AC units (one roof A/C, TV, in motion satellite) from the inverter rather than the genie?

Personally, if I need to run the roof air, I'd fire up the generator. Check the power consumption on the a/c.

The following is taken from an article on inverters in our library. I hope it helps rather than confuses.

How long will an inverter run before the batteries need recharging?
This really is a function of the amount of load (number and duration of appliances used) and the type and size of batteries. The greater the load and the longer the duration the load is applied, the sooner the batteries will discharge. The larger the battery capacity, the longer it will take before the batteries discharge. It would be helpful to make a list of the appliances that will run off the inverter, their power consumption (in watts) and the number of hours you expect each to be operating during a 24 hour period.

Calculate how many batteries you need
Take your list of 120 volt appliances, power consumption in watts and estimate of operating hours and calculate the amp-hours of capacity drawn from the batteries in a 24 hour period from the formula:

Amp-hours = (watts x hours)/11 (allowing for efficiency)

The following example might help, but be sure to use the actual power consumption from the owners manuals of your own appliances and adjust for your own usage of each:

Appliance          Watts    Hours   Amp-hours
Microwave oven     1500       0.5      69
Coffee pot         1200       0.5      55   
TV                  180       3        49
DVD                  55       2        10
Computer            100       2        18
Stereo               60       3        16

Total                                 217

Number of pairs of batteries required = (total amp-hours)/110
                                      = 217/110
                                      = 2 pairs of 6 volt batteries
                                        (or 4 12 volt batteries).

 

[joesolo]

Tom,

Fantastic. That info will help tremendously. I will proceed with some degree of knowledge now.

Thank you for your expertise.

Joe

 

[Karl]

Joe,

Number of pairs of batteries required = (total amp-hours)/110
                                      = 217/110
                                      = 2 pairs of 6 volt batteries
                                        (or 4 12 volt batteries).

In this equation, you need to substitute the 110 with the ampere hour capacity of your batteries. The 110 shown here was for 6 volt golf cart batteries, which you may or may not have. Also, both 6 and 12 volt batteries come in a wide range of capacity and types, and not all types are suitable for deep-cycle RV use. I suggest you click on the "Library" button above, then select "Tech Topics", and then select "Installing an Inverter" for in-depth coverage of this topic.

 

[Tom]

In this equation, you need to substitute the 110 with the ampere hour capacity of your batteries. The 110 shown here was for 6 volt golf cart batteries, which you may or may not have.

Karl, you're correct. I used 6V golf cart batteries in the example, which have roughly 220 amp-hours capacity. If substituting different batteries, one needs to use half of the battery capacity, on the assumption that you can't or shouldn't discharge below 50% of capacity.

 

[BernieD]

Joe

I'm afraid your boating experience has too darkly colored your anticipations regarding your coach electric service . First, I assume that you have 4 house batteries in your Phaeton (total of 6 including 2 chassis batteries). That gives you over 400 amps of electric service from the batteries.

Next, the invertor, the batteries and the alternator all serve different functions tho they can be connected. All your inverter does is convert the 12vDC power in the batteries to the 110vAC power used by most of your appliances. You have a charger, usually built into the invertor to recharge the batteries. It is unlikely that you will be able to run your air conditioners off the batteries via the invertor, even while driving. You will still need to run your generator whenever you want to run the A/C (assuming no shore power). The only reason to turn your invertor on when driving is to power your refrigerator via AC rather than propane and to run any 110v chargers you may be using.

When we are boondocking, we will run the generator 1-4 hours a day to recharge the batteries and run everything else (not the A/C) off the invertor the rest of the day. I make my coffee in the morning, we watch TV, etc. off the invertor and then run the generator when the batteries get down to 40-50% discharged, usually an hour or two in the morning and the same in the evening.

The system is designed to use the batteries off the invertor. Don't be afraid of it.

 

[Tom]

The only reason to turn your invertor on when driving is to power your refrigerator via AC rather than propane and to run any 110v chargers you may be using.

That's pretty much it for us too Bernie. In addition to the refridgerator, I'm powering a PC and maybe a cell phone charger from the inverter as we go down the road, but nothing else.

(For clarification, Chris is driving while I'm using the PC).

 

[Ron]

The only time we turn the inverter off is at night or when we are not using 110 while boondocking.  When not boondocking we never turn the inverter off.  If on shore power the source of power being used will switch from the inverter to the shore power, if on the road the chassis alternator will charge the coach batteries as it does the chassis batteries.  However, the AC/s are not even wire so they can run of the inverter since it would take a lot of battery and larger capacity inverter to run the AC/s.  When we use the coach AC/s while on the road the Genset is running.  We sometimes do this just to excessive the genset from time to time in the summer.

Do not be afraid to use the genset or inverter that's is what they are for.  A Onan rep once told me that the biggest single cause for genset failure is lack of use. 

 

[Bob Zambenini]

The only time we turn the inverter off is at night or when we are not using 110 while boondocking.  When not boondocking we never turn the inverter off. 

Do not be afraid to use the genset or inverter that's is what they are for.  A Onan rep once told me that the biggest single cause for genset failure is lack of use. 

I  have a Heart 2000 inverter and have always done a lot of turning the switch at the display panel  off and on when needing AC power in coach during dry camping. But I have never been sure if this is really turning off the entire inverter as I believe its hard wired back there and its also my convertor. So maybe that switch up front is just turning off and the panel display. Anyone have a feel for this?

I don't run the inverter on the road as I figure there is a lot heat back there where its located near the engine and down near the road and rear tires. I have a little pocket invertor I plug into the cigarette lighter socket to run my computer and GPS on the road. Again, maybe it is running anyway.

I always make sure the invertor is off before starting the generator, because one day well pulled into Davis-Monthan AFB to dry camp for night and invertor was on when I started the generator and my transfer switch failed! This may have been an unrelated cause but I have been gun shy since!!!

Also, I  use the generator a lot. I have never equalized my batteries as have never had a need to. I was going to before Quartzsite this  but never had a time when I would be hooked up to short power long enough. But it was interesting to note that after a few days at Quartzsite my batteries got much stonger by using them a lot before starting the generator to recharge them. The last day there I ran all day and the night on batteries and they still had well over 50 percent.

Bob

 

[Ned]

I don't know which panel you have, but on our Link 1000 turning off the inverter really does turn it off.  If the AC goes off when you press the button, then you know

The inverter and charger are two separate devices in the same box, so turning one off won't affect the other.  We leave the inverter on at all times except when boondocking.  I doubt that the transfer switch failure had anything to do with the inverter.  The Heart has an internal transfer switch that detects shore or generator power and cuts it through when available and bypasses the inverter function.

Batteries should be used or they will lose some capacity.  It can be restored somewhat by deep cycling them as you did at QZ, but periodic discharge and recharge, even when not boondocking, can extend their life.  I periodically turn off the charger and run on the batteries for a few days even when connected to shore power to excercise them for just that reason.

 

[John From Detroit]

Re: inverter use.. How long you can run off batteries depends on two things.
1: How much are you running and 2: How many batteries (And how big are they) or How much battery

My rig came with a pair of Golf Cart batteries (Six Volt Interstate "Work-A-Holics")

They will run the entire rig for about six hours, then I need to re-charge.

Adding a pair of 12 volt class 8D AGM batteries, and seperating the loads so the inverter (Which has a setting to recharge AGM batteries) and the Work-A-Holics (Which are re-charged by the coach's native recharger) means I can run all night on batteries w/o issue.

My rig has 2 televisions, a dual DVR, sattalite antenna (Automatic) Furnance, frige (Both run of 12 volt and propane if he Generator is off) hot water (also propane, 12 volt controled) and aout a dozen or so lights that we had on during the test (Isle lights) turning them off would have extended battery life

The inverter is good for night use, when the neighbors love the quite,  The generator is used during the day or in places where the noise is not objectionable, or... Here at the house when Edison dumps the neighborhood (2 nights ago) Very nice haveing a spare 5KW in the back yard.

When I finish the power instalation I'll have a switch so the Inverter is hooked to the AGM's when parked, or when re-charging the AGM's (Generator running) but to the Work-A-Holics when driving down the road as they are re-charged by the truck alternator when we are moving.    This is kind of an advanced system.

I've had more than one occasion to be very happy with that Prosine 2000 inverter in my rig though.  And I've only had it about six months