Rv inverter

[Bottomland4x4]

I was in a friends rv over the weekend and I noticed he was running all sorts of electronics and no generator. I asked him about it and he has a large inverter that powers just about everything, even the ac! He had a xantrex I think control panel. It was a really nice setup and I think he has a bank of 6 house batteries. I would like to upgrade my converter to this type of setup, I don't care about running the ac that much but it would be cool to be able to use all the outlets and such. He was driving about a 2008 Alfa see ya motorhome.

Any ideas? I'm just thinking out loud. Lol.

[bushpilot]

Probably have one of the Freedom 458s or Freedom SW.
need a minimum of 4kw just to keep all that stuff running and even more for surge.

the Freedom SW's can be STACKED either in parallel (doubling the wattage) or run in series (for phased voltage).

the SW 3012 is 3kw (6kw surged) is about $2000, plus controller/remote

RV Inverter Charger | Recreational Vehicles | Xantrex

[Bob86ZZ4]

I've got a 2k Xantrex running just my refrigerator. I also have a 600 watt one running my two flat screens, dvd player, surround sound, and phone/laptop chargers. I run them on my 4 golf cart (6 volt) batteries. I can run everything for quite awhile before needing to charge up.

[Bottomland4x4]

I have a small 500w cobra running my 32 inch tv, satellite, and surround sound. I just think it would be nice to be able to use the factory outlets without the generator running. I would like to run all the outlets off the inverter and leave the ac and fridge off. I would like to upgrade to 4 house batteries instead of the two I have now, just to make it more convenient. I wonder what would be a good way to charge house batteries from the main engine when driving down the road. Has anyone ever added another alternator to the mbe 4000?

[bushpilot]

Our coach (mbe4000 w/ single alternator) charges the house batteries when the engine is running.

If yours doesn't I would be surprised.
Further the factory alternated is sufficient to keep up and charge our (3) house batteries.

Does your choach have an emergency gen start (battery combine) switch ? If so then your house and chassis / engine batteries are already wired together via an isolation relay.

[Bottomland4x4]

I do have the emergency gen start button, however I could not get it to work. My house batteries are about 3 years old and are going bad. Over the last weekend I had to jump off the generator/house batteries about 3 times due to running them down too low. I have a digital battery readout and when the emergency start button on it would show no change in voltage. My batteries dipped into the 10.5 volt range when dead.

[Bottomland4x4]

I wonder if the isolation relay is bad? Wonder where it's located?

[bushpilot]

One way to check, put a meter on some 12v circuit of the house....measure the voltage, then start the chassis / engine - if the voltage increases then you know the engine/alternator is charging the house batteries.

chase the house batteries positive cables and see if you have one running to an isolation relay (mine is mounted on the frame rail near the house or engine batteries (I can't remember precisely).

[Bottomland4x4]

I will try that, when I tried the emergency start the voltage did not change, but the engine was off. I will try it with the engine running.

[Bottomland4x4]

With the engine running there is no change in voltage when the emergency start is pushed on. I think something is disconnected or a fuse is blown, when I bought the toter they were having issues keeping the generator running. I done a full service and have not had a single problem with it. I believe the fuel filter was the problem before. Maybe they used the emergency start and blew a fuse or something?

[bushpilot]

on our coach -

the engine batteries are isolated (not charged by shore power or the generator).
the house batteries are charged (by the engine alternator) going down the road or at idle.

the house batteries are charged by 1) the converter charger (on shore power) and 2) the generator alternator (I believe) when it's running.

#2) above Im less certain of, since usually if the generator is running then the converter/charge is running too.

I would look for and test the isolation relay between the house batteries and chassis/engine batteries....If you don't have one, you should add it (theyre cheap).

[Bottomland4x4]

I think my engine batteries are totally isolated from the house batteries. Driving down the road the engine does not charge the house batteries and the generator does not charge the engine batteries.
When stored in my garage I keep the unit plugged in and I put a battery tender on the engine batteries to keep them 100 percent. I would like a way to charge the house batteries while driving, I'm thinking of adding a battery disconnect and connect them together, then I can shut it off if needed and I can turn it on to start the generator if I drain the house batteries too far down.

[ChiefMechanicMark]

I would suggest installing a continuous duty solenoid (NAPA has these, ST85 is the part number I believe.) between the positive points of the chassis and house batteries. Preferably not the actual posts as this is a corrosion point and the fewer the wires the better. Use a junction block it at all possible feeding it with a large gauge battery cable. If you wire the pull in coil into the accessory side of the ignition switch it will keep from connecting while cranking but will allow you to charge both sets off the alternator while driving. The big risk is if you have run the house batteries way down and then parallel them to the chassis you run the risk of over charging the chassis batteries while driving since the alternator is going to pick up the low voltage on the house batteries so the amps will be cranked up to charge them. Alternators are a battery maintainer not a battery charger.
Option two is to put the continuous solenoid on a switch so you can control when the batteries are paralleled.
I do not recommend battery isolators as what they actually do is click back and forth between the two sets of batteries and have a tendency to cause alternator failures due to the no mans land when switching so the alternator goes gang busters charging nothing and shortens their life substantially
Lastly if you were to install a good quality on board battery charger for the chassis batteries I would suggest at least 5 amps per battery (Group 31 for most trucks) plus any other loads you may have like flashlights or tool battery chargers that are not 110 volt. If you wire it into your shoreline connection it will always keep your chassis batteries up too.
Good Luck!!

[bushpilot]

Originally Posted by Bottomland4x4

I think my engine batteries are totally isolated from the house batteries. Driving down the road the engine does not charge the house batteries and the generator does not charge the engine batteries.
When stored in my garage I keep the unit plugged in and I put a battery tender on the engine batteries to keep them 100 percent. I would like a way to charge the house batteries while driving, I'm thinking of adding a battery disconnect and connect them together, then I can shut it off if needed and I can turn it on to start the generator if I drain the house batteries too far down.

It would be unusual for the generator to charge the chassis/engine batteries.
The house (converter/charger) doesnt (usually) charge the chassis/engine batteries either.

when stored I, too, keep a battery tender / maintainer (that can support multiple batteries) on the engine batteries.

You need to be careful and confirm that the house converter/charger is also a "maintainer" (charge wizzard). our coach was built w/ a cheap parallax (iirc) that only "trickle" charged the house batteries - it could/would boil the batteries dry if not periodically monitored....luckily for us that converter/charger gave up the ghost and we replaced it w/ a Progressive Dynamics converter/charger and added the Charge Wizzard.

we have battery disconnects on all the batteries (between the house & house batteries...and also between the engine and the engine batteries).

it would be cheaper (and more automatic) to add a battery isolation relay between the engine batteries and the house batteries - that way you wouldn't have to mess w/ a switch (or forget when he switch was in the combined position).

BlueSea Systems makes some (more sophisticated) relays & switches if you wanna get fancy....otherwise a trip to NAPA etc will do.

I like the BlueSea stuff, because they won't combine batteries if the voltage ISN'T at a CHARGE level -

https://www.youtube.com/watch?v=vPhD7fgYq3w

https://www.youtube.com/watch?v=dyzgfLTQruA

[ChiefMechanicMark]

I agree on it being unusual for a generator to charge the chassis batteries.
That is why I would suggest installing a permanent on board chassis battery charger sized properly to the batteries. Just makes life a little easier when you get parked so you don't have to drag out a battery tender and extension cord to open a battery box and connect everything.
IOTA makes a compact reasonably priced charger that could be mounted in a vented compartment easily. They come in various ratings but are all the same physical dimensions. I would recommend on wiring into the switched A/C power source so it would be on with or without shore power connection so any time there is A/C power you would be charging the chassis batteries. You could put it on a switched A/C power circuit to avoid turning it on while operating the inverter.
I am assuming most people do not run their generator while driving down the road. We all know what happens when you "Assume" things though...

[bushpilot]

Originally Posted by ChiefMechanicMark

I am assuming most people do not run their generator while driving down the road. We all know what happens when you "Assume" things though...

Mark -

we run the generator as we need it....but less now since our Old English Sheep dog passed away last year

In the (Texas) summer - with passengers along for the ride (i.e.: kids, dog, beer drinkin' race buddies) we run the generator to power our rooftop air conditioners, we've never had an issue running the gen while driving.

[ChiefMechanicMark]

I wondered about the roof A/C issues while driving. (Sorry about the dog...) That was why I commented about using the onboard battery charger while driving as this can cause issues as well to the alternator on the chassis. If you installed an outlet for the charger that is switched you could turn off unit while driving.
The other way to do it is just leave it wired to shorepower side only but have the ability to move the cord to your generator output when parked for long periods of time.
Gotta Go!! Fire Call!

[bushpilot]

Large pusher conversions (Prevost, ForeTravel, Newell, etc) sometimes have Over the Road A/C units (separate) ac compressors to cool the "living" area of the coach while moving down the road. IIRC they usually have 2 or 3 extra A/C compressors - belt driven by the engine to run the compressors....no need for them to run a generator going down the road.

those that DONT have Over the Road A/C generally have large banks of (6-8) batteries and inverters than can support the rooftop or basement air conditioners, so they don't require running a generator while moving down the road.

The pusher (conversations) have upwards of 1/2 a dozen alternators to keep all those batteries charged while the inverters are powering the roof air and everything else in the coach....skip to the 9:05 minute mark.....count the alternators in this video of a 2015

Prevost

[Bottomland4x4]

Wow! That prevost is crazy! I've seen them build them on a few different tv shows, it amazes me at all the different systems that are incorporated in them.