Quick Q: Charging house battery question on a 2004 Winnie

Using the main engine to charge the coach batteries charges them very fast and ultra-quiet, as the cabling from the alternator to the coach batteries is a fairly good size, the alternator can supply up to around 60 amps at idle engine speeds, and our idling Ford V10 makes very little sound and is free of any vibration in the coach floor, however it takes around 0.7 gallons per hour to idle the big engine.

Using the 4000 watt Onan to charge the coach batteries makes a bit more noise and vibrates the coach floor just a little, but also wastes fuel because this under-loads it so much, as our onboard charger is only the stock 13.8 volt converter. (However our batteries are AGM, so with only 13.8 volts charging them they still charge fast enough for our needs using just the converter.)

So ... we use a little Honda four-stroke ultra-quiet EX650 to drive both the stock converter and a small Sears battery charger (in parallel with each other - for even faster charging of the AGM batteries) to do most of our drycamp coach battery charging. Here's a spec sheet of discontinued Honda portable generators comparing them, which includes our EX650 model, note that at it's full single speed of 3600 RPM it's noise level is only 54dB:

http://www.tappedin.com/hop/html/litegen.htm

Hi,

After blowing 3 charging fuses I replaced it with an automatic circuit breaker.

The OEM solenoid failed with months and I, too, replaced it with a much heavier duty unit. I chose to add a second charging path, so I have redundancy for alternator charging of the house bank.

I do monitor amps going too and from the "house". It's kind of neat to see the solar system sending a bit of power back to the engine.

pauldub wrote:
I use a little cigarette lighter plug in volt meter in the 12V power receptacle near my dinette.

I set up a slightly different arrangement in order to keep on eye on how the alternator and coach 12 volt system are playing together when going down the road.

I have a digital voltmeter mounted right on the dash so I can read the voltage on our coach batteries while traveling. The voltmeter plugs into a cigarette lighter plug in the coach by the dinette so it is monitoring the coach's 12 volt system all the time. If this voltage reads from 13.5 volts on up into the 14.XX volt range whenever the engine is running, then I know the alternator is doing it's thing to the coach batteries.

This voltmeter on the dash powered from the coach has another good use. I shut off the 12 volt system whenever gasing up at stations so that a cycling refrigerator on propane can't ignite gas pump fumes. If I forget to turn the 12 volt system back ON after starting down the road - the refrigerator is no longer cooling. With a meter right on the dash, I can see if I have turned 12 volt power back ON in the coach so that the refrig is again operating. That has proved useful more than once!

I am not having any problems that I am aware of. We are going on a 4 day cross country trip and I don't want the house batteries to go dead from lack of use of the genset, as I am going to try to not use it. Given it charges house batteries from the alternator as its suppose to, I should be good. Thanks for the input.

Like pnichols, my '03 Winnie had the charging solenoid fail. If your's isn't charging with the engine running, it's likely that the solenoid has died. You can tell whether or not it's charging the house batteries by checking the voltage in the house. I use a little cigarette lighter plug in volt meter in the 12V power receptacle near my dinette.

Virtually every motorhome is designed to have the alternator charge and maintain the house battery while in transit.

You should see the voltage on the house battery rise at least half a volt when the engine is running. If not then something needs fixed, cleaned, replaced or adjusted.

Take VOLT METER and check battery with engine NOT RUNNING, meter should read 12.6, with engine running meter should 14.3 or higher. Then you will KNOW. JMO

The Ford alternator on our 2005 Itasca (built by Winnebago) is supposed to automatically be connected to the coach batteries and charging them whenever the engine is running. Your Winnebago Minnie is probably set up the same way.

However after owning our Class C for only a couple of years, the solenoid that does this hookup started to become erradic so that our batteries would sometimes be getting charged when underway and sometimes not. I changed out the stock solenoid with a much more heavy duty one that has never let us down since.

When drycamped, we can periodically charge our coach batteries three ways: Using the built-in generator, using a small portable generator we carry along, or using the engine alternator with the main engine very quietly idling. Whenever using one of the generators to charge the coach batteries, the main engine battery is not automatically getting charged. (We have never went to solar battery charging in our Class C for a variety of reasons.)