Generator doesn't charge house batteries?

[nbrhapsody]

We hardly ever use our generator, but noticed that when it is running it obviously gives us the 110V we need, but it doesn't charge the house batteries. What am I doing wrong?

2007 Itasca Class C

Thanks, John

[Yarome]

We would need more information about your genset and house electrical setup. Is it safe to assume you're talking about a built in generator? What size and type? Do your house batteries charge normally when plugged in to shore power?

[nbrhapsody]

Yes, it is a built in generator. It is a gas Onan. Not sure about the size, but probably 5KW. The house batteries charge fine on shore power and also when the chassis engine is running. To use the generator, I plug the shore power plug into an electrical box in the compartment where the shore power cable is stored. My assumption was that this would mirror being plugged into shore power.

Thanks for your expertise.

[Clay L]

It should mirror just as you said. My first Winnebago had the same set up with the receptacle in the service bay instead of a transfer switch and since the converter used the house ac circuit so it was powered when the generator was running and providing house ac.

You have a real puzzle on your hands and I can't think of much that sounds reasonable that could cause your problem.

 

Do you have a shore power/generator switch that should be switched to Gen? Some Winnies with 30 amp systems have one to utilize a second 20 amp winding on the 5.5 kw Onans. If so I would check the second (20 amp) breaker on the generator and the Shore power/Gen switch.

The 4 kw Onans don't have the second 20 amp winding - at least I have never seen one that does.

[nbrhapsody]

Thanks so much for your help. I'll check, although the the RV is in storage in San Diego and I live in Chicago so it will have to wait for a while. I appreciate your quick response.

[Kirk W]

The house batteries charge fine on shore power and also when the chassis engine is running. To use the generator, I plug the shore power plug into an electrical box in the compartment where the shore power cable is stored. My assumption was that this would mirror being plugged into shore power.

It does supply the output from the generator to the RV in exactly the same way that shore power does. It is possible that the generator is not supplying proper voltage. The output from most converters is subject to the supply voltage, how much effect that would have depends upon the particular converter that you have. If your generator is supplying voltage at 10% below normal, then the voltage from the converter would also be approximately 10% less than normal.

[nbrhapsody]

Thanks Kirk. I'll test the voltage coming out of the generator and also try to test it going into the converter. Good idea.

[Jack Mayer]

Kirk's idea is about the only thing I can think of if you are plugging the shore power line in directly to the genset, AND there is power at the genset outlet. All that should be pretty simple to diagnose with a multimeter.....I HAVE seen a breaker integrated into that shore power outlet from the generator. Generally a little red button. Make sure you don't have that version and it is popped.

[Clay L]

One other thing that occurred to me. When you say the generator is supplying 120 vac ,are you basing that on being able to run the microwave, air conditioner or other 120 vac appliance?

[Jimalberta]

You need to use a multimeter and measure the voltage at the batteries while the gen is running. It should read somewhere around 14 volts on a bulk charge. Also realise that the converter you have takes quite some time to charge....it wont do it in an hr.

[nbrhapsody]

Thanks again for all of these responses. The generator is supplying 110V for the TV, air conditioning, microwave, electric portable heater, etc. The 110 all seems to work fine. We don't boondock a lot, but when we do, the house batteries of course lose power over time. Running the generator doesn't seem to do anything to charge them back up. Running the RV engine charges them fairly rapidly. I thought I was possibly missing something obvious in the procedure to have the onboard generator change the house batteries. When we get back onboard I will do more testing with the multimeter. This is all very helpful. This is a great forum.

[kjtdrt]

Also it could be the converter, ours was under the refrigerator. it went bad had to have it replaced and all works fine now,

good luck

[Kirk W]

. The generator is supplying 110V for the TV, air conditioning, microwave, electric portable heater, etc. The 110 all seems to work fine. We don't boondock a lot, but when we do, the house batteries of course lose power over time. Running the generator doesn't seem to do anything to charge them back up. Running the RV engine charges them fairly rapidly. I thought I was possibly missing something obvious in the procedure to have the onboard generator change the house batteries. When we get back onboard I will do more testing with the multimeter.

Are you saying that your meter measures 110V out of your Onan? If so this is too low as an Onan should be supplying between 120V & 122V if working properly. Your converter is probably set to operate between 130V and 110V so that would be at the low end. Are we understanding correctly that you believe that shore power will recharge the batteries in what you consider to be a reasonable period of time, but the generator does not? Or might it be that your batteries get charged, but it actually takes all night or longer and you are wanting the generator to do it in only a few hours? Generally speaking, the engine's alternator is a better battery charger than is the typical OEM converter found standard in many RVs, but we would have to know what your converter is to be able to judge what you should have.

 

When you say that your generator don't recharge the batteries, how long do you run the generator when expecting the batteries to get charged? Keep in mind that when you are driving the RV your demand on the 12V system of the RV is less because you are not using many of the appliances that operate from it. No interior lights, no water heater, no furnace, no water pump, and so on. When you stop with shore power the converter has all night and all of the time that you spend in the campground so you may be expecting too much from it when on the generator.

[nbrhapsody]

No, I haven't measured the voltage coming out of the Onan, but will do that. All I'm saying is that the supply to the 110 circuit seems to power all the 110 needs properly. You might be very correct that I'm expecting too much, too quickly, out of the converter. I think the last time I ran the Onan other than just exercising it, I ran it for 2 or 3 hours and it seemed to make little or no difference to the house batteries though. The RV is 2000 miles away from me right now, but I will do lots of testing with the multimeter when we get back to it. And then I will have to locate the converter! Thanks for your help!

[Jack Mayer]

If you have a depleted typical battery bank of two house batteries, and a typical converter, you are not gong to get much satisfaction (charging satisfaction) out of a two hour generator run. Your are probably not running the genset long enough, or have a poor converter, or have batteries that are not in good condition, or a combination of these factors. This would be especially true if you have heavy 12-volt load demands....like running a furnace.

[Kirk W]

It wouldn't do much for your batteries if you were to connect to shore power for only 2 or 3 hours either. Remember that you are using part of the power from the converter just to operate the lights and appliances inside of the RV. You could probably improve things by upgrading the converter to one with a multi stage charging charging supply and one with a higher current capacity. You could probably also improve things by using a high quality automotive charger to supplement things by connecting it to the batteries and using the generator to supply it but even then if your batteries are depleted they will not fully recharge in only 2 hours. It takes a lot of current to recharge two depleted batteries.

 

I'm wondering also if you have checked the battery electrolyte levels? It is important to keep them at proper levels in order for the batteries to be able to accept the wished for charge.

[nbrhapsody]

Thanks Jack and the Kirk. You are probably correct that I am expecting too much out of the generator and converter. The batteries are properly maintained and should be OK. I'll do more checking when we get back to the RV. I really appreciate your help. Hopefully this won't be much of an issue next winter because we are trying to get Camp Host positions in the San Diego area.

[Kirk W]

Most host positions, whether paid in an RV park or volunteer at a public park are supplied with full hookups, I highly doubt that your generator is the problem, just too little time for the converter. There are some neat volunteer positions in that area if that is what you want, but I'd be looking to set one up now as it is an area that usually fills pretty early.

[nbrhapsody]

We spent February and part of March at several different parks in the San Diego area and fell in love with it. It sure beats winters in the Chicago area, where we live. So far we have applied at both Santee Lakes and Lake Jennings. It is still a little too early for them to commit for next winter, but we're hopeful. We have also applied at Lake Cachuma, near Santa Barbara. We have also posted on the job forum here. Thanks!