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Old 11-05-2008, 04:30 PM   #1
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MH/Battery Charging?

I have read here that the converter is only used when you are plugged in to shore power. If thats correct, how does the Onan charge the coach batteries when boondocking without shore power available, or doesn't it ?

My question concerns our 345LE w/6.5 gen-set. Thanks.

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Old 11-05-2008, 06:25 PM   #2
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The generator puts out 120 volts into the coach, and the converter, which is plugged into the coach, uses the 120 to charge the batteries.

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Old 11-05-2008, 06:51 PM   #3
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Your 345 has a "transfer switch" that is always looking to see if the generator is running if at anytime it detects the generator running it will automatically feed power from the generator to the MH.
The generator provides the same type power as shore power.
Anytime the generator is not running the transfer switch looks for power from the shore power plug.
If you are plugged in to shore power "and" have the generator running at the same time (nor recommend) power will only be provided by the generator.

So your converter is charging the batteries anytime the generator is running or you are plugged into shore power.

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Old 11-05-2008, 07:32 PM   #4
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You'll find that charging the batteries with generator takes a long time if their power is low. Maybe 12-15 hrs. I start the engine & let it idle around 1000 rpm for 1 hr. This uses the alternator to charge them much faster while using less gas.
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Old 11-06-2008, 12:13 AM   #5
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Originally Posted by 3 Dog Nite View Post
You'll find that charging the batteries with generator takes a long time if their power is low. Maybe 12-15 hrs. I start the engine & let it idle around 1000 rpm for 1 hr. This uses the alternator to charge them much faster while using less gas.
The charge time depends on your converter and what charging algorithm it uses. My WFCO will charge my 4 grp 27 coach batteries from 50% charge to 90+% in about four hours.

I went through several alternators until I figured out that they were being burned out by running at full load for long periods. Now that I have a 220 amp alternator I have not had any problems.

I have a friend with a 40' diesel motorhome with a 120 amp alternator, his owners manual says that if you are going to start driving with discharged coach batteries you should run your generator to avoid burning out the alternator.
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