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Author Topic: Dead Batteries  (Read 1793 times)


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  • Ned Jones
Dead Batteries
« on: June 12, 2010, 07:22:53 AM »
I recently purchased a '07 American Eagle. The coach has a 10000 Onan Generator and a 3500 watt inverter. Normally I have the coach parked in my driveway and plugged in to a 50 amp outlet. On Monday I moved the coach so my driveway could be paved and in less than 48 hours my batteries were completely dead. I had to use auxillary start to get the generator started.  Now to the best of my knowledge the only thing running was the refridgerator which was on propane. Obviously something was drawing it down. Is is it typical for the batteries to drain that quickly? Again I have only had the coach a short time so I don't know what is normal.
2007 American Eagle
Co-pilot Martha Jones
2000 Harley Road King
2007 Custom Built Bobber

Gary RV_Wizard

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Re: Dead Batteries
« Reply #1 on: June 12, 2010, 07:32:11 AM »
Yes, coaches such as your Eagle are power hogs and do indeed have a lot of "parasitic drains" that suck down the battery amps.  But you said Aux start worked to start the genset, so at least one of your battery banks was still ok. Are you aware that the house and chassis (engine starting) batteries are isolated and separately maintained?    And I believe the generator on your '07, like my '04 Tradition, starts from the chassis batteries, which apparently were dead. Using the Aux start switch couples in the house batteries, so they were probably ok.

It is possible your chassis batteries are in poor condition after only 3 years, but itis also possible they simply are not getting charged adequately. There is a fairly complex piece of circuitry that manages that and it won't charge the chassis batteries from shore power unless the house batteries reach a fully charged state first. Typically this means about 13.3v. If the house batteries don't get that high, then the chassis batteries won't get charged even though you are plugged in, and they will run down within a few weeks. One bad house battery is enough to drag the voltage down so this situation occurs.  I know this from experience!
Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL


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    • PressurePro
Re: Dead Batteries
« Reply #2 on: June 12, 2010, 10:30:05 AM »
Did you check the water level in the batteries if they are not sealed units?
Bernie & Marlene Dobrin
Home is Goodyear, AZ
Missing our Travel Supreme

John From Detroit

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Re: Dead Batteries
« Reply #3 on: June 12, 2010, 12:39:44 PM »
I would do a systems check, Start with Bernie's suggestion above.

Now, First thing.. If you are parking it, DISABLE the inverter (Turn off or use the disable switch if it has one) since nothing in there needs 120vac if it's not occupied.

Then lift the NEGATIVE wire to the chassis off the battery and insert an ammeter,  Start with the highes range and click down till you get a useful reading (Hopefuly the load will be under 20 amps, most 10 amp meters can take 20 amps for a few) or better yet use a clamp-on DC ammeter on said negative wire (Sears sells a good one)  These can measure starter current.

Now you have an idea of how much load the rig presents.

If the rig is presenting less than 20 amps.. Have your batteries tested (That is for a single pair of G-31 or CG-2 batteries, if you have 2 pair double the amprage)  You should be seeing less than 10 amps of load depending on the fridge settings and if it is operating, Likely less than 5 amps

Some numbers:
CG 2 pairs about 220 amp hours, they can provide 10 amps for 10 hours and still crank the generator

G-31's are around 125 amp hours EACH, and thus a pair can provide 10 amps for around 12 hours and still crank the generator.

(you can safely use 1/2 the battery's capacity)
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