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05-02-2010, 10:36 AM
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#1
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Rivet Master 
1989 34.5' Airstream 345
Silverton
, Colorado
Join Date: Oct 2003
Posts: 2,102
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Impossible electrical problem...I think...
This will take awhile to lay out...
The moho has been in storage for about a month. As our chassis battery(Optima red) won't hold a charge, I get to go visit every 2-3 days to do a short-wire jump from the solar-charged house batteries so I can get the steps to drop, and if I have some time, I let the solar kinda top off the chassis with the short wire jump.
Yesterday, I started the same procedure, as the steps would not drop...I opened the bat drawer, and the steps dropped, albeit somewhat sluggishly...so, out with the short wire jump, and BIG flash(blew the clamp off the end of the wire)...after my heartrate dropped back down below a kazillion, I got out the voltmeter...this is what readings I found to be contradictory:
House bats 14.36
Chassis bat 5.53
Chassis (+) to House (-) 5.55
House (+) to Chassis (-) 14.36
now,
Chassis (+) to House (+) 8.82.....(???!!!)
OK, so I disconnect the Chassis (+) clamp, and check the Chassis (+) clamp to the House (+) terminal.....14.23......(???!!!)
I did crawl under the battery drawer and find an abraded (+) cable, which I repaired, but I'm still getting (+) and (-) off the (+) chassis battery...
Anybody have any ideas or suggestions?
mike
__________________
Michael & Tracy
1989 345 Motorhome
CHARTER MEMBERS: FOUR CORNERS UNIT, AND PROUD OF IT!!!
We live for the moment, 'cause when you get there, it's gone...
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05-02-2010, 11:35 AM
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#2
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Site Team

2002 25' Safari
Dewey
, Arizona
Join Date: Mar 2005
Posts: 15,719
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Your numbers look fine except that your chassis battery is dead. The house numbers are a bit high, but the solar is most likely charging them. Lets look at the numbers...
House bats 14.36 - Good
Chassis bat 5.53 - Dead
Chassis (+) to House (-) 5.55 -Dead
House (+) to Chassis (-) 14.36 -Good
now,
Chassis (+) to House (+) 8.82.....(???!!!) - 14.36 - 5.55 = 8.81
OK, so I disconnect the Chassis (+) clamp, and check the Chassis (+) clamp to the House (+) terminal.....14.23......(???!!!) There is something in the Chassis that is tieing the + to ground. It might be a very small load like a radio or clock or on board computer. They have very small draws, but when you disconnect from the battery, the (+) connector becomes ground. What you are seeing is the House (+) to Ground which is around 14+ volts.
Bottom line is your chassis battery is dead, either because it is bad or it has a constant draw which is pulling it down.
Travel safe and see you soon. Say hi to Tracy from the both of us...
__________________
Richard
Wally Byam Airstream Club 7513
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05-02-2010, 04:58 PM
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#3
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Rivet Master 
1989 34.5' Airstream 345
Silverton
, Colorado
Join Date: Oct 2003
Posts: 2,102
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Richard,
Thanks for the explanation...So, if I put in a new battery, will that solve the flash, or will I get a bigger flash?...I'm beginning to develop a real complex about electric stuff, as it really hurts when I find shorts and things...the current blisters should heal in a couple of weeks, but I'm gonna be gun-shy awhile longer...
Hi back to you, Jan, and give the kids a skritch or two...oh, heck, give Jan a skritch, too...
__________________
Michael & Tracy
1989 345 Motorhome
CHARTER MEMBERS: FOUR CORNERS UNIT, AND PROUD OF IT!!!
We live for the moment, 'cause when you get there, it's gone...
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05-02-2010, 06:33 PM
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#4
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Site Team

2002 25' Safari
Dewey
, Arizona
Join Date: Mar 2005
Posts: 15,719
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If you put in a new battery you should not have to jumper the house battery to get the steps down. That is assuming that it is just a bad battery and you don't have a short that is pulling it down.
Always be safe when working with electricity.
__________________
Richard
Wally Byam Airstream Club 7513
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05-29-2010, 01:52 AM
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#5
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Rivet Master 
1989 34.5' Airstream 345
Silverton
, Colorado
Join Date: Oct 2003
Posts: 2,102
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New battery did the trick...Sam's Club replaced it for free, and it turned over the engine just like...well...a real engine...I think I found the major drain where the shroud protecting the solenoids had rubbed thru the cable, but still seem to have a bit of a drain, somewhere...I'll keep looking...the underside of a moho is really ugly...m
__________________
Michael & Tracy
1989 345 Motorhome
CHARTER MEMBERS: FOUR CORNERS UNIT, AND PROUD OF IT!!!
We live for the moment, 'cause when you get there, it's gone...
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05-29-2010, 06:26 AM
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#6
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Rivet Master 
2000 31' Land Yacht
Central
, Florida
Join Date: Aug 2007
Posts: 1,489
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you can use an ampmeter to check battery drain by pulling the positive clamp off and connect between clamp and battery with your meter on amp setting. Start with high setting and work down.
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05-29-2010, 10:05 AM
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#7
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4 Rivet Member 
2000 31' Land Yacht
Join Date: Sep 2003
Posts: 497
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Much safer to pull the negative. No chance of a short between the wrench and chassis.
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06-01-2010, 06:26 PM
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#8
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Silver Bullet
1986 34.5' Airstream 345
choctaw
, Oklahoma
Join Date: Mar 2006
Posts: 853
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I had a battery cable short to ground one dark, sleety, rainy, windy morning just outside Ft. Worth on I-35W. It killed the engine, the lights and sucked all the V's out of all the batteries. Did not pike out Mel's fun meter that day. Have replace the alternator belt several times and it still squealed. This year I replace the house batteries and no more belt squealing. Think I had a shorted cell of two.
mel
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