mikeb9550
MI
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Is this normal? My voltage reads full but once I start turning on the fan (low draw) and more than one light, the lights dim and the voltage drops. It that normal? I wouldn't think that would be too much draw for GC batteries?
Mike
2006 Ford E350 Van (standard length)
V10, 3.73, 5 Star Tuner, Hellwig Rear Sway Bar, Prodigy BC, Hensley Arrow Hitch
2006 Jayco Jay Flight 26BHS
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MNtundraRet
Bloomington, MN
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How did you read the voltage of the batteries? Did you use the "idiot" lights or read the voltage directly at the battery terminals?
It sounds to me like the batteries are very sulfated and can no longer take a real charge. That comes from using them without ever fully recharging after use.
You also need to check all connections to batteries, solenoids, converter/charger, grounds, along the 12v circuits to lessen resistance and allow correct charging. You did not mention age of batteries but I suspect they made need replacement.
Mark & Jan "Old age & treachery win over youth & enthusiasm"
2003 Fleetwood Jamboree 29
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mikeb9550
MI
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Using a volt meter. The batteries are 1 year old and charge fine and last a very very long time. They were like this when new also. I just expected them to hold higher voltage when higher amps are drawn.
Anyone know of a chart that shows what the amp readings should be at a certain draw?
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garym114
Bluff Dale, Texas
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All you describe is normal except for the dimming lights. This should not happen. I would clean and brush up the battery posts and their connectors and the + and - battery connections to the RV.
Voltage drop under load is entirely dependent on your system, battery capacity, cable and wire size and length.
Where are you measuring voltage? At the battery?
I would expect the voltage to drop on the circuit the lights are on. How much depends on wire size, length and load.
* This post was
edited 05/26/12 08:23am by garym114 *
2000 Sea Breeze F53 V10 - CR-V Toad
Some RV batteries live a long and useful life, some are murdered.
Get a Digital Multimeter and Learn How to Use It
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mena661
Southern California
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How much do they drop?
2009 Newmar Canyon Star 3205, Ford F53 V10
Trojan L16 6V's 740 Amp-hours
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trickyvic3
Raymond NH.
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You need to measure at the batteries themselves using a good meter. If both batteries test good, than I would check and clean all connections.
Also check batteries with a hydrometer. If you don't have one, you can get them at any auto parts store for under $10.00. You could have a bad cell in one, and this would also cause this type of problem. Happened to me in our MH.
Vic
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wa8yxm
Wherever I happen to park
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While I have never tested as you have.. The other day I went to make a cup of java.. Plugged in the one cup auto-drip machine, filled it, took note of the voltage AT MY INVERTER and pushed the button.
49 amps. (At battery voltage) caused a drop (At the inverter) of 0.3 volts.
Personally.. I'd like to see less drop but in truth,
Well your lights are about 2 amps per lamp bulb.
Nothin adds excitment like something that is none of your business
Kenwood TS-2000 housed in a 2005 Damon Intruder 377
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MNtundraRet
Bloomington, MN
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I noticed you have a trailer on your picture. Most motor-homes have 0 or 2 gauge cables to the batteries. If your trailer uses smaller wires to the batteries, a larger drop in voltage and noticable dimming of a 12v light may happen due to more resistance in the wiring. Replacing with heavier gauge cables would help.
The exhaust fan on low setting and one or two lights is very little draw on a battery-bank.
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mikeb9550
MI
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Its raining out now so I am not able to check the voltage at the battery. Using a voltmeter at the 12V plug, here are the readings. Will also pick up a gravity meter.
Lights are all 921 2 bulb fixtures.
nothing turned on = 12.8 - 12.9 v
Running the furnace 11.9 - 12.0 v
Nothing turned on = 12.8 - 12.9 v
One double light = 12.6
Two double light = 12.3
Three double light = 12.0
Four double light = 11.7
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mikeb9550
MI
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MNtundraRet wrote:I noticed you have a trailer on your picture. Most motor-homes have 0 or 2 gauge cables to the batteries. If your trailer uses smaller wires to the batteries, a larger drop in voltage and noticable dimming of a 12v light may happen due to more resistance in the wiring. Replacing with heavier gauge cables would help.
The exhaust fan on low setting and one or two lights is very little draw on a battery-bank.
Good point. It made me want to run out in the rain and check it at the batteries. 12.6v at the batteries where inside the trailer was only reading 11.7.
I will have to see if changing the wire out for a larger size would be easy to get to. They probably have it running behind the walls.
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