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Old 10-07-2013, 06:33 PM   #1
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Engine battery drain

I just replaced my starting battery saturday, after installing started up fine. I turned off all sytems went out today, battery dead. How do I trouble shoot where the battery drain is coming from.

1989 Fleetwood Southwind, Chevy P30, Banks System.
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Old 10-07-2013, 06:42 PM   #2
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The first question is how much do you understand about diagnosing electronic problems? If it were me I would start by obtaining a wiring diagram for the motorhome and research all of the circuits that draw off the engine battery. I would then find out what fuses feed which circuits. I would then hook up an ammeter in series ( or use a clamp on ammeter) and start pulling one fuse at a time until the draw goes away. I would then find out what is powered by that circuit and start disconnecting components.

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Old 10-08-2013, 07:30 AM   #3
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Exactly what slemnah, said.. Get the battery fully charged backup. Keep it disconnected when not using it. You could have a light under the step that is "ON" or even a light under the hood.
2004 National Sea Breeze LX8375, Towing a 2012 Liberty.
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Old 10-08-2013, 06:50 PM   #4
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Yes...get the battery fully charged which may be best done with a charger out of the coach.
2nd...get yourself a clamp on ammeter and hook it around your positive battery wire...you'll read the amp drain in total. Then start pulling fuses one at a time to isolate where your drains are coming from.
Assuming you can live with the loss of radio station presets etc....then you should hook up a battery disconnect switch.

I would suggest that your battery was significantly less than full on installation and you need to QUICklY get it fully charged again as leaving it in a completely discharged state will do even more damage than you've already done to it.
Good luck!
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Old 10-08-2013, 07:12 PM   #5
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A little tool I have found helpful is diagnosing electrical drain problems is a Fuse Buddy which replaces a fuse in the automotive fuse block and reads amps. This is also useful for knowing what 12V accessories etc. actually draw. 20 Amp Automotive Fuse Circuit Tester
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Old 10-08-2013, 10:03 PM   #6
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The easiest way to track down a parasitic current draw is with a 12 volt test light. Disconnect the negative battery cable and jumper the test light between the cable and the negative terminal on the battery. The light will be on at this point. Begin pulling chassis fuses until the light goes out or dims. If it dims you have found one source, but there is still another. Continue pulling the fuses until the light extinguishes. The circuit causing the draw will also illuminate the light. There should be a draw for the radio, memory function. Good luck.
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Old 10-11-2013, 06:18 PM   #7
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I finally had a little free time this afternoon to revisit my battery drain issue. Charged up the battery put ammeter between battery and ground. With the power turned on to the main I get about 4.5 amps of drain. With the main off I am only getting .o4 amps. I pulled all the fuses on by one, outside under the hood and inside under the dash, no change. When I activate the switch to turn on the main, I hear a relay turn on sound somewhere in the dash area. I am assuming this is the isolator. Any hints where to go from here?
1989 Fleetwood Southwind, Chevy P30, Banks System.
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Old 10-11-2013, 06:28 PM   #8
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Do you park the coach at your residence or at a storage facility?

You are always going to have phantom loads on your coach. You can't eliminate ALL of them. You could just disconnect the negative cable on your chassis battery but that gets old after a while.

If it's parked at your home and plugged into 120 VAC to keep the House batteries charged then I would invest in either a Trik-L-Start or an Amp-L-Start which will keep your chassis battery fully charged. The former one is about 5 amps of charge and the latter gives 15 amps of charge.

Ultra TRIK-L-START Starting Battery Charger/Maintainer

AMP-L-START Starting Battery Charger/Maintainer - Overview Page

Dr4Film ----- Richard
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Old 10-12-2013, 01:50 AM   #9
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4.5 amps is a bunch.

You have lifted fuses, so next is creative.

Start by lifting wires at battery or starter.

Then wait until dark, open everything and look for light, there may be something powered up with an indicator.

Next flip switches, if battery is off and switch works then device may still drain battery.

Last, get non contact thermometer, 4.5 amps is 52 watts, over time it will be warm, so at night when cool look for warm spots.

Leave everything in disconnect mode and charge with portable charger.
Tony & Lori
1989 Country Coach Savannah SE
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Old 10-12-2013, 01:51 AM   #10
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Some steps have connection to starting battery, bad controller can do this, it will be warm, or you can unplug it at steps

Tony & Lori
1989 Country Coach Savannah SE
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