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Old 08-26-2014, 06:08 AM   #1
Join Date: Feb 2014
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Possible battery problem?

I had my MH in storage for about 6 weeks, turned the battery disconnect off for both batteries during that period. When I went to pick it up the alt/charge light stayed on and was beeping.

The software that I use with my computer said that the charge was at 11.9 vdc and 12.00 vdc for the abs volts. Drove it back to my place which is about 15 miles and the reading stayed the same, it did not appear to be discharging.

Charged it up overnight and the charge was 13.57 when charged. Started the engine and the light and beep are still there? The reading is now 12.6 after starting the engine and leaving it on for a few minutes. Could one or both of my batteries be shot? Any ideas

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Old 08-26-2014, 06:15 AM   #2
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How old are they? How was fluid level in every cell? If all you have are two batteries, it's probably worth doing an annual service on them, and take them for a load test.

Rick and Sandy
2003 American Eagle, 52K miles
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Old 08-26-2014, 06:31 AM   #3
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They are sealed batteries, interstate. It does not appear to have any tops that come off, not like my 6 volts do. I purchased the MH last year used, so they are ( I'm guessing) probably at least 4 or 5 years old. I know the 6 volts are due to be changed.
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Old 08-26-2014, 07:49 AM   #4
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Even though 5/7 years is about the run for batteries you are showing full charge and you have used them for start. So I'm guessing you have a charge problem. The alternator it self OR the battery cables or wires running to from alternator.

2004 Clss C 31' Winnebgo
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Old 08-26-2014, 10:29 AM   #5
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I agree that is seem like a charging problem. When your engine is running what does your voltmeters show as the charge rate?
Tony & Ruth........... FMCA#F416727
Newmar Dutch Star 4320, Spartan MM Chassis, Cat C9, Jeep Grand Cherokee Hemi, Blue Ox Aventa LX, and Brake Buddy. TST 507 TPMS
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Old 08-26-2014, 11:45 AM   #6
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It does sound like a shorted cell.

Had that same issue with my house batteries a few months ago, twice (Different batteries) of course with 9-10 year old batteries, not unexpected. All new now.
Home is where I park it!
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Old 08-26-2014, 07:03 PM   #7
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Ok, I took my MH to my brothers shop today and it appears that the alt is not working. it is not giving out any charge. The exciter wire was very rusty and the nut broke off. It appears that it had been broken for some time, just never came off. You could see where it came off and the shaft was all rusty so it did not just break. When he first checked the alt it was reading 12.47, now it is 12volts in and 12volts out. When I put the key in the ignition even before I turn the key to start the alt/charge light stays lit and beeps. This continues after the engine is started. Question:

1) How do I know for sure it is the alt? I had no previous problems and put it in storage for 6 weeks and when I went to get it that is when the alt/charge light came on. Can they go like that? Are there specific tests?

2) How many volts should be coming from the ECM to the exciter/trigger wire. It read 0.75volts.

3) Any other suggestions of what it could be. When we put a load on the batteries when the engine is running it starts to drop down.
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Old 08-26-2014, 07:10 PM   #8
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Your alternator should be putting out over 14 VDC when charging. If it is lower like 11-12 then it is not working.

I don't know what the voltage should be at the exciter wire.

Sounds like you are due for an alternator rebuild. It should cost a little less than $200 to rebuild at a reputable rebuild shop.

I would not recommend replacing it with a new one for two reasons. #1 - they are over-priced compared to a rebuild. #2 - alternators for RV's are built a little different than ones for trucks and cars.

Dr4Film ----- Richard
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Old 08-26-2014, 07:18 PM   #9
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Should I go with one that is higher than 160amps if I get a new one? I have 25,000 miles on the MH, how could it be shot? In all my years and having owned 3 MH and countless vehicles I have never had to replace an alt!
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Old 08-26-2014, 07:32 PM   #10
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If the wire is exciter then it needs 12 vdc.

Look up the alternator and check it.

The wire you see may be the idiot light wire.

If you assume it is bad then test it in vehicle.

Tape the exciter wire...removed from alternator.

Get a piece of small wire that will allow you to connect the 12 battery to the exciter pin on the alternator.

Start engine and with helper measuring charging voltage flash the wire on the exciter pin and see if you get a bump in voltage.

If you do then hold it there to confirm.

If it works alternator likely good.

No suggestions going other way as I have no experience with what you have.

It usually is just key switched 12 volts if internal regulator or variable is external regulator.

You need to determine what you have before proceeding.
Tony & Lori
1989 Country Coach Savannah SE
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Old 08-26-2014, 07:48 PM   #11
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(If the wire is exciter then it needs 12 vdc.)

Does the exciter wire come from the ECM with 12volts? or go to the ECM with 12volts from the alt?
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Old 08-26-2014, 07:55 PM   #12
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If it is exciter it is TO the alternator.

It is the on/OFF switch for the alternator.

However as stated before...you need to confirm exactly how it needs to work by confirming what alternator you have then verifying the input.
Tony & Lori
1989 Country Coach Savannah SE
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Old 08-26-2014, 09:01 PM   #13
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So if I understand this right, the exciter wire coming from the ECM should be bringing to the alt a 12 volt supply? What if it is not? The mechanic told me it was reading 0.7 volts. could he have got the wrong wire (idiot light) what does the exciter wire look like? Thanks for your help

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