Battery light in dash keeps coming on - Page 2

javelin · 10-16-2019, 12:46 PM

Well if you read the first part of my post #16 again, you had said that the dash battery lamp did not illuminate until about 1-2 minutes after the engine was started......which could have been the time when the interconnect relay closed to connect the coach and chassis batteries together for charging from the alternator. You had also said that you had purposely totally discharged the coach battery. So possibly the alternator was now trying to charge a totally discharged coach battery plus if the use/store switch (coach latching relay) was on, it would be feeding the coach DC fuse panel loads and also be connected to the output side of your failed converter. So “perhaps” the damaged output of the converter (you say shorted? Not sure about that though.) had “some additional impact” on the alternator output voltage.

Machinetools1 · 10-16-2019, 02:15 PM

Hi. It is strange that the dash battery lamp came on after a minute or two of the engine running......sounds about the time it would take for an interconnect relay between coach and chassis batteries to be turned on by a BIRD or BIM battery control system (give or take). Since your coach and chassis batteries are seeing the same charging voltage (clearly at a charging level of 13.3 vdc; BIRD, BIM are enabled by alternator above 13.1 vdc approximately if I recall correctly). So is the closing of the interconnect relay causing the battery lamp to light? I don’t see why it would be since you are not on shore and gen is also off. I wonder if both battery strings (coach and chassis) would test good on a load test? It also sounds like the battery light is staying on once it comes on.

The other issue to me is that the charging voltage of 13.3vdc is very low for a “working” alternator especially feeding healthy lightly loaded batteries;....should be 14vdc minimum I would expect (14.5 ish). So my WAG is a bad regulator in the alternator or bad diode(s) perhaps......assuming good batteries; all charging system cables/connectors are clean and tight. I am just guessing here and don’t want you to spring some $$ for a new alternator (and related “class A” work required to change it) if that is not the problem or there is some easily repairable connection being missed.

When I had wrote the last statement we were on the tail end of our camping trip. When we left and on the 6 hour trip back home the battery dash light never went out but had a constant 13.2 volts coming from the chassis battery when I stopped and checked with a volt meter and by the firefly panel in the motorhome. Once We got home I concentrated on the converter issue first to try and find that issue.

You had also said that you had purposely totally discharged the coach battery.

I did discharge the batteries when I was concentrating on the converter issue. I had the motorhome on shore power for a few days and all batteries were charged after I found the converter issue.

Once I figured that issue out and had the motorhome on shore power for a few days and all three (3) batteries were charged I disconnected from the shore power and took the motorhome out, this is when I checked the volts coming from the chassis battery from a volt meter at the chassis battery and at the firefly panel. The battery light being off in the dash.

Are you thinking the converter might not have had a short or an issue with it? it never worked correctly until I put the new converter in.

javelin · 10-16-2019, 03:56 PM

So I think what you are saying is that the dash battery charge light was on solid even when the coach batteries were fully charged (so they weren’t causing high charging current from the alternator). It would have been interesting to have turned off the use/store switch when the dash battery lamp was on, just to see if disconnecting the old bad converter from the coach batteries, was the problem. So unless there is some other intermittent problem with the engine alternator or its charge circuits, then the old converter’s output circuits “may” have been a potential issue for the alternator.

Are you thinking the converter might not have had a short or an issue with it? it never worked correctly until I put the new converter in.

No, I think you proved the old converter had an intermittent problem OK.....even before replcing it. The 120VAC inputs from shore or gen were solid but the old converter outputs were not behaving in a stable way. I just meant that the converter output + and – were probably not a dead short or you would have had some blown fuses (or breakers) I would expect.

It is always nice to know exactly what failure mechanism(s) has caused your problem(s), for peace of mind that you found the fault(s). Monitor the situation for a while and if the dash battery charge lamp does not come on again in a similar way as before......then maybe that converter was a contributing factor. If you have the old converter repaired it would be interesting to know what actually was the problem with it......and have the circuit schematic for it also. At least for now you are a happy camper again. Maybe other readers would have a theory as well?

Machinetools1 · 10-16-2019, 04:45 PM

That is correct... Knowing what I know now and what I have learned, I should have turned off the USE/STORE switch to see if it had made a difference. I know now there is at least a 2 minute delay in the BIM and I would have never known that without this Forum.

When I contacted the motorhome dealership and told them of my battery light in the dash problem, they said it was a Ford issue and not a Thor issue. I guess it could have been a Thor issue if the USE/STORE switch was in the on position and the converter was bad. I guess time will tell if the problem still exists, I only hope it does not but I should be able to separate the motorhome form the chassis with the USE/STORE switch. I guess I will find out on the next road trip.

You are correct in trying to find the issue as we all benefit form the problems of others. I did not want to throw parts at something and hoping it got fixed. First off, you never learn what the problem is and it always costs more money.

Before I changed the converter I tested the alternator and thought for sure it had a bad diode. New Ford Motor craft alternators were $500.00. I could not see spending that IF I did not have to. Let alone the labor to change it. I was going to do it myself but was afraid it would have void my warranty. So I hope this was the ticket.

Tom N3EQF · 10-16-2019, 07:01 PM

There are a lot of good theories and/or troubleshooting in this thread. Having been down a series of alternator/charging system issues lately, and still ongoing, I want to throw in a potential monkey wrench, however.

In another thread (http://www.thorforums.com/forums/f8/...tml#post199620) I had issues with what was determined to be a bad alternator. It was first replaced with a rebuilt alternator and I thought all was well as it was charging nicely at 14+ volts. I then found that the alternator was also putting out 30 volts AC and when the engine was off the alternator was actually drawing several amps of current from the chassis battery. This indicated a bad diode so the alternator was then replaced with a genuine Ford $500 one.

This brings me to the current issue and my reason for posting in this thread. The new alternator puts out 13.3 volts, and never changes with load changes or engine RPM. It is "charging" as when the engine is not running the battery is stable for many days at 12.7 volts. So you definitely see the increase in voltage from the alternator, but it is a lower voltage than typical. The battery dash light comes on after a couple minutes when the engine is running and stays on. I think these symptoms are very similar to that of the OP, if I'm not mistaken.

My 2014 Windsport has the Battery Control Center (BCC). In my troubleshooting, I completely removed the House Battery system from the BCC, so that only the Chassis Battery is in the circuit - no connection at all to the house. The symptoms are exactly the same! So in my situation, the problem cannot possibly be the Converter (newer unit, working great) or the BCC system. The batteries have been load checked and are almost new and in good condition. It's a problem with the F53 side of things, and most likely just a bad alternator off the shelf. Hopefully I will find that's the answer but I'll let you know when I find it.

Machinetools1 · 10-16-2019, 08:20 PM

Hey Tom

Was your motorhome under warranty or are you doing the work yourself? I was afraid of diving in and working out the bugs as it might void my warranty. This could also get expensive if the problem is not resolved. It does in fact sound very similar to the problem I was in countering. Mine now charges 14+ volts at the chassis battery. I hope yours is just a bad alternator off the shelf but some how I doubt it. Please keep us posted on your results and fixes.

Tom N3EQF · 10-16-2019, 09:43 PM

My MH is about 5 years old and I've done lots of mods and upgrades so warranty concerns are long gone. I do most of the work myself but in this case I had a local mobile RV mechanic change the alternator. He's going to follow up with this soon, although I have to be on a non-RV trip until next week. Hope to know then and I will follow up here when I get it resolved.

Tom N3EQF · 11-26-2019, 06:11 PM

Hi All,

Just to come back to this thread and say the issue with low alternator output (13.2 volts) with the new ($500) Ford alternator remains. I've taken the RV out a few times and the voltage never rises, although so far no battery problems from under-charging.

The mobile RV tech that installed the new alternator has stopped returning my calls, so it looks like I might be left to work this out by myself. It's either a bad alternator or it's something very rare with the PCM, although there are no other symptoms besides the lower than expected voltage output and the constant dashboard battery light.

By the way, there are no error codes being generated; only the battery light.

Machinetools1 · 12-01-2019, 04:58 AM

Wow...that is very frustrating indeed. It sounds funny but I had a bad house converter. I changed that and the battery light went away on the dash and the alternator is producing over 14 volts.

Tom N3EQF · 12-01-2019, 03:02 PM

Quote:

Originally Posted by Machinetools1

Wow...that is very frustrating indeed. It sounds funny but I had a bad house converter. I changed that and the battery light went away on the dash and the alternator is producing over 14 volts.

Thanks for the note - I did see where the converter was causing the problem for your RV; as strange as it seems the 12 volt systems are automatically tied together in many cases, so I understand how the converter might have caused the low voltage. In my troubleshooting, I completely removed the coach 12 volt system so that only the Ford V10 electrical wiring was connected. The problem remains the same.

I've read so many cases where alternators are "bad off the shelf" that I won't be surprised to find that my new alternator is bad. My problem now is compounded since the mobile RV tech purchased the new alternator from Ford and he isn't answering my calls. So I might have to "eat" the cost of a new or rebuilt alternator a second time.

Machinetools1 · 12-02-2019, 12:12 AM

it could very well be a bad alternator. Just because its new does notm mean its good. please keep us posted on your issues. these types of issues help all of us. Good luck.

Tom N3EQF · 08-01-2021, 05:35 PM

Well, it has been a long (and expensive) journey to get my electrical system back to 100%, but I wanted to close the loop on this old thread. Maybe it will help someone else.

The pandemic limited my travels over the past year, but when I did use the RV I still had a low (13.2 volt) output from the alternator, no matter what RPM or battery condition.

I took the Windsport to a huge Ford dealer here in the Orlando area. Their diagnostics showed my "new" (replaced by a mobile RV technician) alternator was bad. OK, so another expensive alternator was installed. Unfortunately, although the alternator output was a little higher than the original, the dashboard battery light stayed illuminated. The diagnostic then revealed a bad PCM (Powerplant Controller Module), or more generically; "the computer".

In the end, replacing the PCM fixed the problem and things are running normally. The PCM monitors temperature, engine RPM, temperature and battery voltage to tell the alternator what its output should be. As it turns out, with the PCM dead, the alternator just cranks out about 13.2 volts no matter what.

So there you have it. Quite an expense just to get rid of the idiot light!

javelin · 08-01-2021, 06:31 PM

Sorry to hear your repair was more involved and expensive than hoped for. Hopefully that mobile RV tech installed alternator now becomes your spare alternator.......assuming the PCM replacement was the problem all along; and your original alternator was also actually bad? Two spares maybe? At least you are back in business; and thanks for posting your findings on the forum to help someone else.

jscanlon · 08-25-2021, 06:41 PM

So, for the past year in my 2011 Thor Ace I have had the dash battery light come on and off while driving. I had it checked and got no answer. "Just a glitch". I have had no problems starting it, driving it or with the chassis battery with steps etc. battery. Engine has always started right up, even in the winter.

Last week I was returning from Michigan to Ohio. Stopped for gas twice. Each time the engine seemed to "chug" before turning over, but it started. Never had this before. Got home to the storage lot. Turned off ignition for about 20 minutes while cleaning it. Tried to start it again and got nothing. No click. No chug. Nothing. Its dead.

Relay or "salesman" switch is on and green. Chassis Battery seems to be putting out 12.8 volts, and the steps and headlights seem to be working fine.

Before I get it towed, hoping somebody has a suggestion. Levelers are not extended, nor is slide-out.

BTW, while hooked up to power at the park in Michigan, I did leave the relay on for the chassis battery. Was this wrong?

Thanks to all.

**16ACE27** · 08-25-2021, 06:57 PM

Quote:

Originally Posted by jscanlon

So, for the past year in my 2011 Thor Ace I have had the dash battery light come on and off while driving. I had it checked and got no answer. "Just a glitch". I have had no problems starting it, driving it or with the chassis battery with steps etc. battery. Engine has always started right up, even in the winter.

Last week I was returning from Michigan to Ohio. Stopped for gas twice. Each time the engine seemed to "chug" before turning over, but it started. Never had this before. Got home to the storage lot. Turned off ignition for about 20 minutes while cleaning it. Tried to start it again and got nothing. No click. No chug. Nothing. Its dead.

Relay or "salesman" switch is on and green. Chassis Battery seems to be putting out 12.8 volts, and the steps and headlights seem to be working fine.

Before I get it towed, hoping somebody has a suggestion. Levelers are not extended, nor is slide-out.

BTW, while hooked up to power at the park in Michigan, I did leave the relay on for the chassis battery. Was this wrong?

Thanks to all.

Step 1 - Remove, clean and reinstall both chassis battery terminals.
Step 2 - Check all chassis battery cable connections from the terminals to the starter and ground for tightness and corrosion.
Step 3 - Leave the voltmeter on the chassis battery and try to start the MH watching what happens to the battery voltage.
Step 4 - Charge and load test the chassis battery.

Of course you could always use the Emergency Start switch and/or jump the chassis battery to start the MH. If that doesn't work you do have bigger problems and may need a tow.

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