Chassis Battery going dead 2011 Vista 26P

Fishalert · 05-06-2023, 03:50 PM

My alternator is charging the Starter battery and house batteries at 14.57 volts but after it sits for an hour or two, the starter battery has drained down but the house batteries remain good.

Could one or more of the disconnect or BIM solenoids cause my starting battery to drain like this?

Thanks for any help.

**creativepart** · 05-06-2023, 04:20 PM

Hi and welcome,

Anything is possible, but the simple answer is a worn out Chassis (starter) battery. That would be an excellent reason for the battery to not hold it's charge.

You've not told us enough information to truly be helpful. We pretty much always need to know the YEAR, MODEL and FLOORPLAN of your RV before we can begin to provide meaningful help.

Fishalert · 05-06-2023, 05:00 PM

The battery is new and just installed to perhaps fix the problem. After it draining down, I recharged the battery up to 13.35 and disconnected it. The following day the battery was still reading 13.34. After it set for an hour I noticed the battery draining down. I put a 12v troubleshooting light on the ground terminal and one end on the ground lead and the light lite up, which indicates a drain. MH is a Winnebago 2011 26P Vista. Thanks for any help.

**creativepart** · 05-06-2023, 05:08 PM

Tell us how much it's dropping. Because a charged battery is 12.7v. When you see 13-14 volts those are charging voltages. And the battery holds a surface charge for a while, sometimes hours, before dropping to 12.7v. The voltage can read high until any load, no matter how small is put on it and then it drops to normal voltage.

Fishalert · 05-06-2023, 06:40 PM

I'll have to check it. It is draining though because it is lighting up the 12V troubleshooting light when connecting only the negative lead. I'll hook it up though and check it tomorrow morning. Thanks for the help.

**creativepart** · 05-06-2023, 06:56 PM

Quote:

Originally Posted by Fishalert

It is draining though because it is lighting up the 12V troubleshooting light when connecting only the negative lead.

I'm not exactly sure what that means. How about writing more about the issue and what you've done. We're getting details piecemeal and don't really know the whole story.

Morich · 05-06-2023, 07:05 PM

There are almost always "parasitic draings" on both the chassis and coach batteries, unless we do something very speciifc to cut them off more than the normal battery disconnect switch.
One item which may be running down the chassis battery is the step light. It may be on and not noticed in daylight, so a quick check if that is doing the dirty may be quicker than any other plan?

General idea on battery voltages is that when we see aobe 12.8 we have been charging and seeing the remnants of that charge. Just the chemical makeup of lead acid is that it will not go above 12.7-12.8.
So if you are thinking it has a drain due to it dropping from the charge voltage down we would say that is normal.
However the light bulb lighting the way you have is showing something more than I would expect to find. Not used that form to measure or test but it would seem to show a pretty big drain to light a bulb??

I might want to get into checking things that are connected before any chassis battery disconnect and might be left on. Things that are normally left on are radio presets, any auto functions like door locks, etc.
But it is pretty common for folks to add things to an RV and not consider where they are tying them in. If this is a "new-to-you" RV, it may pay to look carefully for things they may not have wired the best?
Rear view camera that is left powered while the monitor in front is turned off can be a trick to discover!

Morich · 05-06-2023, 07:23 PM

Quote:

Originally Posted by creativepart

I'm not exactly sure what that means. How about writing more about the issue and what you've done. We're getting details piecemeal and don't really know the whole story.

As I understand what they mean?
I see how the light might light, but not a test I've seen or used as it tells so little that a meter would tell much more?/

The idea is that the test light is put into a circuit (circle) to make the path complete.

If we think of how the current flows from battery to some item like a light, through it and back to ground using the frame as a path to get back to make a full circuit, it looks like this in simple form.

Then if we take any part of that full circuit loose and add a test light in the path, the current has to go through the test light to get the full circle made!!

Click image for larger version

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It proves current is able to flow but we already know that as the radio presets and all those things are working when we come back!

Fishalert · 05-07-2023, 05:34 AM

Last night a hooked the battery back up and it read 12.68 volts. This morning after about 10 hours, I checked it and it was 12.63 volts, so maybe I'm not having a problem like I thought. It must of been the old battery. I had it checked at Advance Auto and they said it was alright. I took it about 20 miles to have new tires put on and when I tried to start it to return, it just turned over and I didn't think it was going to start but it did. After I got home and it set for two days I went out to try starting it and it wouldn't turn over. That's when I got a new Optimum battery. I charged it to 13.20 volts before installing it and the battery was down to I believe about 12.57 volts the next day. That's when I started thinking I had a battery problem with it draining down. I'll wait and see, I might not have problem. Thanks for everyone's help. I still don't understand the troubleshooting light lighting up though. I got this test off of YouTube. It said to disconnect the negative lead from the battery, hook the positive lead on the light to the negative lead and the negative end to the battery post and if the light light's up then I have a drain. It lights up. Anyway, I'll monitor it the next few days and see what happens.

Morich · 05-07-2023, 08:54 AM

Sometimes the internet is great and other times it just SEEMS great as we can get some good or not so good!
The test light idea is new to me but when I think about it, kind of okay?
What the tiny test light bulb needs to light is a tiny bit of current but he faulty part of the info is that we don't have to put it at any specific point in the circle as the amount of current flowing through any point on that circle has to be the same when we are talking a simple single path.
You get the same result putting the light on the positive side or any other point along the line but that IS only true on simple circuits and NOT true if we get into most of the wiring we have on RV or cars.

Batteries are so simpe, yet have so many ways to trick us, that we get lots of bad ideas at times.
Big one that snags a lot of people is that the battery is a chemical process and it works pretty slow, so voltage readings at the posts can really trick us.
If we think of charging as pouring molassas into a barrel, we may see it full if we look in the hole, but if we stop pouring and come back in an hour, we may find the barrel is not full at all!
The charge we put in the battery moves slowly through ALL the chemicals in all the cells, so if we check too soon after we have been charging, we get what is called "surface charge" and we may not actually have filled the battery at all.
Battery builders have charts that show it takes 6-8 hour to get a really low battery brought back to full charge!
Gotta give that old molassas time to settle down and get stable before we look!!

One way it can catch us?
If we camp all weekend and get the batteries way down, then drive home for 45 to an hour. If we get out and check the batteries, we may see them reading 13 volts, so we don't bother to put a charger on them.
Next week we go out and find the darn batteries are near dead! They just never really had a good chance to get charged fully. Just the first cell may have looked good----until it spread out to all the other cells!

**creativepart** · 05-07-2023, 09:00 AM

Do you have the Chassis battery disconnect switch set to OFF when it loses this much voltage? Or is the disconnect solenoid ON?

I'm assuming you are not on shore power during this testing... correct?

A drop from 12.68 to 12.63 in 10-hours doesn't sound bad. Especially if the disconnect is not activated.

Fishalert · 05-07-2023, 10:07 AM

Thanks a lot for all your help. You make a lot of sense and I appreciate your help and understanding.

Fishalert · 05-07-2023, 10:10 AM

Yes, the disconnect switch is off. I have the shore power going and house batteries are reading 13.20. I don't believe the shore power will charge the starting battery, or not?

Morich · 05-07-2023, 11:23 AM

Quote:

Originally Posted by Fishalert

Yes, the disconnect switch is off. I have the shore power going and house batteries are reading 13.20. I don't believe the shore power will charge the starting battery, or not?

Not in mnay cases! But there are some RV which have a small item like a Trik-L-Start added which is a small (2"X 3"inch?) box often enar the batteries or solenoid and it can let some current go to the chassis when the coach is charging.
Normally the solenoid is only connecting the two when running or when we are pushing the dash switch!

Fishalert · 05-07-2023, 01:14 PM

Thank you very much for your information. Just checked voltage at starter battery and it'
s 12.65 so looks like all is good. Appreciate everyone that contributed to helping me with this. Thanks !!

Bobn1957 · 05-15-2023, 11:50 AM

Quote:

Originally Posted by Fishalert

Last night a hooked the battery back up and it read 12.68 volts. This morning after about 10 hours, I checked it and it was 12.63 volts, so maybe I'm not having a problem like I thought. It must of been the old battery. I had it checked at Advance Auto and they said it was alright. I took it about 20 miles to have new tires put on and when I tried to start it to return, it just turned over and I didn't think it was going to start but it did. After I got home and it set for two days I went out to try starting it and it wouldn't turn over. That's when I got a new Optimum battery. I charged it to 13.20 volts before installing it and the battery was down to I believe about 12.57 volts the next day. That's when I started thinking I had a battery problem with it draining down. I'll wait and see, I might not have problem. Thanks for everyone's help. I still don't understand the troubleshooting light lighting up though. I got this test off of YouTube. It said to disconnect the negative lead from the battery, hook the positive lead on the light to the negative lead and the negative end to the battery post and if the light light's up then I have a drain. It lights up. Anyway, I'll monitor it the next few days and see what happens.

The gas detector might be your main drain as well as the radio memory, these loads are always on. If you have a multimeter set it to measure amps and connect it between the negative post and ground with the negative wire disconnected and you will measure the drain current, it should only be a few milli-amps.