Engine battery problem

Muttibear · 10-31-2020, 01:54 PM

We have a 2003 Winnebago adventurer and are having some problems with our engine battery. We had it checked and the battery is fine, but there are times when we have it parked and go to start it again after just a few hours and it doesn’t want to start at all — it doesn’t kick on. We use the battery boost and we can get it restarted every time, but we are wondering why the battery keeps draining like this? Recently our automatic stairs would not go in and out and we realized that it was because the battery had gone dead. Once we restarted the battery or the engine using the battery boost the stairs started working again. We’re just not sure what the problem is and why it seems like the battery in the engine keeps going dead.

Winterbagoal · 10-31-2020, 01:58 PM

Quote:

Originally Posted by Muttibear

We had it checked and the battery is fine, but there are times when we have it parked and go to start it again after just a few hours and it doesn’t want to start at all — it doesn’t kick on. We use the battery boost and we can get it restarted every time, but we are wondering why the battery keeps draining like this?

Who checked it, and how?
Sounds like your battery is toast (won't hold a charge), based on the rest of your symptoms.

Old Navy · 10-31-2020, 02:17 PM

A starting battery that has been repeatedly discharged is likely toast. But your steps should work off of your house batteries. Sounds like your coach electrical system is running off of your starting battery rather than your house batteries.

Morich · 10-31-2020, 02:17 PM

Quote:

Originally Posted by Winterbagoal

Who checked it, and how?
Sounds like your battery is toast (won't hold a charge), based on the rest of your symptoms.

At first glance, this sounds totally right, so it is a good question on how it was tested. There are way too many folks who think it fine to test the voltage on a battery which has just been charging and if it has 12 volts, they deem it okay.
So if this is what happened it can go down this way. If you drive it to a store and they check the voltage, the engine alternator has been pumping power into the battery and that gives it what we call a "surface charge". In other words there is a charge right at the post but down deep and all through the chemicals in the batteries there may not be much charge at all.
So when the voltage shows good but a couple hours later all the chemical reaction in the battery has leveled out and there is not much there!
Several much better ways to test. specific gravity of each cell but very few do this any more. Load test, which is the way most parts stores do it or charge the battery fully for like 6-8 hours, wait a couple hours and THEN test the voltage and expect about 12.7 or near when it has leveled out.
But it is always a good time to take a good look at things like the battery cables and especially the ground cable where it goes to the frame as ground is just as important as the hot side.

**creativepart** · 10-31-2020, 09:35 PM

I'm with the others. Your starting battery can't hold a charge. It is not maintenance free you have to add water to it. So, you can use a hydrometer to test the cells. You'll no doubt find some or all of the are weak.

You could also remove the battery and take it to an auto parts store like AutoZone and have it load tested.

Muttibear · 11-03-2020, 12:11 AM

Quote:

Originally Posted by Old Navy

A starting battery that has been repeatedly discharged is likely toast. But your steps should work off of your house batteries. Sounds like your coach electrical system is running off of your starting battery rather than your house batteries.

This is a point we are wondering about— this morning we had trouble getting 1 of our slides to go back in - like not enough power - but we were still plugged in to external power - then when we tried to start the engine, the battery needed a boast again - once we got the engine started, we let it run for a few minutes, then turned it off and put the key in aux position and presto the slide went in. My point is- seems like something is crossed. When the starter battery is dead, the stairs or slide won’t work so my question is, whats going on?

We had our mechanic - who is really good - check the starter battery and he said it was fine. Any other thoughts?

**creativepart** · 11-03-2020, 07:09 AM

But,but, but.... the steps and the slides ARE powered by the Chassis battery not the House batteries.

Shore power doesn’t help put slides in or out and standard procedure is to start the motorhome when activating the slides.

Why do you think that “something is crossed?”

Seon · 11-03-2020, 08:00 AM

The OP doubting it's the battery reminded me when a sign reads, "Wet Paint" and one still wants to touch the item.

Old Navy · 11-03-2020, 09:20 AM

Quote:

Originally Posted by creativepart

But,but, but.... the steps and the slides ARE powered by the Chassis battery not the House batteries.

Having a trailer vice an MH, I would have assumed differently. Sounds like just a shot battery.

DavidM · 11-03-2020, 09:32 AM

Old Navy:

Trailers always use the trailer batteries for slide and step movement if they have them. But if the slide won't move or is sluggish, connect the TV and run its engine for 15 minutes and try again. Even better connect the TV's battery to the trailer's battery with jumper cables which will supply more current and let it move immediately.

Muttibear:

Despite what your mechanic says you probably have a shot chassis battery or you are somehow letting it run down and that has probably damaged it. It was run down when you tried the slide and the boost switch let it start. After running for a few minutes the alternator charged it enough to move the slide.

Your slide and steps are acting normally, nothing crossed. It is the way it was built.

David

Morich · 11-03-2020, 11:00 AM

Step one to getting a better chance at ANY of the electrical things on ou RV to work is quite simple. START the engine first!
Without it getting into heavy thinking, this is what often happens, whether we have things that work off the coach or the start battery, one or the other may be somewhat run down for whatever reason and they may be a bit funky at doing their job. But if we start the engine, the alternator will automatically begin putting out higher voltage to charge the start battery and at the same time most motorhomes will have relays or solenoids to connect the coach and start batteries together.
So if you really just wan things to work and don't want to study too hard, just start the engine to get both batteries strings as well as the alternator putting out a charge level voltage and use three sources to do what you want done.
Check the manual to see if your RV doesn't recommend doing this when you are doing the heavy job of leveling or extending slides.
It can get you by--even when the start battery is weak/bad like in this case.

iezzif · 11-19-2020, 05:26 AM

I think that everyone is missing the point of Muttibear's question. Like him, we have a 2003 Itasca which has annoyed me with lots of electrical gremlins, all since fixed except for a parasitic drain on my NEW chassis battery. No less that 3 RV service centers, including a Winnebago Dealer, could find it. A couple of bad grounds here and there, but no real obvious cause. Installed an AMP L Start with no effect, even when hooked up to shore power. Would like to find the problem once and for all.

Morich · 11-19-2020, 07:50 AM

Quote:

Originally Posted by iezzif

I think that everyone is missing the point of Muttibear's question. Like him, we have a 2003 Itasca which has annoyed me with lots of electrical gremlins, all since fixed except for a parasitic drain on my NEW chassis battery. No less that 3 RV service centers, including a Winnebago Dealer, could find it. A couple of bad grounds here and there, but no real obvious cause. Installed an AMP L Start with no effect, even when hooked up to shore power. Would like to find the problem once and for all.

This is where I think most of the answers were leaning. We were wanting to make sure the batteries were good by asking how they were tested as we know far too many miss a simple weak battery when they do a voltage test. Maybe there should be a rule against using a voltage test on batteries, since it misleads so many?
We many of us know from dealing this this sort of complaint is that the batteries are the power to all the little decisions that the mechanical parts have to make and if they are not good, the rest of the process is suspect. We also know that many mechanics do not know much about batteries!
It takes time and knowledge to correctly test a battery and it is not done by simply driving through and have a guy use a meter for a couple minutes!
That combined with knowing that there are almost always drains on batteries, even when we think we have disconnected them, leads us to asking about the batteries.
Point one on your problems might be to ask if you have done the extra work to fully disconnect things which are left on? On the start battery, those can be things like the radio which has presets, the ignition, automatic locks and all those convenient little gizmos we don't think about. A GPS, tire minder or camera with a power brick still plugged in will still be drawing power when the unit may be turned off!
On the coach batteries, we often find the safety items like CO and propane detectors are still drawing power after we use the battery disconnect.
Not a hard problem to run down but it takes a dedicated, driven person and time to get the correct answer and those folks are rarely found in the local garage--unless it's you!

That's where a forum, even with all the faults, can be better than a mechanic!
We can be a group of folks made up of nobody knowing all the different aspects, but when totalled, there is likely to be several who DO know the specifics of some problem and many of us are just kind of looking for entertainment while waiting until it is safe to go out again!
AND--We do work cheap!!

Elkman · 11-28-2020, 05:05 PM

Attach a volt meter to the battery when starting the engine. You can tell if the voltage drops below 12.6 volts then you have one or more bad cells in the battery. Auto batteries are good for 5 years on average but I have to replace the electronics battery in our Prius every 3 years.

Old Navy · 11-28-2020, 08:08 PM

Quote:

Originally Posted by Elkman

Attach a volt meter to the battery when starting the engine. You can tell if the voltage drops below 12.6 volts then you have one or more bad cells in the battery.

Voltage at the battery terminals will drop significantly while cranking. With a single battery, I wouldn't be concerned unless it dipped below 10.5. I have dual H8 batteries providing 1800 CCA's in my truck, and even those can drop below 12V when starting.