I have a chassis battery puzzle in my 2014 Navion

[john_Navion]

Recently my 2014 Navion chassis AMG battery has discharged while in storage. For years I have had my RV in a storage yard when not in use. We've put 117k miles on it, so it hasn't been idle for long, but the chassis battery never dropped below 12V in storage. Recently the battery has dropped to 11.8v or so after just a week between checks. The battery was several years old so I thought it needed changing. After checking several local garages about the procedure, I decided to have my local Mercedes dealer (which was the most expensive option) put the new battery in. That was Oct 14 and I paid $600. The RV was again left in storage afterward but I checked it twice before Monday, Oct 27 and it was at 12.2V.
On Monday I checked the battery and it was at 5V (FIVE Volts)!
I immediately bought a Wolfbox 4000A Jump Charger and air compressor, which Amazon delivered the same day, charged it up and tried it yesterday The jump start worked in getting the RV started and after running about an hour I turned it off and the chassis battery settled in at 12.4V. I'll keep checking.
So my puzzle is what is draining the battery? I called the MBZ service manager but he didn't have any suggestions besides taking it in to have it checked and get a battery maintainer.

Since I didn't have this problem for over a decade after I purchased the Navion, what is happening now?

I'd use a battery maintainer while in storage, but I don't have access to power. Even at home, parked on the street, I can't easily run power for a maintainer (and parking regulations limit my curb-time). However I have two 10w solar chargers hooked to each battery bank, chassis and house, which has kept the house battery up but apparently wasn't enough for the chassis battery.

Notes about my 2014 Navion: it is more-or-less OEM, having had most of the engine-chassis work done by my local MBZ dealer, who is a Sprinter maintenance specialist. (I'm willing to pay extra for the expertise and care I've gotten from MBZ service, and their location is convenient.) In storage, the house power switch is off. I've disconnected the chassis battery when we've left the RV in storage for weeks at a time, like earlier this spring when we traveled to Europe for 4 weeks, but not for short-term. We're in our 80's so our RV travel has been curtailed from cross-country, month+ trips to infrequent week-long trips within CA. When camping in the RV, we are usually plugged into power.
Any suggestions or theories about what is happening to the chassis battery to cause the sudden drain?

PS The Wolfbox 4000A Jump Charger and air compressor also worked on my bicycle tires this morning. You can set the pressure and let it run, so I got my tires up to 55# and it made a big difference to the bike's performance.

Thank you for your attention,
John Beeley
14NiQ-G
Mtn View CA

 

[Waterbug]

IT is easy to accidentally leave something that runs off of 12v turned on. Does your RV have a battery chassis disconnect relay? If so, use it. See what you think doesn't have a drain works. If it does, it is a drain while stored.

 

[Morich]

A few things that pop up?
One is that there are battery drains left on both the chassis and coach batteries even when we use the disconnect switches. In your case, I only see the coach having the standard disconnect switch and relay. your RV uses a plug type disconnect on the chassis 12Volt.
So if it is the chassis side and it seems to have changed, that can leave more questions on why it now runs down sooner.
One of the better things to avoid this would be to use the disconnect system every time you park it!
But since you have not been in that habit, there are likely other things involved.
you could have something like a wire has rubbed and now has a high resistance short to ground. Hard to find without know what each circuit should look like.
A second thing might be easier to check. Some things will always be left on and on the chassis, it is things like radio presets and any auto locks. Often the steps are on.
Do the steps pop out when you have the engine turned off and open the side door? That shows the chassis power is left on for the steps. Is there a light under the steps and it may not be noticed when leaving in the daylight? Any chance you have the dash radio set to use chassis battery and it is turned on but down to a level that you don't hear it?
Check for some sneaky things that is on but not noticed and you are now doing some small point differently than the first years?

Just lots of possible things but another point might be how well you are getting the chassis battery charged when you see it down. A reading of 12.2 on a lead acid is actually down quite a lot and running the engine for a short time like an hour is not likely to get it fully charged.
The problem with batteries is that we only test the voltage right at the post and that can leave us mislead about what is all down through the other cells.
Batteries can be compared to a barrel where we store some think item like syrup. When we are adding syrup and look at that tiny hole we may see it full of syrup as we are pouring it in! But if we come back in an hour and that syrup has had time to settle, we may find the barrel is not full at all. It takes TIME for the syrup or the battery charge to level out all through the battery and let us get a good idea of what we have in there!
Battery readings need to be taken after at least 4-5 hours after we have taken the charge off to get usable info!

One way that can catch us is when we run the engine for tooo short a time to actually get the battery fully recharged. Maybe we only get it back to 80%? Then we use it again and repeat the less than full charge.
Lots of variables involved but we can get into a pattern where we let the battery drain, only get it part way back and if we repeat that move, it eventually go flat!

IF there is something like that, it is true that the more often we let a lead acid go too low, it puts a bit of dent in what we can get out the next time. They are fussy about getting run down and each time we do it and the longer it stays down, the more damage we can get.

Hope there are a few hints in there for you to look over as the batteries ARE on of the biggest headaches we hear about here on the forum.
So simple but so confusing! ARRGH!

No way I'm saying that is a for sure deal but just a suggestion to check as easier to think over what we do than it is to try to chase hard stuff like wiring shorts that might be doing us dirty!

 

[john_Navion]

A few things that pop up?
One is that there are battery drains left on both the chassis and coach batteries even when we use the disconnect switches. In your case, I only see the coach having the standard disconnect switch and relay. your RV uses a plug type disconnect on the chassis 12Volt.
So if it is the chassis side and it seems to have changed, that can leave more questions on why it now runs down sooner.
One of the better things to avoid this would be to use the disconnect system every time you park it!
But since you have not been in that habit, there are likely other things involved.
you could have something like a wire has rubbed and now has a high resistance short to ground. Hard to find without know what each circuit should look like.
A second thing might be easier to check. Some things will always be left on and on the chassis, it is things like radio presets and any auto locks. Often the steps are on.
Do the steps pop out when you have the engine turned off and open the side door? That shows the chassis power is left on for the steps. Is there a light under the steps and it may not be noticed when leaving in the daylight? Any chance you have the dash radio set to use chassis battery and it is turned on but down to a level that you don't hear it?
Check for some sneaky things that is on but not noticed and you are now doing some small point differently than the first years?

Just lots of possible things but another point might be how well you are getting the chassis battery charged when you see it down. A reading of 12.2 on a lead acid is actually down quite a lot and running the engine for a short time like an hour is not likely to get it fully charged.
The problem with batteries is that we only test the voltage right at the post and that can leave us mislead about what is all down through the other cells.
Batteries can be compared to a barrel where we store some think item like syrup. When we are adding syrup and look at that tiny hole we may see it full of syrup as we are pouring it in! But if we come back in an hour and that syrup has had time to settle, we may find the barrel is not full at all. It takes TIME for the syrup or the battery charge to level out all through the battery and let us get a good idea of what we have in there!
Battery readings need to be taken after at least 4-5 hours after we have taken the charge off to get usable info!

One way that can catch us is when we run the engine for tooo short a time to actually get the battery fully recharged. Maybe we only get it back to 80%? Then we use it again and repeat the less than full charge.
Lots of variables involved but we can get into a pattern where we let the battery drain, only get it part way back and if we repeat that move, it eventually go flat!

IF there is something like that, it is true that the more often we let a lead acid go too low, it puts a bit of dent in what we can get out the next time. They are fussy about getting run down and each time we do it and the longer it stays down, the more damage we can get.

Hope there are a few hints in there for you to look over as the batteries ARE on of the biggest headaches we hear about here on the forum.
So simple but so confusing! ARRGH!

No way I'm saying that is a for sure deal but just a suggestion to check as easier to think over what we do than it is to try to chase hard stuff like wiring shorts that might be doing us dirty!

Thanks for the copious information! Yesterday I went to the storage yard with the intent of connecting the 10W solar trickle charger to the disconnected chassis battery. With difficulty I checked the existing charge level of both the battery (12.5V) and the solar charger (14V mid-day). Then I connected the solar to the chassis battery terminal and measured around 9V! I quickly disconnected the solar and the chassis battery measured about 12.4V. So I'm thinking that the solar charger is a little weird. I left it to think it over. Next time I'll try it with the other solar trickle charger (that's hooked to the house battery) and see what happens.
Stay tuned,
John

 

[Morich]

That seems like it is trying to tell you "something" !
But it seems to be giving you odd/wrong info??
If we think of voltage, it is something like looking at water, If we connect a couple tanks of water together, one being 12.5 inches deep and the other 14 inches, we would not expect the level to go down to 9 inches!
In fact if we want to get charge moved from one point to another we have to have the charger higher than the battery we want to charge!

Seems there is something wrong there somewhere that we are not spotting??
One thought might be to look that there was not some way that a short to ground was created when you connected the solar to the battery?
I would have expected a pretty big arc involved in doing that but if you have 12.5 and add 14, getting to around 9 would seem wrong!

Gremlins eating power somewhere!!

 

[bigbAZ]

In looking at all your numbers I don't see any evidence that the new battery was ever fully charged.
When the new battery was first installed you should have charged it all the way, that could take many hours depending on how long the new battery sat on the shelf before it got installed in your rig. When you found the battery at 12.2 volts it was then less than 50% charged, at that point starting and running the engine for 1 hour was not even close to enough to bring it to full which is 12.7-12.8. Don't forget just starting the engine drops the battery even further and part of that hour was just replacing what it took to start it.

Later when you measured 12.4 volts that was only a only 60% charge, and depending on how long you waited before testing some of that could have been a surface charge. It should have gone on a charger then as well, for many hours.

In summary I suspect you are dealing with a battery that has been over half discharged since it was installed and it has never been even close to fully charged since installation. It needs to spend some serious time on a charger or go for a many hour drive. This should be done asap as every day a lead acid battery remains at a low charge it suffers irreversible damage. (If the battery actually did drop to 5 volts it could already be compromised).

Once you get that battery to 100% the next step would be to look for a parasitic load if the problem persists but no way to know that when working with a battery that is only 1/2 full and could now be compromised.

 

[Bobn1957]

Recently my 2014 Navion chassis AMG battery has discharged while in storage. For years I have had my RV in a storage yard when not in use. We've put 117k miles on it, so it hasn't been idle for long, but the chassis battery never dropped below 12V in storage. Recently the battery has dropped to 11.8v or so after just a week between checks. The battery was several years old so I thought it needed changing. After checking several local garages about the procedure, I decided to have my local Mercedes dealer (which was the most expensive option) put the new battery in. That was Oct 14 and I paid $600. The RV was again left in storage afterward but I checked it twice before Monday, Oct 27 and it was at 12.2V.
On Monday I checked the battery and it was at 5V (FIVE Volts)!
I immediately bought a Wolfbox 4000A Jump Charger and air compressor, which Amazon delivered the same day, charged it up and tried it yesterday The jump start worked in getting the RV started and after running about an hour I turned it off and the chassis battery settled in at 12.4V. I'll keep checking.
So my puzzle is what is draining the battery? I called the MBZ service manager but he didn't have any suggestions besides taking it in to have it checked and get a battery maintainer.

Since I didn't have this problem for over a decade after I purchased the Navion, what is happening now?

I'd use a battery maintainer while in storage, but I don't have access to power. Even at home, parked on the street, I can't easily run power for a maintainer (and parking regulations limit my curb-time). However I have two 10w solar chargers hooked to each battery bank, chassis and house, which has kept the house battery up but apparently wasn't enough for the chassis battery.

Notes about my 2014 Navion: it is more-or-less OEM, having had most of the engine-chassis work done by my local MBZ dealer, who is a Sprinter maintenance specialist. (I'm willing to pay extra for the expertise and care I've gotten from MBZ service, and their location is convenient.) In storage, the house power switch is off. I've disconnected the chassis battery when we've left the RV in storage for weeks at a time, like earlier this spring when we traveled to Europe for 4 weeks, but not for short-term. We're in our 80's so our RV travel has been curtailed from cross-country, month+ trips to infrequent week-long trips within CA. When camping in the RV, we are usually plugged into power.
Any suggestions or theories about what is happening to the chassis battery to cause the sudden drain?

PS The Wolfbox 4000A Jump Charger and air compressor also worked on my bicycle tires this morning. You can set the pressure and let it run, so I got my tires up to 55# and it made a big difference to the bike's performance.

Thank you for your attention,
John Beeley
14NiQ-G
Mtn View CA

First of all, if your battery discharged down to 5 volts, it has been severely damaged, and I wouldn't trust it to be reliable anymore! For storage, you need to have a charger attached, either a solar panel (if shore power is not available) or a conventional multi-stage charger!

 

[bigbAZ]

If there is no power available in storage the Sprinter has a battery disconnect in the cab that is very easy to pull and re-attach.