Engine start battery draining too fast?

[Antonio]

After 2 days of being with the engine off at a campground we see the low chassis battery warning on the BMPro monitor and on the third day the battery icon actually disappears from the monitor like if it was disconnected. Coach lithium batteries are OK as we are plugged in to shore power.

Fortunatelly, I was still able to start the engine but I could tell the battery was low.

Perhaps, while camping we open many times the doors and the console is powered on every time we do this with related battery consumption. But 2 days seem to be a short time. I think there is some other problem.

I also noticed that sometimes, while seating at the front seat reading, even without opening the doors, the MB console powers on and shows the startup screen like it does when I open the doors.

As a fix we are now disconnecting the battery every time we stop for more than a day. But this is not pleasant.

I know this may be a Mercedes issue and may not be related to Thor. Has anyone experienced something similar?

[DavidEM]

This is a long shot, but worth checking. Do you have a Precision Circuits BIM 160 battery isolator. See the attachment for a pic and installation instructions.

It will usually be installed under the hood somewhere near the chassis battery.

Thor usually wires these backwards. The Bat A terminal should be wired to the chassis battery and the Bat B terminal wired to the coach/house battery.

That might be causing your problem.

David

[robertj1961]

It may be worth having the chassis battery load checked to see its condition. Any auto parts store can do that. I have purchased new vehicles before that had bad batteries (covered by warranty). You can also purchase a load check device fairly inexpensively. I have also used this inexpensive device on other car batteries and seems to work well. It is easily installed and has an app you can check easily:

https://www.amazon.com/QUICKLYNKS-Ba...NsaWNrPXRydWU=

[16ACE27]

Originally Posted by robertj1961

It may be worth having the chassis battery load checked to see its condition. Any auto parts store can do that. I have purchased new vehicles before that had bad batteries (covered by warranty). You can also purchase a load check device fairly inexpensively. I have also used this inexpensive device on other car batteries and seems to work well. It is easily installed and has an app you can check easily:

https://www.amazon.com/QUICKLYNKS-Ba...NsaWNrPXRydWU=

So a $25 bluetooth voltage meter which tells him the same info on his phone that he already gets on his current system monitor?

[robertj1961]

Originally Posted by 16ACE27

So a $25 bluetooth voltage meter which tells him the same info on his phone that he already gets on his current system monitor?

If he can get a cranking test from his "monitor" it is much more advanced than mine.
The only information I get from my "current system monitor"(BM Pro) is battery voltage for the chassis batteries which tells nothing about the condition under load (starting).
Not like I am selling this but it has worked on other vehicles I have owned as low cost way to monitor chassis batteries with simple installation.

This device provides:
Trip Monitor
Charging Test
Cranking Test

[Lt Keefer]

Originally Posted by robertj1961

If he can get a cranking test from his "monitor" it is much more advanced than mine.
The only information I get from my "current system monitor"(BM Pro) is battery voltage for the chassis batteries which tells nothing about the condition under load (starting).
Not like I am selling this but it has worked on other vehicles I have owned as low cost way to monitor chassis batteries with simple installation.

This device provides:
Trip Monitor
Charging Test
Cranking Test

Bingo.

[fourthgear]

I just replaced my Chassis Battery last week on my 2022 Thor Sanctuary 19P , had the exact same issue , I too got warnings from the BMPro , with battery voltage dropping to ( at the end ) 11.6 VDC & it kept dropping even out of the Van .

I was told by MB dealer , that MB will not warranty any new Vehicle Battery , if they replace it with a new one , they will .I also added a Battery Maintainer to the Battery Terminals , so I can plug it in when camping if needed , I have it plugged in now , since I'm on SP & if I wasn't the 400AH Li system can operate it even camping if no SP .

[robertj1961]

A battery maintainer on the chassis is probably a good idea and probably should consider that. I have read on the Promaster Forums that the Dodge vans can cause the batteries to go dead within a month due to parasitic draw even with just a stock non customized van. I guess that is one reason Dodge installed the "quick disconnect" battery cable to the chassis battery. We keep our van moving at least every couple of weeks so hasn't been a problem (yet).
It seems that Dodge blames Thor whenever they can for warranty issues because of the customization. So far we have been lucky and the van problems have been minor!

[fourthgear]

I drive our Sprinter almost every day, its my daily driver, I do have weeks that it only gets driven one or two days out of a week ,but who knows how the Battery was treated at Thor & the Dealership & I have seen it happen to a Neighbor in his brand new Toyota Pick up , didn't last 6 months . Difference is , his was replaced under warranty . Bad new vehicle batteries are not rare .

Funny thing is , the Die Hard Battery is made in Germany & the MB factory Battery is made in the USA , I read that the 4x4's shipped to the USA were reassembled here on the USA , so maybe they didn't ship Batteries with them .

[robertj1961]

Originally Posted by fourthgear

I drive our Sprinter almost every day, its my daily driver, I do have weeks that it only gets driven one or two days out of a week ,but who knows how the Battery was treated at Thor & the Dealership & I have seen it happen to a Neighbor in his brand new Toyota Pick up , didn't last 6 months . Difference is , his was replaced under warranty . Bad new vehicle batteries are not rare .

Funny thing is , the Die Hard Battery is made in Germany & the MB factory Battery is made in the USA , I read that the 4x4's shipped to the USA were reassembled here on the USA , so maybe they didn't ship Batteries with them .

Agree and I have had at least two new vehicles with bad batteries replaced under warranty but am certain that would not be the case if our van battery was bad. Ours has also been more of a "daily driver" since getting rid of a class A which we don't miss given all that goes along with it.
We are happy to be in Florida for a while near Crystal River where at least not worried about the winterization.

[Civrot]

Originally Posted by DavidEM

This is a long shot, but worth checking. Do you have a Precision Circuits BIM 160 battery isolator. See the attachment for a pic and installation instructions.

It will usually be installed under the hood somewhere near the chassis battery.

Thor usually wires these backwards. The Bat A terminal should be wired to the chassis battery and the Bat B terminal wired to the coach/house battery.

That might be causing your problem.

David

Sir,
since the OP stated he had lithium batteries wouldn't he need the LI-BIM 225???

https://www.amazon.com/Battle-Born-B...7DY8S815&psc=1