"Emergency Battery" Under Seat

220629

Well-known member
The fact that there is a small battery mounted under the VS30 driver seat surfaced in a thread today. It seems to me like one of those things that many owners would not be aware of. Thanks goes to Hilld and contributing members. :thumbup:

A sticky seems appropriate. Feel free to add to the general knowledge of what the battery does and possible operating symptoms that may be related to it.

No I mean DRIVERS seat. Unless you have the factory auxiliary battery system, then it might be different.

On VS30's this is called the emergency battery and is about the size of a small battery you might find in a residential alarm system. Maybe the size of 3 or 4 packs of cigarettes. Here is a pic to help sort things out. View attachment 184964
1623706501527.png


Unrelated to the "Emergency Battery", but it is another battery located in the area.

What you experienced [the symptoms described in the Original Post] is very close to the experience I had. I won’t go into details because you’re stuck. Get towed to the nearest MB sprinter dealer and tell them to check the main battery [chassis aka start battery] disconnect is properly attached to the battery. Mine was not and had come loose to where it was only resting against the connection point.

I didn’t see the service tech do any of the work. Im telling you what he told me. You will also need to have them run a diagnostic test on your main battery. It will be toast and need to be replaced. Don’t let them go by the voltage reading in the HU display. It will show slightly lower than normal and will drive but it won’t hold a charge
vic
 
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OrioN

2008 2500 170" EXT
In my 2008, the battery allows for the factory alarm to function if the main battery is defeated.
 

RVBarry

2023 AWD 170 DIY CamperVan
Related thread
 

sanomechanic

Well-known member
The Distronic will not work with that battery un plugged. It has something to do with GPS communication. Found that out during my build and knocking a plug off while pulling wiring.
 

sprintguy

16+ yrs Master Commercial technician
The emergency park battery is there as a redundant system in case the main voltage supply is interrupted to the ISM, or the signal from the transmission controller to the electronic ignition controller states the vehicle has not shifted to park even though the shift to park has been requested. If these situations happen ie “no shift to park “ when requested . The EIS (electronic ignition controller) then uses the emergency park battery to override the main shift control by suppling voltage to a backup control solenoid to bypass normal shift operation. In the event of a weak or dead main battery the EIS only has a split second to move the transmission to park, so in reality that little battery is only used as a type of capacitor. As of late build 2020/2021 vans the emergency park battery has been replaced with a capacitor. This puts the commercial vans more in line with the passenger cars.
Carl
 

sprintguy

16+ yrs Master Commercial technician
The Distronic will not work with that battery un plugged. It has something to do with GPS communication. Found that out during my build and knocking a plug off while pulling wiring.
Distronic as of now does not normally use GPS to guide the van. What happened in your case was the voltage of the Park battery is distributed throughout the communications bus to multiple modules example: from EIS to SAM, CDI or ME, ISM and ESP etc. ESP is programmed to work in conjunction with The Distronic Radar sensor and multi-function camera. So if ESP Does not “like “ the voltage signal of the “P” battery it will set a fault code as current thus shutting down cruise control all together .
 
"As of late build 2020/2021 vans the emergency park battery has been replaced with a capacitor. This puts the commercial vans more in line with the passenger cars. "

How can one find out if they have a battery or a capacitor on a 2020 3500 Cut-away Cab chassis?
 

Happy29

2020 2500 OM642 4x2 170HR
My late October build 2020 has the 1.2Ah under drivers seat. I guess they were short on super capacitors that day. On my build sheet it also says 70Ah starter battery but the physical battery says 95Ah. Go figure.
 

autostaretx

Erratic Member
In the past, all US-delivered Sprinters had one of the optional (95 or 100) AH batteries. The 70 AH is/was standard in Europe.
(i've heard of a few 70AH in the US, but very rarely)

--dick
 

Cactus123

New member
Newbie here, sorry if this is in the wrong place but I have a 2019 2500 commercial I just got, former Amazon delivery van, 60k miles, dash light says aux battery malfunction but doesn’t seem to have one under the seat as described. Any advise would be appreciated.
 

RVBarry

2023 AWD 170 DIY CamperVan
Newbie here, sorry if this is in the wrong place but I have a 2019 2500 commercial I just got, former Amazon delivery van, 60k miles, dash light says aux battery malfunction but doesn’t seem to have one under the seat as described. Any advise would be appreciated.
Hi, do you have your build sheet, or can you post your VIN?

If you have the E36 relay option, then you probably have a large AUX battery either under the passenger seat, or in the engine bay.

The emergency battery is under the driver seat, and all 2019's should have it.
 

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