Exploding battery....no injury

[Mr_logan]

The Red Onion sprinter had the battery under the passenger seat explode while driving. All of the parts and pieces were contained under the seat but the explosion cause hearing damage to the driver. Very lucky this time. Is this a rare or common ? Sorry I don't have the model numbers to share, I am not the owner but trying to prevent this from happening again to others. I don't seem to able to post a picture from my iPad

[Altered Sprinter]

Two factors for an exploding battery : One is an over charge that exceeds 14.4v where the peak charge produces Hydrogen gas. in theory the Sprinter can't exceed 14.4v as the diode pack once exceeding 14.4 v recycles excess voltage back and forth between the alternator, where voltage is maintained between 13.8v and 14.4v peak voltage with the battery,'however' this is dependent on battery type and condition.
The second is an open-circuit surface charge, where temperature can keep the battery in an Altered State of operation. the latter is rare but a known factor.
Scary thought.
Richard

[Mr_logan]

Richard,
Thanks for the rapid and informative reply. This van has a fabric cover over the entire seat pedestal that would trap the gas over the battery and just wait for an ignition source. What do you think would cause an over voltage condition? Voltage regulator? The driver squawked that there was a rotten egg smell a couple of days in advance to the explosion but no one followed up. So it was over charging for sure.
Thanks
Scott

[Altered Sprinter]

Originally Posted by Mr_logan

Richard,
Thanks for the rapid and informative reply. This van has a fabric cover over the entire seat pedestal that would trap the gas over the battery and just wait for an ignition source. What do you think would cause an over voltage condition? Voltage regulator? The driver squawked that there was a rotten egg smell a couple of days in advance to the explosion but no one followed up. So it was over charging for sure.
Thanks
Scott

Hi Scott It's more guesswork as to 'Why' the battery failed, or to the extreme exploded.
If gas was present as indicated, then the gas-off was hydrogen with a battery in an enclosed area. How old was the battery and what type? ...Deep cycle or AGM if deep cycle it should be ventilated.

However if the battery was charging at peak voltage this can only be tested with an on-board voltage tester digital that shows both voltage charge and temperature ratings combined or menu-select back and forth to monitor the battery's operational mode.. An example of Midtronics on board digital monitor, shows peak voltage variations at maximum alternator charging at 14.4v, 'second stage' shows an icon of the 'alt and battery' as to recycling over voltage back and forth between battery and alternator.

When the battery is charging it will show 14.4v as the battery reaches full charge, the alternator diode pack recycles excess voltage back into the battery which shows 14.2/3v charge.fluctuations depending on rpm are indicate of a current loop this is an open charge circuit charge.

Battery condition:Not an easy call as to type of battery and condition.
'However' this is an example of operation. Deep cycle 88amp 800H amperage in perfect condition.
The battery relies on charge from the alternator. where it can fail is based on both voltage and temperature. If a battery is gassing-off then we have an explosive nature in wait, as to the right conditions for a battery to potentially denote.

The battery gassing-off is a sign that a cell is failing under certain conditions a perfect storm can be created as to maximum voltage setting of a gas-off in an enclosed environment. Voltage peak ...High evaluation and out side ambient tempestuous conditions with a damaged battery cell 'can create the battery's low amperage of say 400Ah to overheat as the alternator is fully activating a battery charge once in a constant mode of 14.4 v the battery will boil and the gas-off becomes more obvious, this results on an open circuit surface charge where sufficient heat from the battery's wiring is enough to create a melt down and generate an electric spike resulting in the battery exploding.

The condition is rare but not rare enough to say it's a one off but manufactures have been sued as to battery's exploding ."Who's to blame"! likely the owner, but some battery's are defective from the build date, which may involve litigation.

The idea as to best practice is to monitor your battery over it's life span, keep the terminals clean , check wiring visually for signs of corrosion etc.

My original OEM battery is close to eight years old a cell has failed as via monitoring the battery I know it;'s now starting at 440Ah on a cold crank start, I' never thought it was possible for the voltage to drop below 8.5v and still start the van in Winter conditions. but time to replace the battery.

There are many reasons for battery failure the above are just a few.
Richard

[autostaretx]

If it's a T1N, the battery under the seat is the auxiliary ("house") battery.
Was it an "original (optional) equipment" installation, or an after-market who-knows-how-they-did-it job?
(real Mercedes installations should include a vent tube running from the battery to the drain hole in the floor)

There should be an isolating relay between the charging system and the auxiliary battery.
That won't prevent explosions like this (it's to prevent engine-off draws from draining the starter battery)
Other contributing factors could be "mixing technologies": say an AGM for the starter, yet a wet cell for the Aux.
(or vice-versa). Or a "gel cell" as the Aux battery (they can quietly go dry and then burst, but usually not so spectacularly).
Having a cell plate warp (frequently due to a cell going partly dry) can also trigger the steps to an explosion.

Added: even with an outgassing battery, you *also* need a spark to light off a hydrogen explosion.
The plate-warping can do that, but you might also have had a "simple" heat explosion (battery acid going to steam, battery case going BOOM). Forensics needed.

Glad to hear no one was hurt. (only needing to change their pants?)
--dick

[Altered Sprinter]

If passenger was sitting on the seat his pants were a wipe-out.
Richard

[mendonsy]

It's the new MB ejection seat option!

[NelsonSprinter]

It is rare, but the use of a vent tube to the floor is supposed to reduce that to near nil.
Do you know if the tube vent was used?
Was the alternator replaced with a higher Amp one recently?
I hope your hearing returns and your nerves aren't shot.

[Mr_logan]

I am meeting with the owner today to review some recent work done on the house battery installation and associated electronics by a dealer. There has been issues with cabin lights and a/c and I suspect we will find a cause. I am going to get off the iPad and get to the laptop and see if I can attach a photo of what is left of the battery but just picture two post connections and a bunch of messed up plates. No top.
Once again, thanks to all of you for and can you give me an opinion on whether the
Red Onion should continue to drive their other identical van or park it? The drivers are getting gun shy
mr. logan

[Mr_logan]

Here is a photo of the battery compartment or what is left of it. Wow, things went to hell in there.