Battery emergency at home fix( or sealed batteries suck )
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Battery emergency at home fix( or sealed batteries suck )
Car: 2013 e550 4-matic , Single battery , the OEM original that cam with the car
As luck would have it my car had the stuck in 'P' problem due to the battery then would not start.
The problem is after charging I was not going to risk driving it to get a new battery .
The solution was simple add water and fully charge. "Add water , no way its a sealed battery"
Being in a bind and having on one car that works, I needed a solution. The battery is a VARTA OEM .
At the factory they seal it with "tighten only" double o-ring sealing plugs on the top of the battery.
Simple removal was to dremel a slot ( 1/16" deep" on the top of the plug to allow a 1/2" wide flat head screw driver
to remove the plugs. The battery had no fluid at all . I put in enough water to cover the plates plus 1/8 ".
It charged to over 13 v then settled out at 12.8. Must have been out of water for a while , but the car loves
the full charge.
I plan on "maintaining" all sealed batteries this way from now on .
As luck would have it my car had the stuck in 'P' problem due to the battery then would not start.
The problem is after charging I was not going to risk driving it to get a new battery .
The solution was simple add water and fully charge. "Add water , no way its a sealed battery"
Being in a bind and having on one car that works, I needed a solution. The battery is a VARTA OEM .
At the factory they seal it with "tighten only" double o-ring sealing plugs on the top of the battery.
Simple removal was to dremel a slot ( 1/16" deep" on the top of the plug to allow a 1/2" wide flat head screw driver
to remove the plugs. The battery had no fluid at all . I put in enough water to cover the plates plus 1/8 ".
It charged to over 13 v then settled out at 12.8. Must have been out of water for a while , but the car loves
the full charge.
I plan on "maintaining" all sealed batteries this way from now on .
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Joined: Jun 2020
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'11 E350, '11 E550, '98 M3, '95 E320
Single battery?
Your solution worked and I've done it myself on batteries that had fill plugs. However my experience is once the "water" level drops significantly below the plate tops... the battery is not long for this world. Whether it's a reaction of the exposed lead plates, but the capacity is severely reduced and the battery life is short. So while its a good temporary solution, I would use it to drive to the parts store and buy a fresh battery.... especially if this is your only vehicle you depend on.
Your solution worked and I've done it myself on batteries that had fill plugs. However my experience is once the "water" level drops significantly below the plate tops... the battery is not long for this world. Whether it's a reaction of the exposed lead plates, but the capacity is severely reduced and the battery life is short. So while its a good temporary solution, I would use it to drive to the parts store and buy a fresh battery.... especially if this is your only vehicle you depend on.
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Joined: Jan 2019
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2015 E350 4Matic Wagon, 2018 GLE350 4Matic
I thought the whole design of AGM (absorbed glass mat) was that it was not supposed have free flowing liquid like "flooded" batteries.
I recently decided to part with $210 to replace my original battery (stamped 04/15) with a new one from Autozone. I'm not sure why I usually feel compelled to wait until I get stranded somewhere before replacing it. "But I can get one more week out of it...."
I recently decided to part with $210 to replace my original battery (stamped 04/15) with a new one from Autozone. I'm not sure why I usually feel compelled to wait until I get stranded somewhere before replacing it. "But I can get one more week out of it...."
MBWorld Fanatic!
Joined: Jun 2020
Posts: 1,363
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'11 E350, '11 E550, '98 M3, '95 E320
Yes, the fluid is not sloshing around in AGMs, but there's an electrolyte (liquid) inside the battery. Even though its "sealed" its still "vented" thru a valve that generally nothing passes thru as the internal gasses are recombined. However during overcharge situations, gasses can escape and thus, in-part, eventual loss of "water".
I'm not expert, maybe with time the valve loses some properties and doesn't hold back those gases as much as it should.
I'm not expert, maybe with time the valve loses some properties and doesn't hold back those gases as much as it should.
