Battery Charge and AutoStop behavior
11-03-2020, 03:34 PM
#1
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Battery Charge and AutoStop behavior
Recently I had both front seats out as part of a lengthy project and didn't drive the car for 3 weeks or so. I was a little surprised when I got it all back together and the battery charge was too low to even turn over the engine. Since my battery is now close to six years old, I figured I would be buying a new one. But when I took it to be tested they told me they would have to put it on the charger for a while and actually ended up leaving it to charge overnight. The next morning the guy said it tested ok but could use some more charging time, so when I got home I put in on my home charger for several more hours.
It's been working fine since then and I even noticed the car is auto-stopping more frequently and, especially interesting, it starts back up more smoothly and quickly. Since I've had the car I was always surprised that a restart sent a noticeable shudder through the drivetrain, thinking Mercedes couldn't have meant for that to happen.
My experience in Texas is you're doing well to get 3 years from a car battery, but miles driven, number of starts, etc. must also factors in longevity as well because this one's still going after almost six years (and only 19k miles). It may also be true that the AGM technology and/or the Mercedes/German OEM product are superior to the 'regular' batteries I've used over the years.
It's also interesting how much better auto-stop works when the battery's fully charged. I knew the computer looked at several variables to decide when to invoke auto-stop and a low battery would block auto-stop, but the way it works now with a good charge is surprisingly more effective. I think I read our cars are limited to a max 30-second auto-stop, but I even wonder if that's true now that mine is working correctly. One day while waiting for a long light I'll have to look at my watch and see if it actually is going beyond 30 secs.
It's been working fine since then and I even noticed the car is auto-stopping more frequently and, especially interesting, it starts back up more smoothly and quickly. Since I've had the car I was always surprised that a restart sent a noticeable shudder through the drivetrain, thinking Mercedes couldn't have meant for that to happen.
My experience in Texas is you're doing well to get 3 years from a car battery, but miles driven, number of starts, etc. must also factors in longevity as well because this one's still going after almost six years (and only 19k miles). It may also be true that the AGM technology and/or the Mercedes/German OEM product are superior to the 'regular' batteries I've used over the years.
It's also interesting how much better auto-stop works when the battery's fully charged. I knew the computer looked at several variables to decide when to invoke auto-stop and a low battery would block auto-stop, but the way it works now with a good charge is surprisingly more effective. I think I read our cars are limited to a max 30-second auto-stop, but I even wonder if that's true now that mine is working correctly. One day while waiting for a long light I'll have to look at my watch and see if it actually is going beyond 30 secs.
Last edited by Tom in Austin; 11-03-2020 at 03:38 PM.
11-10-2020, 09:19 AM
#3
MBWorld Fanatic!
Thread Starter
Interesting discovery ... the other night I noticed there's a reading light above the back seat that has been on for who knows how long.
Never even knew it was there, probably turned it on by accident when I was working in there. Helps explain why the battery ran down after several weeks not being driven ... also a reminder of why it's never a bad idea to just disconnect the battery when undertaking some long project.
Never even knew it was there, probably turned it on by accident when I was working in there. Helps explain why the battery ran down after several weeks not being driven ... also a reminder of why it's never a bad idea to just disconnect the battery when undertaking some long project.
