Battery charging
Thread Starter
Junior Member
Joined: Jul 2018
Posts: 26
Likes: 7
E350 Cabriolet
Battery charging
I purchased a CPO 2012 E350 Cab in 2015 with 12,000 miles on the odo. I now have 18,000 miles on the odo. Not driving more than once a week or so in the winter here in Seattle I used a charger to top it off every 2 weeks. Last fall the time to fully charge the battery exceeded 15 minutes so I brought the car to the MB store where she was purchased and they installed a new battery. Yesterday I tried to charge the battery and it would not fully charge after 25 minutes of trying. The battery voltage reads 12.8 so I think it is OK. I checked the manual for any information about charging the battery and found a warning that stated I should not charge the battery while it is still installed in the car. Further it stated that MB has a charge unit for charging a battery while installed. I read some posts from a year ago where owners said they use a trickle charger to keep the battery on their lightly used MB's fully charged. Have any of you been able to use a trickle charger to keep your battery fully charged? I am concerned that a trickle charger may be as ineffective as my normal charger which charges at 12 volts and 2 amps. This charger works just fine on my 2013 Audi A6 with the original battery.
Super Member
Joined: Sep 2005
Posts: 723
Likes: 32
From: Central Jersey
2003 E500, 2004 G35X
I have been using trickle charger, Battery Tender, for several years now with the Porsche Macan, don't drive it that often in the winter bad weather. Got it from Coscto some time back. I think there are two models, get the one around $30. You can just leave it charged all the time, no harm to the battery. It works great.
Super Member
Joined: Sep 2005
Posts: 723
Likes: 32
From: Central Jersey
2003 E500, 2004 G35X
I don't recall specifics in the manual, but I think Battery Tender can charge most cars without issues unless your car manual mention specific charging instructions. I don't think my MB has any caution about charging.
Junior Member
Joined: Sep 2013
Posts: 64
Likes: 14
From: Massachusetts
CLE53 Cab
Flash Gordon has the right idea. A trickle charger will give 0.1 to 0.25 amps. This could take days to charge the battery, but will not over charge it.
Batteries give the best life when kept between 10% and 90% charge. Google "Battery Voltage Charge State" to get a voltage chart. Be aware that the voltage varies with battery temperature and that you need to disconnect the charger and any load for at least half an hour before measuring the voltage.
You don't need to do this. I have a 2014 E550 Cab in the Boston area. Original battery, 32K miles, summer tires.
It goes into the garage before Thanksgiving. I try to drive it at least 50 miles every 4 to 6 weeks on a day when the roads are clear. Four winters and I never connected my charger.
Batteries give the best life when kept between 10% and 90% charge. Google "Battery Voltage Charge State" to get a voltage chart. Be aware that the voltage varies with battery temperature and that you need to disconnect the charger and any load for at least half an hour before measuring the voltage.
You don't need to do this. I have a 2014 E550 Cab in the Boston area. Original battery, 32K miles, summer tires.
It goes into the garage before Thanksgiving. I try to drive it at least 50 miles every 4 to 6 weeks on a day when the roads are clear. Four winters and I never connected my charger.
Last edited by jerrya; Jul 29, 2018 at 07:31 PM. Reason: typos
Newbie
Joined: Apr 2016
Posts: 6
Likes: 7
2012 E550 Cabrolet
Keeping the battery charged is not that complicated. Just make sure you get a maintainer and not just a charger or trickle charger. The Schumaker crap sold at Wally world is just that crap. I found this one worked good.
https://www.harborfreight.com/automo...ner-63350.html
https://www.harborfreight.com/automo...ner-63350.html
Thread Starter
Junior Member
Joined: Jul 2018
Posts: 26
Likes: 7
E350 Cabriolet
MB Accessory
I was looking at the MB USA web site and found a battery charger accessory when I was building an E class wagon (2018). Price was $190. Seems too rich for me but like all things MB the price is usually more than I would like to spend. The description of the piece did not allude to the charger being specific for MB E class cars. I guess I will hold off for now since the battery was new last Nov.
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Junior Member
Joined: Aug 2018
Posts: 71
Likes: 13
From: Louisville, KY
2017 E400 C4 Coupe
Probably the best charger for the M-B is this:
https://www.ebay.com/p/Genuine-Merce...82227&chn=ps-- but it is just a Ctek
Go to Amazon and look at the Cetek MUS 4.3-- it's more than $100 less and will be just fine. You don't need to pay a C-Note+ for that M-B logo.
https://www.ebay.com/p/Genuine-Merce...82227&chn=ps-- but it is just a Ctek
Go to Amazon and look at the Cetek MUS 4.3-- it's more than $100 less and will be just fine. You don't need to pay a C-Note+ for that M-B logo.
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