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Hi guys, I’m an owner of 2015 s65 with 48k miles on it. I’m new to the forum and would like to get some help from experts in the forum.
so I have owned my car for about 9 month and the car is mostly great but have some issue with battery.
The car will be dead if I do not drive it for about 6-7 days and I would have to jump it. Is this normal for the lithium ion battery for S63/S65?
I checked the battery voltage, etc from the workshop page in car and it looks to be normal, but I let AutoZone to test the battery and they said the battery test failed probably because CCA is lower than expected? I’m not sure how accurate that is.
I’m not sure if the battery itself is bad or there’s something that’s consuming amps abnormally or the car is supposed to like this.
would appreciate any information and help!
The reading when the car is not started and sits for 4 days.
My 2015 has 50k miles and still has the original battery. The trunk mounted aux battery was replaced once. I have never had to charge a battery. The car routinely sits for up to three weeks, no issues starting it, the battery works normally. First we are in SoCal by the ocean so there are no substantial temperature extremes. The car is always parked in the garage, the lowest temperature in the garage is about 62 deg. A really cold outside night temperature is 50 deg. The car is not used for short trips to the store. Our 2017 S65 Cabriolet still has its original battery, never a need to charge it That car is used for short trips and only has about 25k miles on it. The original trunk mounted aux battery was replaced a year ago.
My 2015 has 50k miles and still has the original battery. The trunk mounted aux battery was replaced once. I have never had to charge a battery. The car routinely sits for up to three weeks, no issues starting it, the battery works normally. First we are in SoCal by the ocean so there are no substantial temperature extremes. The car is always parked in the garage, the lowest temperature in the garage is about 62 deg. A really cold outside night temperature is 50 deg. The car is not used for short trips to the store. Our 2017 S65 Cabriolet still has its original battery, never a need to charge it That car is used for short trips and only has about 25k miles on it. The original trunk mounted aux battery was replaced a year ago.
Thanks for the input. So seems like there’s something wrong with my electrics/battery.
How do you know the aux battery needs replacement? Could that be related to the main battery drain as well?
I think I might need to check the battery date first, and then find a specialist to check the root cause of the drain.
On the 2015 S65 I got a low battery warning in the instrument cluster for the Aux battery. Also the cruise control went offline when the warning came on. The 2017 S65 Cab was different. We were getting random accessory offline messages on startup. After about a week I realized all these messages were for accessories powered off the aux battery. I took it to the dealer and sure enough, the aux battery was bad. Dealer said the S65 aux batteries are usually good for 5 years, give or take. The S65 main battery supposedly can last well over 10 years, but some can fail earlier. Completely different than our E63S. In 4 years it was on its 4th battery, we have sold that car.
A weak main battery should not affect the small trunk mounted aux battery. Completely different functionallity than the SL has. In the SL a failing underhood battery can affect the large trunk mounted AGM battery. The SL has electrically actuated brakes so one battery backs up the other for vital functions. The last thing we want is both batteries to fail. I had that happen once on my 2005 SL600. It is possible to stop the car but it is not easy and it is not quick.
Last edited by Quadrobenz; Feb 10, 2025 at 05:24 PM.
Try topping off the battery with a trickle charger and see how it is over the next couple of weeks. I've left my 63 untouched for 6 weeks with (thankfully) no battery issues. If and when the lithium battery does need replacement, I would consider the AGM route w/ coding vs. lithium replacement. There was a lithium battery shortage a little while ago, not sure if its been resolved.
Try topping off the battery with a trickle charger and see how it is over the next couple of weeks. I've left my 63 untouched for 6 weeks with (thankfully) no battery issues. If and when the lithium battery does need replacement, I would consider the AGM route w/ coding vs. lithium replacement. There was a lithium battery shortage a little while ago, not sure if its been resolved.
AGM batteries have a float option on a trickle charger is there a similar one for lithium ion? Will that help at all?
Doesn't Benzninja offer coding to allow for AGM battery options for these LiON based vehicles? For a while I recall you couldn't find a replacement for these elusive batteries 🔋
Doesn't Benzninja offer coding to allow for AGM battery options for these LiON based vehicles? For a while I recall you couldn't find a replacement for these elusive batteries 🔋
Try topping off the battery with a trickle charger and see how it is over the next couple of weeks. I've left my 63 untouched for 6 weeks with (thankfully) no battery issues. If and when the lithium battery does need replacement, I would consider the AGM route w/ coding vs. lithium replacement. There was a lithium battery shortage a little while ago, not sure if its been resolved.
I have a 2A tickle charger from NOCO and I have tried that one and it seems like it’s working but the Amp is probably not enough lol. I have changed it to the lithium ion mode and I’m noticing that the charger will show charging at first but will show red light after charging for couple days.
Yes he indeed does. There are pros of lithium in cars I would think otherwise MB wouldn't had them, I think?
I’m thinking of AGM from Benz Ninjia if my battery is bad. From what I learned the main benefit of the lithium ion is the weight saving and the longevity of battery, which I don’t think is any helpful since it’s a pain to find one and they are way more expensive than AGM.
I’m thinking of AGM from Benz Ninjia if my battery is bad. From what I learned the main benefit of the lithium ion is the weight saving and the longevity of battery, which I don’t think is any helpful since it’s a pain to find one and they are way more expensive than AGM.
I’m thinking of AGM from Benz Ninjia if my battery is bad. From what I learned the main benefit of the lithium ion is the weight saving and the longevity of battery, which I don’t think is any helpful since it’s a pain to find one and they are way more expensive than AGM.
I don't know why so many people claim lithium is better in longevity (assuming you also heard this from someone else), lithium-ion is ancient technology and a phone battery drops in capacity after only a few years. Although I understand different use cases. Lithium-ion is also sensitive to temperature changes.
I have a 2A tickle charger from NOCO and I have tried that one and it seems like it’s working but the Amp is probably not enough lol. I have changed it to the lithium ion mode and I’m noticing that the charger will show charging at first but will show red light after charging for couple days.
Do you want to try CTEK first before swapping to AGM mode? CTEK is the equipment manufacturer for MB I heard.
I was not aware of this lol. Maybe I should buy one of these that’s specifically for lithium ion batteries if my battery is still good. I got NOCO since I have the NOCO jump starter and it works great on my s65 so I get the maintainer as well.
as for the battery life, I heard on the forum that many people claims the lithium ion could last 10 years whereas AGM lasts 5years, not sure how true that is but I personally hated lithium ion just because how hard it is to find one and it’s not compatible with AGM.
I was not aware of this lol. Maybe I should buy one of these that’s specifically for lithium ion batteries if my battery is still good. I got NOCO since I have the NOCO jump starter and it works great on my s65 so I get the maintainer as well.
as for the battery life, I heard on the forum that many people claims the lithium ion could last 10 years whereas AGM lasts 5years, not sure how true that is but I personally hated lithium ion just because how hard it is to find one and it’s not compatible with AGM.
I guess automotive lithium ion batteries are different to phone batteries then because phone batteries really don't last long.
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