bcrounse

AMG Community. I've owned my E43 for about 18 months. I love the car and have had very few issues since my purchase of the new vehicle. Within the last few weeks, I've been getting the message (with Battery Icon on main dash) "Start Engine. See Operator's Manual" every morning before I start the engine. I believe this started after driving in a very bad rainstorm a few days earlier. I did some freeway driving to recharge the battery. The pre-start warning went away for that day, but was back again the next morning. Yesterday, I took my car to my AMG-certified dealership. They told me my problem was "not driving the car enough to keep the battery charged". They said both the main battery and accessory battery were in good shape, although the main battery was low and they charged it up. My driving habits have been pretty consistent since buying the car; frequent short trips around town and some free way driving. It seems to me this is a new problem. The technician suggested I keep the car locked when in my garage to limit possible drain on the battery when the car isn't in use. He also suggested I buy a trickle charger. I've been researching this issue on the web and find that mysterious battery drain has been an issue in many, recent Mercedes models. I've seen "water penetration" as a cause of some problems. Others relate to Command Module issues and other phantom reasons for battery drain. I'm reaching out to the AMG community for advice on this. I'm not sure I believe the tech who told me the problem is due to my driving habits. Thanks for any advice the community may be able to offer.

JTK44

Hope this helps:

There are many threads on battery drain.

After all is said and done, a battery tender is the most efficient solution:

Here is the model I recommend:

bcrounse

Thanks JTK44. I appreciate your answer. I did check the Amazon link you included. When I sort for my particular car 2018 AMG E43, I am told that this trickle charger is not approved for my car.

JTK44

I cannot imagine why.

From CTEK:





https://www.ctek.com/products/vehicle/xs-0-8

elnos

My 17 e43 has the same issue. Start noticing that message for the last 2 weeks every time I turn the engine off, before opening the door for leaving.
Didn't think it was something serious, might take it the dealer soon.

bcrounse

Elnos, thanks for your comment. Please let me know if your dealer discovers a cause. My problem hasn't resurfaced since the dealer charged up my main battery. I'm still concerned that the heavy rain storm I drove through the day before my battery problem started may have triggered the event.

ua549

I had similar issues with my BMW. The technology in newer cars never turns off, thus battery drain while "off". I solved the issue by driving the car enough to replace the energy used during the first few minutes of operation - starter, headlights, high speed AC fan, rear window demister. My average trip time is 5 minutes. The dealer suggested driving for at least 20 minutes.

bcrounse

Thanks for your input. I recognize that short trips aren't the best for battery recharging. I now lock the car when it is in my garage (as suggested by my service tech). That seems to be helping as the battery warning hasn't reoccurred. It's a shame that our cars now can't be used reliably for short trips to the store, etc. Driving for 20 minutes only to keep the battery charged wastes a lot of gas and time. Thanks again.

2012 merc amg

I just give mine a good charge once a month with the battery maintainer. As has been said on the forums the battery only charges a max of 80 percent by the car to avoid overcharging and try to maintain battery life. Then I'd suspect the first message battery partly charged comes on showing up on the app at around 50 percent charge and then the battery critical probably around 30 percent and below state of charge. By charging once a month brings the battery up near 100 percent charge and then when I do most of my around town driving I generally drive in sport plus mode as the engine is turning faster rpm's therefore charging the battery more efficiently. If I'm doing longer trips I don't seem to have any issues, it's mainly if the car sits unused over a week in which case I'll hook it up to the battery maintainer. If or when I do ever have to replace a battery I'll probably put a Optima yellow top battery in the car. I'm willing to bet it would go a lot longer than a week ago or two before hitting battery Critical with a battery like one of those in the car.

bcrounse

Thank you for your input. I really appreciate receiving so many helpful tips here on MBWorld. I guess I'm due for a trickle charger, although somehow I've managed to get by without one all these years starting with my first Mercedes in 1984 through more than a dozen since then.

ua549

The cause is all of the new electronics some of which are always on.

saintvir

If the car will be parked for an extended period, put the car in Standby Mode (assuming battery is charged high enough to begin with). Having said that, I wonder if Standby Mode would help avoid battery drain every time the car is parked ... even for just a day or two!!!

bcrounse

Saintvir, Thanks for your comment. I'm aware of Standby Mode. My Mercedes manual suggests Standby Mode be enabled if the car is going to be parked and not used for 4 weeks or more. I'm OK with that. However, it doesn't seem reasonable that I should have to put my car in Standby or use a trickle charger on a daily basis to keep my battery charged even if I'm only driving the car 3 to 5 miles every few days. This was never a problem with any of my other Mercedes over the years. Of course, most of those vehicles didn't have internet connectivity and stop-start accessory batteries, etc. Welcome to the future....

robert c

I have several collector cars that I use Granite Digital battery maintainers on as some have actually a gel battery within the case and these maintainers have technology to adjust for them as as we know the charging requirements for them are different. Because of normal battery drain I have started using one of them on my new Mercedes with great results. I don't attempt to use the "storage" feature of the vehicle just open the hood attach the maintainer then put the cover on.
Robert
https://www.batterysaver.com/store/p13/1200.html

bcrounse

Thank you, Robert. I truly appreciate your input.

Ecab2018

My 2019 A238 / E450 Cab was showing as discharged on the Mercedes Me app, and wasn't showing as fully charged after a 30 minute ride or two. Being in winter storage, it was clear that I needed a battery maintainer. I bought a cheap one from Costco for the old '83 Buick and have used that for years, but for my new baby I splurged and went with the Mercedes-Benz battery maintainer that I purchased from the dealer at prices that were competitive and sometimes less than what I see on Amazon. It looks like the CTEK, which is cheaper, but I wasn't sure which model to buy. The reassurance I got from the MB dealer that the MB unit they sell was the correct one was worth the extra money to me. My only complaint is that they didn't sell one in designo Diamond White to match the car...

rraisley

No designo Diamond White??? What is it, made of coal??

bcrounse

Thanks for your input Ecab2018. I agree that it may be wise to go with the dealer option. I'd hate to buy a trickle charger somewhere else only to learn that it destroyed my battery or the car's sensitive electrical system. If I buy what the Mercedes dealer recommends they are less likely to blame me if something goes wrong. My dealer suggested I buy their Mercedes-branded charger for $130. Is that about what you paid?

whoover

This is the charger you want. It's made by CTEK, the industry leader (who also makes the MB-branded charger). It's much later technology than the MB OEM one, which is quite old. It's even safer for our AGM batteries than the the older CTEK that MB sells. It will absolutely not void your warranty as it meets the specs that MB lists for battery tenders. In fact, CTEK wrote those specs for Mercedes! And it's half the price. It is the best accessory I ever got for my E63S.

JTK44

Sorry to repeat my post #2


As this is only a trickle charge, I recommend this one:

whoover

Read the product description:
"The CTEK US 0.8 battery charger is tailor made for small utility and recreational vehicles. It is the smallest 12 Volt charger in the CTEK program. The charger is a compact and fully automatic 6-step charger for 12 Volt lead-acid batteries from 1.2 – 32 Ah. The state of the art technology is perfect for charging batteries in motorcycles, jet skis, ATVs and lawnmowers."

That is too small for a car battery.

JTK44

No it is not.

You are talking about a trickle charge. Very little current is needed to maintain a battery. This unit will do that.

bcrounse

Whoover and JTK44. Thanks for your advice. When I use the Amazon tool (to sort for car make and model) for either of your recommendations it says "this item doesn't fit your car". Perhaps this is because the tool is meant to select parts that really are make and model specific, but it does make the buying process a bit confusing. I'm not all hung up on needing a Mercedes branded OEM charger, but I certainly don't want to use anything that might void my warranty or give my dealer an excuse to say any problems I'm having with my battery or electrical system were induced by me.

whoover

It will strain to do it if the battery is not in very good shape to begin with. But the manufacturer does not intend for that to be used with auto batteries. It's designed for motorcycle batteries. For another $30, it REALLY makes sense to get the one I linked, which has a motorcycle/auto selection switch. If you're using it for small (<32 Ah) batteries, you select the low-current mode. With an 80 Ah car battery, the normal charge cycle should be around 4 amps.

The initial problem is that the car's electrical system does not fully charge the battery. That's why people get the low-battery alerts. The "absorption" phase to full charge should be around 4 amps. Even so, it will take anywhere from 24 to 48 hours to reach "float" starting with what the car considers charged. After absorption, the "float" phase can use lower current and is what you are calling "trickle" charge. But a motorcycle charger will never get to float.

Bottom line, why would CTEK sell one for maintaining motorcycle batteries and another for car batteries if the motorcycle charger was sufficient for tending car batteries? It's the wrong charger.

whoover

I notice that the Amazon parts-fit interface doesn't work for chargers at all. If you ask what charger "fits" your car, it says none do!

I have used this one, which is the current model recommended by CTEK for a year and those alerts are a thing of the past. Lots of others here have used it as well. Call CTEK if you want. But the manual lists the charging requirements in terms of maximum voltage, etc., and the CTEK specs conform. Their charger was CTEK's state-of-the-art 4 years ago, but CTEK has improved the technology for safely maintaining AGM batteries and recommends the one I linked. There is no way MB would have a case that the newer charger could damage the battery or car.