Battery Charging - In Situ

[T5R+]

For various reasons battery has run right down and needs a charge - would rather charge it than jump-start and drive around for a duration.

Can I simply leave it in the cradle on the car, remove the positive lead and attach my charger and leave it charging for a few hours? Dry environment and no risk to others.

Part of why I want to do this - it is a W164 and some of you will know the fun of getting a battery out of this car* thus would rather leave it in place.

* It is under the driver’s seat, you need to cut the carpet, remove seat, and use new stretch bolts.

 

[barian]

If you check your manual, you may well find that there are dedicated charging/jumpstart terminals under the bonnet which you can use without any need to disconnect the battery.

 

[T5R+]

If you check your manual, you may well find that there are dedicated charging/jumpstart terminals under the bonnet which you can use without any need to disconnect the battery.

There are indeed - which are what I have used to date to jump start this vehicle but now wanted to charge the battery itself via a charger.

Are you suggesting that can attach my battery charger to these under bonnet jumpstart terminals whilst battery still connected under the seat - feared something strange may happen given the gremlins that live within ML electronics.

 

[barian]

As I said, check your manual but with modern battery management systems you are often advised to charge this way so the car can monitor the charge status.

 

[chic0821]

As above, use the under bonnet charge points , but you can leave your battery connected & connect your charger to it. If you want to remove the positive connection, you will loose all radio memory presets, probably memory seat positions & anything else that has settings. I have my S63 off the road in the winter as near 600bhp, rear drive & icy roads is not the best combination, so its permanently connected to a Ctek charger for months. Starts first time

 

[Bobby Dazzler]

I use a CTEK MXS 5.0 conditioner to charge the battery in my W164 by using the charging posts under the bonnet

Check the instructions for your battery charger to make sure they don’t state that the battery must be removed from the car.

Some require it, but many modern battery chargers (or conditioners) are designed to be used with the battery in situ.

 

[Qwertycls]

As above, check manual, but I’ve never known a car that couldn’t be charged in situ.

 

[milleplod]

Just one proviso though! Your charger needs to be a smart(ish!) one.....don't use one of the old-style, higher-current ones on a battery that's still connected.

Pete

 

[Spider10]

I also charge via the charging posts under the bonnet

 

[Ted]

Perfectly ok to charge with a modern charger with the battery still connected ad long as the charger is in good order.
And if you want to remove one terminal, do the negative not the positive.

 

[T5R+]

Appreciate the advice. Manual says nothing other than Jump-start procedure and connection points under the bonnet.

Have a "classic" charger - hence suspected the need to disconnect one of the terminals.

As an aside, neither the CAT 1200A nor Clarke 4000 booster packs were beefy enough to start the car however, jump starting off of a decent diesel works. If anyone swears by a portable jump/booster start pack that can handle 4.0 - 6.2 litre cars please let me know. Suspect will also buy a CTEK MXS 5.0 as recommended by "BD".

 

[Bobby Dazzler]

Appreciate the advice. Manual says nothing other than Jump-start procedure and connection points under the bonnet.

Have a "classic" charger - hence suspected the need to disconnect one of the terminals.

As an aside, neither the CAT 1200A nor Clarke 4000 booster packs were beefy enough to start the car however, jump starting off of a decent diesel works. If anyone swears by a portable jump/booster start pack that can handle 4.0 - 6.2 litre cars please let me know. Suspect will also buy a CTEK MXS 5.0 as recommended by "BD".

If it’s an older charger - and not a more modern smart charger - then I would avoid using it in situ unless you can check the instructions to confirm that it’s safe.

Amazon’s pricing varies most weeks in the CTEK chargers; but for the most common MXS 5.0 it’s usually competitive and will arrive same or next day in many cases.

The MXS 5.0 will charge both lead acid and AGM batteries which makes it right for the vast majority of car batteries. Don’t use it on a lithium battery though.

Regarding jump packs I had a very old one which had served me well for 20-25 years but I have recently replaced it with a CTEK CS FREE wireless conditioner.

Rather than jump start the car the idea is to connect it for 15 minutes during which time it will charge the car battery enough to be able to start the car under it’s own power..

They’re expensive but it contains all the very latest CTEK charging technology, and you can use it as a traditional charger too by plugging it into the mains electricity.

I hope this helps.

 

[chic0821]

Bin your classic charger & get a Ctek. They have lots of models. Mine is MXS 5 which is very popular. It charges then goes into pulse mode if it has been on for a couple of weeks. The final green light comes on which brings the battery up & down keeping it at an optimum. As I previously said my S63 is on for months at a time never looked at under an indoor cover & starts first time. All my cars have Ctek. I have the comfort connector connected up permanently & unobtrusively hidden by the grille so you don't even have to lift the bonnet to connect it.
I bought a "TrekPow jump pack from Amazon at a good price which starts cars up to 7 litres, but have never used it so cannot comment on how good it is. Bought for when my car is lying at an Airport extended periods

 

[Tonye]

Just a side note, don't try to start the car with a charger connected, its not a starter pack, you will toast the fuse in it.

 

[SeagullFan]

Ive got a Ctek and the extension so it can charge through cigarette type socket which i could do on previous car.

ideally i’d like to charge via the boot, does anyone know if there is a socket in a 2017 SL400 that can be utilised?

 

[Deleted member 126251]

There are indeed - which are what I have used to date to jump start this vehicle but now wanted to charge the battery itself via a charger.

Are you suggesting that can attach my battery charger to these under bonnet jumpstart terminals whilst battery still connected under the seat - feared something strange may happen given the gremlins that live within ML electronics.

It is what MB recommend for my car & I do the same in my wife’s 2014 Bclass.

The positive (jumpstart) will just be a fat wire to the starter solenoid and another fat wire from the solenoid to the battery. A charger gently getting the battery charged is far less current than when jump starting.

However check your manual - don’t take my word for it.

 

[ALFAitalia]

I just bought a new Ctek....the new 6 stage one to replace my old 4 stage one. After five years of service I noticed it getting hot enough that some of the casing had melted onto my drive.....lucky I was just doing a quick top up....not the overnight charge I usually do with the charger under the bonnet....otherwise the melted plastic would be on my engine! Despite the unexpected and premature failure I still recommend them to keep batteries in tip top condition....especially if your car has long spells of being idle.

 

[Deleted member 126251]

Ive got a Ctek and the extension so it can charge through cigarette type socket which i could do on previous car.

ideally i’d like to charge via the boot, does anyone know if there is a socket in a 2017 SL400 that can be utilised?

There are no suitable sockets.

Why do you want to charge via the boot?

I’ve been charging my SL 400 (2017) for 5 winters now (with my 15 year old CTEK) using the jump start points as recommended in the owners manual. No issues.

Make sure you use AGM mode!

 

[Deleted member 126251]

I just bought a new Ctek....the new 6 stage one to replace my old 4 stage one. After five years of service I noticed it getting hot enough that some of the casing had melted onto my drive.....lucky I was just doing a quick top up....not the overnight charge I usually do with the charger under the bonnet....otherwise the melted plastic would be on my engine! Despite the unexpected and premature failure I still recommend them to keep batteries in tip top condition....especially if your car has long spells of being idle.

Wow - I’d talk to CTEK about that. Mine is about 15years old and has been used and abused and still going strong. As stated above - I’ve been doing the SL for 5 winters without issue. I actually use it all year round as I don’t do much mileage (18,000 now and that is mostly road trips).

 

[Trickythemerc]

Appreciate the advice. Manual says nothing other than Jump-start procedure and connection points under the bonnet.

Have a "classic" charger - hence suspected the need to disconnect one of the terminals.

As an aside, neither the CAT 1200A nor Clarke 4000 booster packs were beefy enough to start the car however, jump starting off of a decent diesel works. If anyone swears by a portable jump/booster start pack that can handle 4.0 - 6.2 litre cars please let me know. Suspect will also buy a CTEK MXS 5.0 as recommended by "BD".

I have a Nocoboost jumper pack , used it a couple of times and very impressed with it. Capable of starting 5.0 litre diesels.