SL400 (R231) Battery Conditioner

[BoristheBounce]

My SL400 I've just bought is mainly for Sunny days ad Sundays plus a bit of touring.

Other cars I've had for this purpose I've always used a mains battery conditioner for and so whenever I go for the car its ready to go I just unplug it from the battery and go and never lets me down.

I intend to do this with the SL400 but I have a couple of questions.

A) can I use the jump start point and the body as the point to which I connect the battery conditioner?

B) I'm aware (now) that the car has two batteries one being an auxiliary battery, what is this for please and is it ok just to leave it for a few months unattended/unused?

Cheers in advance

 

[ToeKnee]

My old R230 SL would regularly flatten the boot auxiliary battery so that convenience functions wouldn't be available and I kept that on a charger constantly while it sat in the garage, my current R231 SL doesn't have that problem. Although I still use the charger on a regular basis I've left it off for weeks at a time and had no problem with any starting or electrical problems, so I think that the 231 doesn't drain anywhere as bad. The auxiliary battery on the 231 sits behind the drivers seat, not entirely sure what it powers but I think it's mainly there for when stop start kicks in.

 

[BoristheBounce]

My old R230 SL would regularly flatten the boot auxiliary battery so that convenience functions wouldn't be available and I kept that on a charger constantly while it sat in the garage, my current R231 SL doesn't have that problem. Although I still use the charger on a regular basis I've left it off for weeks at a time and had no problem with any starting or electrical problems, so I think that the 231 doesn't drain anywhere as bad. The auxiliary battery on the 231 sits behind the drivers seat, not entirely sure what it powers but I think it's mainly there for when stop start kicks in.

Cheers Tony I will see how it goes; so the Aux battery wont render the car un-drivable then?

 

[V6GBJ]

Cheers Tony I will see how it goes; so the Aux battery wont render the car un-drivable then?

The R231 maintains charge much better than the R230 but this obviously depends on the age of the battery since capacity declines with age. If you get a smart charger such as a CTEK MX5 you can have it connected whenever the car is not in use. Mine is on for 3-4 months during lockdowns/winter . Incidentally, it should be connected to the terminals under the bonnet. The positive is obvious and is under a push down cover, the negative looks like an elongated nut and is a few cm. away at the top of the suspension tower. Ther is no need to charge the batteries separately as with the R230.

 

[BoristheBounce]

The R231 maintains charge much better than the R230 but this obviously depends on the age of the battery since capacity declines with age. If you get a smart charger such as a CTEK MX5 you can have it connected whenever the car is not in use. Mine is on for 3-4 months during lockdowns/winter . Incidentally, it should be connected to the terminals under the bonnet. The positive is obvious and is under a push down cover, the negative looks like an elongated nut and is a few cm. away at the top of the suspension tower. Ther is no need to charge the batteries separately as with the R230.

Fabulous, that was going to be my next question about doing it separately.

I already have a smart charger used on my previous summer cars.

What invaluable information offered by this forum, I can't thank you all enough

 

[ToeKnee]

Cheers Tony I will see how it goes; so the Aux battery wont render the car un-drivable then?

Not as far as I'm aware, although I'm happy to be corrected. I have a flying lead for my Ctek attached to the battery rather that the poles under the bonnet.

 

[BoristheBounce]

Not as far as I'm aware, although I'm happy to be corrected. I have a flying lead for my Ctek attached to the battery rather that the poles under the bonnet.

Might do the same actually, unless that won't charge the Aux battery as well.????

 

[Slartibartfast]

My SL400 I've just bought is mainly for Sunny days ad Sundays plus a bit of touring.

Other cars I've had for this purpose I've always used a mains battery conditioner for and so whenever I go for the car its ready to go I just unplug it from the battery and go and never lets me down.

I intend to do this with the SL400 but I have a couple of questions.

A) can I use the jump start point and the body as the point to which I connect the battery conditioner?

B) I'm aware (now) that the car has two batteries one being an auxiliary battery, what is this for please and is it ok just to leave it for a few months unattended/unused?

Cheers in advance

fyi

 

[BoristheBounce]

Moving on from all these posts did anyone know about the attached?? is it there I'm at work car is at home I haven't checked yet?

 

[Deleted member 126251]

1) Make sure you set the charger to AGM battery type.
2) The aux battery is to keep the sensitive electronic bits happy when the car is in stop/start (ECO) mode.

Never seen the trickle charger port and I’ve had the area stripped to install my SmartTop. It is also not mentioned in my manual. My experience of MBs is that the manual often has features that are not included in the car I own. Now I have to go and double check

 

[BoristheBounce]

Checked mine, the hole is in the bodywork but no connector

 

[jotter22]

When i purchased my CTEK MXS5 it came with (i think they called it a comfort connector) that clamps to the battery terminals and stays in situ, You can then stow the business end wherever you see fit to enable quick connection to the charger/conditioner when needed, it also has a little condition light so you can see when it needs a charge. Would not be without one now.

Tony.