R230 Dual Battery On-board Electrical System

[Hotspur]

Have a trickle charger on each battery...seems to keep the batteries in good shape (so far)..

Took her for a sunday morning run before the sun got too high...she drives beautifully for an old girl.

 

[greg elmassian]

I just went through 2 batteries (a new one failed). Quite a few modules threw faults from under voltage.

I cleared the faults with my icarsoft, since the faults did not clear on their own in just a few minutes.

But maybe they clear after some time... a lot of SAM modules threw faults...

I'm not sure, but I know for positive changing the battery threw faults that did not clear right away, and I am happy I have a tool to reset them right away.

Greg

 

[s5tuart]

I have too short a drain hose from my consumer battery. The vent is on the wrong side of the battery and is just dangling into the boot well.
Any idea where I can get some longer tubing to exit the drain into the proper hole?

 

[00slk]

I have too short a drain hose from my consumer battery. The vent is on the wrong side of the battery and is just dangling into the boot well.
Any idea where I can get some longer tubing to exit the drain into the proper hole?

Motor factor might have washer tube to extend the hose.

 

[s5tuart]

Motor factor might have washer tube to extend the hose.

That's a good idea! Thanks

 

[s5tuart]

Motor factor might have washer tube to extend the hose.

I got some from eBay in the end. Half a metre should be enough

 

[NJS5]

Since I bought my SL I have always charged each battery from time to time.

A neighbour who also has an R230, but is not on here, told me very forcefully that one really only needs to charge the rear (systems) battery, as in "later" R230s the car would start from the systems battery if the front (Starter) battery was discharged.

Is this really so? No matter what the answer is I think I will keep on charging both batteries.

 

[Hotspur]

I charge both of mine - if its only going to parked for a few days then I charge the rear only, but if its likely to be a week or more then both...

 

[Big Janner]

Always charged both batteries, in my R230 and my R231, never had an issue

 

[Mark Q]

Only charge the rear, the front seems to keep its charge, it did let me down a few months ago after a few short trips up and down the drive, I fitted a new front battery. I've had the car 10 years, had to change the rear one 2 years ago, the front one a couple of months back - both were Mercedes batteries, but not sure how old they were when I bought it.

 

[NJS5]

A neighbour who also has an R230, but is not on here, told me very forcefully that one really only needs to charge the rear (systems) battery, as in "later" R230s the car would start from the systems battery if the front (Starter) battery was discharged.

I am convinced that my neighbour is wrong. I put my rear battery on charge first thing this morning & it's been fully charged for some time. The SoC for the front battery remains unchanged.

The second question is, if the front battery is unable to turn the starter motor, will, as my neighbour suggests, the rear battery do so?

NJSS

 

[Misterdog]

I have a 2010 A Class, the rear battery is that of a motorcycle and runs the ancilliaries, radio, lights etc. whilst on stop to prevent discharge of the main battery.
The main battery starts the engine.
The stop/start system adds 25Kg in weight to the vehicle over the non stop start version (Blue Motion).

Back during the oil crisis of the 1970's, we were told to remove all excess weight to save fuel.

Now the narrative is that carrying an extra 25Kg in weight is somehow 'saving the planet' and giving us better MPG.
IIRC the saving in fuel was quoted as 1litre per 1000 Km. This will only occur in the urban environment, on longer journeys, ex-urban the additional 25 Kg is worsening your MPG.
So I have removed the fuse from the rear battery which switches the stop start system off- permanently. Or you can just disconnect it .

Apparently on later vehicles this will trigger an error message on the dash.

If you wish to save emission's/fuel when you perceive a long stop you can always use the ignition key
As we used to in the 1970's when lead pollution was the enemy.

The lead by the way that was going to kill us all and lead to brain damage, is still around today as it doesn't biodegrade, so all the 'dust' is full of lead.

Lead from leaded petrol persists in London air despite ‘90s ban | Imperial News | Imperial College London

Research from Imperial College London has found that lead from leaded petrol persists in London’s air despite its ban in 1999.

www.imperial.ac.uk

AutoHex diagnostic scanner and information about Mercedes benz 169 - 245 ECO Start system

www.micro-tronik.com

 

[00slk]

I am convinced that my neighbour is wrong. I put my rear battery on charge first thing this morning & it's been fully charged for some time. The SoC for the front battery remains unchanged.

The second question is, if the front battery is unable to turn the starter motor, will, as my neighbour suggests, the rear battery do so?

NJSS

Disconnect the front battery, then try starting the car. If it starts, he might be right??

 

[LostKiwi]

On our (early) 230 the front battery went flat. Rear battery fully charged. Car would not start.
Charged front battery all good again.

 

[SL63 Mark]

On my 2004 SL55 R230, I had to keep the rear battery on trickle charge, if I left it more than a few days, due to the current drain. I never charged the front battery. I replaced both batteries with new MB ones during my ownership, it did not make any difference.

The R231 never seems to need charging. I have never once received a "consumers offline" message. I did once put it on trickle charge while we were on holiday. I have never checked for current drain, presumably it is minimal. I will do so and report back.

 

[Mark Q]

Car will not start if front battery goosed. With brand new and charged rear battery I had (one of many) ABC issues and had to start and stop the car with the key numerous times on a single short journey eventually it would not start again, I had to walk home to collect the pickup and jump leads onto the front battery to get it going again. Following this it was slow to start so eventually I replaced front battery, now no more issues. Ive had car 10 years soon, rear battery changed after 8 years, front after 9 so not bad for a 20 year old car.

 

[Conor]

+1 on charging on rear only.

My understanding is that you only need to charge the rear battery, because it's connected to the front in some way and will maintain that also.

 

[NJS5]

"You only need to charge the rear battery,"

That's my understanding too. I hope someone can document this though.

NJSS

 

[Richard Moakes]

https://mbworld.org/forums/attachments/sl-class-r230/425370d1591305151-electrical-issue-consumer-battery-won-t-charge-r230-dual-battery-system.pdf

 

[Conor]

https://mbworld.org/forums/attachments/sl-class-r230/425370d1591305151-electrical-issue-consumer-battery-won-t-charge-r230-dual-battery-system.pdf

Ah yes, I read that before my post.. was going to reference it but after a quick skim I didn't see the reference to charging only the rear...although I am sure that's where I read it originally.