R230 Dual Battery On-board Electrical System

Timeandleisure

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For charging purposes I use an MXS10. Must be getting on for 10 years old now.
Originally bought for charging big leisure batteries for my Defender.
Since I need just enough charge to ensure the boot lid engages and will only need to charge it fully later... a 10 would save on the time needed to resuscitate it! Thank you for the further info to help concentrate the mind.
I was used to the car charging itself up by driving
 

Timeandleisure

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Is the test and charge MXS5 different and is there any advantage please?
 

Blobcat

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Is the test and charge MXS5 different and is there any advantage please?
I think the normal will do just nicely, these 2 are for my SLK and smart.
FC1AA086-E67D-4C55-8509-CC6D0FB90A7C.jpeg
 
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I recently replaced my SL500 '03 consumer battery for a lead acid type of same rating £60. Also purchased an Absaar pro charger £30. So far no problems at all. Absaar read out shows a 13.5 v maintenance level. Presumed that AGM type batteries weren't around in 2003 so hoping it will be good for a few years on the LA type?
 

LostKiwi

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I recently replaced my SL500 '03 consumer battery for a lead acid type of same rating £60. Also purchased an Absaar pro charger £30. So far no problems at all. Absaar read out shows a 13.5 v maintenance level. Presumed that AGM type batteries weren't around in 2003 so hoping it will be good for a few years on the LA type?
AGM have been around for decades.
The charging profile for lead acid is different to AGM. I would not be at all surprised if you get issues with the lead acid battery as it will be overcharged on the AGM profile the car uses.
Lead acid charges at 13.8 - 14.4v whereas AGM is generally 14.6 - 14.8v.

My 2002 R230 uses AGM.
 

SL63 Mark

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Yes AGM only for the Consumer battery on the R230. I believe the starter battery is lead acid, but the battery in the boot must be AGM, I got mine from MB, it was not expensive.
 

NJS5

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I entirely agree with LostKiwi - I have 2 x AGMs in my 2011 SL350 when I bought it it had one AGM + one LA which caused problems!

Surely there will be a definitive statement somewhere on the web (from MB, not a battery supplier !) as to what should be fitted to your car? I had a quick look, but couldn't find anything.

NJSS
 

SL63 Mark

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I entirely agree with LostKiwi - I have 2 x AGMs in my 2011 SL350 when I bought it it had one AGM + one LA which caused problems!

Surely there will be a definitive statement somewhere on the web (from MB, not a battery supplier !) as to what should be fitted to your car? I had a quick look, but couldn't find anything.

NJSS

It's an MB part number. MB recommend you buy an MB battery.
 
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AGM have been around for decades.
The charging profile for lead acid is different to AGM. I would not be at all surprised if you get issues with the lead acid battery as it will be overcharged on the AGM profile the car uses.
Lead acid charges at 13.8 - 14.4v whereas AGM is generally 14.6 - 14.8v.

My 2002 R230 uses AGM.
Good info, thanks. My battery supplier is going to take the lead acid back and give me an AGM type for £27 more. Just within the 30 day return ts & cs !
 

Hotspur

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Sorry to ask such basic questions, I am trying not to be the one that attempts to do a preventative act (like putting battery on a maintenance charger) but actually by doing so causing some other issue in the process due to doing something incorrect (haven't read the manual yet and coming from mainly a BMW history) - so, when you put a trickle charger on your consumer battery (R230 SL350), is it ok to:

1) Leave your boot open or should you close it with the risk of trapping/fraying/cutting the wires?
2) Lock the car whilst its on the trickle charger or leave it unlocked?

Thanks in advance.
 

LostKiwi

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Sorry to ask such basic questions, I am trying not to be the one that attempts to do a preventative act (like putting battery on a maintenance charger) but actually by doing so causing some other issue in the process due to doing something incorrect (haven't read the manual yet and coming from mainly a BMW history) - so, when you put a trickle charger on your consumer battery (R230 SL350), is it ok to:

1) Leave your boot open or should you close it with the risk of trapping/fraying/cutting the wires?
2) Lock the car whilst its on the trickle charger or leave it unlocked?

Thanks in advance.
1. I put the trickle charger in the boot and close the boot lid. Been doing it for 4 years and no issues. The boot rubbers are soft enough not to cut anything.
2. I lock the vehicle.

If you didn't want to shut the mains cable in the boot rubbers you could get a waterproof connector and fit it under the car then connect the charger to that.
A small Anderson connector would work fine.




Fit the first one to your battery and through a small hole in the boot floor (using a rubber grommet). Then cut the charger lead and fit the two in the second link to each of the cut ends. Just make sure you follow the same polarity all the way through and double check before connecting anything, then check again.
 

Hotspur

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1. I put the trickle charger in the boot and close the boot lid. Been doing it for 4 years and no issues. The boot rubbers are soft enough not to cut anything.
2. I lock the vehicle.

If you didn't want to shut the mains cable in the boot rubbers you could get a waterproof connector and fit it under the car then connect the charger to that.
A small Anderson connector would work fine.




Fit the first one to your battery and through a small hole in the boot floor (using a rubber grommet). Then cut the charger lead and fit the two in the second link to each of the cut ends. Just make sure you follow the same polarity all the way through and double check before connecting anything, then check again.

Thanks.

Sorry one more question - I am going to store the car at a classics car storage firm over the winter due to other cars needing the indoor space in the colder months, the storage firm put it on a trickle charger, but I was wondering if they keep the consumer battery maintained....does that charge at all the starter battery in line? or does the starter battery need a charger too? and if it does, any issues both charging at the same time?

I guess the same applies in the summer, overnight whilst in one of my garage at home?
 

rich.g.williams

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For the entire winter, personally I would take the batteries out of the car and trickle charge them. Don't know much about these Starter batteries but 13.8 Volts is good for trickle charging. Could you connect both batteries in parallel outside the car then only one charger needed?

Likely not if one is AGM and other is wet Lead Acid.
 
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greg elmassian

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Terminal charge voltage is different for AGM from LA, but charging to a slightly lower voltage is ok, just don't let it drop.

But recommending to remove the batteries, then a number of systems will need to be reset and require a service tool of some sort.

Greg
 

SL63 Mark

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Terminal charge voltage is different for AGM from LA, but charging to a slightly lower voltage is ok, just don't let it drop.

But recommending to remove the batteries, then a number of systems will need to be reset and require a service tool of some sort.

Greg

It's fine to remove either battery on the R230, no service tool required. I have done it many times.
 
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