W210 Guy

Long time, no post!

I've had an S600 for a while now (2004 MY) but I've not been driving it much lately. Maybe once a week or so. When starting the engine it has gradually been getting a little trickier over the last month or six weeks but assumed that was as a result of the cold weather as much as anything (Below freezing constantly). Will always get going first time around but tonight I can't get it started. It almost reacts as if the battery is flat. When trying to start it tries to get going but then you just get that fast clicking sound.

Is there any way of being able to tell if it's the starter motor or battery that needs replacing? I believe MB Roadside Assistance will replace the battery which would be really handy.

kraut56

before anything else:

turn key to position 2
select MILAGE XXXXXXX page
push "R" button on cluster 3 times, this will display battery voltage, must be about 12.5
if not, recharge battery
if yes, crank engine and watch voltage, should not drop below below 9.8

report back

W210 Guy

Thanks for the tip for the future. This time around it was only a flat battery.

Not been driving the car much (about 5 miles per week!) but didn't realize that little was enough to slowly flatten the battery!

PeterUbers

You need a trickle charger

cybertronicify

If you have the OEM Mercedes battery, it will be the AGM Valve Regulated Battery. Which is better at handling deeper cycles and lower temperatures, but below freezing means your battery has less power and your starter requires more power. So if the voltage dips below 9v it should be fine as the starter is working extra hard to crank that v12 which is freezing. (assuming no block heater was installed?) I would suggest a trickle charger or a battery regulator, it will keep the battery topped off and keep it at a good temperature. BTW your alternator cannot fully charge the battery in one go, as it will overheat and temporarily disconnect leaving the engine running on the battery until it cools down.

Critter

If the battery is dropping into the 9 volt area when cranking then the battery
1. not fully charged or
2. needs replacing. load test battery if only a few years old
9 volts with surely damage the starter in continued use.
Battery at 5 years with minimal use has probably had its day.
Yes a .75 amp trickle charger for the new battery when the car is not in use would be a wise investment.
Good Luck

wallyp

You need a "battery maintainer", not a "trickle charger".

The trickle charger is a dumb charger, that keeps charging even when the battery is fully charged. This will eventually damage the battery.

A battery maintainer is a smart charger, that turns off when the battery does not need charging. The better maintainers (which will cost $50 to $80) will also have a battery conditioning feature that helps with long-term battery life. I would strongly discourage any maintainer that costs less than $25-$35.

The better units come with interchangeable connectors on the charging cable. This will allow you to attach the ring connectors to the Mercedes battery and run the cable out of the battery compartment into the trunk area. You can then leave the maintainer hooked to the cable most of the time. If (when) you need to charge the lawnmower battery, or another car battery, you can unplug the maintainer from the attached cable, plug on the cable end that has the battery clips and clip to the other battery.

cybertronicify

Oops i actually meant to say Float Charger.