Does Mercedes make a battery maintainer for the R230? I tried using 2 BMW sourced battery maintainers with no luck. I would appreciate any advice.

 

I use a Battery Tender Jr on the rear battery between weekly drives. If can be used with the supplied mini clamps or hard wired with the also supplied eyelet connectors. It only takes a few hours to get the battery fully charged after 4 or 5 days of sitting. For the initial install, I cut a small chunk out of the eye connector with some wire cutters. This allowed me to slip the connector (which looks like a U connector now) over the battery terminals and not have to disconnect the battery. Now all I have to do is pop the trunk and connect the two plugs together and not have to lift the trunk battery cover, put on the clamps etc..

 

Thanks for the info!

I keep getting the "electrics offline" message after letting the car sit for 3 weeks while I was overseas. I thought my cigarette lighter based BMW unit would have worked, but it did not.

 

Ctec also makes good battery tickler:
http://www.ctek.com
I use them on both my front and rear battery when I put my car away for the winter.

Nicke

 

I have the "BMW" charger which is rebadged Deltran Battery Tender Plus (1.25 amps). This will work fine if you hook it directly to the rear battery. MB's will not charge via the lighter like BMWs/GMs/etc will, so you must use a direct connection at the battery. You can buy the pigtails for clamps or hard wire on Amazon or anywhere that sells Deltran stuff and these should work on your BMW unit.

 

What is it with the SL and the 'convenience feature' battery going dead all the time anyway?

 

There is a lot of stuff still using the rear battery, alarms, and??? I got my battery tenders from Sears and hard wired one of the pigtails to the rear battery, leaving just the connector and a short lead poking out from the side of the boot bottom. Pop the boot and plug it in. I can even close the boot on the wire with no issues.

 

how do i gain access to the rear battery to charge it?

 

It's in the trunk, under the carpet.

 

thank for the info!!!

 

I went to my dealer expecting to shell out $100+ for the MB trickle charge, and they recommended I buy the off-brand unit they were selling for around $25. Works great, as I only drive my sl55 on nice days. It sits around a lot. I got tired of the "electrical consumers offline", and the dealer confirms the batter is healthy. It just needs the trickle. Never had this problem with my SLK sitting for weeks at a time, but it didn't have all the fun toys the SL55 has...