Streamliner

I've tried doing a search for this but can't find exactly what I want: Does MB offer a factory approved trickle charger? If so, does it plug into the cigarette lighter socket? If not, where does it connect? Will it charge the accessory battery or just the starter battery? If no MB charger, can someone recommend a quality aftermarket unit? Any potential pitfalls in using a trickle charger on these cars with all of their electronics? just don't drive my SL much and am constantly running into battery problems. Any info, tips, etc. would be much appreciated. Thanks.

funymuny

There will be lots of replies and opinions about the type of charger/maintainer. MB at one time offered one with their label however it was some version of the CTEK MUS 3300. The CTEK line of chargers is as good as they get. Not saying they are the best or that there aren't others just as good but they are good ones. I have 4 or 5 of them. Using the cig lighter...I believe this gets into the issue of whether your lighter is 'switched' or not. I may have the wrong term. Some cars you can go through the lighter (my vette did) and some do not. Aside from whether or not it will I evolved to the belief that the best way to use one is attached directly to the battery. Fairly certain the voltages produced by the CTEKs will not harm any of the finicky electronics in the car. The MUS 3300 line is one of their most popular smart chargers/maintainers. I have a couple of Schumacher 1.5 amp maintainers. From all I can read they are fairly smart as well and for $20 a great value. But I went with the "if it costs more it must be better" approach and got the CTEKS. Mark

BlownV8

I have a factory MB trickle charger for my SL. It connects directly to the battery in the trunk. I believe the cigarette lighter is switched off when the ignition is off so I don't think one through the cigarette lighter would work.

Ejbrock

Ejbrock
I use the CTEK 3300 on my cars. The product does a great job keeping my batteries charged. I am replacing batteries less frequently.

CPDay

I have a couple of the CTEK 3300's and greatly appreciate their intelligence. On my SL, I annually hook a CTEK up to the accessory (i.e trunk) battery for the 5-month winter storage. Both of my factory SL batteries lasted seven years, so I think the CTEK charger was good for them. The starter (front) battery will survive many months without ANY charging. I've never used a trickle charger on the starter battery.

The CTEK comes with a quick-connect plug and lugged cable that can be installed on the accessory battery. This makes it easy to plug in and charge when needed.

carguyshu

If you have a trickle charger on the rear battery it also charges the front battery.

CPDay

I've heard this statement from several 230 SL owners over the years. I don't believe that this is true in non-emergency circumstances. A trickle charge cannot flow from the accessories battery to the starter battery unless N82/1 has energized/de-energized relays K75 and K57 to allow it. This happens in an emergency, as when one of the batteries has died. In such a situation, the accessory battery can then start the engine, or the starter battery can power things other than the starter (i.e, in 'limp home' mode).

So, it is possible that the trickle-charged accessory battery will assist a weak or dead starter battery in certain conditions, but could the trickle charger actually charge the starter battery? I am not certain how that would happen.

The N82/1 is a very thoughtful engineering feature, but it also leads to many problems and confusion.

Here's a link to a source document that answers many questions:
http://www.benzworld.org/forums/atta...battery-system

Ejbrock

Ejbrock


CPDAY
Thank you for the reference article and your overview on your use of the Ctek3300

carguyshu

The n82/1 charges the starter battery through the DC/DC converter diagrammed on page 28.

The K57 relay only comes into play in an emergency situation. At that time both batteries are tied together and it is one circuit the alternator charges. If the starter battery only got charged in this emergency situation, it would not last that long. This is why the DC/DC converter charges it under normal operation, which allows the 2 circuits to remain separate, but also allows the front battery to get a charge.

Since this pathway is 1 way, connecting a charger to the front battery will NOT charge the rear one. Connecting it to the rear one WILL charge the front one through the DC/DC converter.

The only way to charge the rear batter via the front batter is if the relay K57 is tripped and the 2 circuits are connected, which is the emergency situation you are speaking of.

CPDay

Perhaps I wasn't very clear in my comments. I didn't say that the alternator doesn't charge the starter (front) battery under normal conditions. Obviously, it does. N82/1 monitors both battery voltages and charges each battery as needed.

What I did say was that a trickle charger applied to the accessory (trunk) battery does not charge the starter battery. I think the schematics support that statement.

carguyshu

If the DC/DC converter is active when the car is off, then the starter battery would also get charged.

Ejbrock

Ejbrock


carguyshu,


Thanks for you contribution statement

dRockSL55

I use a deltran battery tender waterproof 800 on my sl, works flawlessly. Some more info and pictures;
https://mbworld.org/forums/sl-class-...ml#post6027136

CPDay

So the DC/DC converter is active when the car (and alternator) is off?

carguyshu

that's what I'm trying to figure out as the diagram isn't clear. I'm pretty sure there is something in WIS about this, but I don't have my STAR tool with me to search it.

Streamliner

Thanks to all who shared their info here. I bought a CTEK charger, but my battery was dead and buried. So, today I called MB Roadside Assistance and they installed a new battery and my SL is running again. Tomorrow, if it doesn't rain, I'll get her washed and take her for a drive. The MB tech said that the red warning lights should go away after driving for a few hours. We'll see. Thanks again!

CPDay

Well, at least you now have a nice new CTEK charger.

nikk777

Has anyone ever had a trickle charger burn up the battery control module? I have another post about it but I'm also wondering if the trickle charger could cause damage? I'm replacing my second BCM with only 48k miles on the car. 20k while I've owned it. 2004 SL500....

Ejbrock

Dear nikk777,


I have been using a CTEK 3300 with no problems. I keep it on the consumer/accessory battery with no problems to date.

carguyshu

what type of trickle charger are you using?

Streamliner

Shortly after I started this thread, I purchased a CTEK charger. I also got the Quick Connect wires that connect to the battery cable binding bolts. As noted previously, I found that my battery was totally dead & had it replaced. Now, I wish to maintain it with the CTEK. Question: is it advisable to disconnect the battery cables during trickle charging or am I good to leave everything connected? I haven't put a charger on a car battery since I drove a '62 Oldsmobile and I don't want to fry anything. Thanks.

cal1

For what it is worth, up here in Wisconsin depending upon the winter, my SL has sat for up to six months without starting. All I have ever used is a trickle charge on the trunk battery. When I start the car after all that time, the engine cranks like the battery is fully charged. Not sure if that means I have a damn good engine battery or if the trickle charger is sending some juice to it.

Ejbrock

Leave everything connected. I installed the quick discount that comes with the Ctek unit. It is attached by the eyelets to the battery.

Streamliner

Just the info I needed. Thanks!