arnsbrae

Hi,

I have A 2010 SL350, which is a fun car for weekends and will sometimes sit in the garage for a few weeks at a time. I understand that the battery may well be okay for this usage pattern, but nevertheless I intend to use a trickle charger.

I have a CTEK charger and I have Googled as well as searched this forum but cannot find an answer to my question...

Which battery should I attach the charger to and why?

Also, what type are the batteries? Are they both AGM?

Thanks

geharmon

I store my SL550 over the winter (November through April/May) and use a CTEK trickle charger on the consumer battery - the one in the trunk. The battery in engine compartment is dedicated to starting the car so there is no draw. I've never had to change either battery

arnsbrae

Thanks geharmon - that's just what I needed to know.

At the risk of being a pest could you tell me how you deal with the cable? Presumably you just close the trunk lid on it - any tips - a certain part of the boot seal? I was wondering if the seal might get distorted and leak later...

geharmon

I'm not sure if your SL230 trunk lid (boot lid?) is the same as my 2009 SL550, but if it is, with the trunk open, follow the edge of the trunk lid (either side) down toward the back window. At the end of the trunk lid, come back up approximately 1.5 inches and you will see a depression in the lid before it gets thicker again. I close the trunk with the wire going in through the depression. Doing so leaves no pinch mark on the wire or trunk rubber gasket. If my message is unclear, let me know and I'll try and take a photo.

arnsbrae

Thanks for the detailed response - definitely no picture required!

Rdub

A totally dedicated circuit does not slow down the slow degradation of that particular battery. It would be wise to alternate trickle charger schedules.

geharmon

I'm sure Rdub is correct regarding the slow degradation of the starter battery. None-the-less, I would not alternate the charger as the Consumer battery experiences a significant drain with the car off. While I've never done it (nor have I read of anyone else doing it) I'd add an additional trickle charger if you must. My SL came out of hibernation two weeks ago and started right up.

cal1

Agree 100%. I have been putting my 03 to bed for the winter for many seasons now. This last horrible winter resulted in the car sitting from November to April without a single start-up. The first engine start-up of the season was no different than if I had started it the day before.

To the OP. I have a suggestion if you might happen to be **** like me . I have always been worried about myself or worse yet the wife deciding to take the SL out and forget about the trickle charger still being hooked up. My charger came with a set of alligator clips and a bolt on wire with a quick release. I use the quick release wire and actually leave in bolted to the battery at all times. When the charger is connected, I take the gator clips and hang them over the steering wheel. It is the perfect reminder to ensure I don't ever drive down the road with a trickle charger dragging behind

Rdub

Obviously a battery will start a car, until it doesn't. So....

This is not to "PUSH" a battery charger brand (the market is HUGE and the price ranges are all over the place) but the Deltron Battery Tender Plus has an interesting and very graphic indicators. Time it takes to get to a steady green light is an indicator of amount of discharge

When the battery is first connected, it lights a steady red. When the battery gets UP to 80%, a green lamp slowly flashes (with the red lamp still lit) if at that time one wants to disconnect, fine. However the recommendation is to let it go to UP to 100% or a steady green light.

So for example on a 12 VW Touareg TDI, it took close to 4 hours to get back to 100% (steady green lamp) sitting in a 70 degree garage for 1.5 weeks. In contrast, when driven more regularly, more like max 30 mins to a steady green lamp.

geharmon

Like Cal1, I also use the bolt on CTEK connector and leave it on the Consumer battery year round. It just provides a clean, quick connection. I also have 2 Deltron Battery Tender Plus units that I use on my motorcycles. They are reasonably priced and fine connectors.

arnsbrae

Thanks again to both you and cal1.

I'm going to use the bolt on connectors with the CTEK and use a similar trick to cal1 as a memory prod!

Cheers guys.

dRockSL55

I use a deltran tender (the sealed, waterproof 800 model) on my consumers battery whenever the car is parked. It offers similar staged charging and maintenance to the ctek units though is not quite as advanced. Very simple plug in and go for nearly all battery types. I have used one on every "toy" car I've had with great success.

On my SL I did not want any cords hanging into the trunk, leaving the trunk open, hanging over/closed into trunk seal, or hanging over the paint. I also did not want to have to pop the trunk each time I parked or wanted to move the car just for the tender connection, or have any cords visible in the trunk area. So, I ran the wiring through the existing trunk drain grommet in front of trunk pan, with the eyelet terminals connecting to battery posts. This is all under the trunk well carpeting. I then ran the wiring outside of the car between the trunk pan and the black plastic rear underbody shielding to the rear tow eyelet opening. I simply disconnect the tender, tuck the cord in and close the little flap when I take the car out (alternatively you can just run it to the opening on the side of this shielding and again tuck it back when not in use, not dealing with the little tow hook cover) - nothing visible or dangling.

The waterproof 800 model I use is epoxy sealed and very rugged, I've driven over them countless times, dropped, thrown around the drive, left one outside and in use for years and they always work great. I recommend this particular model for indoor applications too as again it is very rugged, much more so than the popular "junior" model. Highly recommend, very economical too at around $35 street price!

Attached are a few pictures of the vehicle side of my setup on my SL, the battery tender just sits on the ground and plugs into that connector to use. Click any pic for the full size

cal1

Very nice set up.

rmk-raven

I've stored my SL55 for over a year without starting it (I'm ashamed to say that!) and had no issues with my front battery provided I keep the rear battery charged. My bet is that the charge goes through to the front battery but it's one-way current flow; you can't charge front to rear. I've used the full size Battery Tender and had good success; my rear battery went 10 years before I had to replace it and the front battery is still going. I switched up a year ago to an Optimate 6 Charger. I use the Optimate 3+ Chargers on my motorcycles and have had good success there as well. The key is to keep them charged.

F1BHP

rmk, the reason you have had no issues is because you have a DC/DC converter between the rear and the front battery which tops up the front when it drops. So as long as the rear battery is charged then the front will be fine.

glasgow2

TheSaint

By the way i just read on CTEKS homepage that it is CTEK that makes the "original" Mercedes trickle charger

RLandis

Which model CTEK trickle charger?

RLandis

Which model CTEK??

DomiNOOCH

I just got Model CTEK MXS 5.0 (40-206) last week; it was the model recommended by CTEK (I e-mailed tech support for recomendation). Works like a charm.

Frederick NL

Mats Wesen

They make trickle chargers for a lot of different automobile/motorcycle brands. I've got a couple of them in my garage with Harley-Davidson logos on.

TheSaint

When it comes to putting the power cable for the charger in the trunk/boot i just place the power cable at one of the corners (close to the tail light) so it is not close to the lock. Never had any problems with the power cable being pinched with the cable placed in the corner of the trunk

The eyelid cable with the connector that you bolt on is a bit short i think so i checked some shops that sells CTEK chargers for a longer cable but nobody had any "loose" cable so i emailed CTEK and asked if they could provide me with a longer cable with the quick connector
Got a reply the same day that they would check and a few days later i received a eyelid cable with the connector for the MSX 5 free of charge from CTEK. Great service