giffie

I am thinking of buying a CTEK battery charger for my 2011 350.
The CTEK Multi US 3300 seems to be the one that MB is rebadging and selling at double the cost (goo . gl/6dDhx)

There is also another charger by CTEK - the CTEK Multi US 7002 (goo . gl/YS4pQ)

Can anyone tell me which charger to buy? The more expensive one 7002 says that it comes with "patented desulphation functionality" ... not sure if this is the one that I should get...

TIA

Fourdiesel

You'll probably need a battery charger only if your rig is parked for long periods without being used. Battery sulfation is usually an issue only with older batteries that are near the end of their useful life. Desulfation will NOT obviate your need to replace the battery when it dies. In my opinion, this 'patented' gimick isn't worth anything for a battery in a diesel vehicle.
Whatever kind of charger you get - if you get one - make SURE it is designed to work with the AGM technology batteries on your Mercedes.

alx

do not agree on the sulfation.

any acid-based battery left to fully discharge and stay that way for some time (about a month or so or more) will sulfate and be very hard to recover just by simple charge.

i have a couple of the 7xxx cteks and i have recovered to a point numerous batteries that would not take charge otherwise in my lawn equipment, atv and motorcycles.

in my mind the desulfation function is the only reason to buy a ctek and not a $10 harbor freight charger.

Fourdiesel

alx, what you say is true, but I taylored my answer to what I perceived TIA would most likely need, and that does NOT include long periods of holding a battery fully discharged (which, you are correct, causes heavy sulfation).
Also, the Harbor Freight float charger is NOT designed for AGM batteries and the Harbor Freight ad specifically states that fact. It is NOT suitable for the Mercedes batteries.

alx

Agm batteries can be charged with normal charger as they do not require any "special" charging procedure or current or voltage. The gel batteries are the ones that cant be charged properly with a regular charger as they require higher voltage. The ctek charger reflects that as it has a "gel/ winter" mode that provides up to 18 volts for charging gel batteries or regular/ agm batteries in cold weather.

Fourdiesel

I referred only to the float charger NOT an ordinary battery charger. The float charger Harbor Freight sells is NOT compatible with the AGM batteries. Since the GL series cars ALL use AGM batteries, it simply makes sense to check to see if a (float) charger claims to be usable on these cars.