I plan to do my own service B (26k mile service) on my W251 soon. I looked over the checklist, and everything seems pretty straightforward except for the battery test. It notes that the battery should be tested with a Midtronics MCR 717.

To all the pro MB dealer techs out there, is this absolutely necessary? Would a Schumacher BT-100 be fine? I realize the MCR 717 has the ability to do more advanced analysis of the charging and starting systems, but the checklist specifically states "check battery condition".

Am I missing something here? Thanks in advance!

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Alternatively, when I called AutoZone the employee I spoke with said they use a Midtronics tester with a built-in printer, though he didn't know exactly what model. Sounds at least similar to the MCR 717. Would having a free test run by them with a printout or cellphone snapshot suffice for warranty coverage?

I tried looking for a MCR 717 and it doesn't seem readily available for purchase.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Bump - anyone have any ideas?

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

All the tester does is analyze the battery. Most of the time it simply says charge and retest. The latest midtronics was implemented because of MB keeping the battery on newer cars @ 80% charge so there is room for absorbing the charge from the regenerative braking function. When your car doesn't start or cranks slow... start worrying, otherwise unless you have a large MB black battery (AGM) they quit whenever they like.

Regenerative braking - did you wander off the Prius board? Am I missing something here?

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

No, he is correct. Newish Mercedes use software to manage battery charging. They charge aggressively while the car is coasting, on the theory that when rolling toward a stoplight the car's kinetic energy is going to be discarded as heat anyways, and might as well use that energy to spin the alternator. These cars moderate charging during acceleration and cruise to reduce alternator load, and hence reduce fuel consumption.

Interesting...

__________________
08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280

Chances are your R class has the AGM battery, or should. These are notorious for quitting without much warning. The negative cable post ends tend to leak and since its hidden conveniently under the RF seat, its a ***** to replace...
Sorry about owning an R class.

Sorry for grave digging ,

But the Midtronics 717 is not needed. Any conductance bat tester that can do AGM batteries (most quality ones can) and has an option for glow plugs ( If yours is a diesel ) in its test cycle will work.

Generally you will need a heavy duty conductance bat tester (cause of the glow plugs).

The Midtronics MCR 717 is just a Mercedes branded Midtronics MCR 700.

A little late but someone might find it useful.

M