I have Mercedes SL350 car and the Auxiliary battery need replacing in the boot. As I want to change it myself, can you please give me the part number or the Bosch model that will fit.

Call the dealership and ask.

An auto parts store can also tell you.

What year?

What year is your SL350?
You realize the vehicle will require reprogramming after the battery has been replaced?

Its 2003, how much they charge for reprogamming?

Its 2003, how much they charge for reprogamming?

Rates vary significantly from region to region so it would be best to contact a dealer or qualified shop directly regarding price and time needed to take care of your vehicle's needs.
Try looking in your area through here: www.iatn.net/shopfinder
Tell them what you're doing and see if they can address your vehicle's needs.

In my case for a 500 the battery and reprogramming were over $500. I don't know how that broke down, I had the work done at a MB dealer, it was under warranty.

Captain, If someone was swapping batteries, couldn't they hook a battery at Starter or Solenoid terminals, and ground to maintain Programming.
Then swap batteries and treat the cables as if they were Live, because they are. Then remove the temporary battery?

I only know what the dealer told me when I asked if there was a way not to lose programming and they said no.

Curious to see what "Captain" has to say.

Judy.
The Dealer is an Idiot and needs the Money, its like a memory board battery, if you jump an external battery, and change the battery, nothing is lost.
He Is a Dealer, not a Tech.

In my area there is ONE MB dealership and two others more than two hour drives away. Needless to say, MB gets to make the rules. They've been sued within the past year and have been warned several times that "they" could lose the NYS MV Inspection Permit.

I never walked out of the place with a less than $200 charge.

Would I buy another one? I've had several, the repair/maintenance costs get higher and higher to the point of ridiculous - No, I would not buy another IF I had to deal with this particular dealership. I do, however, have a great mechanic who works on the cars (which need almost nothing) so I'm a happy camper.

Some day we can talk about replacing the windshield wiper blade on my summer car - the charge was $160 for two blades. The problem is that the car has ONE windshield wiper arm.

Again, someone should put reins on this particular dealership.

I have to add, the method I described would be dangerous or not likely covered by their insurance.
I would do it on my own car, and maybe put a 20 amp inline fuse to minimumize the danger/Spark.
It is Dangerous, but possible.

The "Dealer" is an entity. A for-profit business just like plumbers, power companies and doctor's offices.They're not just one person. I would also refrain from calling them "idiots!" What brought that on?

As far as reprogramming, the module being reprogrammed is the Battery Control Module (BMC). When you see the "BATTERY" message on the IPC, the charging system is disabled to prevent overcharging attempts by the charging system that could result in disaster. The current battery's serial number gets input as well as the key-off, no-load battery voltage so the control module has a new reference, or threshold.
Also, if the "BATTERY" message is displayed on the Driver's Information Center, resetting the BMC is how you turn that message off.

Can you use a "memory saver" to save the radio presets and seating presets, etc? Yes,you can but you must be certain that absolutely no loads are introduced during service and even then only if that message is not displayed.