Battery Maintenance or not

Load test to 400 amps. Interstate Distributors* have genuine load testers. Other places have toys.

Place 400 ampere load for full 15-seconds. Does voltage drop to less than 9.6 volts? If yes, regardless if the battery was made last week it is weak and it's your decision.

*"Do you have a variable load carbon pile battery load tester?"

I would be very tempted to replace with AGM* because VARTA batteries are insanely over-priced and Delco may or may not have your group size. Resist replacement with a conventional battery. You do not need to breathe sulfuric acid and lead vitamin supplements - neither does your family.

Bosch charging systems use notoriously low voltage set-points which are perfect for AGM. The question is "Can you find the correct BCI group size?"

MEX, thanks for the education-----------------I am not familiar with the Calcium-Calcium battery. The battery doesn't look that old but maybe someone can decipher the Numbers I posted.
Thanks again, Marvin

This looks like a group 53 battery. VARTA made in Strousberg Deutshland. It is NOTa VRB meaning sealed battery but it is indeed a full-on calcium/calcium plate battery. Minimum gassing corrosion and water loss. The Germans are famous for in-car battery locating the old beetle with a battery under the rear seat (group 42) is a perfect exanple.

A 53 is a large battery. Bigger than a group 65 or 29-30-31

Because of its location I most strongly urge you to strictly stay with a calcium calcium battery and definitely NOT replace it with a standard battery. An AGM 53 would be fine. Group 53's do not grow on trees. It is a hard-to-find group size while on the road.

Many of the older Bosch batteries had cell plugs. Twist hard enough and they'd pop out - for good. Not threaded.

If original that battery is nine years of age. If diesel you will need ONE GAUGE truck jumper cables to jump start. Far larger than all but the most expensive jumper cables.

Delco USED TO HAVE a calcium-calcium 53 replacement.

But a pre emptive repacement is up to you. Now you are aware and now you have the info to make a decision in your best interest.

Over the years, I've had two batterys just suddenly short internally and die. Cant jump them and your just stuck until you replace them.
Because I don't want my family stuck someplace in the boonies I replace them every 6 or 7 years.
Also, that little clear indicator is only for the single cell it's over. It is no indication of health of the other cells.

Can't find a date on it because I did not take it out but I did copy the numbers. Battery seems good and it cranks fine.
The reason I looked is that "Check all Batteries" was on my Honey Do list. I only have 17 and now 9 is all I have to check--rest are Maintenance free.
Marvin
Here ar the numbers on the top. Three different lines.

A000 982 33 08 Varta
12V 100AH 760A (EN)
000982 33 08 112 734 310 869

Sealed battery, No fluid check
You can get it load checked, special test
Then you need to fully recharge after load test
Because load test is a heavy hard drain on the battery
If that is the oem battery I would replace it, nine years old is old for a chassis battery

Mercedes batteries are maintenance free. IF the battery is more than 5 or 6 years old, I would replace it. Doug

I'd look it up on google.

Its appears to be a sealed battery. if the eye is green it's good.

Chassis battery? I would wipe it clean and forget about it.