Just got C230 with battery living it's last days. Was very difficult to start engine next day, so I went straight to battery store.

Unfortunately they didn't have AGM batteries (and none of other stores do where I live, everything is on per-order with 3 days waiting time).
They suggested "normal" battery claiming it will work 1-2 years as opposed to 5 years of AGM battery. Price was reasonable and I was cornered so got it.
Few days down the road it works as a charm. But as I will not be driving it every day with possible pauses for a month or so, would community recommend switching to AGM? As current capacity may not be enough for a month of staying in garage.

Or just use it for a year and then get a proper AGM?

 

My suggestion is to use the battery for as long as it lasts. If you will not be using the car for a week or more get an inexpensive 2 amp battery maintainer or “trickle” charger.

 

I had to replace my battery about 2yrs ago and the old battery lasted 7yrs according to the date of manufacture. That was a Mercedes AGM H7 battery and I went with the same Mercedes battery this time. I was looking around for a replacement and actually the Mercedes dealer near me was the least expensive, except for Walmart which I never even thought of checking but wish I had because they do have them in stock for less money with a longer warranty. All the local autoparts stores around me were much more expensive, some by over $100. I never thought to get a regular battery, I wanted a direct replacement.

Since you already have the battery theres really nothing left to do but use it I think. Im not an expert on batteries so know just what I searched around online. The AGM battery is "better" in my opinion, but I dont see why you would go out and spend money on another battery. use it till it dies I say. I don't put many miles on my car so i'll hook my Noco Genius 5 charger to it once a week to bring it to full charge, im hoping that will extend the life of it. Can you leave a battery maintainer connected while you're not driving it?

I dont have a garage and my cars parked outside, 10" from the ocean so I wanted something I can run an extension cord and charge the battery within a few hours and pack it all up. I originally bought the Noco Genius 1 and while that did work great it took over night to finish the charge. I sold that and bought the Genius 5 and that takes no more than 3hrs to complete, i guess it does maintenance and desulfates the battery if needed. Can leave it hooked up if you wanted. The Genius 1 is only $30, sometimes its on sale.

 

I have the charging harness installed in the car, positive to positive battery post and the negative connected to the same ground the battery is connected to in the engine bay. I read its not a good idea to have the ground connected to the battery, it should be to the car. To charge the battery I run the extension cord through the front grill in the top left corner, it just fits. Put the charger behind the right headlight and connect to the harness. I used some wire loom so its not even noticeable. Can close the hood and lock the car.

Red arrow points to the harness connection.





Positive and ground hooked up.






Extension cord run through the grill, place the charger in the open space behind the headlight.

 

CTEK is the manufacturer of the Mercedes-branded trickle charger. Here's my personal recommendation. I've acquired a few CTEK chargers over the years and and find them to be excellent. The particular model below is good for maintaining and reconditioning batteries. It supports AGM and non-AGM batteries.

 

I have this trickle charger on the Boxster and the BSA. Works perfectly.

 

@TimC300 Very interesting, thank you for the detailed response. Am I right to think you just put it there and drive with it? And just connect external cable via grill whenever needed?

 

Coincidentally I also don't have a garage and car is parked at condo 10" from ocean The condo doesn't have power outlet at parking seems like, although I will speak around. Thank you for good ideas with chargers.

 

the battery sensors on ( - ) side needs to record the battery charge current goung across its measurement shunt resistor. The internal chip sleeps and wakes up by itself. It live across 12Volts, it does not rely on F-SAM to get powered It is ultra-low power chip much like the TPMS that broadcast tire data for 10Yrs on one coincell... unbelievable, right?

When and if you do whole car "reboot"... you can unplug the tiny connector to reset and force the battery sensor to relearn your battery.

 

No the charger is not permanently mounted in the car, I just put it in there when I'm charging it. The Genius 5 has a two piece cable so you can easy disconnect it from the clamps/eyelets. The Genius 1 is a solid cable so you cannot disconnect it from the clamps/eyelets. The clamps are screwed on through the eyelets, so you can either use it with the clamps or permanent install like I did. I don't see a need to leave the charger in the car, especially in the engine bay where it can get destroyed. I installed an aftermarket HID kit and the ballasts are getting pretty weathered in there, probably water getting in from the grill. Im sure you can mount it in the car, the Genuis 2 without the clamps says its made for mounting in the car.




I bought another set of clamps so I can use the charger on another car or battery. And because the Noco uses there own special connectors I bought there adapter they sell that connects to a standard SAE type harness. The adapter is like $27 normally so I just kept looking on Amazon until I came across listings for "Used-Like new" and I think I paid $11 for it, same with the spare clamps. The packaging may have been opened but the parts are brand new. Can always return it if you don't like it.




When connecting the eyelets I had to modify the positive one, the nut on the battery post does not completely unscrew so I snipped some of the eyelet away to make a spade type connector to slide in under the nut then tightened it down. For the ground I had to use a hand file and make the inner diameter of the eyelet larger to fit on the nut.









I have an exterior outlet on my deck so I run a surge protected power strip then connect an extension cord down to the car. I figure its safer if it were to snow or rain. But I never leave it plugged in if im not around anyways, thats why I wanted a faster charger so it doesn't take long. I meant to say my cars 10 feet from the ocean, not inches.

Blurry zoomed in photos from security cam. When I had the charger hooked up over the weekend.

 

Thanks a lot @TimC300 . gonna get one for myself as well. I mistakenly put inches instead of feet - being non american it's difficult to quickly transform distances

 

 

While we’re kidding around —
It’s far easier to go the other way around:
2.5cm=1” (inch)
30cm=1’ (foot)
100kph (km/hr)=60mph (miles/hr)
14mm=9/16”
Leave the precision to the engineers.
If the nut doesn’t fit, try another one.
That’s all I have ever needed.
😊