[mav238]

I started a previous thread on replacing my battery in my CLA. So I ordered a battery checker from amazon , see below.
I plugged it into my car, and it displayed 12V, and when I started the car , the voltage went down momentarily to 11.4V, and over the next 2-3 secs, the voltage went to 14-15V and stayed there.
Should I still go ahead and change the main battery ? The battery is about 6 years old.

 

[Geo K]

Yes, Both IMO.
If you search through the Member experiences, you will see instances of sudden failures due to age.

 

[jmc]

Keep a cheapy jump battery pack in the trunk (i got one in there fully charged) until the main batt gives … cuz who knows the darn thing may last you a few more months or few more years
Though 12.2 is baseline ok … 12 is weak
My current 5yr old battery drops to about 11 when cold start and 12 when warm … and i am just waiting for it go before i pop in the wally special - which has been holding up quite well on the shelf
all that said … as @Geo K has pointed out … and from my experiences … failure mode is like a cliff

 

[Northern Al]

My 2 cents;

Go ahead and change it a.s.a.p. This is the time of year when it's most likely to fail due to our cold weather. With the intermittent shortages going around right now you still have the option of shopping for a good aftermarket battery at a reasonable price. If it dies away from home out on a frosty day you'll need a tow or road call and you'll be forced to take whatever replacement is available, at whatever price they demand.

Like JMC says; It's going to go and it will go suddenly, without warning. My factory battery lasted 9 years but I don't drive it much in the winter and I do drive longer distances when I do take it out. I was lucky enough to have it die in my driveway, so I jumped it and headed to the parts store 2 hours away where I located one. Two months earlier I asked the MB dealer to test my battery during a service and they said it was perfect. I opted not to change it then as they wanted $500.00 plus labor to change it.

You've recently said you're working from home and most of your trips are now short ones. I don't believe you have a few more years and they're not getting any cheaper.

 

[jmc]

N I N E years before it croaked?
Good lord you must have sulfuric sipping angels sitting on that battery keeping it charged
I am at 9 too … except its a chorus of 2 + 2 + 5
🤪

 

[mav238]

I changed out the auxiliary battery today with an energizer one from Costco. pretty straightforward , if not for the reinstallation of the battery cover , which took the longest to put back. the energizer battery was a direct fit. After reinstallation, restarted the car to make sure installation of new battery did not cause any issues.
now waiting for my main energizer H7 battery from Costco to arrive on monday.

 

[jmc]

i recall wrapping the aux leads in heavy plastic ... in case they touched something -- knowing my luck.
in your neck of the woods ... what's the costco h7 warranty?

 

[mav238]

i recall wrapping the aux leads in heavy plastic ... in case they touched something -- knowing my luck.
in your neck of the woods ... what's the costco h7 warranty?

Warranty is: 5 years limited, 100 months prorated

Battery Specs	Energizer Group H7-AGMAbsorbent Glass Mat Automotive Battery
Amp Hour	80
BCI Group Number	94R-AGM
Cold Cranking Amps	850 Amps
Cranking Amps	1000 Amps
Reserve Capacity	140 Minute
Voltage	12 Volt

 

[jmc]

well much better than benz warranty 🙃

 

[mav238]

I finally got the main battery replaced with the Costco purchased Energizer AGM H7 battery.
And JMC, you’re right about that the factory battery is a H7.
but replacing it was quite a chore. Everything is so tight , space is a premium there. The positive terminal was easily removed , but the negative terminal felt like it was “glued” to the connectors. It took a lot of jiggling and pulling on the connectors , almost 15 mins to finally got it out. Then pulling out the battery was a chore and putting the new one in was a bigger chore.

anyway , once the new battery is all installed

guess what

the auto start stop system started working again!

and the gas consumption seemed to have improved and the the car seemed much peppier.

 

[mav238]

Honestly, the car also felt like it has a new improved efficiency to it. I always thought may be my car engine internals was a bit dirty and need deposit cleaning, which was may be the cause for the poor consumption. Anyway, the battery replacement helped in a significant way to fix this issue.

 

[jmc]

thats it
i am gonna run a parallel h7 in the trunk
🤪😛😝

 

[mav238]

thats it
i am gonna run a parallel h7 in the trunk
🤪😛😝

That's funny. But seriously, the battery replacement seemed to have fixed the electronic gremlins (auto start/stop, blind spot warning, forward collision warning, automatic emergency braking system). Today I was approaching a car a little fast and close, and it's been a long while since I heard the FCW go off.

I was posting about my 9.5L/100km consumption a while ago , before the battery change, and now after the battery change, back to the regular 7.5L/100km in regular city driving.

 

[jmc]

those pesky electronic subsystem voltage rails dont exist without a good power source

btw
if a battery change improved mpg then the alternator must have been working overtime in an attempt to maintain the old battery soc
your battery subsystem software was working it seems 😋