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oneslow55

StarvingArtist

!!.5 is good at the track, not so good in a battery. I replaced my 12 year old oem battery with one from the dealer. A surprisingly reasonable $160

cetialpha5

I have a regular W211. Winter I get as low as 11.5. I just fully charged my battery as the alternator was dying. After charging it, it sat at 12.5 volts although while under charge it was as high as 12.7 right afterwards. After I hooked up the battery, display voltage was 12.1 volts. Remember 12.5 was the no load voltage, once it's hooked up, it has a load on it. It was warmer a while back, house temperature was probably 70. Outside temperature was about 50 at the time, but I hooked it up and started it pretty much right away. Mine is the OEM AGM battery which is almost 11 years old at this point. You get the battery low warning once the voltage drops below 11 volts.

Anyway, put it on a trickle charger and see what happens. Never charge a frozen battery, but you're getting good voltage and it doesn't sound like it's that cold out there.

drothgeb

The alternator dying was probably related to you using a bad battery. Replace the battery when it stops holding 12.7, it's cheaper and much much easier than the alternator.

cetialpha5

Car had close to 100k so it was about time for the alternator to go. They go all the time in that mileage range. It was fried. Replaced it and it's fine. Battery is still holding at 12.0 with the car off. Voltage is up to 14-14.2 when driving. It wouldn't go above 12.3 with the bad alternator.

That 12.7 voltage is a fully charged battery at 70 degrees with no load. You never hit that when it's connected to the car. As the battery ages, it can no longer hold that maximum voltage, but you don't really need 800+ CCA in order to start the car. You'd be wasting a lot of money every time you replaced a battery that wasn't at 12.7. Mine was at 12.5 voltages and if you look at a state of charge chart, that's about 80%, not bad for an 11 year old battery. I'll think about replacing it once it hits 50% which would be at about 12.1 volts.

drothgeb

That is a bad battery. If you can't maintain a 12.7ish voltage on your battery with normal use your battery is bad. Battery capacity is not measured in voltage its in amperage. Trying to state that a battery that will only hold 11.X volts is 50% life span is a complete theoretical misunderstanding. Capacity of the battery measured in CCA, with a float charge from normal driving even as you loose capacity you will still keep 12.7ish charged voltage. All things the same if temperature goes down voltage of a lithium ion battery would actually increase but CCA capacity go down. Don't spread bad information, if. Your battery is to the point that fully charged it is low 12s voltage, it is bad and could easily kill your alternator. Sitting in an airport on my phone right now but a little later I'm sure I can dig up some good references to help every one a little bit instead of taking my word for it.

cetialpha5

While that's true, you can use a battery state of charge chart to determine if the battery is fully charged. Normally you'd just load test the battery to see if it's good or not.

Don't worry, I'm an electrical engineer, I probably understand it a little better than you do. You really have no idea what a no load voltage really means. We're also talking about an AGM lead acid battery, not lithium.

I also don't think you have a good grasp of what kills an alternator. Typically either the voltage regulator or the bearings go bad and that's typically a function of age/mileage. Very rarely will a bad battery fry an alternator, and that's typically with a dead cell which would normally mean you can't even get to 12 volts.

cetialpha5

Oh, here's a copy of the chart, there's many out there but they're all basically the same.

https://modernsurvivalblog.com/alter...-charge-chart/

Remember, open circuit voltage is NOT the same as the voltage displayed on the dash. That's under load.

tlambert

Critter

Personally would not run an 11 year old battery in any Benz,
Not even my lawn tractor
Why tempt a failure.
Little is proven when you are broke down
Also the alternator is meant to recharge not rejuvenate.

Yuille36

This happened to me, with my 11 yr old battery. Luckily I was at home, just getting ready to leave for work.
I picked up a new one from the dealership. And have no further issues.

cetialpha5

That's why I put it on a charger afterwards so the new alternator wouldn't have to charge the battery up. Still holding at 12 volts with a load. Why replace a battery if it's not bad? It's an AGM battery and they last longer than regular lead acid batteries. And because mine is in the trunk and I'm in a colder climate, then it's not surprising it's lasting. Most other cars put their battery in the front by the engine where the heat bakes the battery. It's really the heat that kills a battery. I'll just keep an eye on it. Lowest it's been is 11.5 volts in the winter when it's been about 10 degrees Fahrenheit. You start getting warning messages about low battery voltage when it's at 11 volts.

Yuille36

Also make sure that your replacement battery has at least 850-900 Cold Cranking Amps (CCA), as the E55/63 starters need to turn over a big engine.

Critter

"And because mine is in the trunk and I'm in a colder climate, then it's not surprising it's lasting".
My friend, an 11 year old battery is not saving you any money, do yourself a favor and replace before some other electronic components fails
These cars are power hogs and you will find out, most likely at the worst time that " oh I guess my luck has run out "
Guaranteed you will not fail outside of the Benz dealer or other battery shop, most likely in the middle of no where
Use your old battery as a trade in on a new AGM battery and give yourself peace of mind.
The trickle chargers are great, my cars are all on them now sitting in their garage until winter passes

cetialpha5

I do have peace of mind. You're the one that doesn't have it because you don't seem to know how batteries work. I've had the car 4+ years so it's always been like that, it's not like it just started doing that. Plus if I get rid of the car next year, it saves me from not having to buy a new battery. I have AAA plus and 100 miles of free towing and I have another car so it doesn't really matter. If the voltage dips much below 11.5 during really cold weather, I'll consider replacing it, but it's in the 50's now and holding at 12 volts, didn't even have it on the charger before so it's actually showing a stronger voltage than before. I also don't think you realize that you just need around 100-200 amps to start a car. The battery in the Benz is a little over sized due to things like heated seats, bluetooth, satellite radio, etc., has a lot of electronic components and they wouldn't last long without a large battery.

drothgeb

That oversized battery is a pretty hefty load on the alternator when you continue to use them as they loose capacity and fail to maintain adequate voltage. I've personally seen repeat alternators go while using batteries that would only hold low 12s with full charge until the battery was replaced. But you're an electrical engineer so I'm sure you know better and will continue to give people bad advice that could end up costing them money or leaving them on the side of the road. Hopefully any one that stumbles on your knowledge in the future takes it with a grain of salt. Better safe than sorry.

cetialpha5

I don't think you're making any sense. What's the voltage of your car battery now? Max voltage of a battery at 70 degrees with no load is 12.7 volts, once you put a load on it like connecting to a car, the voltage drops even more. Switch to temperature display and hit the reset button three times, that should display the voltage on the dash. MB only warns you about low battery voltage when it gets down to 11. I've heard of alternators going also, it's usually not because of the battery, it's mostly due to bad QC and the reman process, sometimes it's not completely rebuilt and some other component fails. Mine wasn't too hard to do though, has a lifetime warranty. The only real way to tell if a battery is good is to give it a load test.

Critter

Thanks Drothgeb and Yuille36 I knew I might have brothers somewhere.
Was just trying to assist other Benz owners that might go into a dealership service center or Battery outlet and say "But the battery is only 10 years old"
It still has another few years left
Why does the car not turn over ????
There will be no changing his mind ( he is an Engineer ) of the electrical kind, but hopefully a member does not purchase this miracle car next year

Oh yeh!! my lawnmower uses a 300 CCA battery would this be a good mod.

cetialpha5

As mentioned earlier, the proper way to diagnose whether you need a new battery or not is to load test it. I'm fine with mine as I believe it's at about 80% of a new one. No point replacing a battery that isn't bad.

You can easily keep an eye on the voltage of the battery on the dash, switch to temperature with the car on but not running and hit the reset button 3 times.

In the really old threads and maybe in the other forums, people were using lithium batteries, has a lot lower CCA rating, but you don't need much to start a car in normal weather, in cold weather, CCA requirements go up and because batteries are still a chemical reaction, the current from a cold battery is lower than a warm one. When those two lines intersect, the car doesn't start. The lithium batteries weight a lot less though so maybe slightly faster 0-60 times.

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