What is typical battery degradation?

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hallcp

Well-known member
Joined
Jan 7, 2019
Messages
127
I am looking at a B-Class on one of the local used car lots. It seems like a wonderful car, but I'm a little disappointed in the range. This is a 2014 with 22,000 miles on it. The battery at full charge appears to have 62 miles range. Is that normal battery degradation for these cars? One thing I read implied the warranty would kick in if the level dropped below 70% within 8 years or 100,000 miles. This car would be well on it's way to that. (.7 * 85 = 59.5)

What do you guys think?

[ PS - I tried searching the forums but I didn't find anything, could be user error, so sorry if this has been discussed 100 times before. ]
 
hallcp,

I leased a 2014 for 3 years and reupped for 2 years on 2017. Gotta love the big cabin feel in a small footprint. 22K in 5 years is about right for regular but not excessive use.

To your question.

1. The indicated range is a guess like in a gas car, depends on last miles driven. You may want to reset the indicator and compare charge level against reset range. It is a very rough indicator of battery health.

2. Best is to take the car to a MB dealer who can run out battery report and check car out for you. The battery test is a annual requirement and if they know what they are doing (questionable), they can access the past reports online.

3. You need to find a local MB dealer who can service the car. Stuff will happen (per posts) and if there is any remaining warranty on the car and it ports to you, you still need a place to have it dealt with.

4, You didn't find much here because as far as I can remember, severely degraded battery has not surfaced in these cars yet. They are Tesla batteries and motor and others have found useful info on other car forums.

NOW TO THE CENTRAL QUESTION OF RANGE. YOU ARE FREE TO READ THE POSTS OF COURSE.

Not all 2014s had the option to top up the battery to 90 percent of capacity. GlennD has posts that state that MB sets max charge of batteries at 80 percent (but translates to 100% in car indicator) Confused yet?

The option gives 12.5% more range and I use it all the time, particularly when the outside temps drop below 50 degrees.

You will want to consider daily use, places to charge, and if you are so fortunate, a dedicated plug in your warm garage.

I clearly get by even though I live in an apartment building and park on the street. It is something you are well advised to work out before you buy or lease to anticipate the dreaded "range anxiety" attacks. Not recommended but I have driven both this car and gas cars down to 0 range and managed to make it to a fill up location.

Good luck.
 
Thanks JeffRay, this is all very helpful. I visited my local dealer and they actually had a tech who has worked on these cars (there's at least one other one in town!). As near as he could tell there was no record of previous battery maintenance, so that kills the battery warranty. But I have the car for a day-long test drive today and so far the range estimator is definitely conservative. I'll try that reset thing at lunch if I can find the setting.
 
If you are in an area that is cold right now that can affect the range also. I have the same year model with 12k miles on it (1.6k my own) and when the temp is above 60 I can see 84 miles range, but 60 - 70 are what I'm seeing when temps his 30 - 50 outside.
 
The temperature last night was in the 40's, now in the daytime it's about 55. So I guess that could account for some of the loss.

Thanks for your info!
 
Bingo! I reset the ECO display (and everything else I could find) and full charge came back up to 72 miles. That's more in line with what I expected. And as you say, from then on I could tell that the indicated range was very conservative. I could drive 9 miles and the range would drop only 6, that kind of thing.

I was a little disappointed that Mercedes won't honor the warranty without annual inspections. That doesn't even sound legal (neither Tesla or Chevy has any such requirement). That and the used car dealer refusing to deal on the price has killed the deal for the moment.

But I really enjoyed my 24-hr test drive and the local Mercedes dealership was very helpful in answering questions, as of course were the folks who responded on the forum.

What a nice car.

Thanks so much!
 
Hey I thought I'd add an update to this thread. The used car guy called me back with a deal I couldn't refuse and I am now the proud owner of 2014 Model B!

So now there are apparently 2 of these cars in Raleigh, NC.
 
Uh, other than a horse head in the bed, any chance you can clue us in? I offered to buy out my 2014 lease for the $15K they would have sold it for at auction, but my dealer declined.
 
They had it listed as $15,989. I offered 15,000 and they refused. Four days later they called back and countered with $15,500. But then of course mysterious other fees were tacked on and it was $17,087 to get out the door.

In refusing my original offer they pointed out that $15,989 was cheaper than any other one on the internet (which appeared to be the case) and that could sell it for wholesale and make more $$$ (maybe).

In any case, I just don't think they could sell it here in Raleigh at any price, except to an EV enthusiast. Although after the fact I poked around and I guess 90% of the Leafs on the road today have comparable range.

I can't imagine that the local dealer knew what he was getting when he bought one of these. But it may be that things are changing. They had a Cadillac of some sort that was electric (Voltec?) and they're beginning to see Teslas.
 
Well I've been driving this car for a couple of months now. I love it! But what's more amazing is that the dashboard display is now showing 88 miles of range! That must be what it had when new. So either the battery likes being a daily driver, or my driving style is being rewarded by the algorithm used to guess at the range. I have not done any drive-to-zero range test, but in practice it seems accurate enough.

merc-range.jpg
 
Charles,

Nice. No question that as the outside temperature warms up to the 70s, the car will perform at its best as there is little heater use to sap the battery. 88 sounds good for the GOM. The high I recorded in my 2017 with the range extended was 100 so that translates to 88 miles for non-range extended.

As to battery degradation, there are posts on this but figure I figure 1% per 25K miles. This is because the Tesla system only allows charging up to 8)% and manages rate of charge if battery is overheating or too cold.
 
I bought a 2014 with just over 22k miles on it over 6 months ago and have been tracking the battery religiously. I live in Florida with a daily commute of just under 73 miles so any battery degradation would quickly impact my ability to get to work everyday. I am happy to report that I have seen no measurable degradation.

NWyiSr0.png
 
Fascinating! Can you explain a bit more about what I'm seeing? What exactly does "capacity@home" and "capacity@work" mean? I imagine when you get to work your capacity is low, but when you leave work it is high. Same for home. So what do the lines represent?

But I guess the most obvious take-away is that none of the capacity lines is trending down. And perhaps that minor temperature variations don't correlate that well with capacity variations.

I wish I had paid more attention in that college stats class 50 years ago!
 
Krazeivan,

So first question is what do you do at the bottom of the hour? You don't have to answer this question (HfRO movie reference).

Very nice graph you posted. As I read it, here are my takeaways (C+ in last statistics course but A in accounting courses):

1. You are lucky to be driving in an area that doesn't go below 50 degrees and only occasionally goes above 90 degrees. Perfect for electrics.

2. Your current commute is made for our B250e. Charge up every night to 100% and home with at least 10% to spare. Nirvana.

3. Given almost symmetrical Kw usage, your commute must be pretty flat. Nice.

4. This would suggest your long-term battery degradation will be no worse than average when you do the annual battery test. Do you have any data on that from the dealer? Read elsewhere that depending on mileage and how many times we charge to 90% of battery capacity vs. 80%, the long-term observed degradation of our Tesla batteries is pretty negligible.

Enjoy the ride, the B250e is a perfect commuter car for you.
 
Oh, OK, now I get it. I was thinking the commute was 73 miles one-way and you charged at work.

If on the other hand it's a 73-mile round-trip commute and you don't charge at work, then the graphs make perfect sense.
 
@hallcp You are correct, my commute is 73 miles round trip and I only charge at home. I start each day at 100 and by the time I hit work (Capacity@work) I am usually in the 60s% remaining. After the drive home (Capacity@home) I usually clock in around 24ish%. What you don't see in the graphs is that I note ifI did any extra driving that day, e.g. grabbed some milk on the way home. Some of the days where I used significantly more charge than others are probably days I drove more than 73 miles.

@JeffRay One of the nice things about living in South Florida is that often our overnight lows are warmer than the midday highs in the rest of the country. It's nice that it takes much less energy to cool the cabin 10 degrees then it is to warm it up by 40 degrees. The other thing about Florida it is super flat, the only hills that we have in the state tend to be landfills. Some of the buildings in downtown Miami during a king tide are at once, below sea level and taller than the highest natural point in the state. As to your last point, I don't yet have a yearly battery review to look at. I've only had the car for 8 months or so. Before I bought the car, I brought it to a MB dealer for a pre-sales inspection and even though I asked several times if they can service/inspect a 250e, 5 minutes after I show up it was pretty clear they had no clue. However, they were able to tell me that my 12V battery was in excellent shape.

I wanted an EV commuter car and had a whole spreadsheet of possible ones that could support my commute, the 250e was perfect. I was a little worried at first because so many of the online forums said that the 250e was not the most efficient, only around 2.5 miles/kWhr. That would have been barely enough to get me through the day. The most generous said 3.0 m/kWhr; I was pretty stoked when I realized I was average 3.4 miles/kWhr, but as stated above, it's pretty much the most ideal of driving conditions.
 
Where do you think that discrepancy in efficiency comes from? I'm guessing you're just driving it more efficiently, right?
 
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