Broken B250e

[Bugladyhb]

Hello All, I’ve been following this thread and wondering if the DU issues are isolated to certain model years? Any insight would be helpful as I am considering purchasing a 2017 lease return and wondering what the chances are of this happening to that car.
Thank you Kindly!
Hannah

 

[JeffRay]

Bugladyhb,

On this forum, my recollection is that it is 2014 and 2015 models who have reached around 40K miles. A small percentage but bad regardless as it tends to happen after the 4 year warranty is up. Check me on this.

It is my understanding that this was a fault with the first Tesla DUs which they resolved later. The question is whether MB also switched to the new DU in 2016 or continued to use the older model DUs. I don't know the answer to this. MB dealer would not know. My instinct says MB would have received newer Tesla DUs rather than continue to buy the prior faulty ones.

Remember that the warranty is only for 4 years so have the DU checked out by a MB dealer and also have them certify that the annual battery check was done so the 8 year battery warranty is valid.

It is a fine car and only a small percentage have this problem but you don't want to be one of them so good to check things out. If I were to buy mine at the end of the lease, I would be betting that with my low annual mileage, I would be safely below 35K miles driven. If it craps out, I would write it off as a casualty loss and post the usable parts on eBay for remaining owners.

CORRECTION, I made a mistake by referring to Tesla DUs. I meant Tesla motors reported to have had issues. Learned the difference between DUs and motors thanks to FordAnglias comment below about the difference.

 

[Bugladyhb]

Thanks for your insight Jeff. That is really helpful. I will try to look into the DU a little more, if I find anything I will post.
What is a casualty loss? Is that for an insurance claim or taxes?
Cheers!

 

[JeffRay]

Bugladyhb,

Oh sorry about that. For insurance, check you auto policy if it covers a mechanical breakdown that triggers a total loss. For tax purposes, it depends where you file taxes but it used to be that a loss like theft, fire, etc, not covered by insurance could be taken as an itemized deduction in the U.S. Check that as well as you state tax laws.

I have not check insurance policy as it is so bloody complicated to read and understand. If you have an agent, ask them what types of casualty losses are covered, i.e. crash, fire, water, act of god, mechanical failure, etc.

 

[chuckh007]

Boy am I sorry to give you guys this bit of bad news. My wife drives a 2014 B250e and it is at the MB dealer waiting for a new drive unit. The car has only 12K miles on it. Up to a few days ago, there were zero problems with the car. Then one day while downtown, my wife starts the car and nothing happens.....tries again and the car goes into limp mode.....pulls into a parking lot and turns off the car, waits and tries again.....this time everything works perfectly. Take it to the dealer and they can not figure out the problem ( even after I told them about the coolant leaking problems of others ) The dealer opens up a "case" with MB/Tesla and they decide the car needs a new drive unit. We live in California so the unit is supposed to get here on Thursday (today is Mon.) . I have an extended warranty with MB (it was cheap) and almost didn't get it since the car seemed like a "tank". Who knew ??

 

[JeffRay]

ChuckH007,

Sorry to hear. Keep us posted. Note you have extended warranty. Will be interested to learn how much of DU work it covers as a member said it excluded motor. What the difference between DU and motor is not exactly clear to me.

Wish you success in this, low mileage problem like this is so rare. When the dust settles, please let us know. Thank goodness it happened when car was parked.

 

[FordAnglia]

My wife drives a 2014 B250e and it is at the MB dealer waiting for a new drive unit. The car has only 12K miles on it. Up to a few days ago, there were zero problems with the car.
...
I have an extended warranty with MB (it was cheap) and almost didn't get it since the car seemed like a "tank". Who knew ??

Chuckh007,

Sorry to hear of your wife's B250e problems, and at such a low mileage.

You said "Drive Unit" - to me that is the electronics above the Motor. This confirms that the car stopped suddenly and then went to "limp home mode"
The other failures reported here (and at higher mileage) are "Motor" - this is the coolant cooled motor and coolant cooled "Inverter" electronics that drives the motor, and is one unit, with shared plumbing. When coolant leaks into the motor it is reported to make a whining noise. If the Inverter is flooded with coolant the Motor will not run at all.

I think MB dealer tech support is limited to troubleshooting to the major assembly level and installing replacement units, not at the component level. This has some strong business support (labor cost, training, cost and size of parts inventory) but seems awfully wasteful.

As a side note, there are now third-party Tesla repair shops that will salvage assemblies by replacing electronic components and re-flashing firmware (in the case of replaced EEPROM chips that "wear out" due to Tesla's penchant for collecting vehicle data and storing it in non-volatile RAM)

Fingers crossed that MB steps up at no cost to you. Please report your progress.

Peter,

 

[JeffRay]

ChuckH007,

Fingers crossed the the warranty covers the DU replacement. Thanks for clarifying Peter.

 

[FordAnglia]

Fingers crossed the the warranty covers the DU replacement. Thanks for clarifying Peter.

Looks like I have to back-track on my understanding of Tesla names for their EV systems. Search for "Tesla Drive Unit" on eBay brings up the large metal "Lump" that has the Induction Motor, Reduction Gear Box, Differential, and Electronic Inverter (that powers the Motor)

The Drive Unit is connected to the Tesla In-Vehicle Charger and BMS (Battery Management System) This is really the controller, and also manages high voltage battery charging, REGEN charging, and DC-DC converter. That in turn supplies the 12V system and charges the low voltage battery.

We'll have to wait and see if ChuckH007's B250e has an electrical/electronics or mechanical or fluid leak issue.

Peter,

 

[chuckh007]

Ok....wait is over. It was not a fluid issue but an intermittent fault in the drive unit. They set up a PTSS case after doing an isolation resistance testing of the HV system at the drive unit. Results were sent in and drive unit was recommended to be replaced. According to the invoice (without prices) the electrical motor was replaced and the electric drive ( this was a remanufactured unit ) .....not too surprising since why would Tesla keep making old 5 year old units.

 

[chuckh007]

I forgot to mention that I had a GLC 300 for a week as a loaner and the entire repair/replacement was zero dollars. The M.B. extended warranty paid off big time.

 

[JeffRay]

ChuckH007,

Good news and happy you have the car back. Thank you for letting all of us know the details. That is the headline. Also, interesting that you came out cost free save inconvenience and putting gas in the loaner. Pays to check coverages before assuming what is and what is not covered

Excellent news.

 

[chuckh007]

Yes, good news , BUT, why is this electrical problem occurring for so many, I thought that this car was pretty "bullet proof" with M.B. an d Tesla sharing the technology. Now I wonder if I should start looking at other EVs for reliability and longer range. I have the extended warranty until Feb . 2022. This is also a great selling point for a private sale.

 

[FordAnglia]

chckh007,

Congrats on repair at no cost (through the warranty)

why is this electrical problem occurring for so many, I thought that this car was pretty "bullet proof" with M.B. an d Tesla sharing the technology.

May be I missed it, but what exactly was done to your vehicle? Was this an electrical or a mechanical or other issue?
Was it solved by the dealer using replacement components, or a wholesale replacement of a large system (motor, Drive Unit, EV electronics)?

I'm concerned that the only repair being offered by MB service is "swapping" suspect systems. More so if the root-cause is not known. Perhaps only a penny-cost component (such as a coolant seal) is to blame?

Peter,

 

[chuckh007]

Please read Dec 2 thru Dec 6 on page 3 here.......the entire drive unit ( including motor) was a re-manufactured one and yes, this does bother me somewhat. But what can I do about it ? It seems that M.B. prefers to replace components that are questionable or impossible to repair with an entire unit that includes the component......cheaper in the long run. My main concern now is what if this problem happens again or some collateral damage shows up later ? The autos made by Hyandai are starting to look pretty good (the electrical ones ) . But are they reliable ? Oh I still feel that M.B. can build a quality car but there cars still come off an assembly line production.

 

[FordAnglia]

Please read Dec 2 thru Dec 6 on page 3 here.......
"They set up a PTSS case after doing an isolation resistance testing of the HV system at the drive unit. Results were sent in and drive unit was recommended to be replaced. According to the invoice (without prices) the electrical motor was replaced and the electric drive ( this was a remanufactured unit ) .....not too surprising since why would Tesla keep making old 5 year old units."

The silver lining may be that a re-manufactured motor has fixed the apparent coolant leak issue reported here by others.

Oh I still feel that M.B. can build a quality car but there cars still come off an assembly line production.

Assembly line production is not the issue. All vehicles (with very very few exceptions) are built the way Henry Ford invented. Today's vehicle assembly lines employ more robotic tools and more frequent precise measurements leading to better fit and finish and consistent units.

The B250e issue might come down to either the assumption by MB that Tesla had a solid and reliable Drive Unit, or that MB didn't conduct enough long-term reliability testing. Reported here the Drive Unit coolant leaks show up at about 56km (35k miles)
Another possible reason is that the B250e is FWD, but Tesla Model S use that same Drive Unit in a RWD arrangement. Any FWD is going to put additional strain on the transmission and drive shafts due to combining traction with steering.

Here's a good article reporting the now infamous Milling sound of a dying Tesla Model S Drive Unit

Best of luck going forwards, please report any new problems (or shout out for MB if they are treating you well)

Peter,

 

[chuckh007]

Well Peter, as you already read, the problem was not a cooling leak but rather an electrical fault in the Drive Unit. Who knows what that means ?? It was interesting however that when I looked up the Part no.( on my Invoice ) for the Drive Unit it did not show up as a 2014 part but a re-manufactured part for the 2016 and 2017 Model.....that is what they put in !!

 

[chuckh007]

Another update......got malfunction error, visit dealer workshop followed by another message to not run engine with icon of a "battery".....needless to say the car would not start !! Later when the tow truck showed up, the car started ( great for loading the car ) and off to the dealer it went. Dealer found faults with the 12V battery and replaced it and end of story. However, that failed 12V battery was replaced just 22 months ago...???? This battery issue and the previous electrical problems have me VERY anxious about the future. What would I replace this car with that is all electric and has a solid build, and not EXPENSIVE ? The foreign country forums where the electric cars have already been around for a year have a very troubling history regarding reliability.

 

[FordAnglia]

Dealer found faults with the 12V battery and replaced it and end of story. However, that failed 12V battery was replaced just 22 months ago...????

chuckh007,
Across the EV spectrum there is a high failure rate for 12V batteries. This is odd for a couple of reasons;
- An EV does not generate the high temps found in the engine bay of an ICE car. Heat kills lead-acid batteries. My co-workers in Phoenix report frequency summer time battery failures in their ICE cars.
- An EV (and hybrid Gas-Electric) does not have an alternator as found in an ICE car. The 12V battery is recharged by a DC-DC converter* off the high-voltage battery. In general DC-DC converters are more precise than mechanical alternators, more efficient, and certainly less prone to wear.
(*my day job...)

I've read that the number one service complaint on Tesla Model S is the 12V battery. Read in another source that the number one service complaint on early Model S vehicles was the pop-out door handles, so not sure which is accurate.

A coworker with a Honda Clarity hybrid was stranded this week due to a failed 12V battery. There's no alternator in this vehicle, and he uses it mostly in EV (not Gas) mode. It's almost one year old.

Could it be that the "Car battery" doesn't like the cold after all? This issue may have not appeared in ICE cars that keep their battery warm once the gas engine starts running.

The B250e 12V battery is a wet cell lead-acid type (aka "Car battery") This is likely the most economical solution, but other lead-acid battery types (SLA or sealed Lead Acid, Gel Cell, and AGM or Absorbent Glass Mat) and non lead-acid battery types (Li Ion, LiPo) exist and have size and weight advantages. Probably not a cost advantage.

As the 12V battery is needed to 'boot' an EV, and support heavy loads, many due to cold weather, (electric defrost, heated seats, climate control warm air heater, high voltage battery coolant heater and circulating pump) a lead-acid "car battery" is a smart choice for the same reasons it is used an ICE vehicle under cold start conditions.

Peter,

 

[barsaec]

So with that being said, would you consider replacing the 12v battery as maintenance item? If so, what interval? We haven't replaced ours yet (purchased in Sep'17 a 2015 model). I'm simply trying to prolong our use of this car, knowing how problematic they can be. We have been going strong on the new drive unit (14k miles and 18 months). MB wouldn't sell us an extended warranty, so I'm hoping to make it to the Model Y release.