Can the B class be used to jump start another car?

[pavan]

The battery on the second (gas) car is dead. Can I use the 12V battery on the B class to jump start the gas car? Has anyone tried this, and are there any risks with doing this with an electric vehicle?

Thanks!

 

[JeffRay]

You raise a good question. If it is not referenced in the included manual, I would use a portable battery starter instead. Better to spend $50 vs. messing up your baby.

 

[wtzouris]

I wouldn't risk the power spike/surge associated with jump starting. The 12volt is totally independent of the "Drive" or "Traction" battery and if you drain the 12v battery the B-Class does not operate.

 

[Stretch2727]

Guys, I am an electrical engineer and worked in the auto industry for 15 years.

No risk here. Just be sure the B-class is "ON" so it does not completely drain the 12 volt battery. The HV battery will recharge the 12V. There is an onboard charger the keeps the 12V battery charged from the HV battery like the alternator on a regular car. Think of the other car you are charging as just an additional load on this battery, just like if you turned on your radio or lights. Of course, get the polarity correct! Red on Red, Black on Black.

I did many times with my Focus Electric when my Honda battery/alternator was giving me issues.

Don't worry about draining the HV battery either as a typical 12 battery has a few hundred watts of capacity. Nothing close to the capacity of the HV battery.

I will also add you can do the opposite. Use another car to jump the MB. Did this with the Focus Electric as well. It turned out to have a bad 12 volt battery. It had sat on the dealer lot for a long time before I purchased so I guess it was discharged completely which is not good the life of lead acid batteries. The dealer replaced after it went dead on me 2x. Yes the car would not "start"!

I think the 12V battery will stay on electric cars for a long time, if not forever. It allows the use of all the ICE developed components (radio, lights, instruments) and avoids the risk of high voltage in the passenger compartment. It is the bridge to the dinosaur cars. Tesla has one so this should make it clear it is here to stay.

 

[tom]

Stretch2727,

Thanks for the explanation above regarding the 12v battery.

This is off topic. I noticed you also have the e-Golf. Can you tell us how do you like the e-Golf? What you like about it and what you don't like about it (vs. LEAF and MB B ED)?

(I test drove the e-Golf couple times earlier this year, and I would compare it to the Nissan Leaf, but not to the MB B ED. IMO, the B is a much better electric car because of the Tesla drivetrain and battery)

Just curious of your opinion and experience.

 

[Stretch2727]

Stretch2727,

Thanks for the explanation above regarding the 12v battery.

This is off topic. I noticed you also have the e-Golf. Can you tell us how do you like the e-Golf? What you like about it and what you don't like about it (vs. LEAF and MB B ED)?

(I test drove the e-Golf couple times earlier this year, and I would compare it to the Nissan Leaf, but not to the MB B ED. IMO, the B is a much better electric car because of the Tesla drivetrain and battery)

Just curious of your opinion and experience.

I will layout what I see as the differences.

-eGolf Parks easier, Standard with all parking sensors etc
-eGolf Handles Better
-eGolf Departure charging works!
-eGolf power steering is too light. Feels like an old american car...maybe this was their target given the VW push here. MB feels much better here.
-eGolf has a touchy accelerator. Too much initial response...again something like most american cars
-eGolf screen is touch which is nice. I still struggle with the knob on the MB.
-eGolf backup camera resolution is no where near the MB. I have a hard time seeing things in the eGolf screen.
-I prefer the MB paddles for Regen compared to the shifter on the EGolf.
-Both drive me crazy that they will not default to the full regen I prefer after each start.
-I prefer the regular shifter on the eGolf. I do not like the steering wheel shifter on the MB.
-With the eGolf you leave the in your key pocket to start the car which is nice. I know the 2015 MB has this.
-The down side with the eGolf is if you open the door and do not move in certain time it shuts off the car even if I leave the key in the car. Drives my wife crazy as she wants the radio and air on.....an it can't be restarted from the passenger seat. (At least not easily.)
-The MB is faster and has better range than the eGolf.


We bought the eGolf as mainly my wife's car. She has a business with short drives where she is parking in tight spaces etc. For this it is better suited.

So I guess reading the above they both have their pluses and minuses. The MB is bigger and more substantial to justify it's higher price.

Tony-

 

[pavan]

Thanks for the all replies. I ended up getting a portable battery with jump start capability that I can also use to recharge my phone. Glad to hear that the B class can be used safely to jump start another car.

 

[Electrons]

I have successfully used my B-class to jump start a regular ICE car without any problems.

 

[evnewbie]

Guys, I am an electrical engineer and worked in the auto industry for 15 years.

No risk here. Just be sure the B-class is "ON" so it does not completely drain the 12 volt battery. The HV battery will recharge the 12V. There is an onboard charger the keeps the 12V battery charged from the HV battery like the alternator on a regular car. Think of the other car you are charging as just an additional load on this battery, just like if you turned on your radio or lights. Of course, get the polarity correct! Red on Red, Black on Black.

I did many times with my Focus Electric when my Honda battery/alternator was giving me issues.

Don't worry about draining the HV battery either as a typical 12 battery has a few hundred watts of capacity. Nothing close to the capacity of the HV battery.

I will also add you can do the opposite. Use another car to jump the MB. Did this with the Focus Electric as well. It turned out to have a bad 12 volt battery. It had sat on the dealer lot for a long time before I purchased so I guess it was discharged completely which is not good the life of lead acid batteries. The dealer replaced after it went dead on me 2x. Yes the car would not "start"!

I think the 12V battery will stay on electric cars for a long time, if not forever. It allows the use of all the ICE developed components (radio, lights, instruments) and avoids the risk of high voltage in the passenger compartment. It is the bridge to the dinosaur cars. Tesla has one so this should make it clear it is here to stay.

Any idea on the amperage of the DC/DC converter in MB used to charge the 12v battery from the HV battery? I am wondering what size DC/AC inverter (e.g. Xantrex PROwatt) I can connect to the 12v battery.

 

[wtzouris]

I think BMW i3 owners have issues with their 12v battery lasting past the 2-year mark. It's usually under warranty but it completely disables the car. I guess some folks either don't drive a lot or let the HV battery get completely drained before charging -- that's gotta hurt the 12v battery?

 

[TheStig]

Seems to me the B class has a very small 12v battery, the clicks and noises it makes even when off and not charging seem to be the high voltage battery being engaged to top off the charge on the 12v battery. Seems like all you have to do sometimes is open a door and a few seconds later it starts the 12v charger for a short time.

The high voltage to low voltage battery charger has to be big enough to run just about every non power train item in the car, so on par with the gas or diesel powered B class's alternator. Something like 75-100 amps maybe.

 

[wtzouris]

Has anyone seen the Mercedes 12v battery? Where is it? Can someone take a photo of the top of it? What is the size?

 

[JeffRay]

No gots.

 

[GlennD]

Has anyone seen the Mercedes 12v battery? Where is it? Can someone take a photo of the top of it? What is the size?

All you have to do is lift the hood. The battery is obvious.