Jump to content

Custom Search

Welcome to the Ford C-MAX Energi Forum

Sign In  Log in with Facebook

Create Account
Welcome to the Ford C-MAX Energi Forum. You must register to create topics or post in our community - but don't worry this is a simple free process that requires minimal information for you to signup. Be apart of Ford C-MAX Energi Forum by signing in or creating an account.
  • Start new topics and reply to others
  • Subscribe to topics and forums to get email updates
  • Get your own profile page and make new friends
  • Send personal messages to other members
  • Create a photo album and post images. . .more.
Click here to create an account now.
Guest Message by DevFuse

Get you C-MAX Energi Registered in the official Ford Authorized Registry. More here.

- - - - -

Jump-starting another vehicle


  • Please log in to reply
2 replies to this topic

#1 OFFLINE   stolenmoment


    New Member

  • C-MAX Energi Member
  • Pip
  • 346 posts
  • Region:U.S. Northeast
  • LocationBoston
  • My C-MAX:2013
  • Current Vehicle:Maxwell Smart

Posted 07 December 2018 - 07:16 AM

Yesterday I learned something that I should have already known: you have to turn on the CMax before you jump-start another car!


My son's Subaru's battery wouldn't start it, so we cabled up my CMax Energi via the 12v posts under the hood, and it would crank once or twice and stop.  It took me three tries to remember that the CMax battery is indeed not hefty enough to start an ICE, so I reached in, pushed the Start button, and once my 12v had the HVB to back it up, his car cranked immediately.


Like I said, I should've expected that behavior!  I just hope I didn't shorten my relatively new 12v battery's life...

Lose this advertisement by becoming a member. Click here to create a free account.

#2 OFFLINE   rbort


    Energi Member

  • C-MAX Energi Member
  • PipPip
  • 4,280 posts
  • Region:U.S. Northeast
  • LocationFranklin, MA
  • My C-MAX:2017
  • Current Vehicle:Cmax Energi Titanium with Moonroof

Posted 07 December 2018 - 07:33 AM

I just hope I didn't shorten my relatively new 12v battery's life...


No you didn't but I've told my friend before with a Cmax probably not the best idea to use the Cmax to jump start other cars, because of the small 12v battery, but like you said, once powered up then you get the help of the DC to DC charger that maintains the 12v battery and runs off of the 340v battery.



#3 OFFLINE   cr08


    New Member

  • C-MAX Energi Member
  • Pip
  • 246 posts
  • Region:U.S. Great Lakes
  • LocationColumbus, Ohio
  • My C-MAX:2013
  • Current Vehicle:2013 Ice Storm C-Max Energi

Posted 07 December 2018 - 09:21 AM

I also wouldn't recommend it mostly due to the expensive DC-DC converter. While it is probably a long shot of damaging it (due to stuff like reverse polarity or excessive draw) I'd rather not risk it personally. Additionally if memory serves the high amperage fuse for it was an absolute PITA or possibly expensive on its own to replace. This is especially relevant IMHO when cheap LiPo jump packs exist. I keep one in my car charged up at all times in case of emergencies. Stuffed in the storage compartment under the passenger seat. About once a month I take it out and top it off if it needs it. I'd much rather attempt using that first and if it doesn't do the job, jump off the C-Max as a last resort.


I believe Toyota for example with their Prius in some model years recommend not using it to jump start other vehicles in their owners manuals. Ford tends to be a little vague in theirs but seems to be more a dumb copy/paste job from other models than anything.

Edited by cr08, 07 December 2018 - 09:28 AM.

0 user(s) are reading this topic

0 members, 0 guests, 0 anonymous users

Privacy Policy TERMS OF SERVICE ·