Ask the EV Experts: To Plug or Not To Plug?
11.28.2016 - by John U'Ren
Ask the EV Experts: To Plug or Not To Plug?

Next up on our new series, Ask the EV Expert, we answer a question from Eileen in Connecticut. Have a question of your own? Post it on Facebook, Tweet at us or email us at info@pluginamerica.org #AskTheEVExpert

I’m leaving town for a few weeks, and I have three questions!

Question:

Should I leave my car unplugged while I’m gone or should I plug it in?

Answer:

This is a very common concern among electric car owners. It’s always suggested to consult your owner’s manual first, as different cars have different protocols. If you have a Chevy Volt, a Ford Energi, or a BMW i3, then yes, please do keep it plugged in while you’re away. For these vehicles, leaving the car plugged in allows for the battery’s thermal management system to function optimally. If you have a Nissan Leaf, it is suggested that you leave your car unplugged but adequately charged, as leaving the car plugged in for weeks on end may drain the car’s 12-volt battery (although the traction battery will be fine). Should this happen, no problem, just jump-start your Leaf like you would any other car. Tesla recommends that owners keep their cars plugged in but set for 50 percent charge.

Question:

Will leaving the car plugged in or unplugged for several weeks hurt the battery?

Answer:

No, it will not do any damage to your battery. Definitely do follow the instructions in your owner’s manual, but know that modern electric car batteries are very sophisticated and very robust, and leaving them plugged in or unplugged for several weeks likely won’t do any damage.

Question:

Does it cost me anything extra on my electric bill to keep my car plugged in for a few weeks while I’m away?

Answer:

Assuming that your car is designed to be plugged in while you’re away, the cost will likely be miniscule. Once the battery is full or charges to the preset level, the car will only draw more power if needed; it won’t be continuously charging the car for weeks on end.

6 comments on “Ask the EV Experts: To Plug or Not To Plug?”
  1. B Stacks says:

    Just got a new C-Max Energi. No one reviewed with me the basics of don’t plug in the car first and then plug to the wall, although the first few times I did that without problem. The last time I did plug it in the plug on the house needed to be “reset” so I pulled the plug out reset it and started to plug it back in. It sparked loudly and flashed burned one of the prongs on the cars cord. I dropped it quickly.

    What I want to know, is did this damage the car or the car battery in ANY way ? Secondly, since one prong of the plug is scorched, do I have to buy a new cord to charge the car???

    The cord is the one that comes with the car. It’s called the confidence cord and it plugs into a regular house hold current, with a three prong plug. It takes 7 of so hours to charge at the lower current.

    By the way, this blew a fuse on my house, that I had to replace.
    Before charging again, I’ll have an electrician verify the outlet on the house is okay. Our local Ford car dealership is not that knowledgeable and I just want some knowledgeable feedback on the car and the cord .

    Thankyou ,
    B Stacks

  2. Jorge says:

    I have a 500 Fiat e. Can I leave my car charger plug into the wall but not into the car? Will that increase my electric bill even though my charger is not plugged into my car?

    1. John U'Ren says:

      Hi Jorge,

      It will not increase your electric bill to leave the car charger plugged into the wall. In fact, this is how it is designed to function. The charger only draws power when it is plugged into the car and the wall. Do be sure to always unplug the charger from the car first.

  3. Howard Conant says:

    Is an EV suitable for one who must leave a vehicle in the garage for 3 or 4 months a year? Are certain makes more ir less suitable? Thanks!

  4. Leondro Duran says:

    I have a 2017 Chevy volt half gas half electric will it charge when the the car is started

  5. Daniel Watkins says:

    Actually, the car may draw power endlessly if in extreme temperatures if you leave it plugged in.
    The last point of the video of the car increasing the electric bill by leaving it plugged in, I think you should have gone into detail about the thermal management system.

    But the battery should be fine with higher temperatures if you drain your Volt, Leaf, Tesla, etc to 50% charge. Colder temperatures shouldn’t damage the battery, will only impact how well the car starts up

    and drives cold soaked.

    So to all cars listed, leaving them at a partial charge unplugged for a few weeks is probably the most efficient method, and battery longevity shouldn’t be concerned unless u are expecting some crazy

    temperatures.

    Partial charge vs full charge, lessens the longevity impact from increased temperatures.

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