Chevy Bolt EV Forum banner

1 - 11 of 11 Posts

·
Registered
Joined
·
322 Posts
Discussion Starter #1 (Edited)
When I gave my sister her first ride in an EV, the battery was low and naturally we talked about range. I plugged my smartphone into the 12v USB charger I have in the car, since the phone was low as well. My sister questioned if that was a good idea since the car was so low and she didn't want us to get stranded. I was dumbfounded with her concern as the battery sizes are about three orders of magnitude different.

My sister's lack of perspective and experience with EVs is representative of the average consumer's. So here's my Public Service Announcement about charging your smartphone with your car.

First and foremost, EV batteries are HUGH compared to anything with which the average person has experience. The Bolt EV has a 60,000 Wh battery. A typical smartphone battery is about 11 Wh. The EV battery stores about 5,500x more energy than the phone's!

How much will charging the phone reduce the EV range? Not enough to care, but we can calculate it! Assuming an hour long drive in an EV with 4 mi/Wh efficiency, the car's drivetrain will use about 15,000 Wh. A 2.4A charger in the car will fully recharge a phone during that trip using about 11 Wh, ignoring conversion losses. The phone consumes 0.07% of the EV battery. That's equivalent to less than 250 ft of driving distance.

There are a number of factors that affect EV range that drivers should consider; such as temperature, winds, elevation changes, and driving style; but phone charging is not one of them. Charging a phone for an entire trip uses far less energy than a single, mildly-spirited, 50-Wh acceleration away from a stoplight.
 

·
Registered
Joined
·
1,486 Posts
:D Thanks for the public message. I assume people who don't know the difference between a car battery and the one in their phone have never actually taken a look at the average car battery in non electric vehicles. Those things are pretty big and that's just one of them.
 

·
Registered
Joined
·
639 Posts
:D Thanks for the public message. I assume people who don't know the difference between a car battery and the one in their phone have never actually taken a look at the average car battery in non electric vehicles. Those things are pretty big and that's just one of them.
Good reason for going to auto shows and looking for those half cut models and typically during the busy days they have people their to answer questions.

Then of course there's what you can find online, Media portals that car makers make available publically.
 

·
Registered
Joined
·
1,486 Posts
Don't need to go to auto shows for those, just the local car store with car batteries for sale. I had to grab one when the old battery in my car died.
 

·
Registered
Joined
·
39 Posts
Seems common sense that the car batteries are way bigger than the smartphone batteries. Obviously it takes more power to move the car physically than it does to light up a screen and send signals. Having said that, I would be generally careful to not overuse the battery in the car because it will drain the battery quicker. Phone charging, plus A/C, etc... Those things will add up.
 

·
Registered
Joined
·
322 Posts
Discussion Starter #7
Phone charging, plus A/C, etc... Those things will add up.
True it adds up. But some things draw so little power compared to others that it's not worth fretting over. Phone charging is one of those, as is using the radio and even headlights.

The heavy hitters for battery usage, besides propelling the car, are resistive elements heating air in the cabin (like a hair dryer) in the winter or the A/C in the summer. We don't know yet whether the Bolt with have a resistive heater. The Spark EV does have resistive heaters and it uses about 2-3x the energy as the A/C, depending on temperature of course.

The bottomline is that besides climate control the other battery drains are basically in the noise with respect to affecting available range.
 

·
Registered
Joined
·
1,486 Posts
Ouch. Didn't know the heat and ac element drew so much power from the battery, especially the heat and where I live, you're going to need it for around half the year. Doesn't GM have a more energy efficient heating system?
 

·
Registered
Joined
·
322 Posts
Discussion Starter #9
Ah, things they don't say in the brochure! EV driving is quite different than ICE or PHEV. There's always plenty of excess heat with an ICE. The EV efficiency means there's no excess heat energy to put into the cabin.

Preheating while pulled in yields a big savings in battery usage. I do it daily through the winter whenever it's below 50 deg or so. If you're not careful, climate control can take as much as 10-20% of the battery or more. For me, it's rarely above 5%.
 

·
Registered
Joined
·
1,486 Posts
Would a seat warmer be more efficient in terms of draining your battery or is it around the same? A way to conserve battery while you're on the road after warming up the car while plugged in.
 

·
Registered
Joined
·
322 Posts
Discussion Starter #11
Yes, absolutely. That's why all BEVs have seat heaters, sometimes for the rear seats and steering wheel too. The small resistive elements in the seats require much less power than heating all the air in the cabin.

This is EV 101 kind of stuff, so your question is indicative of the challenge to educate the public on how EVs work and how they're different than ICE vehicles. Most people won't find internet forums to seek out information like you have!
 
1 - 11 of 11 Posts
Top