Volvo XC40 Forum banner
1 - 16 of 16 Posts

·
Registered
2021 XC40 Recharge
Joined
·
7 Posts
Discussion Starter · #1 ·
I've had my XC40 Recharge for one month and, like some of you, already went through the minor ordeal of having a defective infotainment head unit replaced during week two. Other than that, things have been generally good with the vehicle.

I hope this isn't a silly question: Since everything electrical in the car draws down the battery, I was wondering if there's any appreciable impact on range by charging one's cell phone while driving. Out of habit, I was charging my phone anytime I drove (regardless of how charged the phone was), but I started to think about how much power this was taking. I'm not an electrician or electrical engineer, so any feedback from better educated forum members would be appreciated.
 

·
Registered
2015 X1, 2017 BRZ
Joined
·
137 Posts
Doing some rough math, I'd guess a phone today with a large battery is going to be around .015 kWh to fully charge, which is about 00.02% of your car's 78kWh battery.
 

·
Registered
Joined
·
160 Posts
Yeah I wouldn't be too worried about it. I did some back of the envelop calculations in the other direction (going from kWh for the car battery to mAh of your phone).

A 78 kWH 396 V XC40 Recharge battery holds a charge of about 197,000 mAh.
Your phone probably hold a charge of about 2,000–4,000 mAh.

So my numbers are different from @improvius by a couple orders of magnitude, but are still small enough that I wouldn't fret over it.

I think that charging a phone with a huge capacity battery from 0–100% could take about 1–2% of your car's charge. Measurable but not a huge factor. The pitch of the road and the direction of the wind would dwarf the effect.
 

·
Registered
2015 X1, 2017 BRZ
Joined
·
137 Posts
Yeah I wouldn't be too worried about it. I did some back of the envelop calculations in the other direction (going from kWh for the car battery to mAh of your phone).

A 78 kWH 396 V XC40 Recharge battery holds a charge of about 197,000 mAh.
Your phone probably hold a charge of about 2,000–4,000 mAh.

So my numbers are different from @improvius by a couple orders of magnitude, but are still small enough that I wouldn't fret over it.

I think that charging a phone with a huge capacity battery from 0–100% could take about 1–2% of your car's charge. Measurable but not a huge factor. The pitch of the road and the direction of the wind would dwarf the effect.
I could be totally wrong, but I think maybe you're not adjusting for the voltage difference.
 

·
Registered
2021 XC40 Recharge
Joined
·
154 Posts
I think maybe you're not adjusting for the voltage difference.
I agree, the phone battery has 2 orders of magnitude less voltage.

Maybe, it's easier to see it compared by watt-hours:
  • Car battery: 78,000 Wh
  • Phone battery: 14.8 Wh (4Ah * 3.7V nominal)
14.8 / 78,000 is about 0.02%
 
  • Like
Reactions: improvius

·
Registered
Joined
·
160 Posts
I could be totally wrong, but I think maybe you're not adjusting for the voltage difference.
Oh I think you're right. I was thinking about the voltage of the XC40's battery at 396 V, but not the voltage it was delivering through the USB port (5 V?). At first glance it seemed to make sense because I had in mind 1–2% of car battery to charge a phone up completely...but of course, that's a battery in a lowly ICE car.

With that in mind, your numbers seem spot on. I guess the 12 V battery is powering the USB port and the traction battery is keeping the 12 V going? Maybe a touch above 0.02% of the vehicle's capacity to account for a bit of voltage loss.


1247
 
  • Like
Reactions: improvius

·
Registered
Joined
·
160 Posts
Listen to @improvius and @JT Rock, they have it right.
Charging your phone is probably about as much impact on range as driving through a swarm of mosquitoes.
 
  • Like
Reactions: improvius

·
Registered
Joined
·
1,674 Posts
Listen to @improvius and @JT Rock, they have it right.
Charging your phone is probably about as much impact on range as driving through a swarm of mosquitoes.
How could you even think of driving your car through a swarm of mosquitoes.

My car over heard you saying that and thinks it’s a thing now and is considering what sub system she is going to have have fail so she can stay in the garage nice and safe.

I am going to have to coax her out with a nice ha d wash and wax to get her over this swarm of bug guts!! (I am joking of course)
 
  • Like
Reactions: Mereoshop

·
Registered
Joined
·
428 Posts
A 78 kWH 396 V XC40 Recharge battery holds a charge of about 197,000 mAh.
Your phone probably hold a charge of about 2,000–4,000 mAh.
EDIT: never mind - I think the post above with the voltage correction may be more correct.

Sounds correct to me:
XC40 battery capacity = 78,000 Watt-Hours / 396 Volts = 197 Amp-Hours = 197,000 milli-Amp-Hours.
iPhone 12 Pro Max capacity = 3687 milli-Amp-Hours
or, about 1.9% of car's battery capacity.

Don't know for sure - but I'd expect that inductive phone charging wastes some energy as heat or something. Plus there's probably some loss converting from 396V to the 12V DC electronic system in the car. So I'd guess charging a big iPhone might use a bit more than 2% of the car's reserves.
 

·
Registered
Joined
·
91 Posts
I love the math in this, you guys are proper nerds and I love that. You are very correct, charging a phone is negligible, your cabin fan burns more energy far quicker.
 

·
Registered
2021 XC40 Recharge
Joined
·
7 Posts
Discussion Starter · #11 ·
Oh I think you're right. I was thinking about the voltage of the XC40's battery at 396 V, but not the voltage it was delivering through the USB port (5 V?). At first glance it seemed to make sense because I had in mind 1–2% of car battery to charge a phone up completely...but of course, that's a battery in a lowly ICE car.

With that in mind, your numbers seem spot on. I guess the 12 V battery is powering the USB port and the traction battery is keeping the 12 V going? Maybe a touch above 0.02% of the vehicle's capacity to account for a bit of voltage loss.


View attachment 1247
Thanks for the information (and math)!
 

·
Registered
Joined
·
31 Posts
Forums for other (much lower range) EVs I've had always have questions like this. Should I turn my radio down? Should I stay cold/warm to increase range? Should I leave the wipers off in the rain? Should I switch the lights off in the dark?!!!
Moving a car takes a lot of energy - ever tried pushing one? The only things that will even make the slightest dent in the (noticeable) range is the air con, and if you're addicted to it, the rear heated windscreen.
But if you're really worried about range, put down that burger, check the tyre pressures, check the weight of your clothing, and give the car a good tidy.
 

·
Registered
Joined
·
31 Posts
Basically, go on a diet, go to the toilet, make sure your tyre/tire pressures are right, wear less clothing, and carry less stuff in the car, all to save weight, which will make more difference than charging your phone or not.
 

·
Registered
2021 volvo xc40 recharge
Joined
·
17 Posts
How could you even think of driving your car through a swarm of mosquitoes.

My car over heard you saying that and thinks it’s a thing now and is considering what sub system she is going to have have fail so she can stay in the garage nice and safe.

I am going to have to coax her out with a nice ha d wash and wax to get her over this swarm of bug guts!! (I am joking of course)
Mine farted just hearing the mention
of a swarm of mosquitoes 🦟
 
1 - 16 of 16 Posts
Top