Electric cars question

DrEskimo

coffeehound wrote: »

Interesting info, thanks. Does the battery not warm up overnight by the charging process?

Yes, but the BMS knows what the ambient temperature outside is. Essentially the car just monitors the efficiency of the car over the last few journeys and makes extrapolations on the range. It's no different to the 'miles left to refill' you get on the odometer for ICE.
Of course if you don't drive in the same manner and conditions as the previous journey's, the predictions will be out, but it gives a good estimate generally. Mine tends to underestimate.

For it to be an issue, you would need to be doing commutes that are the theoretical maximum range of the car, which would be a bit daft. Mine would be 180miles, so a 90mile commute there and 90mile commute back. You would certainly struggle to do this in winter, so would advise a longer range EV (or probably a different job...!).

scaredofdebt

AnotherJoe wrote: »

First of all, knocking somewhere between 2-8% isnt "decimating the range"

It is in the historical sense of the word.

But yes, I've certainly heard at worst you'll lose 30% of the range, in sub-zero temperatures. Usual cold winter weather is about 10% or so range reduction.

You wonder if heating the battery would help but I'm sure they've thought of that.

almillar

Let's agree to differ then,

You're arguing, or agreeing to differ, over 2 sets of advice.

1. Don't store Li-Ion batteries for a long period at full or empty.

2. Do charge a car to '100%' the odd time, to help keep the cells balanced, and keep the BMS calibrated.

Come 6pm, the car has been sat out in the wintry showers all day. The battery has chilled down and now lost x many miles of range and you haven't enough to get home.

Yes, there absolutely is, and I've experience range going up and down, whilst sat still, plenty. The BMS will smooth it out a bit but it's a simple fact that a car sat at 10 degrees C can go further than one at 0 degrees C. I would imagine I haven't seen more than a 10% change.

Interesting info, thanks. Does the battery not warm up overnight by the charging process?

Batteries do warm up whilst charging/driving, but unless you've set a timer, your car could be charged in the middle of the night. And at home you're likely only charging at 7kW, which wouldn't really trouble the battery.

Yes I was just throwing it out there as a possible though unlikely scenario, really. I suppose it's something the app or internet-enabled car could forecast.

It's the kind of scenario, that if the worst happened, would be solved by driving at 60mph instead of 70.

You wonder if heating the battery would help but I'm sure they've thought of that.

They sure have. Plenty of new things coming through but even my Soul EV shares the cabin and battery air. Since humans and batteries like 20 degrees C, it's useful. Liquid cooling/heating, and more agressive management, like using power to heat the battery, to get it to a good temperature, will be made to work, if not already.
You can do it yourself too. Do a few sets of harsh acceleration before charging, and you'll get that time/energy back in the faster charging due to the battery being warmer!!

wongataa

coffeehound wrote: »

^ Good grief, the loom on EVs must be hellish complex.

The looms on modern ICE cars are complex. EV is no different really, they just have an extra on for the drivetrain.

NigeWick

scaredofdebt wrote: »

I've certainly heard at worst you'll lose 30% of the range, in sub-zero temperatures. Usual cold winter weather is about 10% or so range reduction.

My Hyundai Kona will use about 2% in below freezing weather with the heating & aircon on. That's 4 miles out of a bit over 200 at 70mph in 28F temperature. There was frost on the bonnet when I got home as there were freezing fog patches en route.

NigeWick

wongataa wrote: »

The looms on modern ICE cars are complex. EV is no different really, they just have an extra on for the drivetrain.

The Tesla Model Y will have a far simpler loom.

50Twuncle

No matter what anyone says - there is always going to be a fear of running out of juice on a long journey with nowhere to refill - unlike petrol !
And how long does a 75% refill take ?

Car_54

almillar wrote: »

Do a few sets of harsh acceleration before charging, and you'll get that time/energy back in the faster charging due to the battery being warmer!!

Just what we need on the icy roads on a winter morning: loads of EV drivers accelerating harshly.;)

ElefantEd

50Twuncle wrote: »

No matter what anyone says - there is always going to be a fear of running out of juice on a long journey with nowhere to refill - unlike petrol !
And how long does a 75% refill take ?

Except there are plenty of places to refill - just like petrol!


You can easily get another 50 miles of range in 20 mins or so (depending on the charger and your car). Which is longer than it takes to fill up with petrol, sure, but not unreasonable if you need a break anyway.

AnotherJoe

50Twuncle wrote: »

No matter what anyone says - there is always going to be a fear of running out of juice on a long journey with nowhere to refill - unlike petrol !
And how long does a 75% refill take ?

Why would you wait until you needed 75%? This is Petrol thinking.
I'm currently waiting at Gatwick to pick someone up. My car last night was at 60% so I plugged in overnight and left this morning at 100% or so. I don't know what it is now but if I was so inclined, in the time I am waiting I could have it charging and get back to 100%.
Yes it's slightly more inconvenient to plan but then I'm paying the equivalent of 25p a litre Petrol prices so that's a fair trade plus I never have to visit a Petrol station except to buy a Ginsters.