Roadside Assistance

[vfx]

Someone recently pointed out the issue of roadside assistance. What is harder (or easier) to get the fuel-starved stranded motorist going again to a local fueling station?

A gallon of gasoline dumped into a tank.

A generator charge of 20 minutes.

A high compression fill of hydrogen.

 

[WarpedOne]

Answer: A high compression fill of hydrogen.

The other day I was thinking of this stranding problem and came to an idea: a reserve battery. Every BEV would have a common format emergency/reserve battery of standard voltage. This battery would be easily replacable and interchangable and not heavier than 50 pounds.
If you forget to charge your BEV and got stuck somewhere, a fellow BEVer could interchange his full emergency battery with your empty one, thus giving you a few miles of "service range" i.e. helping you get to nearest electric plug.

Unfortunately this idea has same problems as "battery swapping station" does.

 

[BBHighway]

I think I've run out of fuel twice in my entire life. The first time I was one of those young folk who are often not very careful about such things, and the second time the all-nite, 24-7 gas station that never-ever closes was closed about 3 am.

This happens so rarely that I don't think it's a good criteria to decide how our transportation system should be structured.

Even if both of those occurrences had required the car to be towed, consider that over my lifetime I have had to have cars towed at least a dozen times due to breakdowns with my ICE or it's many related components. Broken exhaust, starters, timing belts, camshafts, coolant hoses, carburetors, and many more have all left me stranded and calling for the tow truck.

Worst case is the BEV has to be towed, and even that still puts it ahead of the ICE!

 

[vfx]

The other day I was thinking of this stranding problem and came to an idea: a reserve battery.

This has been discussed before (don't know if there is a thread). A backpack style Refill battery.

Another idea.
If your rescue vehicle is an EV, why not be able to plug the charged one into the dead one? You have a screen that let's you set the amount of transfer charge and while you play cards the charging dings when done.

 

[JRP3]

It would take some really bad planning to run out of juice in an EV. Every car should have a warning system and be setup with a reserve in the pack, this helps preserve the life of the battery and leaves you with some emergency range, especially at reduced speed, which should allow you to get to a plug. If you're taking an EV out in the middle of nowhere and running out of charge then you get towed.

 

[vfx]

If you're taking an EV out in the middle of nowhere and running out of charge then you get towed.

Let's rewrite that sentence.

If you're taking an EV out in the middle of nowhere and running out of charge then you should get _______.

 

[ChargeIt!]

"your head examined" ?

 

[EVnut]

Someone recently pointed out the issue of roadside assistance. What is harder (or easier) to get the fuel-starved stranded motorist going again to a local fueling station?

A gallon of gasoline dumped into a tank.

A generator charge of 20 minutes.

A high compression fill of hydrogen.

But these aren't even the correct questions. Why does the EV take 20 minutes to charge from a generator? Is this some sort of fixed time to get an EV moving again? Must an EV be charged at all to move again? Should we not ask which takes longer?

* A 20 minute battery charge
* A 30 minute hydrogen fill
* A 1 hour fill of gasoline through a straw



Seriously now... of the three technolgies listed here, an EV is the only one that can "self rescue." All this talk about a reserve battery is a bit silly. If you want a reserve, just have the software cut you off before the battery is really dead. Then you press a button and you get another 20 miles of "reserve." Or... just keep an eye on the SOC meter and don't be silly.

And even without that wonderful "reserve" technology (like in the EVs I've owned) you can STILL self-rescue in any battery vehicle. I can drive until the car won't move. I can shut the car off and sit for five minutes. I can start the car back up and drive several miles. I can do this a few times. All battery chemistries that we know of have some recovery when they rest. I've self-rescued in two cars this way, and have never been stranded. (and in my defence I WAS paying attention to the meter, and my meter was off - way off - like 32% off!)

What is silly to me is how many people think that running out of fuel is the only way to get stuck in a car. What if something on your ICE vehicle breaks? The timing chain? A valve? You know - the stuff that has no meter on the dash, and you can't really control when it fails. What do you do then? Well, you call a tow truck of course. But if you run out of battery charge in an EV...well, that's just a show stopper. I mean there's NOTHING you can do! EEEKKK!

 

[johnr]

A jump-start! You're stuck in the middle of nowhere in your electric car that ran out of juice. A friendly motorist stops to help. Fortunately he's driving an electric car as well. So out comes the jumper cables. A few minutes later, he's recharged your car's batteries sufficiently to get you to the fast-charge station a few miles down the road ... and he lost a few miles in the process but he still has enough charge to get to his destination. :smile: Of course this scenario isn't realistic until electric cars become commonplace...but I just had to bring it up anyway...

 

[JRP3]

I can shut the car off and sit for five minutes. I can start the car back up and drive several miles. I can do this a few times. All battery chemistries that we know of have some recovery when they rest. I've self-rescued in two cars this way, and have never been stranded.

That sounds like a good way to permanently damage a battery, especially with lithium.

What is silly to me is how many people think that running out of fuel is the only way to get stuck in a car. What if something on your ICE vehicle breaks? The timing chain? A valve? You know - the stuff that has no meter on the dash, and you can't really control when it fails. What do you do then? Well, you call a tow truck of course. But if you run out of battery charge in an EV...well, that's just a show stopper. I mean there's NOTHING you can do! EEEKKK!

I agree that the running out of charge fear isn't as big of a concern as it's made out to be. Reserve capacity and a "limp" mode should be built into every EV.

 

[Kevin Harney]

Besides doesn't the Roadster have a reserve in a sense. When you drive on Normal driving it only depletes the battery to like 20% right ? And then could you switch to Max range and still use that 20% right ? if necessary ?!?!?!?

That waiting and restarting is a good thing to know - JUST IN CASE.

 

[donauker]

That waiting and restarting is a good thing to know - JUST IN CASE.

You may find the opposite to be true in the Roadster. There was a post in the owners forum about an owner returning home while using range mode with very little range left and due to the fact that there were some cars in the driveway he parked along the street. Upon returning to the Roadster to move it into the drive he found that it would not allow any further movement and had to be pushed into the drive.

I have also noticed a drop from 38 miles remaining to 22 miles remaining after parking my car and about an hour later starting it.

 

[Kevin Harney]

15 miles can be significant especially if you are limping home in the first place or trying to squeak out the last couple miles to your destination.

 

[graham]

When you drive on Normal driving it only depletes the battery to like 20% right ? And then could you switch to Max range and still use that 20% right ?

To be picky, this is not 100% right, although it is an easy misunderstanding. "Range" mode does only use 80% of the battery, but it does by only charging to 90%, and only discharging to 10%. So it is true that 20% of the battery is not used in Range mode - but when you are empty in Standard mode, switching to Range will only get you 10% more.

Your overall point is accurate, though. Switching from Standard to Range in essence gives a driver an emergency reserve.

 

[Kevin Harney]

Thanks for being picky. I really was not sure as to the details of the charge and discharge states and it is good to have some accuracy here !!! Thanks.

 

[JRP3]

You may find the opposite to be true in the Roadster. There was a post in the owners forum about an owner returning home while using range mode with very little range left and due to the fact that there were some cars in the driveway he parked along the street. Upon returning to the Roadster to move it into the drive he found that it would not allow any further movement and had to be pushed into the drive.

I have also noticed a drop from 38 miles remaining to 22 miles remaining after parking my car and about an hour later starting it.

That could be because the Roadster is still using power even when "off". Battery cooling and maybe some other stuff could continue to drain the pack.

 

[Tdave]

That could be because the Roadster is still using power even when "off". Battery cooling and maybe some other stuff could continue to drain the pack.

But not at anywhere close to 16 miles per hour. If that were true, the 120V charger couldn't keep up.

 

[WarpedOne]

That could be because the Roadster is still using power even when "off". Battery cooling and maybe some other stuff could continue to drain the pack.

That water pump stops when the charge drops below 50%. Newer firmware is supposed to stop it below 80%. There should be no discharging in "off" state when the battery is close to empty or damage is inevitable.

 

[TEG]

I think the Roadster keeps some computers running (like the battery pack monitoring systems) even when the key is out. So there would be some small amount of drain while the car is "off".

 

[JRP3]

Good points. I wonder what is happening then to drain so much energy from the battery while parked but not plugged in, and why does it only happen when the pack is low?