I have a question for you experts.

G

Gregg Wilson

New Member
For my cell phone I can get a battery pack. I leave home with it charged and if my cell battery is getting low I plug it into the USB port and whamo, I am good for a few more hours. Why doesn't this work for EVs. Say I have an EV and at one end is the motor and a traditional battery pack under the floor boards with a 75 mile range and all the drive hook ups for recharging from braking etc. At the other end of the vehicle I have a second battery pack in an accessable location to make it replaceable and its only purpose is providing charge to the drive pack and it adds another 150 to 200 miles to the range. When I am not going on any road trips I leave the replaceable pack at the local swap station (the bugger is heavy) and drive around without the added weight burden. When I go on a road trip I take it home and charge it up, and then stop at the swap stations along the way to get to Florida. The replaceable battery is owned by the swap company and in exchange for paying their exorbidant usage and charge fees I don't have to pay for all that range up front when I buy the car. So what's wrong with this scenario?
 
1. How much does a portable cell phone pack weigh versus a car battery pack?
2. What's the voltage and current capacity of the portable cell phone battery pack versus a car battery?

So right there you have two problems, both of which can kill or cause permanently injury. So now you need specialized employees with the skill to handle these issues. Plus you need equipment, including a possible need for a building to do the work in.

3. You are assuming that swapping batteries takes less time then charging them. With a liquid cooled battery, you have to deal with the liquid coolant in the battery too. Do you have to drain coolant out of a portable cell phone battery pack?
 
There have been at least two battery attempts and both have failed. Tesla tried it in California and there was an Israeli attempt. But there is an approach that makes sense, battery or range extender engine-generator.

Bob Wilson
 
bwilson4web said:
There have been at least two battery attempts and both have failed. Tesla tried it in California and there was an Israeli attempt. But there is an approach that makes sense, battery or range extender engine-generator.

Bob Wilson
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I would think noise would be an issue with gas engine-generators, especially at the RPM where the gas engine is most efficient. We see folks complaining about it in the Honda Clarity. Didn't Munro mention that he wasn't impressed with the noise in the BMW toward the end of the Tesla interview?

The good news is that most folks will be able to do the majority of their driving using the traction battery. So they may be able to overlook the noise of the gas engine when it's needed.
 
Gregg Wilson said:
The replaceable battery is owned by the swap company and in exchange for paying their exorbidant usage and charge fees I don't have to pay for all that range up front when I buy the car. So what's wrong with this scenario?
Click to expand...

1. The auxiliary battery pack would need a cooling system, just like the main pack does... otherwise you get premature battery aging, as in the Leaf. That means the auxiliary pack's cooling system needs to plug the cooling system into the main pack, which creates problems with possible leaks, and also means that the main pack needs to have a beefed-up cooling system to handle the extra heat when the auxiliary pack is plugged in. I note that Rivian has a patent to do exactly that, and I've been told that a Rivian rep said they actually plan to put that option into production. We'll have to wait and see if that really happens, and if they do, how well it works. Personally, I take that claim with a pinch of salt.

2. Any auxiliary pack large enough to have much capacity means the car has to be made larger to allow space for it. Larger cars cost more money to make. Putting in a heavy auxiliary pack will also alter the front/rear weight ratio of the car, which may cause other problems.

3. Picking up an auxiliary pack at a "swap station" would be like visiting U-Haul every time you need a trailer. People who only use a trailer (or rent a moving van) for moving, can and do use U-Haul. But those who use a trailer frequently buy their own, because visiting U-Haul every time is inconvenient and expensive. It would be the same for an auxiliary battery pack. It may make sense to visit a special store to rent one if you only need it once a year or so, but if you use it more frequently, then probably better to buy it and keep it.

* * * * *

Now, having said all that... I don't see it as being impossible that we will see one or another EV maker trying out such a scheme. But you asked why we haven't seen it happen yet, and I think I've explained the various reasons why.
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bwilson4web said:
There have been at least two battery attempts and both have failed. Tesla tried it in California and there was an Israeli attempt. But there is an approach that makes sense, battery or range extender engine-generator.

Bob Wilson
Click to expand...

Hmmm, that’s exactly what I drive. Honda Clarity. Small engine will kick in when needed or wanted. Total range 350 miles. Cost? $27K after $7500 tax credit (which I just received, thank you).

One year in, 13560 miles; total of 51 gallons of gas used. The rest all electric.


Sent from my iPad using Inside EVs
 
Would some of these problems go away if it were not an "auxiliary" pack but more like two "main" packs with one of them easily replaceable? The two packs would combine for a good total range, and the weight distribution of the car would never change because both packs would always be present. Would the two separate packs weigh more than if they were combined?
I agree that the application would only really be used for extended road trips and the swap stations would be located along those routes. Even if the replaceable pack were good for say only 200 miles, wouldn't that be a lot better than twiddling your thumbs waiting hours to recharge when you're trying to get to Florida tonight.
 
Why do you think it would take hours to charge? Connect the car to a DC fast charger! Road trips are why they are being installed.

Go look at some videos are removing these car batteries. They are big, heavy, take time to remove and reinstall, and need special lifts, not to mention training so you don't electrocute yourself.

 
It looks as though Rivian may be planning an auxiliary battery pack along these lines, according to a patent application they've recently filed:

http://www.thedrive.com/tech/26595/...e-auxiliary-battery-to-extend-range-on-demand

"The patent application, originally uncovered by the staff at Rivian Forums, is titled "Electric Vehicle With Modular Removable Auxiliary Battery With Integrated Cooling" and describes removable battery packs which can be stored in the bed of a pickup truck. Auxiliary connectors for coolant and power are said to be made available from the rear of the truck's cab in order to properly utilize the extra cells in the packs."​
 
marshall said:
Why do you think it would take hours to charge? Connect the car to a DC fast charger! Road trips are why they are being installed.

Go look at some videos are removing these car batteries. They are big, heavy, take time to remove and reinstall, and need special lifts, not to mention training so you don't electrocute yourself.
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Right. A battery pack capable of replacing the regular battery will be heavy. So unless you have some automation you cannot do it quickly. Again, other than a Tesla, I do not know if the other cars are capable of quick swap (all the other EVs). And even if they were, every car would need a different type of equipment, so you have to have dedicated swap stations and there are no economies of scale. If it was in one center they would have to have many different battery packs in inventory.

The other issue is let us say I have a brand new car and I swap my current battery for a older one with less warranty. What happens to my original warranty. To get around this I may have to lease the battery and pay a battery charge every month.

Hence the focus is on quicker charging rather swaps due to the logistic problems. Here is an article on Tesla's attempt to do so.

https://www.teslarati.com/tesla-shuts-down-battery-swap-program-for-superchargers/Battery
 
interestedinEV said:
The other issue is let us say I have a brand new car and I swap my current battery for a older one with less warranty. What happens to my original warranty. To get around this I may have to lease the battery and pay a battery charge every month.
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Yes, and I think this is one of the biggest reasons why Tesla's Model S battery swapping experiment generated so little interest among Tesla car owners. If you buy an expensive battery pack then you're gonna want to keep it, and not exchange it for another which some anonymous stranger may have misused.

Battery swapping will only be a viable economic scheme if the battery is leased or rented, not owned. In fact, in Taiwan there is a successful battery swapping business. But it's for electric scooters, not cars, and the battery pack is light enough that the average renter can easily swap out packs by hand at one of their "Swap & Go" stations, and/or carry the pack up to his/her apartment for overnight charging.

"Yamaha and Gogoro join forces to build new battery-swapping electric scooters"
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