# Battery Swapping



## tommypress (Jul 20, 2016)

I was pretty excited when I read about battery swapping on this infographic https://www.autoloansolutions.ca/electric-vehicles-are-the-future/

When I checked on Google, I found out that the idea was dropped by Tesla.

Any idea why they did this?


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## Kevin Sharpe (Jul 4, 2011)

tommypress said:


> Any idea why they did this?


A Broken Place: The Spectacular Failure Of The Startup That Was Going To Change The World...

https://www.fastcompany.com/3028159/a-broken-place-better-place

Musk: Tesla "unlikely" to pursue battery swapping stations...

http://www.roadandtrack.com/new-cars/car-technology/news/a25872/elon-musk-tesla-battery-swap/


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## tommypress (Jul 20, 2016)

Do you really think it was due to lack of demand? :/


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## Duncan (Dec 8, 2008)

Hi Tommy

There are costs/benefits

The "cost" is that you lose control of one of the most expensive and vulnerable parts of your car
This is a big deal - is the replacement battery any good?

Benefit
You can "recharge" a bit quicker
But in a Tesla you have just done 250 miles 
Four or five hours driving so a break for a quick meal is actually welcome 
A 20 minute stop at a Supercharger is about right
The "benefit" of only stopping for 5 minutes is really not worth very much


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## PStechPaul (May 1, 2012)

The "FastCompany" article was interesting regarding the viability of battery swapping technology. I think it might be more practical to have a cluster of smaller battery packs, perhaps 5 kWh, that can be connected in series or parallel as needed. At about 250 W-h/kg, a 5 kWh pack would weigh about 20 kg, or less than 50 pounds, which makes it possible for handling by one person. Each pack can have an internal battery usage and health monitor that can determine a trade-in cost or rebate on top of a price for the energy in a fully charged pack. 

My concept would be for each module to have perhaps 48 or 60 volts per pack, making them relatively safe when being handled, and they can also have internal protection circuitry to avoid overcharge or excessive discharge, and an internal disconnect so that any exposed terminals will be dead when removed from the vehicle of charger. There should be significant economy of scale with 8 or more packs per vehicle. And 8 packs would provide 40 kWh or about 160 miles of range. If you need less, you can buy 4 packs, and add more as needed. You might also be able to "rent" additional packs for a long drive, and then turn them in for a rebate afterward.


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## dougingraham (Jul 26, 2011)

tommypress said:


> When I checked on Google, I found out that the idea was dropped by Tesla.
> 
> Any idea why they did this?


Demand was too low for it to be practical. I have a Model S and in the last 9 months I have done just over 15000 miles. Two fairly long road trips (6000 miles) and the rest doing daily driving and weekend day trips. I would not have used the battery swap even if it had been available on any of the legs of my trips. On my road trips with the Tesla the longest I had to wait for a charge in order to get to the next supercharger was about 50 minutes. 20 to 30 minutes is much more typical. But I don't think I was ever just waiting for the car to get done charging. It was usually the other way around. The car had enough charge to get to the next supercharger before I was ready to go.

I could see a battery swap being practical for the long haul trucking industry. It would make sense there because the recharge times would tend to be longer. It could make a truck stop shorter than filling up with fuel is now.

The most common question I get asked these days is where do you charge it. Most are amazed when I tell them any 110 VAC outlet and that I charge it in my garage from a 110vac outlet almost exclusively.

The second most asked question is how long does it take to charge. And that question is harder to answer. Why is it harder? Because it depends on how far you just drove. But it is a question that almost doesn't matter because you charge the car when it is parked in your garage and you are not using it anyway.

The third most asked question is what do you do if you run out of charge. And the answer to that is if you run out it was due to bad planning, just like if you run out of gas in your car. It is harder to do in a Tesla because it will start nagging you when it knows you are going to run out. But the answer to what do you do if you run out is to find a 110 VAC outlet and plug it in. And there are a lot more of those than there are gas stations and usually a lot closer than a gas station. A 110VAC outlet is not a fast way to charge but it will do in a pinch. You get a little less than four miles per hour of recharging. So your bad planning and ignoring the car might cost you a couple of hours of sitting around in order to get to a higher speed outlet or EVSE.

Now imagine if they had not shut down the battery swap. It ended up taking about 15 minutes in the real world because of the shield that was added to protect the front of the battery from road debris. Imagine if you were third in line. It would take less time to just plug in at the supercharger. If it had been one of those things that saw a lot of traffic then they would have fixed it so you just pull into the stall and the machine would have changed it out and then you would pull out of the stall 90 seconds later. When did you find time in that two minutes to get out of the car and use the rest room and get a cup of coffee or soda? You just drove for two to three hours to get there and have another two to three hours after this. You would have to be in a terrible hurry for this to make sense. At some point you would have been better served taking a plane.

Best wishes!


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## PStechPaul (May 1, 2012)

Eventually, perhaps, most gas stations and service shops might have a truck containing lots of batteries charged up and ready to go. If someone in an EV runs out of charge, they could find the closest shop and have them drive to you to give you a high current quick charge, for a fee, of course. A 50 mile charge would be about 12 kW-h, so a 60 kW charge would be 10 minutes, or 170 amps at 350 VDC. Cost of grid power would be less than $2, and an EV owner would probably be glad to fork over $50 to get going again quickly.

This could also be a good "cottage industry", where anyone with an EV could be "on call" to deliver the recharge using their own EV. Just install an EVSE on the vehicle with an energy monitor meter like a fuel pump, calibrated in $/kW-h. Maybe a $10 delivery charge and $3/kW-h?


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## Moltenmetal (Mar 20, 2014)

Battery swapping was a bad idea- not fully thought out. It would only work if you don't own your own battery- if the oems owned the batteries and just leased them to you. I never liked that model personally. Otherwise every battery swap would be playing Russian roulette with the most expensive part of your vehicle.


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## tawma1100 (Jun 23, 2016)

Moltenmetal said:


> Battery swapping was a bad idea- not fully thought out. It would only work if you don't own your own battery- if the oems owned the batteries and just leased them to you. I never liked that model personally. Otherwise every battery swap would be playing Russian roulette with the most expensive part of your vehicle.


This is ga2500ev. My login was lost in the purge. I wanted to chime in.

I think Elon Musk described the situation best. He was talking about superchargers but the idea also applies to battery swapping. To paraphrase, he stated that it makes just about as much sense to drive an electric car somewhere to be recharged as it does to take your cell phone to the phone store to charge it.

In the past there were two fundamental issues in terms of EV power management: charge time and range (both short term and long term). Tesla has done a pretty good job of managing both. First and foremost is taking on the short term range issue for daily usage. While the Leaf is a bit underpowered with a range in the 80's, Tesla's range for all models is 200+ miles per charge. This takes care of the vast majority of daily driving tasks. Coupled with the cell phone charging model of charging at home overnight, essentially for the vast majority of usage,nothing special needs to be done.

So all that's left is long range and charge time. This is where is theory battery swapping would come into play. However, with supercharging, it's somewhat superfluous with supercharging times clocking in under a half hour. Doug's description of using superchargers is just about the same as I hear with from my friends who have Teslas: the supercharging time necessary to move forward takes less time than the people riding need to get resituated.

So in the end battery swapping is a solution looking for a problem. EV power management represents a paradigm shift in thinking.

Now what I wonder is whether or not a wireless charging infrastructure will ever come to fruition. Wireless can be used in all cases: home charging, work charging, charging while driving. But again I'm unsure if it's yet another solution looking for a problem to solve.

ga2500ev


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## tommypress (Jul 20, 2016)

Hopefully we'll have a day where all of these will be available to everyone around the globe.


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## Matej (Dec 4, 2015)

tommypress said:


> Do you really think it was due to lack of demand? :/


Yes. No average car owner is ever going to swap their EV battery. Many people can barely pump their own gas.

Even if it is done by certified people at special stations, there would be all kinds of liabilities and not much advantage. It would also be detrimental to the vehicle design. Similar to how smartphones were able to make better use of their internal space and gained quite a bit of battery life after they started using better integrated non-swappable batteries.

Battery swapping is convenient for motorsports, but it would never work on a large scale.

One alternative I could see working is if someone created a new liquid or 'air' battery technology. Similar to flooded lead acid batteries, but it would need to be more efficient, of course. This way, you could go to a station that would pump out your used water/electrolyte and then pump in charged electrolyte, resembling the way gas stations work today.


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