Vehicle to Vehicle charging in the event of a flat battery.

Vehicle to Vehicle charging in the event of a flat battery.

I have an idea that would assist Tesla owners who become stranded with a flat battery (I recently saw a video on YouTube relating to this topic). I am posting this here in a hope that someone will notice it and the idea will be taken on board by Tesla.
In the event that a Tesla owner runs their battery flat while driving the only option at present is to have the car towed. With a gasoline vehicle, you would call a friend to get you a can of fuel and you would be back on your way without much fuss. But what if a Tesla could be charged directly from another Tesla?

My idea goes like this,

- The car with the depleted battery could choose to send out a distress beacon of sorts to other Teslas in the area requesting an emergency charge. The distress beacon would specify if a Vehicle to Vehicle charge cable was also required.
- A Good Samaritan would accept the request and drive to the location of the Tesla with the flat battery. Details of who was responding to the distress beacon would be logged by Tesla for security.
- A direct charge cable would then be used from one charge port to the other charge port. This cable would also allow communications and handshaking between vehicles.
- Once the cord is in place the driver of the vehicle supplying the power would select how much power would be supplied to the other vehicle and charging would commence.
- The driver of the vehicle with the depleted battery would then be charged for the power as though they were charging from a supercharger. The Good Samaritan would then receive supercharger credit for the same amount of power.

If this Vehicle to Vehicle charge cable was standard equipment Teslas would be better equipped to deal with running out of energy than a gasoline vehicle would. This process would be similar to jumpstarting a gasoline vehicle but much easier.

EVRider | 16 September 2018

Sounds like a solution looking for a problem. It would take more than a special cable to implement this, and the fact is that it’s very rare for someone to exhaust their battery, so it’s not worth the effort. You don’t exhaust your battery by accident — if it happens, the consequences should be unpleasant enough so that person won’t repeat their mistake. | 16 September 2018

To add, the electronics to do this would easily add $1000 or more. It requires more expensive (and physically larger) electronics in car than the Tesla internal charger. For something that may never be used in the life of the car, it doesn't make much sense.

In five years of driving Teslas, I've only encountered one owner in 2015 who ran out of power, and he was already at the supercharger, having been towed 2 miles. He knew it was cutting it way too close, but was hoping to make it. So I've never encountered anyone I could have actually helped, even if I could. | 16 September 2018

Forgot to add, you'd need to pay for and lug along another cable taking up even more space. It might be possible to redesign the Mobile cable to do dual duty, but significant extra electronics is required in all cases. | 16 September 2018

While I'd also love to help out a fellow Tesla owner, not sure I want to waste an hour to two helping get someone enough power to get to a Supercharger due to their incompetence. Even at 10 kW, it's going to take an hour to get 25 miles of range or so. Easier to just have a AAA tow truck come that has on-board power to charge (they are in some areas of California) or tow the car to a supercharger.

ravisundaramam | 16 September 2018

S_marley, I used to worry a lot about the range and think about ideas of fixing these problems. All *before* I got the 3. After driving it for a while, it has become a non issue.

1. Tesla keeps telling you how much range is left and alerts you. You will have plenty of warning to get to a super charging stations.

2. The actual range of Model 3 is 610 miles. Not 310. You will double your range by driving at 25 mph. Yes, it is not ideal, but it is a lot more practical to drive slowly to a charging station than to lug around heavy cables and expensive electronics.

3. I saw a Russian video of a model S being towed at 60 mph and the regen braking was charging the car at some hefty rate. So it could be a simple thing to hire a tow truck to tow the car at half way to a super charger. You will have enough charge in the battery to make the second half on your own power. This practice is not blessed by Tesla, but persuading them to add safety circuits and getting it official approved is an easier solution. But, in general, it is not an issue. Such solutions are not really needed.

Tesla abandoned the battery swap idea too. Range is not an issue anymore.

kcheng | 16 September 2018

I saw that movie. It was called In Time with Justin Timberlake and Amanda Seyfried. Jokes aside, I think that Chinese EV company NIO is offering or planning to offer that kind of service, where minivans can charge you up.

As strange as the idea seems, I think it's pretty cool. Ideally, samaritans wouldn't have to spend long charging you, maybe 15mins, giving you enough charge to get somewhere you can actually plug in, because presumably you know you are low, and looking for a charging location.

JayInJapan | 16 September 2018

When your 12V is about done, you’ll get a notice. After that notice, you’ll have about 2-4 weeks to get it checked. Keep in mind sometimes the notice is a false alarm, especially after your car has been sitting for an extended period.

JayInJapan | 16 September 2018

Nvm, different issue—c’mon caffeine!

s_morley | 16 September 2018

Thanks for that,
It does sound like an answer to a question only some YouTuber is asking. I can also appreciate that the electronics involved might be overly complicated for a situation that would be highly unusual. But I do guarantee you that as Teslas become more popular the number of people who fail to avoid this situation will increase. The idea of mobile charging trucks is good, but if this situation is very uncommon then they might not be able to compete with the versatility of a tow truck. Maybe in the future electric tow trucks will double as superchargers.

reed_lewis | 17 September 2018

If you actually owned a Tesla, you would understand that it is extremely difficult to run out of power. The car basically yells at you with warnings on the big screen pointing you to the nearest charging stations.

Also keep in mind that an EV is different than an ICE car. You cannot 'fill up' your gasoline car in your garage every night. OTOH, I leave my house every day with a car ready to drive the distance I charge it to.

Also with Super Chargers becoming more and more prevalent, the whole need for this capability is gone because I can get power from a Super Charger much faster than another car.

So as has been said above, it is a solution that is not needed.

bp | 17 September 2018

Since fully depleting a battery pack risks damaging the batteries, Tesla has implemented software features to help owners avoid that.

Seems highly unlikely Tesla would do anything to appear to encourage owners to run their batteries close to 0%.

EVRider | 17 September 2018

@s_morley: A truck could never provide supercharging, but could possibly provide level 2 charging speeds comparable to what you would get at home.

ulrichard | 17 September 2018

I just learned that Hyundai has special Ionic cars that can provide up to 22kW from battery to battery. I don't think they sell it to private individuals, and thus there is probably no official price.

ravisundaramam | 17 September 2018

@EVRider : "A truck could never provide supercharging"

I don't think this is true. Supercharging is DC. Battery is already DC. So it should be possible to create special battery pack that can hold 100 kWh and charge using DC circuit. Since the receiver is in low state of charge it can soak up at the rate of 128 kW. It can deliver 16 kWh, good for 48 miles in 7.5 minutes. Enough to reach a supercharger. Truck assist is definitely possible.

rxlawdude | 17 September 2018

Not to mention that some Teslas have 350V HV batteries, and others 400V. Would be a challenge for the former to charge the latter. :-)

saxxon | 17 September 2018

I had an idea like this a couple years ago, and made a suggestion about it.

Have a battery back that fits into the back of a Tesla, IE modified Powerwall, and a connector to hook it to power the vehicle. Then, drive to nearest charger, charge up and return the battery pack to get your deposit refunded.

Fairly sure 10kwh of battery will get you to a charger somewhere.

reed_lewis | 18 September 2018

@saxxon - The issue with this is how do you get the battery to the car? At that point it would be easier to just flatbed the car.

But again, if you actually owned a Tesla you would understand that it is VERY difficult to run out of electricity. The car pretty much yells at you to get to a charger.

2018wesm | 18 September 2018

wouldn't mind seeing the feature now, but it's only viable once there are a ridiculous amount of Tesla's on the road. Another good idea is if other branded EVs can charge Teslas and vice versa

ulrichard | 18 September 2018

The Sion will allow that, but they don't explicitly state at what rate. | 18 September 2018

To be clearer - you cannot direct connect one battery pack to another without a very high risk of literally blowing one or both packs up. You have to use a very precise voltage to charge the battery pack safely. We talk about a battery as 400 V (or 350 V in a 40/60/70/75), but it is a band that drops depending on the SOC. Any two random battery packs are rarely the same voltage, let alone the voltage needed to charge the other battery. You need some fairly expensive electronics to convert the DC to AC and back to DC to the correct charging voltage, which also varies as you charge the battery pack. The more current (and faster the charging) the more expensive the electronics. So it can be done, just not for free or even all that cheaply.

Sono motors sounds interesting, but it's really a paper car right now. You can't buy one. Maybe they include the feature and add $1000 to the base price, but my guess is car to car charging will be a quietly dropped feature if the car ever makes it to production at a competitive price.