Speak EV - Electric Car Forums banner

1 - 19 of 19 Posts

·
Registered
Joined
·
295 Posts
Discussion Starter · #1 · (Edited)
I saw someone post an interesting video on Linked In of an Ioniq EV (I have the same) and he was able to charge it 10% in 3km by having the regen braking on while being towed. It looked from the video like he was doing 40-45km/hr, so it only took him 3 to 6 minutes to charge it 10%- I think with the strongest regen position. I checked and found several other videos with Nissan Leafs and Teslas doing the same. It is basically fast charging, 1kwH per kilometre is achievable according to various reports and videos (very rough estimate, will obviously vary).

I realize this is old news for those of you that have been around the EV scene for years, but I noticed all the articles and videos are from years back. A search on google for "charge tow site:speakev.com" brings up 2016, 2017 and 2018 articles only. I bet I'm not the only one who wasn't aware of this possibility, that's why I'm posting about this again.

So now my new charging location is ...anywhere I want (OK, not a motorway). As long as I have a towbar or even a rope, I can charge anywhere someone is willing to help me out. I think this is really useful to know. Knowing this I might now set off for a 40km trip with an estimate of 55km range left, whereas previously I might not have risked it unless I had 65km. Because finding someone willing to tow you is probably faster and less hassle and embarrassment and cost that trying to sort out a trailer (although cautious people who never do anything adventurous in their life will probably prefer the trailer). I feel that knowing this has added perhaps 10km of useable range to the car. It also makes me feel more confident about one day driving off the charging network. If I'm planning to charge in a hotel, the tow charge is a good back up plan.

Reading through articles and forum discussion, there is a bit of a debate about the legalities, safety and warranty. However, concerns look overblown to me. Certainly there are plenty of cases of people that did it fine, and no cases I saw of a problem that happened. The best argument in favour of the safety of tow charging seems to be that being towed for 5km or 10km or so on max regen (in drive mode rather than neutral) is basically the same to the car as driving down from a mountain pass. We know EVs can do the mountain, and the towing is very similar. Therefore it seems to me very unlikely to damage the car.

The only question mark is whether it would still be safe for the car to tow it for a longer period of time like this - half an hour maybe and get a full charge. No-one has tested that as far as I can see, and that would go beyond the amount of regen used even for a mountain pass. However, I suspect it would work. You might want to stop the car every 10 minutes for the brakes to cool down and the car to have a rest. In effect, wouldn't even that be no different to driving through 2 -3 big mountain passes?

Another curiosity is whether you could use this method to reboot a car that had died, that had literally run the battery to 0.0% and turned off. Has anyone ever tried that? But, given what we know, it would make far more sense to pull over when you are down to 2% or 1%. Maybe more like 5% if you have a good place to stop - e.g. a petrol station where you could more easily request help.

Right, I am going to give it a few days incase anyone here comes along and points out some good argument I haven't thought of. Then I'm getting a rope/towbar. I may even try this out once in advance so I know what I'm doing if I ever really need it.
 

·
Registered
Joined
·
443 Posts
It is indeed possible, but be careful with calculating the actual charge rate. A lot of the clickbait videos on YouTube aren't showing the true charge increase, but rather the car's estimate of range remaining based on the last few miles of being towed (and therefore requiring no energy) increasing.

They used this method to charge the support Rivian's from flat in the "Long Way Up" TV series.
 

·
Registered
Joined
·
431 Posts
The real issue is the fuel source of the towing vehicle. If it's fossil fuel then only around 20% of the burned energy will go into your battery so it's horrendously inefficient and the antithesis of the environmentally friendly EV paradigm.

In practice, a better alternative is to closely follow a coach or lorry. They are already punching that hole in the air so it adds no fuel cost to them, but it saves you a large amount of energy.

In the future of automated driving, I hope we see large convoys of closely spaced vehicles all carefully positioned for optimal aerodynamics, following behind an air-plough of some kind at the front of the line.
 

·
Registered
Hyundai Ioniq 28
Joined
·
7,728 Posts
Obviously, the car would be unable to distinguish between descending a long steep incline and being towed along level ground. In dire emergency, and assuming that a cooperative passer-by could be found, it could add power to the battery. And the combination of the towed distance and the miles gained could reach a nearby Rapid to sort the problem out properly. But I suspect that the need to take such extreme measures will be rare. I have carried a tow rope in the boot for twenty years without uncoiling it. And hope that situation will continue.
 

·
Premium Member
VW ID.3 Worst Edition & Tesla M3 LR
Joined
·
6,647 Posts
They towed the Rivian support pickups quite a bit on The Long Way Up, seemed to work well to get them out of a hole when they were out of range.

That and a diesel generator.
 

·
Super Moderator
Joined
·
7,473 Posts
It does rather depend on the vehicle doing he towing and being towed. My Leaf in ‘eco’ mode, without applying the brakes, is only going to ask for about 10kw of regen. A Tesla? I think they can ask for 100kw of regen. Will the towing hooks on both cars be ok with that additional drag, and will the engine/transmission of the towing car be ok with it? I can’t do the maths but it’s going to be the equivalent of not only towing a car but a car loaded up with bricks!
 
  • Like
Reactions: Petriix

·
Registered
ID3 1st & e-Golf
Joined
·
5,850 Posts
I like your style and as a way out of an emergency would work.
I've towed my EVs when I've run out of energy, without trying to use regen, but it's quite hard work on the vehicle doing the towing, I assume because they are heavy cars. Adding the regen to that will probably be like trying to pull a car with the handbrake on.
I'll be interested to see what you discover but a test run sounds like a very good idea.
I wouldn't be happy to redirect passers by to give me a tow, but a tow truck, that would work of they are willing to help.
 

·
Registered
Joined
·
2,628 Posts
My “EV with a generator instead of a battery” is more efficient than that 😂
 

·
Registered
Joined
·
68 Posts
Checks calendar Nope, a month too early.

You'd be better off getting a tow to the closest charge point if you ran out.
 

·
Registered
Joined
·
295 Posts
Discussion Starter · #13 ·
It does rather depend on the vehicle doing he towing and being towed. My Leaf in ‘eco’ mode, without applying the brakes, is only going to ask for about 10kw of regen. A Tesla? I think they can ask for 100kw of regen. Will the towing hooks on both cars be ok with that additional drag, and will the engine/transmission of the towing car be ok with it? I can’t do the maths but it’s going to be the equivalent of not only towing a car but a car loaded up with bricks!
There are plenty of videos of people doing it fine, so we know it works. Admittedly usually with a big truck so don't ask someone with a Ford Fiesta to do it for you. The person towing you needs to know that they are probably going to burn through 30-50 miles of petrol in the 10 miles they are towing you. So you need to explain this to them, offer to pay, and make sure they keep an eye on the gauge.

Also keep in mind tow speeds are low. Most of the energy normally spent on fighting drag forces is freed up.

Might be a good idea to change the regen settings if you come to a steep hill!
 

·
Registered
Joined
·
295 Posts
Discussion Starter · #14 · (Edited)
The real issue is the fuel source of the towing vehicle. If it's fossil fuel then only around 20% of the burned energy will go into your battery so it's horrendously inefficient and the antithesis of the environmentally friendly EV paradigm.
It doesn't matter because we are just talking about something that in practice you would do probably once or twice in your life for a short distance. So the carbon footprint produced is negligible.

One day I figured I needed 40% and I left the house with 60% which I had got to by charging with purely solar at home so I stopped by a public charger and added an extra 10% (using grid electricity) because I was going somewhere with no charging points. I added that 10% extra so that I could be 99.5% sure that I would have enough rather than just 97% sure.

But had I known about this towing option I could have just settled for 60% charge that day, this enabling my energy to be 100% solar for that whole week. So it could actually be better for the environment that this option exists. I often face this choice - shall I leave the car charging after dark with grid electricity so we have a huge safety margin, or just settle for a more modest safety margin?

If you're in the UK this tow charging might seem a silly option because you are usually a stone's throw from the nearest 7 chargers, but the charging network here in Chile has chargers spaced out about every 100km on average. So even if I stop at every fast charger I pass there it still some risk (the chargers in Chile only work 85%-90% of the time). So nice to know this opportunity exists.

If I turn up at a hotel off the charging network that has agreed to let me charge only to find there was a misunderstanding, the backup plan is there.

One thing I would be a bit concerned about is that every time you are seen running out of charge in EV and needing assistance - whether tow or trailer - you are making EVs look bad and that's really bad from an environmental standpoint. The person towing you in their pickup might still be laughing their ass off to their friends years later and not buying an EV partly for this reason. So that's another reason that this should be the backup emergency plan only.
 

·
Registered
Kia e-niro 4
Joined
·
51 Posts
It's worth bearing in mind that there is a safety risk here. The Kia manual (page 60) specifically states (and I would imagine others do to) that there is a risk of fire if you tow with the front wheels on the ground. The regen equipment probably gets quite warm under normal use, so using it for a prolonged period looks like it can cause damage
 

·
Registered
Hyundai Ioniq 28
Joined
·
7,728 Posts
It's worth bearing in mind that there is a safety risk here. The Kia manual (page 60) specifically states (and I would imagine others do to) that there is a risk of fire if you tow with the front wheels on the ground. The regen equipment probably gets quite warm under normal use, so using it for a prolonged period looks like it can cause damage
That warning is probably presuming that the car has broken down in some way and the towing is with it switched off and in neutral. The manual would assume that the need for a tow was because the car was stopped due to a fault. I can envisage all kinds of issues with that as the cause of the stoppage would be unknown and could be some kind of electrical fault. Best to advise no towing in a breakdown situation for that reason. Quite apart from perhaps the brakes not working as normal due to power loss.

But the manual wouldn't want to distinguish between a broken car being towed and a perfectly sound car being towed. It would take the safest option and want a flat-bed recovery, or at least a front end lift.
 

·
Registered
Joined
·
295 Posts
Discussion Starter · #18 ·
The manual of my Ioniq also specifically warns against towing while the front wheels are touching the ground. But if I have the car in drive and the regen on and being towed, it should be the same as driving downhill as mentioned previously.

In the hill case the car is being pulled forward by a gravitational force and using the regen braking to counter it, and in the other it is being pulled forward by a towing force, and using the regen braking to resist it. The only thing that has changed in the nature of the force, which won't matter to the car.

That being said, I think there is a modest safety risk to any towing, whether EV or not. You have the risk of the two cars crashing into each other, the risk of distraction because you are so focused on how to drive being towed, the reduced ability to react compared to a single car, and the fact that your unnaturally slow speed puts you at risk of being rear ended. So there probably is a slight safety advantage to the trailer, assuming it's with a professional that knows what they are doing.

In my case though, if I ever need it, it will probably be in a very rural place here in Chile, a semi-developed country. It might not be obvious who to call for a trailer. Even if I do figure it out, if the trailer is 100 miles away, they will want advance payment, and they will just be some local business with no reviews or website etc, just someone with a phone number asking you to send someone a bank transfer of £100 in advance and then hope they turn up hours later or the next day. I think the towing will be miles easier in rural Chile.
 
1 - 19 of 19 Posts
Top