Dutch fellow tows Leaf with Tundra while lightly regenning to charge battery

That's too funny! That would be an interesting way for Nissan to provide roadside assistance to people stranded w/dead batteries.

 

There goes the 8 years / 100k miles battery warranty. He just voided the warranty.

 

I'm guessing that they don't recommend doing that in the Leaf's Owners Manual. Just a guess. :madgrin:

 

Must be one of the few tundras in europe.

 

No, towing is not recommended according to the manual. If your battery is dead and have no juice handy you will have to pay for a flatbed towing truck! I can see that in the (not too distant?) future your auto club (CAA/AAA) membership will provide "emergency juice-up", just like they get a can of gas to you to get you going.

However, the fact that EVs can not be towed "on their fours", like any car with manual gearbox, is a MAJOR shortcoming of these cars. There ought to be technology available to disconnect the drive/motor and make them tow-able. Say a switch/selector would have three positions;
- "D" for drive
- "T" for towing
- "R" for recharging while in tow

Please send this idea to all EV manufacturers - an idea at no charge. I bet someone will patent it!!!! :rockon:

 

Essentially what he did was to use the regenerative braking system to charge his HV battery. Normal operation, except that he got it by towing instead of going downhill with the brake on.

 

The battery may not be designed to regen charge that long (thermal concern). The rate of charge and the length may damage or shorten the life of the battery.

If he was just a few miles away from home and the "tow charge" at low speed, it should be fine. I hope Nissan allows this for certain window. I think it is a great idea.

 

It has to be. It's just like going downhill for a long ways. When the battery gets full, the car will shift to using the friction brakes.

 

I doubt the charge rate and length would be a problem for the battery. Leaf's are going to see long downhill stretches at some point in the real world. Level 3 charging (if the reports I've read are correct) supposedly allows the car to be charged 80% in 30 minutes.

I think there might be more a of concern w/motor heating and electronics (inverter?) heating from extended regening.

I'm sure there's a potential safety issue of being towed behind a vehicle w/just a rope. I think I'd me more concerned about the forces on the tow hook and whether it could take all the repeated stresses from starting, turns and unexpected situations (like the Leaf driver not paying attention when following the tow vehicle, thus being off course).

 

I was saying it may be designed and tested to handle only the longest downhill in existence. The "tow charging" may exceed the tested parameters.

 

If there is a limit on tow charging, it's the mechanical brakes. Once the HV battery is full, the vehicle has to switch over to mechanical only. The Prius has the same issue, although obviously with a much shorter timeframe. When the Prius battery is full (actually about 80% SOC), braking switches to mechanical only.

I think you'd need additional instrumentation to have any chance of optimizing a tow charge. You want maximum regen, but no mechanical braking. Something like a ScanGauge designed to identify the balance between them. Also a SOC (State of Charge) meter is needed for the Leaf. The standard display is a guess of remaining miles, assuming that driving condition remains the same.

Towing the Leaf obviously works, but I regard it as a last ditch choice. It would be rather dicey if there were any significant traffic. Maybe a 12V charger for the Leaf would be a good idea. The typical car alternator puts out about 35 amp at 14 volts, for a total of 490 watts. That's about 1/4 the power available from a household outlet. So a Leaf 12V charger could be designed for use via jumper cables from another vehicle with a standard alternator. It could only charge at 1/4 the normal home based charger rate.

I can see it now. A gas engine generator towed behind a Leaf for extended range...

 

this was bounced around the MNL forum as well. as far as damage. the Leaf at the very least must be on but the Leafs capacity to regen is very ample and controlled. the car will not allow any damage to the pack whether its forced or not.

regen is controlled based on the SOC of the pack. the power meter on the leaf has 4 regen circles, 10 power circles. the circles are double walled and that indicates the amount of power that can be either brought in or put out.

for example; on a full charge. all four regen circles will have single wall on display. as you drive and reduce SOC, the circles will become double walled signifying that full regen (30 kwh) is available when all 4 circles are completed.

the same goes with the power circles. the Leaf does all it can to warn you of your battery packs capacity in miles which most people understand. but eventually there is too little charge left to predict range. this puts the car into "turtle" mode. this is where the amount of charge to motor from battery is reduced to protect pack.

there are 10 and they disappear QUICKLY. even at street speeds running 25-35 mph, i was losing circles every few 10ths. i am guessing a max 2 miles of turtle range.

as far as heat buildup? we have several people descending the mountains of CA for up to an hour and 5-7,000 feet with no issues.

 

FYI. for those in California. They law here says that when a vehicle is towed behind another vehicle, there must be a solid metal bar between the two vehicles and not a rope.

Thanks. Good to know.

I'm not sure if there are many hills in Amsterdam, but we have a lot of hills here in SoCal. One would just need to push the car toward a decline then regen. (sure, it wouldn't be prolonged, but it is accessible)

 

The tow charging is way below the real world downhill driving speed. In California, there's a section of I5 freeeway that runs from between Gorman and Frazier Park to grapevine. It's about 12 miles long and the elevation difference of about 3000 feet. I can regen from 2 bars to 8 bars in less than 2 miles. When I go down hill, I drive at least 65mph. It works its way up to 80mph. I highly doubt they're towing at that speed. They probably tow at around 30-40mph since they're doing it in the city. That's nowhere near the freeway speed.
I'd imagine the future tow trucks that're EV charging capable would be something like a dynamometer where they can wrench the EV up to the dyno wheel and spin the drive wheel at 40mph for 10 minutes while it regens at maximum output to charge the HV battery.
If you think this will damage the drivetrain by overheating think about driving on the freeway at 65mph for 30 minutes. Don't tell me that won't heat up the motor or the battery or the inverter more than regening for 10 minutes. Regen at 40mph for 10 minutes will not do anymore damage than driving at 40mph for 10 minutes.

Most Toyota light duty alternators puts out 65 amps. If you get the tow package or a package that enhances winter driveability then the alternator output goes up to at least 100 amps. Most full size trucks alternators are rated at over 100 amps. Back in my stereo installation days, we install systems with up to 1500 watts RMS without replacing the stock alternator all the time without burning out stock alternators. Anything over 1500 watts RMS, we recommend replacing the alternator with either heavy duty alternator or aftermarket competition alternators.

 

The standard 120V charger that comes with the leaf apparently draws 12 amps, or 1440 watts. So it looks like we're in the ballpark for doing a standard rate charge of the Leaf off a vehicle with a 100+ amp alternator.

How large an alternator can you get on today's vehicles?

 

It's not feasible to use an inverter to charge up a Leaf in a case of emergency. It would take about 15 minute charge to get enough energy to drive 1 mile.

They do make super high output alternators at 400 to 500amps that'll rob 8 to 10 horse powers from your engine if you have enough room in your engine bay. Most of those alternators are made for heavy duty trucks. Even with a 500 amp alternator and a 240v 7,000 watt inverter, you're looking at level 2 charging. Now if the tow truck is equipped with a level 3 charger powered by 3 of those alternators, it would burn a good amount of gasoline to charge up a dead Leaf to 80% in 30 minutes.

 

the charging is actually done by reverse current on an electric motor. its output is 80 kwh. its regen capacity is 30 kwh. you only need to be coasting in eco mode about 40-45 mph to get full regen as long as SOC is under around 90%

there is no alternator and if their were to be one, we must remember the Leaf is not running on a 12 volt system. its more like 200 volts

 

This is an example of using a Tundra to make a Leaf get 15 mpg! And the reporter called this guy a genius?

 

I love how the full size truck in Holland is referred to as a "**** the world auto".