essaunders
Posts: 375
Joined: Mon May 03, 2010 7:20 am
Delivery Date: 20 Jan 2012
Location: southern NH

Re: Flat Tow/Recreational tow

Thu Oct 09, 2014 9:58 am

Wufnu wrote:Difference in being towed and coasting down a verrrryy long hill? From the cars perspective, nothing. It's a waste of gas and money, plus needlessly adds miles on your odometer, but there you have it.


How is it a waste of gas? Assuming you'll tow some vehicle, it might be a wash. Once the LEAF is fully charged it'll stop trying to regen. the only 'waste' I'd see is the LEAF baseline load (couple of hundred watts).

Off course, i can't possibly see Nissan saying this is OK...

nerys
Posts: 686
Joined: Tue Sep 09, 2014 10:11 pm
Delivery Date: 09 Sep 2014
Leaf Number: 020441

Re: Flat Tow/Recreational tow

Thu Oct 09, 2014 1:45 pm

if you really think I care about adding 4 or 5 miles to my odometer......

if the car is in neutral it should not be adding any miles to the odometer.
2012 SV 4802miles. 1month 2400 miles. 9 weeks 5000 miles. 6 months 13,300 miles. 4/18 15,000 miles.

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TomT
Posts: 10570
Joined: Sun Aug 08, 2010 12:09 pm
Delivery Date: 01 Mar 2011
Leaf Number: 000360
Location: Foothills of Granada Hills, CA
Contact: Website

Re: Flat Tow/Recreational tow

Thu Oct 09, 2014 1:54 pm

Yes, it does, just as it registers them coasting down a hill in neutral...

nerys wrote:if the car is in neutral it should not be adding any miles to the odometer.
59,991 miles/12 bars/289 Gids/68.54 AHr/101% SOH/101.64% Hx 7May15 w/ new Lizard (barely made the warranty).
71,770 miles/12 bars/256 Gids/59.04 AHr/88% SOH/87.92% Hx 3Mar16 at lease return.

Now driving a 2016 Volt Premier. Model 3 configured.

nerys
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Joined: Tue Sep 09, 2014 10:11 pm
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Leaf Number: 020441

Re: Flat Tow/Recreational tow

Thu Oct 09, 2014 2:13 pm

hmmm then the car is not actually in neutral?
2012 SV 4802miles. 1month 2400 miles. 9 weeks 5000 miles. 6 months 13,300 miles. 4/18 15,000 miles.

Wufnu
Posts: 41
Joined: Mon Sep 08, 2014 7:10 pm
Delivery Date: 08 Sep 2014

Re: Flat Tow/Recreational tow

Thu Oct 09, 2014 5:29 pm

Because charging your vehicle by towing it is a big waste of energy due to regeneration inefficiency and inefficiency in towing. Better off to use a generator. I would only tow-charge if I absolutely had to. It's not free energy; it's like towing a car with the brakes lightly on. Fuel isn't cheap. If it's an emergency one time deal, no problem, but towing it behind and RV? No bueno.

Yes it's really in neutral and yes it's really adding miles to your odometer. The added miles will cause it to depreciate like a brick. If you're going to own it forever, who cares, no big deal. Most people won't. It doesn't have a real neutral so the motor will be spinning. This causes more problems in towing.

Tow dollies are cheap and easy to use. Buy used. Get a tow dolly to drag your Leaf behind your RV and enjoy all the benefits with none of the downsides. If someone can afford a $50,000 - $100,000 RV, the fuel it guzzles, and is looking to tow a $30,000 car then I think the least they can do is spring a few hundred bucks to protect both of their expensive properties.

nerys
Posts: 686
Joined: Tue Sep 09, 2014 10:11 pm
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Leaf Number: 020441

Re: Flat Tow/Recreational tow

Thu Oct 09, 2014 8:35 pm

Well my rv is a little 4cyl jobby :-) and cost me $900.

It is free energy. Well recovery of otherwise wasted energy. When you go downhill in an rv there is no "coasting" your mass will quickly put you over the psl

So you "will" have to apply the brakes which is quite literally burning up energy as pure heat and w&t on the brakes.

Txing some of that into regen captures some of thst energy and puts it to use instead of throwing it away into the brake pads.

All I was trying to point out. Nothing more. My gassers do not add miles when I put them in neutral because the transmission is not engaged and the transmission has to spin in order to spin the speedo gear. Then again my gassers are dirt cheap simply old sticks (geo metro geo tracker) flat towing is common because it is easy fast low maintenance and less complicated. By a lot. Drive up behind the rv attach power and tow bar and drive away. Try that with a tow dolly.

Also an emergency tow charge would be about trading money (gas) for time. 30kw will recharge the battery pretty damned fast

I also have a feeling its not nearly as inefficient as you might think. Regen is 30% right? That is a hell of a lot more efficie t than your ice is.
2012 SV 4802miles. 1month 2400 miles. 9 weeks 5000 miles. 6 months 13,300 miles. 4/18 15,000 miles.

Wufnu
Posts: 41
Joined: Mon Sep 08, 2014 7:10 pm
Delivery Date: 08 Sep 2014

Re: Flat Tow/Recreational tow

Fri Oct 10, 2014 8:42 am

If you only travel downhill, sure it's free.

I regenerative braking efficiency is more than 30%, not sure how much, but that's efficiency of converting work your RV engine produced to begin with. So, for example, if your RV had to produce an extra 10kW to account for the extra force applied by regenerative braking on a flat towed Leaf, your leaf would only get 3kW (or whatever it would be based on real efficiency). When you have to use an ICE to pull it, no it's not more efficient than an ICE. The efficiencies multiply: %ICE*%RB*%EV = a lot less.

Yah, flat towing makes a lot of sense on a typical manual car. Unfortunately (or fortunately, depending on how you look at it), the Leaf is not typical and it doesn't have a manual transmission. Because of the differences, there are a lot of unknowns. For example, the regenerative braking feature is meant to be used intermittently or for relatively short periods of time. It may or may not be capable of running constantly for an hour. Same goes for back EMF. Components are easy to understand but the way components interact not so much. Really, the only way to know is to try. Nissan isn't going to give instructions on it and it would probably be very difficult to get all of the details from them.

I say go for it! Tell us what happens. I'm very open when it comes to experimenting with other people's property :lol:

nerys
Posts: 686
Joined: Tue Sep 09, 2014 10:11 pm
Delivery Date: 09 Sep 2014
Leaf Number: 020441

Re: Flat Tow/Recreational tow

Fri Oct 10, 2014 8:47 am

I think you missed my original idea. Some sort of remote switch to only turn it on "while" going down hill only. Ie regen for a couple minutes now and then when going downhill.

Tow regen on flat ground makes no sense except in desperate times.

Alas if the leaf does not truly go into neutral ie transmission still spinning is not really neutral as I am using the word. Then its probably not wise to flat tow it at all.
2012 SV 4802miles. 1month 2400 miles. 9 weeks 5000 miles. 6 months 13,300 miles. 4/18 15,000 miles.

garsh
Posts: 1078
Joined: Sat Feb 12, 2011 5:27 am
Delivery Date: 05 Apr 2012
Location: Pittsburgh PA

Re: Flat Tow/Recreational tow

Fri Oct 10, 2014 12:23 pm

nerys wrote:I think you missed my original idea. Some sort of remote switch to only turn it on "while" going down hill only. Ie regen for a couple minutes now and then when going downhill.
That would be a great setup. It could be simple like the trailer brakes on a boat trailer - when there's pressure on the back side of the ball joint, you activate the braking.

Alas if the leaf does not truly go into neutral ie transmission still spinning is not really neutral as I am using the word.
The Leaf doesn't technically have a transmission at all - just some reduction gearing. There's no clutch, so if the wheels are moving, then the motor is moving with it. As has been said, the downside is that your odometer keeps spinning, and you'll end up with a "high-mileage" vehicle. But otherwise, I don't see the spinning motor as being a problem. It's not likely to develop a problem like a spinning gasoline engine or transmission would.
2012 Black SV w. G35 wheels, 8 bars, 86,000 miles

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