jkenny23
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Sun Jan 14, 2018 12:30 pm

There is the less elegant option of building a "portable charger". I have played around with this and got it to work somewhat, though I need a bigger battery bank for it to be useful, the current one is quite undersized and the batteries heat up to unsafe levels within 4 minutes. Here's a quick video of my last attempt though as proof of concept:

https://www.youtube.com/watch?v=rTOSSuuuSNY

I suppose the next step up from this would be to tap into the charger so I don't need to hook up the EVSE to the front of the car each time, and maybe upgrade to a 3.5kW 240V inverter. This also has the problem of needing to charge 2 batteries, right now the battery is small enough that I'm charging it with a 160W solar panel in my patio (I live in an apartment, otherwise I'd probably have a real solar array).

camasleaf
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Sun Jan 14, 2018 5:59 pm

mux wrote:But then still - a trailer is just a massive hassle. I don't have anywhere to put the car, let alone a trailer. It's extra air drag, it's pretty hard to interface (you'd have to build a whole secondary interface controller instead of just tapping the existing signals), you have to make a flexible super high current cable that actually conducts a couple dozen kW from the trailer to the car, and the whole thing has to be less than the allowable towing weight (maximum allowable combination weight is 1965kg in the Netherlands, the battery unit is about 300, so that leaves bupkis for the frame, wheels and the rest).


I believe the "push trailer" is the idea were the trailer pushes the car and you use the regeneration system to charge the battery. Easier electrically , but still lot of problems mechanically and dynamically.
2011 SLe 06/17/11 Over 79000 miles 70%SOH 15.2kWh
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EVDRIVER
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Sun Jan 14, 2018 6:03 pm

camasleaf wrote:
mux wrote:But then still - a trailer is just a massive hassle. I don't have anywhere to put the car, let alone a trailer. It's extra air drag, it's pretty hard to interface (you'd have to build a whole secondary interface controller instead of just tapping the existing signals), you have to make a flexible super high current cable that actually conducts a couple dozen kW from the trailer to the car, and the whole thing has to be less than the allowable towing weight (maximum allowable combination weight is 1965kg in the Netherlands, the battery unit is about 300, so that leaves bupkis for the frame, wheels and the rest).


I believe the "push trailer" is the idea were the trailer pushes the car and you use the regeneration system to charge the battery. Easier electrically , but still lot of problems mechanically and dynamically.


Plenty of posts here on that really bad idea. That horse has been not only beaten but blended. Best way to extend the LEAF range is to post it on ebay, then use the proceeds to buy another EV. After hundreds of posts it will become pretty clear.
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IssacZachary
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Mon Jan 15, 2018 12:58 am

EVDRIVER wrote:
camasleaf wrote:I believe the "push trailer" is the idea were the trailer pushes the car and you use the regeneration system to charge the battery. Easier electrically , but still lot of problems mechanically and dynamically.


Plenty of posts here on that really bad idea. That horse has been not only beaten but blended. Best way to extend the LEAF range is to post it on ebay, then use the proceeds to buy another EV. After hundreds of posts it will become pretty clear.


Yes, lots of posts. But how many failed attempts? All I know is that the pusher trailer concept has been done successfully on several occasions. Also adding an additional DIY traction battery has also been done successfully on more than one occasion. There has been at least one occasion where someone was able to get a 30kWh battery to work in a 24kWh Leaf too.

But you have a point that it's worth looking into longer range EV's first. The problem is that for the most part that is the most expensive and limited option.

Maybe I could trade my 24kWh Leaf for a 30kWh Leaf. But the consensus seems to be that they have a faster degrading battery than the 2013 Leaf that I already own.

I can't afford a +$30,000 car, so Leaf Gen2, Bolt and Tesla Model 3 are out of the question for me at this point.

For me, if I want to keep it partially electric, I'm better off with an older hybrid of some sort, perhaps a used Volt. If I can figure out how to get a Prius Prime for under $10,000 like Sagebrush suggested I'd do that. On the other hand I'm tempted to jump back off the EV band wagon for now until EV's become more practical and cheaper.

And yet I need to go farther than just a 30 mile radius from my house. My ICEV died from catastrophic transmission failure last week, so now I'm in a pickle with the Leaf. Part of the problem here too is the lack of charging infrastructure. The 6kW charger and CHAdeMO port really aren't benefiting my right now. I need to go to the next town 65 miles away at least once a week and my Leaf won't make it now that it's winter. Which is sad, because the Leaf would make it if it just had a bit more range than it does now, be that through a charging station of at least a level 2 6kW capacity between here and there or a bigger battery. Which turns me back to the idea of adding at least another 6kW of cells to my Leaf. A $1,000 in cells doesn't sound bad at all, and I'd still be getting +100MPGe between zero to 10 cents per kilowatt-hour.

Either that or a portable generator.
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mux
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Mon Jan 15, 2018 1:19 am

camasleaf wrote:
mux wrote:But then still - a trailer is just a massive hassle. I don't have anywhere to put the car, let alone a trailer. It's extra air drag, it's pretty hard to interface (you'd have to build a whole secondary interface controller instead of just tapping the existing signals), you have to make a flexible super high current cable that actually conducts a couple dozen kW from the trailer to the car, and the whole thing has to be less than the allowable towing weight (maximum allowable combination weight is 1965kg in the Netherlands, the battery unit is about 300, so that leaves bupkis for the frame, wheels and the rest).


I believe the "push trailer" is the idea were the trailer pushes the car and you use the regeneration system to charge the battery. Easier electrically , but still lot of problems mechanically and dynamically.


That is the stupidest thing I've ever heard. Besides, the Leaf has the wrong kind of motor to do efficient regen, you'll at best get something like 70% back from regen. And that still leaves all the other engineering issues... safety...

Sorry, this has apparently already been beaten to death, but I had to respond.

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EVDRIVER
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Mon Jan 15, 2018 10:03 am

Push trailers have been around for many years, same for battery trailers etc. They made more sense then becase range in EVs was low and chemistry was poor. Now that there are and will be many more low cost, longer range options it just seems silly to supplement an EV like the LEAF. I’m sure this point can still be made for generators but people still use them with high frequency. If you take those funds and lost time and get a cheap lease it would be better served.
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IssacZachary
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Mon Jan 15, 2018 5:56 pm

EVDRIVER wrote:Push trailers have been around for many years, same for battery trailers etc.

Yes. And they work. The only ones trying to beat a dead horse are the nay-sayers why can't quite hit the horse because it's alive and well. I've known a couple individuals with perfectly fine working EV pusher trailers who's recommendation to me was, "Do it!"
EVDRIVER wrote: Now that there are and will be many more low cost, longer range options... If you take those funds and lost time and get a cheap lease it would be better served.

Cheap lease? I've never leased. I was always under the impression that a lease was a waste of money. At least if you build a battery trailer the trailer and the car are still yours after a few years.
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TonyWilliams
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Mon Jan 15, 2018 9:53 pm

I think for you in the cold mountains, with a limited range EV that you can't replace, and very limited charging infrastructure, the pusher trailer isn't terrible for occasional use.

But, maybe a used Chevrolet Volt might be smarter? Professionally engineered gasoline and EV power, all in one package.

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IssacZachary
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Tue Jan 16, 2018 12:25 am

TonyWilliams wrote:I think for you in the cold mountains, with a limited range EV that you can't replace, and very limited charging infrastructure, the pusher trailer isn't terrible for occasional use.

But, maybe a used Chevrolet Volt might be smarter? Professionally engineered gasoline and EV power, all in one package.

Yes, I've been leaning towards buying a used a Volt. Either that or some small 4-banger and the Leaf for around town.

It's just that the Leaf is so nice I wish I could take it everywhere. :mrgreen:
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11 bars current. :)
The Nissan Leaf is the fourth best long distance car for highway driving. >>Best Long Distance Cars<<

mux
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Re: Extra Battery, How to Integrate with 24kWh Traction Battery?

Tue Jan 16, 2018 1:53 am

Some more progress report: I've enlisted a friend to help me and I'm in the process of mapping out the available space under the trunk. I'm very much hoping I can build a modular battery pack with a few modules that slide in from the back, but this too may be a bit pie in the sky; the shape of the plastic cover is fairly three-dimensional, it's not a nice rectangle with constant depth or anything.

Has anyone been successful in adding CAN devices to the bus? It would be nice to have BMS readout over CAN instead of building something separate.

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