MetroMPG.com: Electric pusher trailer

[Intrigued]

Sorry 'bout all that... I'm finally getting on Daylight Savings Time here...

I edited my last post. I do think that would be kind of the ultimate fuel-mileage boost to help your in-town driving by hybridizing with an electric system!!!

[Blue Bomber Man]

Personally I like the idea of having an all electric car and then using the trailer as a serial hybrid setup for longer trips. The trailer could even be used to expand the cargo capacity of the vehicle for traveling longer distances. The trailer setup could be standardized so that it could be used with different vehicles that were capable of using the setup. It could also be marketed as a backup generator for a home as well.

[Intrigued]

Originally Posted by Blue Bomber Man

The trailer setup could be standardized so that it could be used with different vehicles that were capable of using the setup. It could also be marketed as a backup generator for a home as well.

Ooohhh! I LIKE it!!! A (biodiesel ) range extender/ generator/ charger/ power backup unit! Handy as a button on a shirt!!!

[razordave]

Why does this thread keep dying? I'm going to look at a junker crx seller is asking $450 for. Auto! Should be a good donor for such a project. Not sure I'll make my Rex elec but maybe freeway cruise with a 10-20 HP engine... I do have a 45 minute freeway commute that could payoff quickly.

I was also thinking about ditching the trailer and just adding a mini bike type solution. Briggsnstratton/Honda horizontal shaft with a sprocket on a swing arm with a motorcycle wheel. The setup could hangout in your boat tail then air shock to the ground at cruising speed.

[Astro]

I also like the idea of a range extender for an EV.
It has been mentioned in other threads.

I am hoping to mount an off the shelf generator to a section of box steel tubing that will slip into the box section on my tow bar. The tow bar gives a nice solid mounting point.
Using this method attaching and removing the generator should only take seconds. A tow bar lock can be added to prevent somebody liberating the generator from the EV.

I realise that the generator will not provide enough power to provide continuous driving but it should increase the range.

I would use such a set up maybe once or twice a month, the rest of the time the generator would sit on a shelf in the shed.

I will try and do some math.

For a long trip i would expect a speed in the high sixties (mph).
Would 20kWh per 100 miles be about right (5 miles per kWh)?

Miles are not my native language

So a 20kWh battery pack gets you 80 miles at 80% DOD. Or about 1 hour 20 minutes travel time. At 60 miles per hour you would need a 12kWh supply to keep going indefinitely.

If you had say a 4kWh generator running for the whole trip assuming a 90% charging efficency. You get 4kWh x 1.333hours x 0.9 efficency = ~4.8kWh That's an extra 24 miles or 24 minutes travel time. During that 24 minutes your generator adds another 1.44kWh getting you another 7.2 miles or 7.2 minutes travel time.
7.2 minutes gets another 2.16 miles or minutes.
2.16 minutes gets another 0.6 miles... And so on.

So roughly 35 miles of extra range (guestimate). Just a bit under 44% extra range.

I am sure there is a nice formula that will give the accurate figure but maths isn't my passion.

So there is no way i am going to be able to fit a 13.3kWh (including charging losses) generator on a small hatchback car. But a 4kWh generator is definitely doable.
It is definitely cheaper than increasing my battery pack size by 44%.

Does this sound correct? My math is probably as bad as my assumptions.

This also gives me a generator that can be used for other purposes.

• Emergency power for the house (limited number of devices, mainly fridge and tv)
• Power supply when camping.
• Portable power for power tools etc.
• An emergency charging source if the EV gets stranded somewhere away from utility power.

[P-hack]

I think of the small generator as more like "emergency use". The "other purposes" stuff is a bit of a red-herring if the main purpose is range extension.

But a homebrew series hybrid is going to be very inefficient, and the number of charging stations is growing daily PlugShare - EV Charging Station Map - Find a place to charge your car!

It just makes more sense to have a beater (possibly as backup) if an ev doesn't meet your driving needs IMHO.

[MetroMPG]

Originally Posted by razordave

Why does this thread keep dying?

I suppose because it's a pretty big project.

I've seen one person create an electric pusher trailer since this thread was originally posted. Let me see if I can find it...



From: http://ecomodder.com/forum/showthrea...html#post33586

I took the ForkenSwift off the road last year due to extensive underbody rust. At the time, I actually had everything I needed to make this...



But and have since sold the EV parts from the blue car. Why? After much soul searching, I realized it's a big project, and I've already got TMFP! (Too Many ... Projects!)

[Astro]

Originally Posted by P-hack

I think of the small generator as more like "emergency use". The "other purposes" stuff is a bit of a red-herring if the main purpose is range extension.

But a homebrew series hybrid is going to be very inefficient, and the number of charging stations is growing daily PlugShare - EV Charging Station Map - Find a place to charge your car!

It just makes more sense to have a beater (possibly as backup) if an ev doesn't meet your driving needs IMHO.

Unfortunately the yearly registration and insurance here in Australia is more than the cheapest cars are worth.
Reg and insurance is $757.70 annually compared to my EV conversion donor car purchase cost of $400.

That plug share site shows only one available charge site on my monthly long distance route. Unfortunately it is located about 2% into my trip so it wouldn't make much difference charging there or before i left. Also it is at a car dealership, there is only one charge point and it would most likely be in use by the cars being serviced. The dealer isn't even the same make of car as mine.

If the generator can extend my range enough to safely get to my destination where i know there are available charge facilities. Then that would be preferable to me. Maybe soon there will be extra charge stations added along the route and i could feel more confident of getting a mid trip top up.

This does lead me to think about what the social conventions around charge points are. At a petrol station there are lots of pumps and once you fill up you are expected to pay and move away from the pumps.

But with an EV the charge time is longish so people would be likely to grab a bite to eat while they wait. But what about when somebody decides to have an hour long lunch while their EV blocks the only charge point? Do the charge points make some sort of attention getting display to attract the attention of the owner when they complete the charge?

What about somebody that commutes to work, parks their EV at a charge point, then goes into work leaving their car all day in the charge point parking spot?

Same for shopping centre car parks, the charging stations there could be blocked for hours by drivers that park there to get their free top up. The top up may only take minutes if they are local yet they could spend hours shopping.

I am hoping for something like a subtle flashing light or beeping sound for say the first 5 minutes after the charge completes but that slowly escalates to a car alarm intensity if the charge cable isn't removed.

[redpoint5]

Originally Posted by Astro

I also like the idea of a range extender for an EV.
It has been mentioned in other threads.

This also gives me a generator that can be used for other purposes.

• Emergency power for the house (limited number of devices, mainly fridge and tv)
• Power supply when camping.
• Portable power for power tools etc.
• An emergency charging source if the EV gets stranded somewhere away from utility power.

I like your maths Astro; it should work out roughly the way you figured it. The problem I see is charging the vehicle while operating it. My PiP will not allow the vehicle to be driven while plugged in, and I'm sure all cars are designed this way.

The first problem to tackle is having an over-ride mode that allows the car to charge and drive at the same time.

Once that is figured out, I'm sure a generator could be added to extend range.

I too like the idea of making things modular and versatile. A generator that can perform all of the tasks above makes it much more valuable.

I'd like to see batteries become more modular so that individual banks can be added/removed from a car, and added/removed to a motorcycle, lawn mower, leaf blower, chain saw, etc. The cost of ownership of all these items would be greatly reduced if the same power source could be utilized.

A generator only makes sense as a range extender if it's also used for other purposes. If the only purpose is to extend range, then a gas pusher makes more sense.

6 kWh generator

[P-hack]

Originally Posted by Astro

Reg and insurance is $757.70 annually compared to my EV conversion donor car purchase cost of $400.

Well a conversion can cost a lot also, have you looked at how long your commute is and speeds, and figured out how much battery you would need? And how much motor/controller you need? It is tempting to rely on a generator but you have to have an EV to attach it too, and have determined the energy requirements before you can sort out how/if to augment the main pack.