range extending generator

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EV_dub
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range extending generator

Postby EV_dub » Mon Jan 31, 2011 10:10 pm

I have been thinking about building a range extending generator trailer.
The Problem with my EV is having to own another car for the extra long trips.

My vw golf at 120v system: (on the flat once up to speed)

battery amps:
60mph= 70-80amps- 8400w-9600w
65mph=75-85 amps- 9000w-10200w
70mph=85-95 amps- 10200w-11400w

My golf weighs in at 1280kg

10x trojan 1275 150ah = 380kg

I was thinking on the lines of a 12kw generator system. Conventional generators dont seem all that efficent and often noisy. My idea is to use a 2x 6kw or 1 x 12kw genset and swaping engine(s) for a more efficent motorcycle or marine engine. Diesels use less fuel but dirtier. Petrols are quieter and cleaner and could run on LPG or maybe Hydrogen??

2x ng3 chargers and 1x ng5 for about 11kw's.

Any thoughts on this??
Last edited by EV_dub on Tue Feb 01, 2011 2:02 pm, edited 1 time in total.
1993 Veedub Golf, 156v, 1200A, 150ah's

andylaurence
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Re: range extending generator

Postby andylaurence » Tue Feb 01, 2011 1:19 pm

I've often pondered the idea too, but nothing to add of any use to you. Sorry!

One thing I have hunted around for is more information on hydrogen conversions. I've found people suggesting that it should be possible in a similar manner to an LPG conversion but I've never found a place that would carry out the conversion, nor any kit that's suitable. What I have found is lots of people doing electrolysis and making bangs in their induction system :roll:
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ChrisB
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Re: range extending generator

Postby ChrisB » Tue Feb 01, 2011 7:53 pm

The nearest I've got to it is my Berlingo with a hoofing great 6.5kw Deisel genny wheeled in to the load bay that in itself weighs 130kg :shock: and all that does is charge the van when I'm going to be going beyond its range and I know theres no charge at the other end.

It sort of works but given that the recharge takes the regular time you do end up sat still waiting for hours and hours :roll: I have wondered if I can charge the batteries direct off the high speed charge point with a home made charger but while the genny is rated at 6.5kw thats its peak its cont. rating is more like 5-5.5kw I suspect, which really only leaves about a spare 2kw which really isnt enough to make much of a dent into the recharge and it would up the fuel comsumption of sunflower oil :mrgreen: on the genny.

Decided it wasnt worth all the grief in the end and just left it with wheeling the genny in and out of the back as and when I need it, which to be fair isnt much.

ChrisB
I reject reality and substitute my own !!!!!!

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EV_dub
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Re: range extending generator

Postby EV_dub » Tue Feb 01, 2011 10:20 pm

ChrisB wrote:The nearest I've got to it is my Berlingo with a hoofing great 6.5kw Deisel genny wheeled in to the load bay that in itself weighs 130kg and all that does is charge the van when I'm going to be going beyond its range and I know theres no charge at the other end


Yea I think a trailer will definitely be needed. I'm hoping to reduce weigh by using 1 motorcycle engine to drive 2 alternators. A single cyclinder 30hp motorcycle engine weighs about 40kg and should be good for 70mpg equivalent.
1993 Veedub Golf, 156v, 1200A, 150ah's

jonathan jewkes
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Re: range extending generator

Postby jonathan jewkes » Mon Feb 14, 2011 12:49 pm

Would a Lynch (or Agni) motor fit the bill? They are compact. If used as a generator it would supply a DC output. Voltage is determined by speed of rotation, so hopefully you could link it to an engine which could run at the appropriate speed. But maybe not a cheap option.
Jonathan Jewkes
Daily EV user for 10years - an enthusiast and also a realist

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EV_dub
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Re: range extending generator

Postby EV_dub » Mon Feb 14, 2011 8:33 pm

Yes they would make a good generator, I have one on the shelf. The problem is the charge control system would be quite complicated to build.???
I would need a way to control the charge current to stop overcharging the batteries.
1993 Veedub Golf, 156v, 1200A, 150ah's

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Jeremy
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Re: range extending generator

Postby Jeremy » Mon Feb 14, 2011 8:51 pm

EV_dub wrote:Yes they would make a good generator, I have one on the shelf. The problem is the charge control system would be quite complicated to build.???
I would need a way to control the charge current to stop overcharging the batteries.


The quick and dirty way to control the charge if you use a PM DC motor as a generator is to use the engine throttle as the control mechanism. The way I'd do it would be to use something simple, like a Picaxe microcontroller driving a RC model servo to open and close the throttle. The Picaxe could easily monitor current and voltage and use these signals to set the throttle setting via the servo. It's take around £10 worth of components to do this, plus a couple of dozen lines of fairly simple code. These simple controllers are the same as the ones that Peter was using in his BMS system.

Jeremy

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EV_dub
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Re: range extending generator

Postby EV_dub » Mon Feb 14, 2011 9:31 pm

hmm interesting stuff.

My 156v system would require a couple of small dc pm motors. would you supply 1/2 of the battery pack with each generator or wire the two generstors in series? Need to learn more about generator systems!
1993 Veedub Golf, 156v, 1200A, 150ah's

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Jeremy
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Re: range extending generator

Postby Jeremy » Tue Feb 15, 2011 8:22 am

EV_dub wrote:hmm interesting stuff.

My 156v system would require a couple of small dc pm motors. would you supply 1/2 of the battery pack with each generator or wire the two generstors in series? Need to learn more about generator systems!


I'd wire them in series and drive both of them from a common shaft/belt/chain drive at the same rpm.

If you didn't want to design and build a control system you could almost certainly adapt a scrap cruise control from a car. Instead of using a speed signal to control the cruise control, just use the current demand from the car, or maybe the pack voltage, as the "speed" signal. The only snag with adapting a cruise control would be setting it, as they normally don't remember speed settings.

The advantage of using the Picaxe microcontroller is that it directly controls RC model servos and has a servo position command that makes driving the throttle to a known position very easy. These microcontrollers also have analogue inputs and can directly measure voltage and are programmed in a version of BASIC that makes learning to drive them pretty easy (they were originally designed for educational use in schools).

A simple control loop that measures battery voltage and adjusts the throttle to keep the voltage constant would be fairly easy to do. All the controller needs to do is move the servo throttle control in the correct direction to get the right output voltage and hold it there, maybe with a small dead band to avoid hunting around the set position (in other words, allow the voltage to vary by a small amount before the controller takes action to open or close the throttle).

Jeremy

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EV_dub
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Re: range extending generator

Postby EV_dub » Tue Feb 15, 2011 8:49 pm

Jeremy wrote:
EV_dub wrote:hmm interesting stuff.


The advantage of using the Picaxe microcontroller is that it directly controls RC model servos and has a servo position command that makes driving the throttle to a known position very easy. These microcontrollers also have analogue inputs and can directly measure voltage and are programmed in a version of BASIC that makes learning to drive them pretty easy (they were originally designed for educational use in schools).

A simple control loop that measures battery voltage and adjusts the throttle to keep the voltage constant would be fairly easy to do. All the controller needs to do is move the servo throttle control in the correct direction to get the right output voltage and hold it there, maybe with a small dead band to avoid hunting around the set position (in other words, allow the voltage to vary by a small amount before the controller takes action to open or close the throttle).

Jeremy


Thanks Jeremy thats really helpfull advice. I do like the idea of this, I have been learning about servo systems lately in my modules.

My Lynch is rated at 200amps continuous, If i had an even battery back say 144 volts, would it be possible to supply 72v 100A to both halves of the pack from one generator??? Because they are all wired in series would that cause an issue??
1993 Veedub Golf, 156v, 1200A, 150ah's


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