# Hybrid with 5hp motor



## cdtomlinson (Apr 3, 2009)

Any ideas on how to hook up a 5hp motor to charge the batteries when they get low? You would need something to detect low voltage (what level to start charging?) and then I imagine a DC-to-DC converter to change the 12VDC alternator voltage to charge your high voltage batteries.


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## IamIan (Mar 29, 2009)

cdtomlinson said:


> Any ideas on how to hook up a 5hp motor to charge the batteries when they get low? You would need something to detect low voltage (what level to start charging?) and then I imagine a DC-to-DC converter to change the 12VDC alternator voltage to charge your high voltage batteries.


You will get under ~4kw output from a 5HP ICE.

Unless you have very low wh/mile usage you will probably start the generator up on any longer trip once you drop under 95% battery SoC... as it is not likely to get ahead of the wh/mile energy being drained away... unless of course you are using less than ~4kwh every hour of driving.

Depending on the efficiencies of the total system ... it might be better to just use an AC motor / generator attached to the ICE instead ... feed that AC output into the on-board AC to DC charger you already have in your EV for when you were charging at home or at work etc.

If you want to do this kind of thing ... many companies already sell reasonably efficient small generators with AC outputs off the shelf... emissions certification might prove difficult.


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## ga2500ev (Apr 20, 2008)

After many threads arguing all sides of the issues, I think the consensus is that a hybrid is a loser:

1. It's not more fuel efficient.
2. It doesn't have improved emissions.
3. It ends up slinging both lead/lithium and gas.

If your application really requires a hybrid solution, then the better solution is to get a highly efficient ICE engine, like a diesel, and use it instead.

If you application doesn't really require a hybrid solution, or is solved by and all electric vechicle more than 90% of the time, then other solutions including more batteries, change in driving habits, using an ICE vehicle when the application calls for it, or as a last resort looking at an ICE trailer when the need arises (check out the EV pusher project here: http://www.jstraubel.com/EVpusher/EVpusher2.htm or here:
http://www.mrsharkey.com/pusher.htm 

This page has a discussion on all types of pusher/generator trailers:

http://www.evmaine.org/html/ev_trailers.html

I personally think that it's time to come to the realization that if you create an unlimited mileage electric vehicle, that it is in fact no longer an electric vehicle. To do it properly requires infrastructure that so far no one is willing to invest into.

BTW what is the application?

ga2500ev


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## IamIan (Mar 29, 2009)

ga2500ev said:


> After many threads arguing all sides of the issues, I think the consensus is that a hybrid is a loser:


Like many things it will depend on the specifics.... Of the setup and the conditions in which it is used.

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I will agree though ... if you can use a straight up EV most of the time ... you are better off ... there is significant added complexity and cost to including both in one vehicle ... and for all the trips you just use the EV part and don't need the REEV part... you wasted energy carrying around the un-used / un-needed ICE generator.

The trailer idea ... to house a temporary / rarely used ... ICE generator for REEV functions... is a great packaging option ... it allows for the normal EV operation most of the time ... and then gives the range extension those few times when it is needed.


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## cdtomlinson (Apr 3, 2009)

Thanks for the help. Most of the time I am under 40 miles round trip in the hills. I wanted an option for a 150 mile round trip. Maybe a standard ICE generator mounted on a trailer would be the best option for that well under 10% of the time I need more range. Would there be some circuit that kicks on the generator at some preset drop in battery level, or just stop and start it up at some point?


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## dtbaker (Jan 5, 2008)

The problem is you will be draining juice way faster than the batteries can charge from a generator thru a typical 120v charger. i.e. if I had a mobile generator to plug in to on the fly, my Zivan charger runs at 10-12amps, so about 1kW per hour in. At 40-50mph I'd have 10 kW per hour going out....

Now if you have Li, or ultra caps.... you could pump in energy faster and maybe keep up. But keep in might that at 40-50 mph you are going to need about 15 Hp to overcome air and rolling resistance. A small 5 hp generator won't cut it even if it were directly linked to motor.


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## cdtomlinson (Apr 3, 2009)

5 HP was just a for instance. So it sounds like if I have a 10 KW generator to use at my house for emergencies, I could also mount it to a trailer to take with me for longer trips to extend the range. I'll look into that option, I wanted an excuse to buy a generator anyway.


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