Hybrid Fiero- Need genset help
 

Hi guys, it's been a long time since I have posted here, but some of you will remember me as they guy who broke one of Paul's first contollers by mounting it directly to a transmission that had an out of balance flywheel. Anyway, I now have a little time to re-work the fiero and wanted to make it a hybrid. I came back to this forum and found that Ben is doing the same thing, good job Ben!

What I need help on is what type of genset to use. I have a 4kw generator with an 8 horse briggs, and I thought of just using a full wave bridge rectifier on the 110v ac output to go directly into my 96v battery pack. Any thoughts on this idea? How big of rectifier would I need? Any help would be appreciated as I want to get the fiero back on the road as soon as possible.

Thanks in advance,
Hondo

I will be interested in seeing what advice comes up... have you given a thought to a fuel cell?? I have no idea how much one costs but it would take the ICE out of the loop... feed it propane for a source of electrons..

I like the idea of a fuel cell, but I just don't know enough about them to attempt it. I talked to an electrical engineer last night and he said the ac generator with a full wave bridge would work, but not as efficient as a dc generator. I think I might try this out as it won't cost much since I already have the ac generator. The voltage (110v) should be right for charging a 96v pack and with the generator I should be able to put 40 amps into the batteries. I see on ebay that I can get a 1000 volt, 40 amp full wave bridge for less than 10 bucks. Anyone know if that will be big enough?

Hondo

You can't just rectify 110V AC power and feed it into a battery, you'll destroy the battery. Rectified 110V AC power will actually vary from 0-162V! The normal black line is regular 110V AC power. The top of the graph (black/red/black/red) is what you get when you rectify 110V AC power. In order to get the 110V RMS, you would need to create some additional circuitry to smooth the power output out. Unfortunately, I can't help you with that because I don't know how.

http://ecomodder.com/forum/attachmen...1&d=1357228021

Thanks Doax, perhaps something like this?

Bonn Charger

That might work. I don't know how well, or how efficient. As I said, the specifics are over my head.

you will need some sort of charger between the generator and the batteries...
voltage will vary with RPM of ICE and the RPM will vary based on how much charge the batteries are taking...

better to have some regulation with is what a battery charger does... with several phases of charge. and if you have LIPO batteries... well they need special balancing chargers...

The generator motor runs at a fixed 3600 rpm and you're right,I will have to run the output through some kind of charger if I use this set up.

I wish I had LIPO batteries, just too much $ right now. I am just running eight 12v leads for now with my home made resistive/voltage controller. This controller gave great performance when I had it set up at 108v/54v with 18 six volt leads, and I thought I could get even better performance if I switched to 12v bats and replaced 620 lbs of lead with a 150 lb genset.

OK, I am re thinking this idea because I don't like the loss of efficiency when converting the ac to dc. I did a little looking on ebay and found that used treadmill motors might be a better idea. They are perm. magnet motors rated at around 2.5 hp at 110 volts (1800 watts) and are being sold a lot to use as windmill generators. They are also cheap ($25-$45 each). I also found a 10 hp diesel motor (new) for around $620. My idea is to use the diesel to turn 3 of the treadmill motors to give me around 50 amps of charging. What do you guys think?

The Inverter series generators from Honda use a DC generator but I am not sure what voltage they output to the inverter.

Your treadmill motor idea sounds good, but I am not sure how you can properly size it. Does input power as a motor = input power as a generator? I really don't know.

You are also going to need to throttle the engine to avoid over charging.
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The guy in there made a bio-diesel series-hybrid Miata and managed to do exactly what you are attempting, but I forget how....

interesting ..... I would think the simplest approach is to get a off the shelf 110v AC generator, plug a battery charger into it...

are you trying to get more efficiency by skipping the AC phase ??? not that I premote harbor fright, but they had some redicuious cheap 1000w generators.

for me,

after my car is finished, I am going to look into DEFC direct ethanol fuel cell,


I did find some hydrogen fired Fuel cells, off the shelf, ready to go... but they are fussy.. and expensive...

or a turbine engine generator.... I am not excited about a piston engine extender...

A 1000W generator is not going to make much of a difference in range.

Here is the aero/HP results for your car:
http://ecomodder.com/forum/tool-aero...ToStep=5-200-5
=5.07HP/3870 watts @ 40 MPH, not counting efficiency losses.
You would need at least that in city driving to extend your range significantly. I believe that's one of the reasons that Ben removed the generator from his Electro-Metro in the end.

Yeah, 1000 watt generator won't do much, thats why I am looking at puting 60-80 amps at 110v dc into the system. That should make me able to do all the city driving I want, since I coast a lot. I just bought 4 treadmill motors rated at 1900 watts at 110v dc each for $40 each on ebay. I don't know if the small diesel I saw will pull that much. I have a line on a 12.5 hp Kohler gas engine with electric start that I can pick up dirt cheap, so I think I am going to get it and do some experimenting with how much power I can generate with 2 to 4 of the treadmill motors. Should be fun. Once I get things sorted out, I would really like to get a diesel that would have enough power to give me my 60-80 amps, and run it on biodiesel.

Cheap generators will only run for maybe 200 hours before you have problems with them.
The cheapest way to get a high voltage DC charger that I can think of is to use a 220v Varrac and set up an array of bridge rectifiers. One that has an input voltage of 220v and has an out put range of 0 to 300v. The decent sized varrac like I have can handle 5kw. But you would need a real generator that puts out 220v power, 110v power would work at greatly diminished capacity.
If you don't know what you are doing this can also be a quick way to die.

Turbine powered generaters suck fuel like you wouldn't believe, I work on those too.

OK, I just picked up the used Kohler 12.5 hp motor. I am going to mount it in the front of the Fiero and belt drive 2-4 of the treadmill motors and see what kind of power I can generate. I will post some pics as soon as I get it in there. Thanks for the help guys, I think this setup will be a lot more efficient than converting the ac to dc.

Hondo

this is one site that is in early development... run it at a high capacity for a short period of time

Bladon Jets | Micro Gas Turbine Engines

no idea of cost...


looking forward to seeing the 3 generator setup...

Just want to add a note of caution to your expectations. All generators produce AC, it is converted to DC by rectifiers or commutation. Silicon rectifiers are very efficient, with forward voltage drop around 2 volts at rated current - like 99% efficient for a 200 volt supply. Schottky diodes have about 1 volt drop at rated current, so half the loss of silicon. Mechanical commutation is notoriously bad, electrical commutaion is quite good, but expensive and complicated. I'm speculating that the generators you have use internal rectifiers. The inefficiency in AC generators is mostly due to using a design that allows the output to be varied independently of the rpm. In general, low cost permanent magnet generators are not variable, except by changing the operating rpm. But that means running your engine at an uneconomical rpm sometimes. However, you can switch your 4 generators on or off so you can have 4 different charging levels, which might work great.
-mort