Simple Cheap Hybrid Car? (DIY)

[pete c]

nimble,

What you say probably makes sense from a practical view point, although, I fear your dollar estimates are a bit off.

But, where's the fun in that? Leave the dreary OEM already engineered to death stuff to boring practical folk.

We are dealing with "The Mad Technician" here who is set on satisfying his inner geek. I think most of us here have an inner geek. We just don't have the bullocks/lack of sense to act on it! Well, some of us don't. Many here have. Perhaps some day I will try something as well rather than just read of it.

I hope chris does this and ends up kicking the pants off prius numbers, which can be done with a little hypermiling thrown in.

Chris, if you do end up placing a motor/generator/starter where the PS pump used to live, will you keep the alternator?

It would be nice to lose it as well, but, would require added circuitry to maintain 12V functions. I think we have already determined that an electric motor assist should operate at a considerably higher voltage to keep the weight of such components manageable. Leaving the alternator to handle this will save you a fair bit of wiring and componentry.

As for a belt drive system having the torque capabilities to handle this duty, I don't see that being a problem. Ribbed serpentine belts in modern cars can easily power an AC compressor and all the other bits. AC compressors by themselves a fair number of hp.

[chrisoverson]

Originally Posted by pete c

nimble,

What you say probably makes sense from a practical view point, although, I fear your dollar estimates are a bit off.

But, where's the fun in that? Leave the dreary OEM already engineered to death stuff to boring practical folk.

We are dealing with "The Mad Technician" here who is set on satisfying his inner geek. I think most of us here have an inner geek. We just don't have the bullocks/lack of sense to act on it! Well, some of us don't. Many here have. Perhaps some day I will try something as well rather than just read of it.

I hope chris does this and ends up kicking the pants off prius numbers, which can be done with a little hypermiling thrown in.

Chris, if you do end up placing a motor/generator/starter where the PS pump used to live, will you keep the alternator?

It would be nice to lose it as well, but, would require added circuitry to maintain 12V functions. I think we have already determined that an electric motor assist should operate at a considerably higher voltage to keep the weight of such components manageable. Leaving the alternator to handle this will save you a fair bit of wiring and componentry.

As for a belt drive system having the torque capabilities to handle this duty, I don't see that being a problem. Ribbed serpentine belts in modern cars can easily power an AC compressor and all the other bits. AC compressors by themselves a fair number of hp.

Thanks it seems you understand my mindset here! lol.

Ok, so I'd probably want to keep the alternator yes, but I could set up a switching system to disconnect it (freely spinning it will hardly consume anything) when cruising or gliding, then reconnect under breaking, low battery voltage or on-demand when I tell it to.

If I put on a motor in place of the power steering pump which I think is the best place for it, then I suppose all I need is to stick a pulley on the end of the motor and bolt it in place. That's the easy part... now how to control it?

Forgetting the wiring, battery power and motor drivers for the minute, I can worry about those later... how should the motor actually perform its task? Should it be made to spin at the same speed the engine is trying to drive it... or slightly quicker? That's the bit I'm not too clear on...

Edit: I have seen an alternator being used as a motor before, could any alternator be converted to perform this task? There is a company near me that refurbishes and rebuilds them, they could perhaps make up one that could do the trick.

[nimblemotors]

I'm all for doing mods. A Prius can get over 100mpg when modded.
I've offered an answer to chris question; the power-steering to motor assist mod it just isn't worth it the effort. Adding a 5th wheel electric drive is my suggestion, can be hidden between the two rear wheels, not ugly tacked on the back like the van pic.

Lighten up the car in a big way would net more gain than a little electric motor assist.

My opinions, do what you want with them, they were free...

Originally Posted by chrisoverson

Thanks it seems you understand my mindset here! lol.

Ok, so I'd probably want to keep the alternator yes, but I could set up a switching system to disconnect it (freely spinning it will hardly consume anything) when cruising or gliding, then reconnect under breaking, low battery voltage or on-demand when I tell it to.

If I put on a motor in place of the power steering pump which I think is the best place for it, then I suppose all I need is to stick a pulley on the end of the motor and bolt it in place. That's the easy part... now how to control it?

Forgetting the wiring, battery power and motor drivers for the minute, I can worry about those later... how should the motor actually perform its task? Should it be made to spin at the same speed the engine is trying to drive it... or slightly quicker? That's the bit I'm not too clear on...

Edit: I have seen an alternator being used as a motor before, could any alternator be converted to perform this task? There is a company near me that refurbishes and rebuilds them, they could perhaps make up one that could do the trick.

[pete c]

There is another thread discussing this very topic where someone brought up the fact that alternators are AC motors, not DC. So, this complicates things. Turning an AC motor gets kinda complicated, especially when you want to do it with a DC power source and control the speed of it. So, I think the way to go is with a DC motor.

As for how fast to turn it, do you mean pulley ratios? I would gear it as low as possible. Figure out what rpm it is capable of and gear it so that it reaches something close to max rpm at engine redline.

I think such a system would allow you to get the considerable percentage of your power from the electric motor at cruise speed. You might even get away with leaning out your fuel/air ratio a fair bit as the motor wouldn't be working all that hard, kind of like honda does with the insight and VX under low load situations.

[pete c]

nimble, your 5th wheel idea sounds interesting and definitely the way to go for pushing you along at mph in a traffic jam, but, would it work at speed? I would think that there would issues with the wheel scrubbing the ground during turns. Did you use some sort of way to get it to steer with turns or do you just yank it up while cornering?

[chrisoverson]

Originally Posted by pete c

There is another thread discussing this very topic where someone brought up the fact that alternators are AC motors, not DC. So, this complicates things. Turning an AC motor gets kinda complicated, especially when you want to do it with a DC power source and control the speed of it. So, I think the way to go is with a DC motor.

As for how fast to turn it, do you mean pulley ratios? I would gear it as low as possible. Figure out what rpm it is capable of and gear it so that it reaches something close to max rpm at engine redline.

I think such a system would allow you to get the considerable percentage of your power from the electric motor at cruise speed. You might even get away with leaning out your fuel/air ratio a fair bit as the motor wouldn't be working all that hard, kind of like honda does with the insight and VX under low load situations.

Hmm, well I had planned on making the car run lean anyway. I might need to incorporate EGR with that to offset the higher emissions though.

Ok I didn't realise that about alternators, so it would have to be a DC motor in that case then . I didn't mean the pulley ratios etc no, I meant in order to lighten the load on the engine does it basically just have to try and spin the engine at the same speed it was trying to go anyway? If that makes sense... So if the engine is running at 2000RPM then you make the motor attempt to spin the engine at 2000RPM. Or does it have to be slightly faster etc... basically a mechanical/physics question rather than a practical one.

Thank you for your input nimblemotors it's greatly appreciated! I understand the 5th wheel idea is probably better in the end than electric motor assist, but on my part it would probably require less mechanical work and is easiest to install and remove. I know that it won't necessarily give the same benefits as it can't drive the car on just electric but saving fuel around town isn't my main concern as most journeys are to customers houses where fuel is paid for anyway, its saving fuel on longer trips I'm interested in .

[pete c]

chris, the motor will spin at the same speed as the engine, assuming the belt's not slipping. It's just a matter of trying to make it spin a little faster. and during regen braking, a little slower.

btw, i think regen can be had although someone earlier said it couldn't. it's just a matter of a somewhat more sophisticated controller. but, seeing as the electrical stuff is your specialty, i think you can do it.