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thingstodo 12-11-2011 01:15 AM

SalvageS10 Build Thread
 
I guess it's time to start a thread.

The SalvageS10 is a 1991 chevy S10. It'll be a proof of concept - proof to my wife that I can finish the thing, proof to myself that the concepts are sound and I really can do direct drive with no transmission. When the proof is done, perhaps I can put some money into a more reliable donor vehicle that I can use as a daily driver. If the SalvageS10 makes it into service as a daily driver, it will likely need to be a hybrid to get the necessary range.

My commute is 30 miles each way, highway driving with 5 corners, each 90 degrees with a yield or stop sign. The posted speed is 100 kph or 62.5 mph but I need to be able to drive at least 70 mph to keep from being run over.

I may be able to convince my boss to store the lead-acid batteries for a high-power charger at work ... we'll see.

The SalvageS10 will be guided by a couple of concepts:
- make it safe
- make it cheap

The next few posts will deal with some of the high-level ideas. I also have some research stuff that I'd like to do with this project. I want to know more about electric motors and how they work. This is how I intend to find out.

I know that Jack Rickard will be disappointed with this build - it will be powered by lead acid. As pricing comes down, and my expertise goes up, that may change.

MPaulHolmes 12-11-2011 01:26 AM

Are you thinking of a series hybrid? Like a high powered charger and generator to charge the batteries onboard?

thingstodo 12-11-2011 01:34 AM

Salvage S10 high level design
 
My desire is to remove as much mechanical stuff as I can:
- ICE engine
- automatic transmission
- radiator
- gas tank
- exhaust system

The main parts of the conversion are targeted to be:
- direct drive from 1770 rpm 40 hp 3 phase 575 Volt electric motor to the 3.43 rear end
- Industrial VFD mounted in the front portion of the cargo box, with heat sinks bolted to the box frame, 302 amps at 575 VAC continuous
- Industrial computer mounted in the back seat of the extended cab to control the VFD, interface to the truck sensors, and control the charging

thingstodo 12-11-2011 01:44 AM

Quote:

Originally Posted by MPaulHolmes (Post 274255)
Are you thinking of a series hybrid? Like a high powered charger and generator to charge the batteries onboard?

It would be a series hybrid, if I can't carry enough batteries to make 30 miles reliably. I have a vertical Kohler 13 HP as well as an 8 HP horizontal Briggs & Stratton that could be cleaned up and put into service. It would need to be a belt drive arrangement to an induction motor (in the 5 - 10 hp range) and using another VFD to create the appropriate output voltage.

That's something I've checked out, it works.

thingstodo 12-11-2011 02:43 AM

Batteries and Power in general
 
I am undecided on how to tackle THE central question of EVs - the batteries.

I have a line on some larger lead-acid batteries (no, I don't have details yet. I don't have them yet) that are regularly 'traded in' for a core charge when they can no longer last half a shift - 4 hours.

The GVRW limit for the truck is 5200 lbs. 1411 lbs listed as the payload.

If I add me - 250 - and make some assumptions about the weights of the stuff that is removed - I have about 1300 lbs for power. That includes the batteries and any power electronics on them as well as the cabling.

1300 lbs, at 150 - 200 lb per battery. Let's say around 96 VDC. I may be able to modify the VFD to run on a lower voltage. The motor would need to be properly matched to work well. 208VAC is about as low as our industrial motors go, and 30 - 40 HP at 208V three phase is not common.

So I'm looking at using a DC-DC converter on each of these large batteries, boosting the 12V up to around 150 VDC. I can use these converters, and chain the converters together in series to boost the voltage but it is inefficient. Around 85% - which makes for a lot of heat to get rid of and a lot of valuable battery power.

Still to be determined

MPaulHolmes 12-11-2011 04:10 AM

Wow this is going to be good! Totally outside of the box. I can't wait to see it come together!

JasonG 12-11-2011 01:33 PM

Looks interesting, like Forkenswift goes pick-up.

You will need higher voltages for the motor and VFD. The motor will run much better on 240 or 480.
This also will reduce you component sizes due to lower amps. Problem is the DC bus voltage on a 480 VFD is around 670VDC !! Most wire is only rated for 600V, but going to 1000V MTW is cheaper than going to larger diameter cables. JUST BE CAREFULL !! High voltage DC doesn't play and will kill you quickly.
Going with 240VAC will drop your bus to 338vdc, much more manageable but at twice the amps to deal with.
Either way, 96VDC isn't going to cut it. 60 some VAC motors don't really exist. A 120V motor will run on it, but will have very low torque.

I look forward to this build.

thingstodo 12-11-2011 02:12 PM

Quote:

Originally Posted by JasonG (Post 274297)
You will need higher voltages for the motor and VFD. The motor will run much better on 240 or 480.

Agreed. I'll be using as high a voltage as I can reasonably get. 600 VDC is as low as I'd like to go. The VFD shuts itself down on overvoltage at 965 VDC.

Quote:

Originally Posted by JasonG (Post 274297)
Most wire is only rated for 600V, but going to 1000V MTW is cheaper than going to larger diameter cables. JUST BE CAREFULL !! High voltage DC doesn't play and will kill you quickly.

The wiring I'll be using is industrial, rated for 1000 VAC. And if I know me, it will be a size or two (perhaps 3) larger than it needs to be. Whatever size I can fit into the lugs and the terminals.

If I'm using DC/DC converters, the high voltage will be somewhat isolated. The DC/DC converter isolates from the input battery voltage to the higher output voltage. The terminals of the DC/DC converters over to the VFD should be the only high voltage 'bus'. Liberal use of fuses (which are not cheap, unfortunately) should limit the damage if a wrench falls where it should not. The DC/DC converters have a rated output current, which is 10 or 100 times lower than the current available at the terminals of a battery string - so I should not vaporize the wrench, or weld it to the terminals.

I have no reasonable way to limit the high voltage current that I am exposed to during a shock to under 4 mA (if memory serves) - the 'safe' limit for the human body according to my Arc Flash documentation (NFPA 70E for the USA, CSA Z462 for Canada). If anyone has suggestions, please let me know.

Quote:

Originally Posted by JasonG (Post 274297)
I look forward to this build.

Me Too! Creating a build log is a way to give myself some incentive to get off the couch and do something.

We'll see if that's successful.

Ryland 12-12-2011 03:40 PM

Quote:

Originally Posted by thingstodo (Post 274258)
It would be a series hybrid, if I can't carry enough batteries to make 30 miles reliably. I have a vertical Kohler 13 HP as well as an 8 HP horizontal Briggs & Stratton that could be cleaned up and put into service. It would need to be a belt drive arrangement to an induction motor (in the 5 - 10 hp range) and using another VFD to create the appropriate output voltage.

How about having a gas engine that is on a direct drive to the drive shaft that is going to the rear axle? use a centrifugal clutch so that it spins free when the engine is not running and have it geared so the engine is running at it's max RPM when you are going 65mph or whatever you want your top speed to be, that way you extend your range while driving on the highway, you also keep it really simple and you don't have the losses from going mechanical to a generator to a speed controller to a motor to the wheels.

thingstodo 12-12-2011 05:00 PM

Hybrid ideas
 
Quote:

Originally Posted by Ryland (Post 274465)
How about having a gas engine that is on a direct drive to the drive shaft that is going to the rear axle? use a centrifugal clutch so that it spins free when the engine is not running and have it geared so the engine is running at it's max RPM when you are going 65mph or whatever you want your top speed to be, that way you extend your range while driving on the highway, you also keep it really simple and you don't have the losses from going mechanical to a generator to a speed controller to a motor to the wheels.

Thanks for the input. I think that setup would be a lot more efficient.

There are a couple of implementation issues.

My present plan for the electric motor is a taper lock that increases the 2.125 inch motor shaft to the 3 inch inner diameter of the drive shaft. The motor is suspended by the normal foot mounts from a pivot on the truck bed frame and the drive end bearing of the motor supports the stub of the drive shaft to the u-joint, before going to the rear end.

This is as simple a connection as I can come up with so far. I'm not mechanically inclined.

My available gas engines all have much smaller shaft diameters and would be challenging to mount between the electric motor and the rear end. Since the engines are much lower horsepower, they may not take the flow-through power.

If the centrifugal clutch was on a belt-driven pulley that was mounted on part of the existing drive shaft, I think more bearings would be required? I make the assumption of belt drive. Would that be a belt or a chain drive? I looked briefly into a chain drive and was told, by someone much more knowledgeable about power transfer than I am, that a chain is not suitable for the speeds involved. He suggested a high speed synthetic belt that did good power transfer, isolated vibration pretty well, and was quite tolerant of getting wet. The problem was the price. The belt itself was over $500, 900 with the shieves (pulleys?).

I know I've got a LOT of losses planned with ICE -> induction motor -> VFD -> DC bus. I just happen to solve most of my issues electrically and minimize mechanical stuff that I need to get help with. We go with what we know.


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