# Planning Tacoma Hybrid Conversion



## a8ksh4 (Nov 13, 2014)

Hi All, this is something I've pondered over for years... I'd like to "bolt up" an ac motor to my daily-driver truck for electric assist and regen to improve fuel economy. I get about 25 mpg normally, but when I've worked hard at the hypermiling, I've been able to average at about 35 mpg. My truck is a '99, 2WD, 2.4L with 230k miles and is well maintained & runs beautifully.  

At this point, I'm just doing feasibility research to entertain my brain, but any advice you have to offer is totally appreciated! Maybe some day this project will be a reality! 

I figure the two ways to do this would be to either put the motor behind the transmission, in the driveline, or to purchase a 4wd transmission and couple the motor to the front driveline coupler on the transfer case. The latter would probably add unnecessary drag onto the whole system, so maybe it's not such a good idea. 

Given my tire sizes and diff ratio, a motor in the driveline would only be spinning 2371 RPM at 60MPH... I'm not sure what this does to my motor selection, as it probably needs to be big and torquey to work at low speeds in this configuration, or if it's small will only push/pull well at high speeds. As far as price->weight->power go, the AC-35 I saw on ebay a while ago looks good, but I think they're wound to peak at much higher RPM. Any advice here? 

I'd like to be able to use the motor for driving slow around town, so I might need a 3:1 gear coupling to get the RPMs up? If I had a ~15 mile electric range, I could run errands around town without burning petrol. At 4k lbs, I'd likely need 400 watt-hours per mile, so 6kW or larger battery? 

*Potential Parts List:*
* AC-35 Motor - $1k
* Crashed Volt Battery pack, or equiv - $1200?
* Home-brew ReVolt AC controller - $800 (maybe less... I think the prototypes all use really big IGBTs...)
* Mounting Hardware (sheet metal and structural steel) - $200
* Fuses, cables, and other electronics hardware - $200?
* Drive Shaft Couplings - $400?
*Total: $3.8k + 25%a slush => $5k-ish* (I'd really like to find somewhere to reduce cost here...)

As far as capabilities go, I can cut, grind, weld, solder and work out designs in cad. I don't have any machine shop experience, although a friend may have access to a shop if needed...


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## major (Apr 4, 2008)

a8ksh4 said:


> I'd like to "bolt up" an ac motor to my daily-driver truck for electric assist and regen to improve fuel economy..


Hi a8,

Welcome to the forum. Hybrid DIY converts ain't too common. In fact, I can't think of any successful attempts. It is a lot harder than what it appears. It will be more expensive than you think and almost certainly result in greater fuel consumption, not less.

I suggest you start your EV adventure with something basic. Maybe even non-road-going. Keep the cost and complexity low until you become better versed in the hobby 

Regards,

major


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## a8ksh4 (Nov 13, 2014)

Probably sage advice. Talking to a friend yesterday, he recommended just buying a toyota highlander or something as it would probably be cheaper... but my petrol-only rig already gets better milage than the (big heavy) hybrid SUVs (making an assumption here). 

Looking around a couple days ago, I found this build, a chevy avalanche. They claimed %15 improvement (lol, 15mpg -> 18mpg) using a dc setup, charge at home and assist around town. Similar to some of the commercial solutions I've seen for delivery vans. The cost on this one'll probably never be recouped. 

This is still a thought experiment, so it'd be interesting to identify failure points in any of the other builds. I feel like there's an unmet need in the DIY area for electric rigs that can travel longer distances. 

I'm curious to find if any of the factory hybrids have an electric-enabled differential that also has a driveline input... like the highlander diff, but with a driveline to the trans, too... *googles*


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## Hollie Maea (Dec 9, 2009)

a8ksh4 said:


> I feel like there's an unmet need in the DIY area for electric rigs that can travel longer distances.


It's much more doable to make a series hybrid with a range extender. Putting two power sources on your drivetrain that work together well is challenging. Better to make the drivetrain fully electric, and charge the battery with a small genset. Since you only have to cover average load, you can size your engine way down, and get something that's tuned to run well at a single RPM point. Likewise, your generator doesn't need to be very big, 20kW or so. That needs to be continuous, though, so liquid cooling is probably needed. No motor controller is needed for the genset, so that helps a little.

Not to say this way is easy, but it probably is doable. A DIY parallel hybrid, on the other hand, is very likely to fail. Still, Major's advice holds true--start with something more conventional to get some ideas of what these projects entail.


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## major (Apr 4, 2008)

Hollie Maea said:


> It's much more doable to make a series hybrid with a range extender. ....


Might seem that way, but.... You'll suffer efficiency due to the extra power conversion between the fuel and the wheels. I've heard the argument that the prime converter can be optimized when decoupled from the wheels, but that hasn't proven to be the case with hybrid cars, has it. They're all some sort of parallel system. I believe some city buses used the series approach with limited success.

Also, the series hybrid requires all motive power through the electric drive motor making it larger/more expensive than with a parallel hybrid electric drive where it can be sized for a portion of the duty.

Here again, how many times have we heard the noobie come here and talk range extender? How many have been built? One, or two, in 20 years of which I know, and those had some company resources behind them. Yet where are they today?


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