# SB-III SR Reefer Trailer Conversion from Diesel to Electric



## bobp (Mar 4, 2014)

I posted this elsewhere, but got only just go buy new responses.
lots of folks don't understand DIY, and saving money, making due.

I recently purchased n older trailer 94' model with a side door and roll up door. 
My goal was to use it as an on farm walk in freezer, freezing fresh fruit seconds for use in value added products at a later date...basically using the freezer to buy me some time until i can get to them. 
The trailer seems pretty tight. Engine starts right up, it holds 0 degrees etc. Never tried -10 but is says it will. the compressor is designed as continuous duty. It runs very well, and holds 0° on the cycle on/off mode. 
My question is in regards to an electrical conversion. 
I intend to pull the diesel engine out and replace with a 15-20hp 240vac 1p motor. 
the units 54000 btu max is just over 20hp...32000 BTU is what it says it is at 0 degrees, is 12.58 HP, my thermal load will be small so i don't see me pushing this threshold.

I am an industrial electrician. Wiring it is not an issue.
I contacted my local thermoking dealer, who put me in touch with a dealer in Wisconsin I believe. 
After speaking with them, it's a fairly common issue. He talked me through it. They offer a kit, with brackets etc.... But I'll fab and install myself. The 3ph 15hp motor from thermoking is $950.00, 400$ for the bracket, another couple of hundred for the Controls....
I'm currently looking for a cheaper motor locally. I'll run it off a 1 phase 240/208v 50% derated inverter. 

I've actually done the 1P inverter 3 P motor load for a customer years ago for a piece of equipment that was critical while the 3 phase utility was replaced. Not sure why I hadn't thought of it previously.

Low voltage will be provided via a 120-12v power supply. They're readily available. 

I'll need to install a relay contactor to control the drive input. But it'll be easy enough.

All in all I should get it done for less than a couple of grand. depending on how i can source it...

The Electric motor offers reliability in the form of a constant power supply. That doesn't need the fuel refilled twice a week, at 200.00 + a week. 
And the BTUs per hour produced via Electric motor are substantially cheaper than on the diesel engine. 
Has anyone here had any experience with this type of conversion? 


Insulation question:
I have been giving thought to enhanced insulation. I will build the cross wall behind the 'man door/delivery door' from 4" closed cell IMP, that i've already got, it's got me thinking that I could decrease my thermal losses via adding a layer of the 4" IMP to the floor as well. I happen to posses enough to do this. It's the tongue and groove commercial type. I'd have to deal the edges, and there would be an added step up but it would certainly reduce the losses I would think? The intent here being to cut the freezer space down to the minimum, the doors location is dictating where the wall goes, and i can use the remaining 28' as dry storage. this should increase efficiency, and reduce the workload on the unit.
i can possibly repurpose the isuzu engine for another project. Or sell it...it starts very easy and runs well. it was under a regular PM service program. 

I realize this is in Orthodox to some, but like I said I already own it, i only gave 2300.00 for it. and it'll freeze right now. Its floor is washable, and pallet jack ready..It's just come off the road a couple of years ago when a company shut down. Its in good shape. And I only need to run it 4-5 months a year. 
My 0 year old polar king walk in cooler does fine with this treatment.

I'll try to source locally for most of the parts...

Any advise is welcome and apreciated???

Model SB III SR 32000 btu at 0 degree 
wabash -10 degree frozen transit


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## Darren (May 10, 2002)

It looks like you've covered all the bases. Does the refrigeration unit just dump air into the front of the trailer or is there a duct that distributes the air aft?


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## bobp (Mar 4, 2014)

It dumps into the trailer. There's a vinyl duct that captures some air, like the top 6" of air column, and let's it run back.
By cutting it down to 20' it should hit the wall and boil down and to the sides. If necessary I can add couple fans but I don't believe it'll need it.


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## SpaceCadet12364 (Apr 27, 2003)

It is not hp that maters it is torque. the diesel puts out a lot of torque for starting the compressor. match your torque and you should be ok. Add foam insulation inside and -10 should be doable. They sacrifice efficiency for weight savings on those things.


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## bobp (Mar 4, 2014)

15hp T frame is what's recommend by thermoking, tourque should not be an issue, if it is I'll adjust ramp setting on the drive.


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## coolrunnin (Aug 28, 2010)

Only place I can see improvement on your plan is the roof, I would put some kind of over roof with air space between built and trailer roof and add insulation up there. The rest of your plan is really well thought out.


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## AbnersFarm17 (Nov 28, 2017)

bobp said:


> I posted this elsewhere, but got only just go buy new responses.
> lots of folks don't understand DIY, and saving money, making due.
> 
> I recently purchased n older trailer 94' model with a side door and roll up door.
> ...


I was wondering if you ever got this worked out. I would like to do this to my reefer trailer as well


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## bobp (Mar 4, 2014)

Well I have all the components except the Motor...But I'm working on it...I'm cheap by nature lol I'm looking for a deal. I had one found on CL on a HYD pump skid but waited too long..And missed it.
It's very doable... I just gotta get it done. 
I have the material for the cross wall...Need to get it done too. 

I guess I just need to get my butt in gear huh...

What brand do you have?


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