Paul & Sabrina's cheap DIY 144v motor controller

[MPaulHolmes]

Could you tell me the part number for the thing you twisted into the side of the base plate? What diameter mill bit was used? how deep? What sort of pump do you use? I've never tried water cooling before, but I am going to. What type of hose do you use for carrying the water? How did you seal the bottom of the plate?

[Bela]

The plate is 1/2" thick aluminum. From the bottom I milled off 1/16 inch to countersink an aluminum cover over the water channels. The channels were milled with a 1/4 inch end mill and are about 5/16 inch deep, so the liquid is about 1/8 inch from the top of the plate. The spacing between the channels is about 1/4 inch except for the middle which is slightly thicker to allow room for screws to help hold down the cover plate.

Permatex Blue RTV was used to make the cover waterproof:


Here is a picture with the cover plate installed:


The holes in the sides were tapped using a 1/8"-27 NPT tap and the barbs were purchased off Amazon. They came in a pack of 10 and were relatively inexpensive. I think this is the link:
http://www.amazon.com/dp/B008TSWWAG/ref=biss_dp_t_asn

The pump is a Swiftech MCP655-B, which I purchased a couple of months ago when it was on sale. The price has gone up since then:
Swiftech MCP655-B 12 Volts Industrial Pump MCP655-B - Micro Center

The tubing will depend on the fluid but I am planning on using nylon or silicon. I am thinking about using a standard mix of water and car anti-freeze. It gets cold here, occasionally well below 0F, so freezing is definitely a concern.

Unfortunately the controller isn't installed yet so I really can't say if the water cooling works.

[thingstodo]

Originally Posted by Bela

The tubing will depend on the fluid but I am planning on using nylon or silicon. I am thinking about using a standard mix of water and car anti-freeze. It gets cold here, occasionally well below 0F, so freezing is definitely a concern.

Unfortunately the controller isn't installed yet so I really can't say if the water cooling works.

I have been told by mechanically-minded people that water/glycol is the best mix for cooling.

Putting water near electronics makes no sense to me ... do you think mineral oil, similar to the type used for the fish-tank type PCs, would harm the pump or the seals?

[mora]

There are different coolants for different cylinder block materials. I guess you'd have to coolant made for aluminium cylinder blocks.

[Bela]

Originally Posted by thingstodo

I have been told by mechanically-minded people that water/glycol is the best mix for cooling.

Putting water near electronics makes no sense to me ... do you think mineral oil, similar to the type used for the fish-tank type PCs, would harm the pump or the seals?

I had to google fish-tank type pcs. Very cool.

There aren't any holes in the base plate that go completely through from the top to the bottom so it is unlikely that any coolant liquid will get into the box. About the only place it could get into the box is where the ports are on the side of the plate. If they leak and squirt upward it would be possible. However the cooling system is low pressure so most likely if anything leaks it will just drip.

I don't know much about the heat transfer characteristics of various fluids or how they would affect the pump.

One thought was to use the same fluid that is used for liquid cooled PCs however most of them don't advertise the freezing point since that really isn't an issue for PC cooling. They are also fairly pricey and I will need several liters, so standard anti-freeze that is formulated for aluminum seems like a reasonable way to go.

[thingstodo]

Originally Posted by Bela

There aren't any holes in the base plate that go completely through from the top to the bottom so it is unlikely that any coolant liquid will get into the box. About the only place it could get into the box is where the ports are on the side of the plate. If they leak and squirt upward it would be possible. However the cooling system is low pressure so most likely if anything leaks it will just drip..

I was thinking that the coolant would have to be the same for ALL of my liquid cooling/heating needs - controller, motor, battery pack, cabin heat/cool

Of course, you get splash from the road into the engine compartment, battery compartment, etc .. you drive through puddles .. there needs to be weather sealing done on everything. Perhaps using oil instead makes no sense at all and that's why no one does it.

I will likely try mineral oil cooling at some point, on some small scale, to see if it works at all .. but that is not likely to be done soon ..

[MPaulHolmes]

Thank you so much Bela!!! I'm going to order some of that blue RTV stuff. I have people helping me that know so much more than I do about so many things, and I really appreciate it!!!! You made that liquid cooling thing look easy. How did you drill the side hole? Was it just with a hand drill?

What radiator should I get? Does the radiator act as the "reservoir", or do you need one of those too? anyone have suggestions? I really don't know what I'm doing when it comes to the mechanical side of things.

[thingstodo]

Originally Posted by MPaulHolmes

What radiator should I get? Does the radiator act as the "reservoir", or do you need one of those too? anyone have suggestions? I really don't know what I'm doing when it comes to the mechanical side of things.

+1 on "don't know what I'm doing when it comes to the mechanical side"

Every EV radiator installation that I have seen has a reservoir as well. It appears to be important.

[Piotrsko]

Most people use a tranny cooler which can be had fairly cheap at discount auto parts places. Salvage pc fan or two, violah. Or if your into car bling..... some all in one kits for $$$$$$

You can go convective or buy a $10.00 fleabay pump. About $10 for a windshield washer tank & pump at pick n pull. I like drip systems for plumbing bits.

Reservoir isnt necessarily used if the cooler is not leaking and you purge system of air bubbles.

5050 premix of whatever coolant you have around as most have additives for aluminum components anymore. Hard to get an iron block today.

[Bela]

Originally Posted by MPaulHolmes

I'm going to order some of that blue RTV stuff.

The blue RTV was available locally at my auto parts store. I think it is a common item.

Originally Posted by MPaulHolmes

How did you drill the side hole? Was it just with a hand drill?

What radiator should I get? Does the radiator act as the "reservoir", or do you need one of those too? anyone have suggestions? I really don't know what I'm doing when it comes to the mechanical side of things.

For the side hole I clamped the plate to a table and then carefully drilled it by hand. First I used a small, maybe 1/4 inch drill bit and then kept drilling larger and larger holes until it was the right size to tap. I supported the drill on the bottom too to make sure the it was stable and straight.

I like Piotrsko's solution of using a tranny cooler and using standard radiator fluid. This isn't my area of expertise but it is my understanding that it is best if you don't mix metals. So, since the base plate for the motor is aluminum then the radiator should also be aluminum.

A reservoir is in the works. Almost any liquid tight container should work but for cosmetic reasons I am building a custom reservoir out of an acrylic tube and 2 aluminum endcaps.