DIY electric water pump - on the cheap - Page 7 - Fuel Economy, Hypermiling, EcoModding News and Forum

oil pan 4 · 05-20-2015, 10:30 PM

You could make a dedicated 16 volt water pump battery and that just might drive it fast enough. Maybe switch it between 12 and 16 volts as it comes up to operating temp.

I don't know if I am going to use an electric water pump on my next engine build because I would like to do an alt delete and it will already have an electric fuel pump sucking down power.

Daox · 05-21-2015, 09:38 AM

I really don't want to mess around with a higher voltage battery just for the water pump. If I do that I'd like to whole car to run off the higher voltage. I considered getting some Leaf cells to do this, but have since axed the idea since my lead acid deep cycle is brand new. Next time!

If your going with an alt delete I don't see any reason not to do it unless you don't have enough battery capacity. My commute is pretty short (7 miles), and my capacity is more than enough for a few more amp draw. If your water pump is pulling THAT much power, its all the more reason to get it off the engine and on to the battery IMO. You'll only see that much more fuel mileage because of it. If your water pump is pulling too much power, then its time for a smarter controller IMO which is why I'm doing the arduino controller. I anticipate this thing only pulling about 50W max.

Daox · 05-21-2015, 01:18 PM

I started messing around with designing a pulley for the motor. Most of you probably know I have a 3d printer by now. So, I wanted to use it to print a pulley which would be infinitely easier than attempting to cobble up something from used parts, and infinitely cheaper than having something machined. The main problem is its made of ABS plastic which is nowhere near as strong as metal. It also can't hold up to engine coolant temperatures (starts to soften around 175F I believe). So, those design constraints will keep things interesting. But, I have come up with what I think is a good and simple design.

The motor has a D shaped shaft end as shown in the picture below. I need to be able to clamp the pulley down so it rotates with the shaft as well as doesn't move front to back on the shaft. My best thought was to embed a small bar of metal in the plastic pulley to give me something solid to clamp to (with the nut that threads on the shaft), and also distributes load so the plastic will not fail. The bar is bolted to the back of the pulley with two #6 screws. The pulley will fit relatively tight on the shaft, but the nut clamps the metal bar to the shaft where the D shape stops, so it carries most of the load.

MetroMPG · 05-21-2015, 05:42 PM

Nice. I like how the bar insert spreads the load plus mates the pulley to the motor shaft.

What about the plastic material characteristics around heat? Water pumps pump hot water you know.

sheepdog 44 · 05-21-2015, 07:12 PM

Just do what Bruce does on this forum. He has a deepcycle in his trunk, and in his back seat, and a Lithium voltage booster etc etc.. He charges them all up off the grid Which is more efficient than from an engine..

Daox · 05-22-2015, 10:29 AM

Quote:

Originally Posted by MetroMPG

Nice. I like how the bar insert spreads the load plus mates the pulley to the motor shaft.

What about the plastic material characteristics around heat? Water pumps pump hot water you know.

Yeah, the water pump will be an interesting one. Wikipedia says ABS is good to 176F, other sources I've seen say its good to 190F. That is a huge difference when your engine runs at 185-190F. I may just bolt a pulley on it and see how it does.

If it softens I do have a couple backup ideas. That first idea is to make some sort of aluminum heatsink plate and/or insulator between the pulley and the water pump. I imagine the heatsink would look somewhat like a front brake rotor with an internal centrifugal fan design to keep it cool. If that isn't enough, I can add an insulating plate (nylon cutting board) between the pulley and heatsink and I'm pretty sure that would work out very well. Perhaps just the insulator would be needed? I'm not sure yet. Here is a visual example of what I'm thinking about.

Another idea I've used before is to make a mold with the 3d printer. With the mold I can pour a 2 part urethane part. The urethane can hold up to engine temps without any problem at all.

Daox · 05-22-2015, 10:31 AM

Quote:

Originally Posted by sheepdog 44

Just do what Bruce does on this forum. He has a deepcycle in his trunk, and in his back seat, and a Lithium voltage booster etc etc.. He charges them all up off the grid Which is more efficient than from an engine..

The voltage is fine with the deep cycle lead acid battery I'm using. In order to get the RPMs I will be changing the pulleys.

Daox · 05-22-2015, 12:54 PM

I tried printing out a section of the belt last night. I was a failure.

I had planned on using a multi-rib v belt just like the car originally came with. However, printing a pulley with ribs on its face is a real trick because the printer can't print at angles lower than 45 degrees off horizontal without putting support structure in place. Well, these rips are 10 degrees off horizontal. So, it printed support structure and it was nearly impossible to remove being wedged between the vs. I'll get some pics to show what I'm talking about.

So, this morning I talked with a friend at work who also has a 3d printer. I told him what I was doing and we talked about doing the pulley in a few different pieces. Then, he suggested changing belt types to a cogged belt or timing belt. This makes 3d printing a lot easier since the ribs go the opposite way.

So, I'm planning on switching to a Gates GT3 style synchronous belt. The new belt will be cheaper. It'll also be smaller and more efficient.