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Old 07-22-2015, 12:14 AM   #1 (permalink)
oil pan 4
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Staying cool with out air conditioning

I would like to build a modular seat cooler. Modular for 3 reasons, one I don't want to build it all at once, I want to be able to use 1 in multiple vehicles and 3 some part of this rig may start leaking (yes it will be full of liquid).

This is using targeted ice and water to stay cool.
The numbers say it could work.
10lb of ice will require some where around 1,440BTUs to melt all that ice. Then require an additional 100BTUs to warm the water from freezing to the minimum useable cooling temperature which we will say is 42'F.
So 10 pounds of ice gives us an number we will just round to 1,500BTUs.
At rest I believe a person puts off something like 400 BTUs per hour at rest and 500 to 600 per hour walking around.
So in theory you could cool your seat for a few hours with 10 pounds of ice (plus some added water to start the heat transfer).
That should work great if you were only trying to cool your back and bottom.

This device will be powered by very small amount of intermittent 12 volt vehicle power and the ice will obviously be frozen elsewhere.

The description will start behind the scenes moving to the outer covering. From the cooler, pump, controller to plumbing and what covers it.

For my cold reservoir I have an old tall narrow party cooler with its lid broken off that would be perfect for this. I want it tall because I would like to attach the pump to the cooler and it would be advantageous to put the pump hardware above the water line. I would like to maybe put the pump inside the cooler for added sound control.
It even has a drain plug for easy removal of spent ice.

The pump I want to use will be a sureflo diaphragm pump. These surflow pumps typically produce 1 to 2 gallons per minute up to 60psi and draw 2 or 3 amps. This system should operate at less than 15psi.
The pump has a built in adjustable pressure switch that I will set low to turn off the pump in case of a pinched main line.

The controls, 2 gallons per minute is just about the entire mass of the cooling reservoir so there is no need to run the pump continuously. Plus the pump will hopefully be inside the cooler so it doesn't need to put off any additional heat.
Good news is there is something specifically designed for a 12 volt application to cycle a pump on and off. Its called a adjustable livewell timer. It cycles a boats live well air pump or live well water pump on and off to save battery power and keep dinner alive.
These timers typically run for 30 seconds, then stay off for a variable amount time, that can be set from a few seconds up to 5 minutes.
30 seconds on and a minute or 2 off should be more than enough.
So simple a drunk redneck can wire it up and get it correct, first try.

To get the cool water from the cooler to the seat I was going to use 3/8'' silicone heater hose I have left over from another project. Its very plush, flexible and kink resistant.

To get the cold water to person interface going I am going to use 4mm lines under the seat. The collector lines will be 7mm and the cross lines will be 4mm. They are thin, you can sit on them and not even feel them and I have like 30 feet of soft made in Germany 4mm soft PVC line.
Run the water in parallel loops using these:

Tie the lines and tees to a plastic mesh backing with some padding.
I will have to pick up some odd size 7mm line and that's about it.

To cover it I was going to take the zip up cover to one of my dogs beds, wash it a few times and use it. Its already the correct size, shape and material.

We are pretty sure this doesn't work:

We must salute dremd for paving the way for how to do this, 7 years ago. Here:

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1984 chevy suburban, custom made 6.5L diesel turbocharged with a Garrett T76 and Holset HE351VE, 22:1 compression 13psi of intercooled boost.
1989 firebird mostly stock. Aside from the 6-speed manual trans, corvette gen 5 front brakes, 1LE drive shaft, 4th Gen disc brake fbody rear end.
2011 leaf SL, white 240v evse mod, trailer hitch, new batt as of 2014.
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