Electric coolant pump speed controller

[oil pan 4]

The electric pump is working. Its actually working too well.
To make it less effective all I need to do is cut its voltage.
The cheapest, simplest most reliable I can think of is to use pure electromechanical controls.

I also use the electric coolant pump to circulate coolant with my http://ecomodder.com/forum/showthrea...9-a-32503.html.

My Meziere coolant pump moves 55gpm and draws 7 amps. That is way more than I need during winter.

Right now the pump is wired through a 1 ohm 300 watt resistor. That drops the voltage across the pump down to 9.6 volts and 4.6 amps. The standard Meziere pump moves 35gpm and draws 5 amps. So my guess is the big pump on a resistor moves close to the same coolant as the standard pump.
On the cool winter days the coolant temperature still only gets up to about 160'F with reduced pump speed.

So I ordered a 2 ohm 300 watt resistor. I could have ordered a second 1 ohm resistor but they are the same price and same size.
Hopefully this further drops the pump voltage to close the minimum recommended voltage of 6 volts. The resistor arrived today, hopefully I will get to test it in the next few days.

Then I still need to get the pump going when I plug in the 5500 watt coolant heater. I can do this 2 ways.
1 way is to wire in a 120VAC relay and use this relay to switch on a pump and resistor circuit. But I figure, why drain the battery when I have a high voltage source on tap.
2 wire in 1 or two 277v emergency light transformers with rectifier to turn the pump when the 240 volt heating element is powered up. I have these transformers, just need to wire them up and test them.
I would like to power the pump with external power so it does not drain the battery and so that the pump automatically turns when the coolant heater is on.

These 277 volt transformers should have a turns ratio of 17:1. So on 240 volt power it should produce about 14 volts AC which is a little low, but should work. For a typical "12 volt system" you want to see up to about 16 volts AC on the secondary side of the transformer. These were free and should work so they will be used first.

The control logic for a cold start will be 30 second time delay for all pump power. Then energize a circuit that will send power to the pump through the 2 ohm resistor. When the pump reaches 100'F to 120'F then a switch will activate the 1 ohm pump circuit. Next use a 170'F to 180'F switch to activate straight pathway for power to the pump.
All these pump circuits will be ran through relays, the switches will control the relays.

Any of the temperature switches being activated will bypass the start up delay and the 277 volt transformers will be wired straight to the pump.

[oil pan 4]

Since winter is here I am more interested in getting the coolant heater circulator setup going.

This part of the speed controller rig will power the pump with external 240 volt power when the coolant heater is powered up.

The high voltage side of the pump controller is starting to take shape.
With the 277 volt primaries running off 250 volt power the transformer produced 15 open current volts.
I tried one 277 volt transformer wired straight onto an old head light with no bridge rectifier. It produced 9 volts at 2.5 amps and didn't heat up as much as I thought it might.
Then I put 2 transformers in parallel, 12.5 volts at 2.5 amps.
Seems like it should work, just as I was thinking it would.

All they need to do is turn the pump and not burn up.
So I put a bridge rectifier on the transformer secondaries and some alligator clips on the bridge rectifier - and +.
Then I unplugged the pump and put the bridge rectifier alligator clips on the plug prongs and plugged it in. It was trying to draw 5 amps at 8.6 volts of pulsed DC, until the bridge rectifier heated up.
This is only the prototype to obtain proof of concept using junk I have laying around. And it works. This is far from finished.


This is the rig while it is powering the coolant pump. The bridge rectifier was really heating up. I have a box of heat sinks and a tube of paste, so this wont be a problem.



If it looks dangerous, that's because it is. Yes that's a clothes dryer cord.

I will use a 120 volt relay to isolate the pump circuit while the high voltage is going so I don't back feed what limited DC power the pump has going to the rest of the electrical system.
I want to be able to plug the coolant heater in, go back in side where its warm and just leave the coolant heater and coolant pump to do their thing.

[oil pan 4]

I attached the 2 ohm resistor with the wires off the 1 ohm resistor just to see what would happen. It was reading 5.3 volts at 3 amps.
The pump was moving a steady but slow stream of coolant through the bypass. Maybe 1 gallon per minute. That would work fine for cold starts but I worry the pump may bind on start up. That is a little too slow for comfort.
I knew that would drop the voltage across the pump down to 5 or 6 volts. This is with engine off at about 12 to 13 volts.
Now if this were normal 14.4 volts I think it would be fine and be at or above 6 volts, but this needs to work under the conditions of an alternator delete.

I went ahead and ordered a 54 watt 1.5 ohm resistor.
That should drop pump power to about 7 volts at close to 4 amps.

[RustyLugNut]

Originally Posted by oil pan 4

I attached the 2 ohm resistor with the wires off the 1 ohm resistor just to see what would happen. It was reading 5.3 volts at 3 amps.
The pump was moving a steady but slow stream of coolant through the bypass. Maybe 1 gallon per minute. That would work fine for cold starts but I worry the pump may bind on start up. That is a little too slow for comfort.
I knew that would drop the voltage across the pump down to 5 or 6 volts. This is with engine off at about 12 to 13 volts.
Now if this were normal 14.4 volts I think it would be fine and be at or above 6 volts, but this needs to work under the conditions of an alternator delete.

I went ahead and ordered a 54 watt 1.5 ohm resistor.
That should drop pump power to about 7 volts at close to 4 amps.

You can purchase ready made units for not a lot of money and kits come for a few dollars. Pulse Width Modulation allows your DC motor to provide relatively high torque while controlling speed. I use simple model train units driving a larger MOSFET in saturation. You can spec your MOSFET to fit your needs.

The chopper circuit is also much more efficient than absorbing part of your power with resistors.

[oil pan 4]

I will try the a PWM controller.
I liked the resistors because they could stay under the hood.
The PWM controller might not care for the heat.
I ordered a 4 pack incase I fry some.

Also picked up some 0 to 60 second time delay relays. That way the engine is not cranking while the pump is trying to run, PWM controllers may not like that.

Only problem I see is these pwm controllers need 12v, with an alt delete system volts may drop below 12 volts some times.

[oil pan 4]

I went digging through my junk collection and refound a 24vac 50va 240/480 volt control transformer hooked up to run 240.
This is a big improvement over the 277 volt emergency light transformers because I was running them at about 20va each, I think they were only rated for 10 to 15va.
All I had to do is connect the link bar to convert it to 480v, hook it up to 240 and it will put out "12 volts".

I tested the control transformer configured for 480, being ran off 240 and it produced 13.3vac which is perfect for what I need.

Hooked the transformer with rectifier up to the coolant pump it produced 7.6 volts at 3.8 amps of pulsed DC, which is perfect.

[oil pan 4]

I went with the larger transformer and put a heat sink on the rectifier.
Then ran the pump with it for a half hour.
Max run time is expected to only be around 20 minutes max.

Warm transformer:


My standard heat sink configuration. The heat sink on the out side of the housing and the rectifier stuck to the heat sink through a hole.




I use heat sink paste between the rectifier and heat sink then seal the heat sink to the plastic enclosure with RTV. I do not use RTV as heat sink paste.


The transformer and heat sink are already attached to their enclosure. Now all I need to do is add gland type strain seals to let the wires in and out and wire it up.

[oil pan 4]

The PWM controllers came in finely.
DHL takes forever.
The main tests for these will be is if they work at slightly under 12 volts.

[oil pan 4]

I tested the PWM controller down to 10.5 volts.
It works great.
Need to test it down to around 9 to 10 volts next.

At 6 volts the coolant pump was drawing 3.3 amps.

[oil pan 4]

I was digging around in my electronics stash and found a DC to DC voltage booster. I had forgotten about these.
According to the Meziere manual their pumps can be used on 16 volt systems.
So I wired the voltage booster to the pump and turned it up to 16 volts. The pump ran real hard drawing 10 amps.
I figure I could use this in the summer when its real hot out and the coolant temperature starts to get too high when towing or something.

So the operational voltage range will be between 6 and 16 volts, favoring the lower range during the cooler months and during warm up.