EWP80 (Electric Water Pump)

coolant temperature is a major factor when it comes to running the engine or not. This is the reason winston's ECT spoofer manipulates just this sensor value. The engine basically runs if the coolant temp is low and or load is requested. at low engine temperatures, the EWP runs the pump slower helping faster warmup. the ECU currently controls the pump via the engine running. Engine temp itself is controlled by a classical thermostat, a radiator and a mechanical water pump. Currently the ECU does not control the mechanical water pump, it won't need to control the electric one. There are pump control strategies beyond what you can achieve with this pump controller, but they are not accessible as we cannot program the Prius ECU. If you would ask me what I would do different programming such a pump controller, I would have little to add.
For a Prius, I'd consider to completely switch the pump off, if the ICE is not running for more than 10 seconds to prevent rapid cool down,.
On the other side, there is already a smaller EWP in the prius running even with the ICE off to provide coolant to the cabin heater.

with the EWP the engine will heat up faster than with the mechanical pump. You're right about conservation of heat. But if you leave the thermostat in the coolant circuit, this won't be an issue, without flow through the radiator, there is little heat loss.



iPad ?

 

since the thermostat impedes coolant flow below a fixed temp, the electric pump might help the ice warm up a little faster. but is it worth the extra expense and hassle of installing it then? with cars, the KISS rule applies. this is why benz's spend so much time in the shop because the krauts don't understand the KISS rule. over complicated solutions to non-existent problems lead to headaches when you have to keep fixing them. is that plastic coolant pump gonna last 100k +? and will you ever get your $400+ back in fuel savings? I don't think so, but then I've been wrong before...

 

Ive, Part of the problem with the Prius is that a normal engine is controlled by the ignition switch deciding if the engine is running or not. There is no easy 12 volt engine running supply available. The Prius engine will turn off while the ignition is on. In this circumstance if the cabin heater requires heat there is another electric pump that is turned on by the AC-ECU to pump hot coolant from the engine to the heater. This pump could be eliminated if an electric coolant pump was fitted to the engine, but it's original supply could be used as a signal to run the new engine pump in those circumstances.
I suspect this is how things work with the Prius C with full ECU control of the pump.
It is quite simple to make a pulse width modulator to drive the motor.
The simple way would be to use a dual 555 timer IC and a FET. One stage of the timer varying the pulse width the second being used for timed over run. All the components for such a circuit could be bought for under £3-$5. There are many other ways of achieving the same result using the Prius OEM temperature sensor.

John (Britprius)

 

by the time you build it all up, I have done such projects a few times, would rather use micro controllers, e.g. from Atmel these days, you will have spend more than $5. Cables, connectors, housing, suplly voltage, relay socket, relays, PCB, fail safety (sensor failure) etc. In my Elise the EWP solves a real problem. In the prius, I agree, it is not worth the hassle most likely. Are that many pumps failing? Are thousands of Prius owners hunted by regular water pump failures?


iPad ?

 

My main aim is not just to replace the pump to make it more reliable but to see if it will save fuel. My thinking is Toyota went this route with the Prius C because it saves fuel not because it is more reliable, and I'm convinced it is no cheaper.

John (Britprius)

 

It would be a nice project.
I have just learned in my many years in industrial R&D that when you can buy something, I usually makes little sense to develop and build it yourself. If bought as a combo, the controller costs some $100 and does almost everything you want.
I would consider developing a small extra controller to disable the pump if the engine stops running for more than 5 seconds. This is less effort indeed. Maybe you can tap into the obi port with a micro controller and read the message for engine rpm. if zero, disconnect the pump via a relay.
Alternatively ill the crank or cam sensor signal. It is inductive, but noting that cannot be solved.

 

I am considering initially of motorizing the existing pump, as an electric motor could easily be attached to the existing alternator mounting point with a short drive belt to the pump. Alternatively a pancake motor driving directly on the end of the pump. If that is successful it would then just be a matter of substituting the Prius C electric pump.

John (Britprius)

 

Are you still into Making a micro controller I know this is an old thread but I’m on or what you’ve done since then I’m having a problem with my GEN three little as a lot of people are GEN three water pumps seem to have issues I’m wondering if if I can’t find a micro controller if somebody hasn’t made something that you could just make it operate independently?

 

The only issue I've noticed anything like "a lot" of Gen 3 people having is where the original pump eventually fails and needs replacement.

But that doesn't seem to be the issue you're having, and scattering the information over all these different threads. It seems you may have done an engine swap, and not all the kinks are ironed out yet, and one of them is some trouble with control of the pump, observed with more than one sample of pump.

Unlike this Gen 2 thread (where the engine water pump was mechanical, and the discussion is about homebrewing an electric-pump retrofit), you've got an engine that was built for an electric pump, you've got the electric pump it was built for, that wants to be controlled, and you've got the ECM that wants to control it. Seems like you're 98% of the way there and it will be easier to press ahead with ironing out whatever kink you haven't corrected yet, so it'll work as designed.