MoTeC Global Forum

I currently have an Electric Water pump that I supply 12V to via a relay, the relay controlled via an output from the motec

I want to input a control circuit, having the water pump on half its output until a certain water temp is reached, probably around 75-80deg, then have the WP on full as before

Any ideas?

A simplistic relay circuit would be to input a 2nd relay circuit, having the motec control relay(1) - (half output) -from engine start obtained via a 6ohm 100W resistor in series with the 12V supply circuit

Having Relay(2) controlled via the motec switching on from say 75-80deg providing the pump with the full output (12V/6-7A)on the 2nd circuit and switching relay(1) off, when relay(2) is energised


The only problem I can see here is I'll be using 2outputs - of which I'm lacking already and the fact my voltage output is defined by the hardware(resistor) that I install, I'm not entirely sure yet whether half the output will be sufficient as I still have to test

No thermostat is being used currently, the aim of this circuit is to allow the engine to heat up but to make sure it does not overshoot i.e not overheat before the pump can bring temps under control

I suppose for test purposes, I could use a pot to find out exactly how much resistance and therefore voltage is needed before the temps overshoot

I do not want to have the Water pump completely off until I get to temp as I've been told that heat spots in the engine can appear very quickly with no flow

I also intend wiring a third circuit to the pump with a manual switch so I can have the WP on whilst I'm cooling my engine trackside with ign off

Hi Bolarbag

here in the UK we use solid state relays that can switch at frequencies and duty cycles

to give a wide control of water pump speed using 1 output from the ECU,

ie
stage 1 at first ECU power up the pump is run at full speed for 3 seconds
stage 2 water temp is controlled by the speed of the water pump, 2 axis table in ecu, et & ground speed, with
a minimum speed to prevent hot spots
stage 3 the ECU is wired for power hold and the water pump is run after engine shut down to reduce heat soak

hope this helps

Steve

GWR Motorsport

As stated by GWMOTORSPORTS

this is a PWM circuit with adjustable base frequency and then duty cycle dependant on the input.

The tricky part is the input based duty cycle control.

Luckily for us, the MoTeC has it built in!

Using a solid state relay

http://www.hongfa.com/products/chp.php? ... sp_type=02


then on the Mx00 series ECU.

Assign PWM Idle Control (#2) to one of the aux outputs.

Then assign the output mode according to how you wired it (Switch to Ground or Switch to battery).

On the table assign Engine Temprature as a X axis and then (as an example)

0-60 degree C = 50
61-100 degree C =100


Done!

It will PWM the solid state relay and basically do speed control on the water pump for you based on temprature!

Hella make a solid state relay that fits into a standard relay socket

Hi Sprinter,

Have you got a Part # or any link to this product?

H41773001

Many thanks guys, exactly what I was looking for

That should teach me to consult with my hardware guys before trying to come up with a solution;)