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MoTec PDM30 and Davies Craig EWP Integration

Practical Motorsport Wiring - Club Level

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Hey guys,

Sorry, another newbie question from me regarding the MoTec PDM30.

I've got a Davies Craig EWP130 and am trying to figure out how best to run it through the PDM to eliminate the 2 in line fuses it comes with. It has a 15 amp fuse in the main 12v feed to the pump controller which seems straight forward enough in terms of using a 20 amp output from the PDM to power the controller.

Where I get stuck is the 15 amp in the power feed from the controller to the pump itself. I haven't been able to find ot documented anywhere whether I can run this wire from the pump controller to an input on the PDM, then from an output on the PDM to the pump in the engine bay?

Sorry for all the silly questions but you guys have been a big help so far.



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You can't run a signal through the PDM. It only controls power from it's single input to the output pins. The digital inputs are just for control, they don't get shared except logically. I would either leave the fuse between the controller and pump in place, or just eliminate it entirely.

You can Power the controller for the pump off the PDM< but will need to keep the fuse between the controller and the pump.

I would recommend keeping the pump controller instead of trying to control the pump any other way. Davis Craig have developed a very specific control strategy for their pumps, and there aren't many products on the market that can replicate it.

Thanks heaps guys.

I'm thinking it would potentially be unwise to eliminate that fuse altogether?

Shame though as it'll quite literally be the only fuse in the whole loom.

Cheers for all your help again, apologies if these questions seem dumb..

Sorry I'm a little late to the party here guys, but this is how I'm wiring mine - I'm not keeping the inline fuse, the PDM provides sufficient protection for the pump.

I am using a double pole relay controlled from the PDM to bypass the controller, I can turn this on and off using the keypad. Figured this would be handy if the controller died for some reason I can still just run the pump full time. I've had it hard wired like this in the past because it allows me to run the pump manually for bleeding etc. The rad fan output feeds a DSI, which I use to trigger the fan output. I can also bypass this using another button on the keypad if I choose to.

EDIT: I'll add that my pump loom never came with a fuse on the actual pump wire from controller to pump. There was only the fuse on the incoming supply, which is obviously no longer in place. There is also no fuse drawn on the diagram you uploaded?

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How did you get on with this as I am looking into doing the same.

What relay did you use?

I've actually decided since watching the PDM webinar to delete my controller. The pump strategies Andre had in place look fine, and it substancially simplifies the system.

Is this the motec pdm webinar? Can you please send me links to the webinar and to the pump strategies by Andre you refer to please?

Thanks Karl

Hi Nick,

The MoTeC PDM only has switched outputs, not PWM as shown by Andre in the PDM Webinar as that Webinar used a ECUMaster PDU.

If I was doing an installation using a DC EWP and MoTeC PDM, I would use the PDM to power the EWP controller, and let the EWP controller control the EWP.

Hi Stephen,

In the webinar https://www.hpacademy.com/previous-webinars/295-basic-pdm-configuration/ around 33 minutes in, the strategy is shown using just a basic flash strategy. Output is on for 10 seconds and off for 30 seconds under 50degC, on for 10 seconds off for 10 seconds between 50degC and 70degC etc. After seeing how the Davies Craig controller works, this is very similar and isn't using PWM control. Unless I'm missing something, this is quite achievable on the PDM30?

My application is full time racecar, so usually the thing just belts away flat chat once I'm on track, anyway.

Hi Nick,

Interesting, all of the DC EWP controllers that I have scoped have used PWM for the initial start-up pulse for the pumps. I have also spoken to DC about controlling these pumps after dealing with a number of failures and they have always stated that the pumps should be soft started using PWM, otherwise they can be damaged.

There is no reason why you cannot start them that way, it's just my experience with them that hard starting them can leave to a premature failure of the pump.

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