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SSR vs Voltage drop resistor with haltech.

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I am looking to run a davies craig EWP150 on a 3SGTE, looking to remove the thermo stat and use an electronic temperature control.

now I know the DC offer an electronic control module that is very nice and does a great job. but I do not want to add another system and sensor if I can help it, so I am looking to use the halech ps1000 to control the pump.

at the moment I have two ideas, a SSR and using a coolant fan PWM with the start temp at -20'c, this will give me a DC of 30ish % at 15'c (coldest it really gets, plus its a weekend toy so not an issue). otherwise I could use a generic duty, my concern with the generic duty is I may want this for other systems later on.

second option is a load resistor or voltage drop resistor, so a 2 ohm 10 watt resistor (with additional heat sinks) to drop the voltage to 6v and then use an inversed fan switch to switch the relay to straight 12v at desired temp.

what are everyone's thoughts?

what have people done in the past?

It really depends on the motors designs, it's usually safer and easier on motors to use PWM

Davies craig use 6v pulses (30 sec of 6v, 30 sec of 0v) and then pwm to full 12v.

so the motor can really run both ways.

You could just run a generic duty cycle table, and then use whatever axis's you want. Just an idea. Ive done that for fuel pump control a few times.

edit:Hmm...interesting. When its set up as a generic duty, doesnt really let you change the axis to anything useful to your situation. it would be nice to have temperature on the one axis, and load, or something like that...im playing with it

I know its an option but I wouldn't mind keeping generic duty available for pwm of nitrous or water injection etc to play with later.

but that is looking like the ideal solution at the moment. expensive too.

That sucks. And as i noted above, it wont really work for your purpose anyways. They dont allow you to define your axis. I would say that using the pwm fan control, as you stated, would probably give the best solution, without adding any additional controllers.

edit: must have been the old map i was editing. newer map allows defining the axis as coolant temp.

i did make another discovery that you may be interested in, but it involves upgrading to the elite. The elite allows naming of generic duty cycle outputs. so im pretty sure you can have more than just one generic duty. pretty cool feature. im still learning the additional goodies in the ESP software.

PWM control using a SSR would be my favoured option as it offers more refined control of the pump. As it's a work around of sorts, you would need to simply try it and see how it works out in practice. You can buy a SSR cheap enough that if it isn't effective then you haven't wasted much.

Elite isn't really an option due to price point. (platinum purchased = free).

apart from haltech, are there any sources for known good SSR's? I have heard mix reports about jaycar SSR's ranging from they are the rebadged haltech ones, to they are utter crap and have huge voltage drops and cant meet the frequency requirements.


Hella do an SSR

any ideas who sells them in Australia?


I got one off ebay.

I just googled it and a variety of options come up depending on your amperage requirements.

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