I need help from any electrical gurus on here (That means you, Tim Rowe)

I've bought an electric water pump to replace the belt driven one on the 4age.

Problem is it's 24v

Rated current 3.5A

So, 84W

I know it'll run on 12v, but slowly. What can I do to speed it up?

I'll look into it. You'd need a dc/dc converter to supply the 24v, unless you want to run a second battery and have a split charge system running. Why can't you find a 12v one? I found one yesterday for a job at work for less than £100. Might end up being a cheaper option.

Cuz I enjoy the challenge

If it comes to it, i'll re-wind the motor - will just have to find some sort of calculator/equation to work it out.

Surely you'd just need double the amount of windings, for the motor to run at the same speed with half the voltage. Can the motor take that much extra copper in it's case size?

I'm still firmly in the camp that you'd be better getting a 12v pump, as it cuts down on connections and components and therefore reduces the chance of failures, which on the water pump I would take as essential.

http://www.mawsolutions.com/html/electric_water_pumps.html

Hmm,
Lessening the amount of windings gives more speed/less torque, but the wire needs to be thicker.

So, to bring the torque back up, I need the same amount of windings in thicker wire - I think you're right Tim.

I'll be doing some trials over the weekend anyway - the pump as it is will do 50liters/min on 24v, and I only need 20-25, so it might work sufficiently as it is.