Bosch 044 External Pump Setup.

[benm]

Cant be as noisy as this, has got me thinking about doing something like ben. Lucky its not my daily or it would have to go

If you don't like it you could sell it to me.

[GTR-Ben]

No I have no diodes.. it is a very basic setup. I think the reason it was staying closed was because the pump was stalled.. if it runs i'm sure this will not be a problem as it does when running 12V.

The current/voltage relationship depends on whether the pump is loaded/unloaded or stalled.. the current and voltage will only increase proportionately to each other in a stalled condition (IE back EMF constant).

In a loaded condition the current will remain fairly constant with voltage change as the back EMF will also vary as the pump speeds up or slows down. If you had no regulator or friction in your fuel line, varying the voltage would do very little to the current draw however.

Sure if you increase the voltage the current will also increase slightly when the pump is loaded but not proportionately. If the pump goes from running at a set voltage and suddenly stalls. For that same voltage you will see a large spike in current. This was the concern.

With your V=IR you are not considering I=(V-E)/R where the real voltage (potential difference) across the windings is important. (E = Back EMF)

The pump resistance may be fixed, but the back EMF changes. If this back EMF hits 0 (Stalled pump) the current seen at the pump will then become input voltage x coil resistance = huge current and a burnt out pump...

A voltage divider is a standard way of reducing a voltage. They use two resistors with different values and the voltage output is determined by the ratio of resistance values of these two. They are in series but the output is taken out between these.

The GTR module is not as simple as a resistor voltage divider as it drives a fairly large load. Usually resistor voltage dividers are used for signal currents only. (IE milliamps)

I have looked at the method you described of adding a bypass around the 044, but it seems silly to add yet another pump when this one will do 800HP on it's own. Why add more when you can slow the pump.. a PWM motor speed controller will do this perfectly.. without reducing voltage supply to the pump.

So I don't think it's all as simple as people are adding here.. and I am fairly confident my setup will work fine with a few tweaks

[GTR-Ben]

Update:

Seems to work a treat. Problem is now that my internal GTR pump running with no pressure against it is now louder than the 044 at 7V..

The 044 kicks in to full voltage at around 2.6V and off at about 1.4V. Took it for a drive around the hills and this seems perfect.

[GeeTR]

Good to hear, nice work!!

[GTR-Ben]

Can finally get my final tune now.

Can't wait

[Boss-zilla]

How did you do it??

[GeeTR]

How did you do it??

...Why add more when you can slow the pump.. a PWM motor speed controller will do this perfectly..

His afore mentioned PWM unit plans noi?

Edited June 17, 2008 by GeeTR