I have a JetsMunt, HP Tech ZP30020S fuel pump for 160N to 230N turbines. I want to run it off of a 3S LiPo using a brushed ESC. I have been searching to try to find data as to amp draw to no avail so that I can use an appropriately sized ESC, and since it will never be running at full speed, ever, will there be an issue with running it off of a 3S LiPo, it is listed as 6V nominal. There are other parts of the system that need the extra voltage of the 3S.
This is going to be the fuel pump for my pulse jet. The pump speed is adjusted to give the proper air fuel mixture, it does not give throttle control. run the pump to slow and the PJ runs lean and burns up, run it to fast and the PJ runs rich and burns up. I will have it set up on a knob on my TX to dial in the pump speed, once I have it just right I will have that channel set up as an on/off switch.
I will be running a separate battery for the flight gear.
So has anyone ever measured the amp draw of their fuel pump?

Why not run the pump at your expected max rate and just measure the current? Use a spare ESC from an old plane and one of the many ammeters that are available. As the pressure builds, the current draw will most likely increase, unless the pump cavitates due to inlet or outlet restrictions. So the peak current most-likely depends on what you have for the specific system's hydraulic resistance at your desired max speed on your system. That's why one needs to be measuring what the actual current is for a specific system.

6 volts nominal should tell you that the 12.4 volts peak of a 3S LiPo is too much. You should use a 6 volt voltage regular (VR) that is also matched to the current draw (i.e. measured peak current + at least 25% margin.) You might get away with less margin. But then again you may not. Just tie your other HV components in before the VR.

Nice idea. It just will take a little bench testing on your specific system to come up with the right components. What someone else comes up with would be dependent on their specific system application.

At the moment I do not have an old brushed ESC for testing. Hat get one a lot bigger than needed. The whole fuel system looks like there should be minimal restriction. the outlet is just the end of the fuel line pointed at the point of a cone to spread the fuel out into the incoming air stream. If I know what the amp draw is in worst case then I can just size everything to be safe at that level. As for my actual flow rate, I have no clue, the first run is strictly trial and error starting low and working my way up till it runs.

I guess I can get a 6V battery pack (old school, 4 "D" cell alkaline) and set up some tests to determine max amps with a severely restricted outlet.

I did track down the actual manufacturer of the pump, they confirmed that the max amp draw is 6A and recommended a 10A brushed ESC. They also said that it will be no problem running it on a 2S or 3S LiPo. They also mentioned that some Small / cheap ESCs have fairly corse steps in the output and it may be difficult to get my proper flow rate.
I now have my mission................

That is a good start. I don't recall ever seeing a ESC spec sheet that showed its output curve and I have a lot of individually purchased ESCs. Maybe a manufacturer can provide one for their specific product or they may it posted on their websites. But it sounds like some bench testing is in order. Good luck. These type of electric projects are fun!

I also enjoy designing and building small electronic projects. It is projects like this that I really wish I had a scope. I am in the category where I know just enough about electronics to be dangerous.
I have been using brushed ESCs for many years to control LED lighting on my night helies, you can definitely see the steps in light output as you slowly raise or lower the throttle. I do not know if those steps will be fine enough adjustment to the the air/fuel ratio correct on the pulse jet. But at least I know that I can just plug in some LEDs to see how fine the steps are. Although you can only see the steeps near the bottom end of where the LEDs are just starting to light up.

OK thinking out loud here, IF I were to hook up the ESC with an appropriate load, would a digital voltmeter be able to see past the PWM and see the steps?
Maybe have to add a capacitor to smooth out the PWM frequency before I can measure the steps?

Scopes are great for what you are doing. The digital meters' sync time just does not cut it to see small changes. Maybe it would sync if you left the ESC set at a fixed point for a time. But, then you are just looking at relative readings, which might suffice for what you are doing. ??

You might want to consider visiting a local Ham Radio Swap Shop. Frequently, there are guys selling older scopes for a song. You don't need a UHF scope for what you are froggin' around with. Should be able to get away with a 30 Mhz older model.

I miss my RF Station Monitor, 500 Mhz direct reading. But as seldom as I was using it, the $10K came in handier. Using the low freq old clunker now.

Hi Jeff,

I don't have an answer or any additional regarding your fuel pump project; however, I do have a couple of questions.

I flew a DynaJet PJ back in the late 50s (speed U-Cntl) and, unfortunately, had to give it up when unable to find anyplace to fly (noise). I haven't kept up with PJs ever since, but was wondering (1) still noisy? and (2) where do you find a place to fly there in WI?

Ed