Sounds like you were pulling more than the rail on that PSU is rated for. Check the ratings more carefully next time.

The power supply I am using is rated for a max 75amp output at 110v. However, I am having difficulty getting above 60 amps out of it. A 17.5 will pull more than that with the red flywheel so…. I tried a 13.5 and the results were not usable. I think to be able to use it for 17,5s and 13.5s you would need one of the lighter flywheels. But that will be a test for another time.

Edit:
As to the voltage drop. Yes, the power supply suffers more of a voltage drop, I looked through the raw data and found low 7s and a couple of 6.9v. Whereas the batteries I use stay above 7.5v. Again I will iterate, I think the lightest flywheel option would be worth testing.

Anyone have one they want to part with by chance?

On the positive side, I did design a cover for the front and print it.

After some looking around it looks like Mean Well has a 900 watt 9v power supply. The output voltage can be adjusted from 7.5-10v. Model # SE-1000-9, roughly $200 from shops in the US. The only issue is that it has a 17 amp load on the AC side, so you will need a 20 amp circuit to run it. This would allow 17.5s to get a full pull on the red flywheel, but most likely wouldn't be enough for a 13.5.

Also, since I have 6 of the HP server supplies, I can try to run 2 in parallel, but again I will need a 20 amp circuit to do that. I'll have to check my basement wiring and see what the setup is.

I've also thought about 8v golf cart batteries, they will have a full charge around 8.5v, and are around 150-200 amp hours. However lead acid batteries have an IR around 20 milliohms. As to price, you are again looking around $200, remember a lot of places you will have to pay a core deposit.

As to the dyno.

There are some things I would like to improve upon it. 1, I am going to get an Allegro ACS772ECB-200B-PFF-T current sensor to run on one of the phase wires (phase current is higher than the inline DC current from the battery, this gives more accurate efficiency). This is really close to the current sensor that is included with the dyno, but it is bidirectional and can measure AC current. Unfortunately I won't be able to hook it up to the board of the dyno since the included sensor does both voltage and amp, also the sensitivity of the sensor I am getting is different. So I will have to use an Arduino for the new sensor. Also I would like to find a way to tap into or use the built in rpm sensor of the esc and output that vs time. The included software of the ESC only has a 10hz sample rate, so no better than my dyno, but if I can figure out how to increase that and output to a spread sheet that would be great.

Also, if anyone who has one is interested. I have changed my pullies and belts to 3mm pitch. I found the 32t online from overseas, but it is 10mm wide instead of 6. The belts from Amazon are 201mm length and 6mm wide. I couldn't find any 16t pullies that had a 1/8" id though so I ordered that through Minipro. With this setup you can run a lower belt tension and avoid a lot of the side load on the bearings. There is a setting in the dyno to switch to 3mm pitch on the belt and pullies, so it adds just a little MOI.

I wired 2 in parallel…
Slot Machine 13.5

I have been testing reading the phase sensors with an arduino outputted to an LCD. Unfortunately DC power supplies are noisy which creates noise on the signal from the sensor board. This can cause misreads from the arduino. On battery the issue goes away and my scope and the arduino are generally within 1hz of each other.

Here are some pics... The nice wave is with the battery running the system. The noisy wave is with the power supply running it.

Just a suggestion: post the screenshots from your readouts instead of a phone image. We lose a lot of detail and data when you only show partials like that.

Since this thread got me interested in a MiniPro, I went and got one for myself.

I was looking for a photo of the voltage current sensor, but it looks like I've already found it. I'm going to see how it compares to my Medusa Research PowerPro meter.