General ESC Theory Discussion - RC-Monster Forums

lutach · 10.27.2007, 06:20 PM

I just did a little test just to see how it went. I ran my DPR in live mode and hooked it up to my MBX5T that is now equiped with a Schulze 18.97 and a 7XL motor. I gave it some throttle and let it go so it would freewheel and the graph stayed flat. I then gave it some throttle and hit the brakes and saw a little spike on the graph. Just to make sure I hooked the DPR to my BPP truck that has a Schulze 40.160 and Neu 1521/1Y. Gave it some throttle and let it freewheel and the graph stayed flat. Then I gave it some throttle and hit the brakes, same thing happened a little spike on the graph.

10.27.2007, 06:40 PM

That's great. Are you able to see the direction of current flow in the graph? The DPR records in both directions, so that spike could be current drawn from the battery or current drawn by the battery...

Quote:

Originally Posted by lutach

I just did a little test just to see how it went. I ran my DPR in live mode and hooked it up to my MBX5T that is now equiped with a Schulze 18.97 and a 7XL motor. I gave it some throttle and let it go so it would freewheel and the graph stayed flat. I then gave it some throttle and hit the brakes and saw a little spike on the graph. Just to make sure I hooked the DPR to my BPP truck that has a Schulze 40.160 and Neu 1521/1Y. Gave it some throttle and let it freewheel and the graph stayed flat. Then I gave it some throttle and hit the brakes, same thing happened a little spike on the graph.

lutach · 10.27.2007, 07:03 PM

Quote:

Originally Posted by Aragon

That's great. Are you able to see the direction of current flow in the graph? The DPR records in both directions, so that spike could be current drawn from the battery or current drawn by the battery...

The spike was upwards so it actually went to the battery.

10.27.2007, 07:39 PM

Quote:

Originally Posted by lutach

The spike was upwards so it actually went to the battery.

Excellent! Do you plan to test it in driving? Braking at varying levels downhill would be interesting to see.

How much does the voltage spike?

lutach · 10.27.2007, 09:31 PM

Quote:

Originally Posted by Aragon

Excellent! Do you plan to test it in driving? Braking at varying levels downhill would be interesting to see.

How much does the voltage spike?

Today I actually got everything back together. The rear diff on the BPP let go and I had an issue with my Aveox in the MBX5T. So I will get some data on Monday if the weather is good. I didn't notice what + volts the spikes were. I just noticed they were there. I'm going to look in my previous data to see if it is there and I'll "prt sc" on a close up.

zeropointbug · 10.27.2007, 11:07 PM

So, you are seeing what I saw then, as far as a voltage spike to the battery? I saw, IIRC, about 0.25 - 0.5 volts spike, so even a little potential over the battery packs voltage will result in decent current levels going into the pack.

lutach · 10.27.2007, 11:45 PM

Quote:

Originally Posted by zeropointbug

So, you are seeing what I saw then, as far as a voltage spike to the battery? I saw, IIRC, about 0.25 - 0.5 volts spike, so even a little potential over the battery packs voltage will result in decent current levels going into the pack.

I will have to agree. The spikes seems like 0.25-0.5. I also noticed a sound coming from the ESC (Schulze 18.97). I listened closely to figure out where it was coming from and it was from the capacitors. It sounded almost like when you take a picture and the capacitor inside the camera recharges after the flash, but it was more like a blow-off valve. I have to see if the same spikes appers with the MM. If so, I think setting a little drag brake might throw some charge back into the pack.