My new contraption

[flraptor07]

All true, HOWEVER, Travis has created an inexpensive *bench* tester, and something I would love to have. It also appears that the commercial device is discontinued, or VERY hard to find. My Eagletree serves me well on the lake, but to move it, and set it up on a bench would be a real pain. I want it just where it is! Perhaps it is the addition of a piece of hardware, or maybe a mathematical equation. I do not know, which makes this thread so intriguing to me. Travis, you have set sail a mystery ship, and I am on board. Ride captain, ride!

I found the Commercial one here in the US and it's pretty reasonable. http://www.hksrc.com/store/index.php...roduct_id=7607

[keithbradley]

I have both of these units, the one Travis is using, and the stand-alone unit that doesn't require an ESC. I will say that the latter is a lot nicer unit and gives much more consistent results compared to the HK unit. However, the same can be done with any datalogging ESC...just use the ESC to bench test the motor on 2s.

Steve sells the SF120 Pro+ for $99. You could use the ESC solely for testing any motor, just put some alligator clips on the motor leads and use a servo tester or rx/tx to operate it. Since the HK unit needs an ESC to work anyway, I really don't see the need for it, especially when it doesn't work correctly.

http://www.offshoreelectrics.com/pro...d=hef-HB61120L

[kfxguy]

I have both of these units, the one Travis is using, and the stand-alone unit that doesn't require an ESC. I will say that the latter is a lot nicer unit and gives much more consistent results compared to the HK unit. However, the same can be done with any datalogging ESC...just use the ESC to bench test the motor on 2s.

Steve sells the SF120 Pro+ for $99. You could use the ESC solely for testing any motor, just put some alligator clips on the motor leads and use a servo tester or rx/tx to operate it. Since the HK unit needs an ESC to work anyway, I really don't see the need for it, especially when it doesn't work correctly.

http://www.offshoreelectrics.com/pro...d=hef-HB61120L

That's actually a pretty good idea but I have a few concerns about it. One is every time I want to test it, I'll have to run a data log and open up my laptop, no?
Second is, I know I got a good esc sitting there....not getting used much....I have a feeling I'll be robbing it to use in something. Lol

[keithbradley]

That's actually a pretty good idea but I have a few concerns about it. One is every time I want to test it, I'll have to run a data log and open up my laptop, no?
Second is, I know I got a good esc sitting there....not getting used much....I have a feeling I'll be robbing it to use in something. Lol

Yes, the info can be viewed via the data log. This is a good thing. I know you're only concerned with testing unloaded kv for now to satisfy your curiosity, but you're eventually going to want to put this info to use. When you log the unloaded info with a SF ESC, you can then run the boat with a SF ESC and compare your loaded and unloaded kv. This will tell you a lot about your setup in regards to motor efficiency and how that relates to prop choice and overall hull setup.

The stand alone unit is good for instant display of kv. If you happen to get a bunch of motors in and want to see how close they compare this is a good tool. And it's fun, I guess.

[Fella1340]

I like the idea of a stand alone sf datalogging esc, sounds like it would be a great tool for setting up a boat and monitoring progress. I have a laptop I can dedicate for the purpose. Is the data logging accurate enough that I can use the sf120 esc for bench testing a motor, then use a sf220 esc (even the sf 300?)in the boat and use its datalogging to compare notes? Sounds cool if it does work that way!

[kevinpratt823]

Only downfall is that sf only logs the last run from all I have seen, you would have to load data every time. Some others will log multiple runs, I think castle does, then you could test multiple motors consecutively an load all at once.

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[Fella1340]

Very good point! The eagle tree records the last 4 hours or more, might be better way to go. I'm going to start with what Travis has going. I have a FDM motor, old style 5660 with the 5692 size can-820kv supposedly (not really sure what FDM sent me) and I also bought the new style 5660 with the 5682 can. I can hardly wait to compare them! Thanks for getting this thread going Travis, it's got me exploring a pile of new ideas. Keep us posted!

[kfxguy]

Got my new motor in. Tested it. At first it was erratic. I think i may have found something. If I plug everything in and let it sit for 20-30 seconds, it seems to read correctly, stable and non erratic. I'll try with more motors. But...I may have found something else interesting. I never thought that you needed to break in a brushless motor (well you don't have to...but when your trying to push it to the limit on its initial run, then may be worth it) i always thought be a use it didn't have brushes, that it did not matter. Well...it seems as if the bearings need a go run in to loosen it up. I feel like this is pretty accurate too...bare with me to explain....

So I did an initial run in. The kv checked exactly 1920kv (unloaded, Cells about 3.8). Then I ran it at half throttle for about 3 or 4 minutes. Ran a test again...multiple times and came up with 1936kv every time. Pretty consistent. That's what it peaked at. I let it run for a bit more and that's where it hovered. So I decided to try ceramics. Well I got bummed because the from bearing on the new style motor is bigger...I had two small bearings. I figured what the heck. Changed the rear. Kv dropped to like 1929kv. Bummed. Thought it would pick up. So I figure maybe the bearing needed to break in. Yea...right, I'm thinking. So I run it in for a few minutes. Check it. It's like 1940kv now. I'm thinking....hey...a gain is a gain, right? So I run it some more (I'm keeping tabs on temps too)...still picks up. 1972kv now. I'm thinking hmm...gotta be a fluke. ...but then I notice something else...the motor sounded quieter, smoother and would turn a lower rpm (it would not start turning till a decent amount of throttle was given) and now it will start turning alot easier. Run on some more. It ended up topping at 1976kv (at 130 degrees f) I've noticed a gain in kv at temp rises. I've only gone to 130 degrees because that's my max temp I'm ok with.

[kfxguy]

Started out....



Ran in the regular bearings

[kfxguy]

Ceramics being run in


Topped out.... (and this was the year I was born lmao!)

[Fella1340]

I'm enjoying the play by play. Keep at it!

[olwarbirds]

Travis, we learned this a few yrs ago on our ducted fan units. I like you thought a brushless motor didnt need broke in. We found out that running them on low voltage in a glass of water (just like we did brushed motors) made for a smoother better performing motor....every few kv make a big diff at the voltages we are running brother... keep up the good work .... DJ

[kfxguy]

I needed to update this. I burned up the esc I was using because I was being lazy and didn't strap the motor down. It twisted and a wire came undone at full throttle. Instant toasted esc. I finally got around to picking up another esc. Remember earlier on in the thread I was having issues with it reading some motors and giving consistent results? Well I guess it was a problem with the esc. The "new" esc I'm using (castle sidewinder) now gives me repeatable results. It reads every motor I have now and appears to be accurate. Every motor I tested Was spot on with what it was supposed to be... plus or minus a few kv. I did have one read 200kv higher. Everything else was very very close to rated kv and it didn't fluctuate. I suppose I just had a bad esc or one that wasnt as smooth as this one. I'm just glad it finally works correctly!

[kfxguy]

Something I just found out. If you let this contraption sit for a while (not sure of the time but I let mine sit overnight) and go to use it again, it may read inaccurate and erratic. I found that a simple recalibration of the throttle fixes it. Not exactly sure why. Once I recalibrate it, it was perfect. Just thought I'd let you guys know in case you picked one up.

[kfxguy]

I tested a few motors. Most of them were pretty close to being spot on and one was questionable. I came up with the same kv on it last night too.

Heres an 1800kv aquacraft motor



Heres an 1800kv castle 1512




2400kv castle 1415