New Eagle Tree Systems Micro Recorder

[tcolesen]

Many of you have probably heard of Eagle Tree Systems data recorders. Well, Eagle Tree is coming out with a newer, much less expensive Micro Recorder. This unit goes in-line with the battery, and records voltage and amps, as well as temperature and RPM. For only $70, it is a steal!

http://www.eagletreesystems.com/MicroPower/micro.htm

These are perfect for us brushless guys. Now we can all monitor our expensive equipment for a small price.

[kufman]

Very cool!! This will make building my dyno even easier.

[Key]

Very nice but I don't see any mention of speed recording features.

[abiye]

you have to get the add on for speed and temp readings... 9.99 each... this is a good (and cheaper) alternative to the spektrum system that's comming out soon... granted it doesn't have all the live stuff but hey for 70bucks its awesome

[tcolesen]

Accurate speed measuring would require GPS. The best this can do with speed is to take the RPM and multiply it by the rollout, but that doesn't account for tire ballooning.

[kufman]

The best this can do with speed is to take the RPM and multiply it by the rollout, but that doesn't account for tire ballooning.

for foam tires this will be pretty accurate. In live mode this will be an easy way to dyno brushless motors vs brushed motors. i can see where this will be very usefull for determining gearing for sedan racing.

[tcolesen]

True, but I don't run foam tires. So, for your purposes it would be accurate, but for mine it would not.

[SpEEdyBL]

At least you will get the absolute minimum speed. Actual speed should be pretty close to that. I'm guessing around 5 mph faster max. I don't know if tire balooning is something you want.

[tcolesen]

Often tire ballooning is good, if you are going for speed runs. The tire diameter gets larger, increasing the rollout and the overall speed. And, it does this without increasing the weight (like larger diameter tires would). Of course, if you're not doing a speed run tire ballooning is bad because you lose friction (due to a decreased surface area), resulting in poorer handling.

[SpEEdyBL]

Can't you just gear higher instead of having the tires balloon?

[tcolesen]

I suppose that's possible :p. I have never put duct tape on the inside of my Rustler's tires, but I did to my monster truck tires, and it really stops the ballooning. Maybe I will try this with the Geolandars I am hopefully getting for Christmas :).

[GordonFreeman]

I'm with kufman on this, just what I've been looking for for a dyno.

[tcolesen]

Well guys, get what I just ordered:
http://www.eagletreesystems.com/MicroPower/micro.htm
I also ordered a RPM sensor, and should be getting a free temp. sensor :).

[ElectricThunder]

Very very cool! This looks like a great little tool, and not big and clunky like the original, larger eagle tree. Where does the temp sensor and RPM sensor go respectively, or is that really your decision? Another toy for t....:D

[tcolesen]

The sensors can be placed wherever on the vehicle. I think I will put the RPM sensor on the spur gear, and the temp sensor on the motor or batteries (not sure yet).

[Key]

I look forward to your feedback and experience!

If we order an RPM sensor does this mean it comes with a speed sensor at no additional cost?

[tcolesen]

I look forward to your feedback and experience!

If we order an RPM sensor does this mean it comes with a speed sensor at no additional cost?

It sure does ;). That is, assuming you know multiplication and division :eek:.

[Key]

Perhaps if this was advetised it would help us calculate ;)

[tcolesen]

It came in the mail today. I am excited to try it, except that my voltage regulator fried my only 2 working servos... and then fried itself. I'll be ordering a 3amp switching BEC circuit from http://www.xushobby.com for $15 along with a Lipo order (4s 4400mah 8C). I can still do testing on the bench with the only load being the tires and drivetrain, so we'll see if there is anything interesting.

[tcolesen]

Unfortunately I can't do any real testing since both of my servos have fried. BUT, I was able to do some bench testing where I revved the throttle with the only load being the drivetrain and tires. So far I tested out gradual throttle input, as well as immediate throttle input. In my Rustler on 3s Lipo with Feigao 12s motor, and HPI Yokohoma tires on 20/90 gearing, the motor hit up to 34,000 RPM, and at one point made a spike to 23amps/10.1v/235watts. That spike was without a load! I can't wait until I get new servos so I can do some real testing!

http://img.photobucket.com/albums/v132/4x4pede/RustlerRevving-.jpg

In this graph you can see the gradual acceleration and the almost instantaneous full-throttle acceleration. Sorry that the file is large (56k'ers).

EDIT:
From the RPM and battery voltage of this (relatively) unloaded setup, the kv of my motor came out to be 2982, and Feigao rates it at 3058.

[Nabors]

I recived mine lastnight also havnt used the rpm monitor yet but did do some loaded test with my feigao 12s and 4s 3500mah lipos it pulled a spike of 1013 watts pulling the voltage down to 9volts with 100+ amp bursts. I didnt think this setup was pulling that much.

[ElectricThunder]

EDIT:
From the RPM and battery voltage of this (relatively) unloaded setup, the kv of my motor came out to be 2982, and Feigao rates it at 3058.
Feigaos motors are rated under no load though, right? So it looks good so far on paper. Cool graph.:D

[tcolesen]

Nabors, was driving your vehicle the load? Or did you use some other form of a load? That's a pretty large spike!

ET, they are rated with no load.

I did some more testing using the same "bench" testing with my X-Terminator (converted 1/8 buggy) as I did with my Rustler. Stats are: Feigao 540C 9L, MGM Compro 12012, 5s LiFePO4 batteries (3.2v nominal). With no load besides the tires and drivetrain, I hit a spike of 425watts (15.2v/28amps! The RPM hit up to 43300, which is pretty high! At that RPM, the battery was at 16.1v, amps at 9.5, and 150watts to hold full throttle. That brings the kv (with small load) to 2691, with Feigao's rating at 2730.

[Nabors]

Yes 9.0:1 gearing with galdiators on the rear wot from a dead stop with no tire spin almost pulled a backflip. Normal setup should pull alot less amps 10ish gearing and wornout bowties.

[tcolesen]

Got some testing done since my servos came in today. But, I am awaiting funds for the purchase of a Lipo battery for my Rustler and a UBEC for my X-Terminator.
In the Rustler, I was using a low-performing (old age/use) 3s 4000mah battery. Since my battery straps had broken previously, I didn't strap the battery in. But since there weren't any jumps or anything, I figured it'd be fine. BUT, the massive grip from the HPI Yokohama tires caused the truck to flip over many times in slow turns, often releasing the battery. In one such turn, the battery was yanked out, and because of the way I constructed the battery, the battery wire cause a couple of tabs to short out. This brought on a quick flame, which did go away. It left the Lipo cells without tabs, rendering the whole battery completely useless. Before this happened, I was able to get some bursts and straight-line runs in.

The highest amp spike was up to 60.0 amps, the battery dropped to 8.34v, to put out 500watts. Obviously, there was no LVC in place, otherwise the voltage would not have gotten near 8.34v. I would tell you the highest RPM hit, but for some reason there is not data on RPMs. This is probably caused by me not putting the RPM sensor close enough to the magnet on the spur gear. But, I had the GPS on the truck (not strapped in), and it recorded a 34.5mph speed - not bad considering low (bashing) gearing with only 3s Lipo! Unfortunately, I can't give any data on amp draw/voltage when holding full throttle for a run for speed, since all the data looks as if I had just been pulling the throttle in bursts. If I had to guess on this data, it looks like 22-24amps are required, at which point the battery's voltage was at ~10.2v. From this, the full-speed RPM would be ~29,000.

Here is the graph, all the way until the end when the battery shorted out. Purple/maroon is amps, dirty yellow is volts, temp not shown (reached only 88 deg.)
http://img.photobucket.com/albums/v132/4x4pede/eagletree_rustler.jpg

[Nabors]

I found the reason why I was pulling so many amps I had a bearing seize in my ideler gear in my tranny causing the gear to melt and strip right after I was making fun of the local losi guy for tearing out his diff gear with my old ss5800. (I was really talking up the associated trannys also then boom)
Next week I should be able to get some data on a flatout 55+mph run.