Finally got me an Eagletree Data Logger! - RC-Monster Forums

BrianG · 12.27.2009, 02:27 PM

Before you get too far, you should calibrate the current and voltage measurements so that you start out with a good baseline. There are two areas; zero and actual values. Zeroing just makes sure 0v and 0A is really 0v and 0A. Calibrating the non-zero values is a little more complex. First, you have to come up with a dummy load that you hook to your packs which will draw around 10A. Hook the load to the pack along with the ET. Measure the voltage and current with a multimeter. Then, see what ET is saying the values are. If different, there is a screen where you can enter the real vs displayed values.

sikeston34m · 12.27.2009, 02:43 PM

Quote:

Originally Posted by BrianG

Before you get too far, you should calibrate the current and voltage measurements so that you start out with a good baseline. There are two areas; zero and actual values. Zeroing just makes sure 0v and 0A is really 0v and 0A. Calibrating the non-zero values is a little more complex. First, you have to come up with a dummy load that you hook to your packs which will draw around 10A. Hook the load to the pack along with the ET. Measure the voltage and current with a multimeter. Then, see what ET is saying the values are. If different, there is a screen where you can enter the real vs displayed values.

Hi Brian,

I did calibrate the displayed voltage.

To calibrate the Amp load display is gonna take a little more work.

I have an outrunner motor spinning an 11 inch prop. This is rigged up to be a fan. The thing really puts out huge amounts of air too. LOL

Powering the "fan" is a Mamba Max ESC hooked up to a servo tester. The servo tester controls the "variable speed" of the fan.

I hook my multimeter in line, along with the Eagletree, to get the 10 amp load. Then calibrate Amps with that.

Hmmm...........gonna have to look at my wiring situation.

Do you think the factory amp calibration will be that far off?

sikeston34m · 12.27.2009, 03:34 PM

Ok, I just did a run on 4S 20C 5000mah Turnigy Lipo.

If you compare this graph with the 30C graph above, you will see they are the same!

The numbers are the same. The 20C and the 30C packs are built with the same cell.

I always suspected this.

The 30C is holding 3.635 volts per cell under a 109 amp load

The 20C is holding 3.652 volts per cell under a 108 amp load

sikeston34m · 04:47 PM

Next up are some packs nearing the end of their useable life.

We've graphed some good packs, now let's do some not so good packs.

Flightpower are some GREAT packs IMO, the packs in these graphs are dying of old age AND have many cycles on them.

They are 4S 3200mah 30C packs, two of them parallel for 6400mah.

2.97 volts per cell under 108 amp load. Not good, considering the run only lasted 12 minutes to the LVC.

These might be ok for a few more cycles in something like a Rustler maybe, but they now need to be retired from MT use IMO.

sikeston34m · 12.27.2009, 04:46 PM

Next up is the end of the run that shows the Truck getting on the LVC.

The LVC is set at 3.2 volts per cell.

This graph shows some interesting behavior of the LVC. It appears the LVC does have a reaction time.

This is shown where the low pack volts are 10.93

That is 2.73 volts per cell. Hmm........

Once the LVC reacts, it is "regulating" amp draw and hold the LVC to around 12.8 volts. Right where it should be.

Interesting.

othello · 12.27.2009, 05:10 PM

Are you using the 150A version?

sikeston34m · 12.27.2009, 05:21 PM

Quote:

Originally Posted by othello

Are you using the 150A version?

No, I'm using the 100A version.

Amp Draw appears maxed out at 120 Amps with this version. I found that out yesterday when the powerboard melted down on my MMM ESC.

Pegged at 120 amps for about 2.5 seconds until I could get the ESC unplugged.

Thing really put out alot of smoke too. I didn't think I would ever get that smell out of my nose. LOL

I caught it all on the Logger. Unbelieveable!