CC125 problem

[Geoff Akerlund]

My CC125 is set to a 9V hard cutoff, but my multimeter says it's cutting around 9.6 or so (I checked with 2 different meters to confirm so I'm fairly sure). I set the cutoff voltage to 8.4, and it is now correctly cutting at 9.0.


My question is:
-Could this be a defect in the ESC?
-If not, what could be the problem and how do I solve it?

Thanks in advance

[RC Man]

Sounds like you need to send it in and have it recalibrated.

.

[Geoff Akerlund]

The castle FAQ states that it could also be cutting due to high resistance in the connectors and/or wire.

Is there any way I can confirm this isn't the problem? The last thing I want is to send it in, have it sent back, and find the problem isn't solved.

I'm using Astro zero loss connectors, with 10ga wire on the ESC and 13ga wire on the battery. The battery is a TP 3S3P lipo at 100A bursts.

[rcelectfly]

Geof,

How much current are you drawing?

Are you measuring the pack voltage under load or after the motor is shut down?

What batteries are you using?

Chuck

[Geoff Akerlund]

Battery is TP 3S3P prolite drawing between 90-100 amps burst (about 15C)

Yes the voltage is under load

[Patrick del Castillo]

Geoff,

You will see some discrepancy between a meter and the speed control for the reason that a meter AVERAGES voltage over time... in other words it sees some of the spikes and they get averaged into the voltage.

The speed control looks at the battery voltage under load, and takes that into consideration. If you looked at the battery output on an oscilloscope, you would see that the speed control is correct in its cutoff voltage.

Thanx!

Patrick

[Geoff Akerlund]

Is there any way I can check what the voltage is? It seems unlikely that the battery is actually dipping below 3.0V/cell. It's supposed to hold a voltage of about 3.2V/cell @ a 20C discharge (as shown on this (http://www.rcgroups.com/forums/showpost.php?p=3407811&postcount=58) graph). I'm running it @ 16C and it's hitting the 3.0 cutoff almost immidiately. I've used two separate 3S3P batteries and both give the same results.

[Bernie Wolfard]

Geoff,

You can check voltage with a True RMS Voltmeter, very expensive. Lipos follow a true bell curve. Out of 100 packs 20 will be good, 60 OK and 20 not so good. So a graph is only representative of the packs tested, not all packs of that type. A Phoenix ESC is accurate on cut off to about .1 volts.

Bernie