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Nov 29, 2005, 06:04 PM
sloping addict
Protocooler's Avatar
Thread OP

1.22V / cell Nimh, very small 11A load on a big CC125, but still shutting down...


Hello,
I have a monster ~2kW sailplane setup designed to handle 20*13 or 23*12 props on 16 of the latest & best NimH cells and a Neu 1509 1.5Y, and the CC125 ESC. I first setup a test bed to measure real voltage and have a Sears clamp meter to measure amps.

Before I started checking for full load, I started with a smaller prop to verify predictions, and at 65A after just 1-2 seconds, ESC shuts motor off...
So next, I check with a ridiculous prop for this system (10*7) and @ 11.5A / 19.5V for 16 cells, the ESC still shuts down !!! So it has nothing to do with LVC (which is set @ 7.4V to allow me to also use 10 cells packs)

Of course I do NOT use the BEC, the red wire is removed.

Here is my exact setup, I have the CC link. What could be wrong, especially with such a small load ?

I also tried with 11 kHz PWM and result is similar (seems to yield a bit more amps and still shuts down after the ramp up).
Please highlight me !
...Proto
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Nov 29, 2005, 06:19 PM
sneu's Avatar
Quote:
Originally Posted by Protocooler
Hello,
I have a monster ~2kW sailplane setup designed to handle 20*13 or 23*12 props on 16 of the latest & best NimH cells and a Neu 1509 1.5Y, and the CC125 ESC. I first setup a test bed to measure real voltage and have a Sears clamp meter to measure amps.

Before I started checking for full load, I started with a smaller prop to verify predictions, and at 65A after just 1-2 seconds, ESC shuts motor off...
So next, I check with a ridiculous prop for this system (10*7) and @ 11.5A / 19.5V for 16 cells, the ESC still shuts down !!! So it has nothing to do with LVC (which is set @ 7.4V to allow me to also use 10 cells packs)

Of course I do NOT use the BEC, the red wire is removed.

Here is my exact setup, I have the CC link. What could be wrong, especially with such a small load ?

I also tried with 11 kHz PWM and result is similar (seems to yield a bit more amps and still shuts down after the ramp up).
Please highlight me !
...Proto
Try the "fixed" throttle setting and also set cutoff type to "soft".

Steve
Nov 29, 2005, 06:22 PM
set your current limiting to disabled first, and see how it does.

If you're no go - set the cutoff voltage to 5v on the standard list (not custom). Sometimes the custom voltages can be a little off.

If it's still not cooperating, give us a call or email, and we'll fix you up.

Shawn
Nov 29, 2005, 07:16 PM
sloping addict
Protocooler's Avatar
Thread OP
Thanks Steve & Shawn,

at this stage with 6V "standard" cutoff, disabled overcurrent and fixed throttle, it works with the tiny prop. Positive steps. I already had soft cutoff.
I'll experiment more tomorrow to isolate which of the setting was the real issue, but I bet Steve was spot on with throttle setting (I have a Multiplex MC 3030 TX). LVC should be of no matter as I am a whole 13V above the threshold (it can't be that off can it ? )

Will keep you tuned what this setup is doing with the REAL props (on +5 yoke furthermore) , but on these I do not wish the overcurrent disabled.
However, what is overcurrent protecting against anyways, what voltage drop is being measured exactly and what is the reaction of the controller - what is the relation with back EMF of the overcurrent protection if any ?

thanks !
Nov 29, 2005, 09:57 PM
I think that its "overcurent" protection , to reduce troubleshooting steps enable it again on same setting as before and see if it misbehaves again.
Nov 30, 2005, 02:39 AM
sloping addict
Protocooler's Avatar
Thread OP
Will do tonight - it was my planned next setp. But AFAIK controllers do NOT directly deduce amps (via a current shunt), in fact even with a shunt it's still a voltage drop that is measured across a known resistance, which allows to deduce current.
Hence my question of what voltage is actually monitored to figure out what happens at current level, and then what is the behaviour of the software to this input.

In fact I do not think an ESC (of any brand) is actually capable of protecting its FETs against a current overload when this overload is due to over-propping. I don't really understand against what kind of overload this overcurrent protection is really useful for, I'd be glad to be explained and hopefully proven wrong.
Nov 30, 2005, 04:17 PM
Its a software bug most likely, don't think too hard about "why???" LOL
Nov 30, 2005, 04:26 PM
sloping addict
Protocooler's Avatar
Thread OP
Feedback with the tiny prop, all tests with 6V predefined cutoff, 16 cells IB3800 pack slightly discharged (charged 5 days ago), 4 cells Rx pack, MPX 3030 TX on throttle stick:

26 kHz / auto throttle / insensitive => works 2 * 10 sec runs OK but then shuts down (14A draw, all being not even warmish)
26 kHz / auto throttle / disabled => idem
13 kHz / fixed throttle / insensitive => shuts down after short ramp up
13 kHz / fixed throttle / disabled => seems to work fine. After 20 sec runs, I measure 12.3A / 18.4V (cold pack).

It looks to me the throttle has nothing to do with the issue (but fiexd throttle is a good setting for my application), while that there is no way I can make it run, at least with this prop, without disabling overcurrent altogether. Is there an explainable technical reason behind that ?
I know this is a super low impedence motor, could it explain some ??
Next will have to fit the big props, but it bothers me not even being able to set ESC to insensitive...
Nov 30, 2005, 04:41 PM
It should bother you if you set it any lower than normal, which technically voids esc warranty.

As I said in the previous post it looks to be software bug, there were a few software versions like this.
You can try earlier software version instead. Report the bug to castle using bug feedback system..
Nov 30, 2005, 05:00 PM
sloping addict
Protocooler's Avatar
Thread OP
Test with 18.5 *12 Aeronaut on +5 yoke = 18.5" * 17.4"
13 kHz / fixed throttle / disabled
=> After about 5 seconds: 11.7V / 54A (yep, pack is really cold and also brand new + on first charge and not a single discharge)

Notes:
- Runs completely cool - for several secs - as expected. Only 630W though, 1/3 of the final expectations with 23" prop and hot cells.
- Once Ri of cells adjusted for this low voltage, Motocalc is spot on within 2% (for static value at least) with heating disabled
- The new ramp up and ramp down looks to work very well, the big prop slows down efficiently but still gently enough. This should effectively remove the issue with the bulkheads being ripped off by huge torque. Thanks for this feature.
- The spinner stayed on the yoke ! No Loctite required yet - the 6mm Aeronaut clamps (in steel) look much more efficient than the 5mm and less (in Aluminum)
Dec 01, 2005, 11:42 AM
Castle's Chaos Corner
Bernie Wolfard's Avatar
Break you cells in, set cut off voltage to 5 volts, change Electronic Timing Advance to 'Low' and run with cells hot of charger. Neu motors like low timing and IB 3800 won't hold voltage if they are not broken in and at least warm.

On 10 cells with a 1509/1D/6.7, 18 X 16 +7% the motor will not run with cold batteries. With a 5 volt cut off the motor stops as soon as it spools up.
Dec 01, 2005, 12:17 PM
sloping addict
Protocooler's Avatar
Thread OP
Hi Bernie, I know the cells must be hot to draw 170A+ out of them and with 10 cells stay beyond 5V. I know I'll have to break them in before I use the largest props and I know @ 54A I should get 16V rather than 12V with these cells, once they are in good conditions. But that is not the point:

In my case I used 16 cells not 10, small 10*7 prop and then 18.5*12, my LVC is 6V and I never yet measured any less than 11.5V. Actually, I had shutdowns even at 20V+ on the small prop.
So, either I use a bad / incompatible setting (=> will change timing advance to low and see what gives, it's the last parameter I have not played with), or there is something bad with the firmware behaviour for the cutoff... At least it works in current disabled mode, but why should I risk to void warranty when it should work "normal"?

Is the cutoff based on absolute voltage, or on some kind of voltage drop ?
Actually I could do with completely disabling voltage cutoff since this feature is useless in a glider with NimH cells, but it's not possible is it ?

Is the 1509/1D setup working with insensitive current, or disabled, and what is the real difference between these two status in such usage ?


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