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Author Topic: System cuts to low voltage cut-off?  (Read 627 times)

Online Dennis Toth

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System cuts to low voltage cut-off?
« on: January 16, 2022, 08:03:00 AM »
Yesterday I had a very weird experience where my flight ended about half way through the planned time (5 min) with what appeared to be a low voltage cut-off. I assumed I had just forgotten to charge the pack as I didn't check it, so I got out the second battery, that I had check before leaving the house, it was fully charged. I flew the next flight to full 5 mins as set in the timer (old Ztron). When I got home I checked the voltage on the first battery and it was 19.6V the second was 18. So it seemed that the first pack was well above low voltage cut-off. I don't know what could cause this type of cut-off if it wasn't low voltage? I had been flying the first pack for a while with no issues. Any ideas as to what to check?

Best,    DennisT 

Offline Mark wood

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Re: System cuts to low voltage cut-off?
« Reply #1 on: January 16, 2022, 08:24:18 AM »
Yesterday I had a very weird experience where my flight ended about half way through the planned time (5 min) with what appeared to be a low voltage cut-off. I assumed I had just forgotten to charge the pack as I didn't check it, so I got out the second battery, that I had check before leaving the house, it was fully charged. I flew the next flight to full 5 mins as set in the timer (old Ztron). When I got home I checked the voltage on the first battery and it was 19.6V the second was 18. So it seemed that the first pack was well above low voltage cut-off. I don't know what could cause this type of cut-off if it wasn't low voltage? I had been flying the first pack for a while with no issues. Any ideas as to what to check?

Best,    DennisT

I don't know but I've had this happen before. I think Howard had an event where the motor cut off and then later started again. I have had a couple similar incidences myself but never a restart. When I'm flying alone, I always have the down line in my hand when I'm moving from the airplane to the handle or handle to the airplane.

I use a small piece of 1/8" masking tape to indicate charges v flown. When I charge the battery, I put a hash mark on a label and then attach a small piece of tape below the label to indicate the battery has been charged. When I finish my flight and unload the battery, I remove the tape indicating the battery has been flown. If I short flight one battery, I separate it from the others because I parallel charge my flight packs.

As far as checking, I'd put a mark on that battery or record it in my log as having had an event. Check the individual cell voltages is about as much as you can do beyond that. Then just keep an eye on it. It's likely your timer or ESC had a glitch maybe from static discharge. Without a monitoring system onboard there is no real knowing.
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman

Offline John Rist

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Re: System cuts to low voltage cut-off?
« Reply #2 on: January 16, 2022, 08:47:07 AM »
Could be a bad cell that has high resistance causing a voltage drop under load.

PS  I use a close pin to indicate a charged battery.  Clip it on the batterie's power lead when charged and remove it to install battery in aircraft.  Won't go in the airplane with close pin in place.  Eliminates the chance of a brain fart on my part.  LL~
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Offline Tim Wescott

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Re: System cuts to low voltage cut-off?
« Reply #3 on: January 16, 2022, 10:12:51 AM »
Could be a bad cell that has high resistance causing a voltage drop under load.

PS  I use a close pin to indicate a charged battery.  Clip it on the batterie's power lead when charged and remove it to install battery in aircraft.  Won't go in the airplane with close pin in place.  Eliminates the chance of a brain fart on my part.  LL~

I put a rubber band on the battery when it comes off the charger, take it off when I load the battery into the plane.

And yes -- it could be anything that causes a high resistance condition in the pack, or it could be a loose connection somewhere.
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Offline John Rist

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Re: System cuts to low voltage cut-off?
« Reply #4 on: January 16, 2022, 12:50:28 PM »
I put a rubber band on the battery when it comes off the charger, take it off when I load the battery into the plane.

And yes -- it could be anything that causes a high resistance condition in the pack, or it could be a loose connection somewhere.
Rubber band is also a good ideal.  y1
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Online Dennis Toth

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Re: System cuts to low voltage cut-off?
« Reply #5 on: January 16, 2022, 03:19:50 PM »
I have a system for keeping track of the charge/uncharge just didn't us it for this day.

So, does anyone know of a way to stress test the battery pack? I'd like to be confident that there isn't a weak cell.

Best,    DennisT

Offline Mark wood

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Re: System cuts to low voltage cut-off?
« Reply #6 on: January 16, 2022, 03:36:06 PM »
I have a system for keeping track of the charge/uncharge just didn't us it for this day.

So, does anyone know of a way to stress test the battery pack? I'd like to be confident that there isn't a weak cell.

Best,    DennisT


Measure the voltage of the cells currently. You can begin a discharge on your charger and monitor the cells. And recharge doing the same thing. If everything balances correctly, I wouldn't get overly panicked about it. Just make sure you use your management methodology more rigorously. Put a mark on the battery and just monitor it. If it has anything going bad it'll tell you by getting puffy which I'm assuming it currently isn't. Connecting your wall meter in and running would be about the best stress test you could do. And if you have one of these, you can plug it in and watch the cell voltages real time:

https://www.amazon.com/CAMWAY-Battery-Voltage-Monitor-Checker/dp/B07DC3LH9C/ref=sr_1_4?keywords=lipo+battery+flight+monitor&qid=1642372502&sr=8-4
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman

Offline Tim Wescott

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Re: System cuts to low voltage cut-off?
« Reply #7 on: January 16, 2022, 04:39:30 PM »
Good point - if you use any per-cell battery tester and run it on the ground then one weak cell will stand out like a sore thumb.
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Offline Mark wood

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Re: System cuts to low voltage cut-off?
« Reply #8 on: January 16, 2022, 04:45:39 PM »
Good point - if you use any per-cell battery tester and run it on the ground then one weak cell will stand out like a sore thumb.

You. Been there done that. I bought the five pack of those battery checkers. Only wanted one. I have them everywhere now. Super handy Dan thing to have around for electric flight.  I keep two in my flight box. One in top and the other in the drawer. Seems like I can only ever find one of them at any given time.
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman

Online Howard Rush

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Re: System cuts to low voltage cut-off?
« Reply #9 on: January 19, 2022, 06:59:25 PM »
Seems like I can only ever find one of them at any given time.

Hook each up to a battery.  When the battery runs down, the checker will beep at 120 dB, and you'll know where it is. 
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Offline Mark wood

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Re: System cuts to low voltage cut-off?
« Reply #10 on: January 19, 2022, 09:37:28 PM »
Hook each up to a battery.  When the battery runs down, the checker will beep at 120 dB, and you'll know where it is.

They are painful. I stuff some foam in the speakers.
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman

Online Dennis Toth

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Re: System cuts to low voltage cut-off?
« Reply #11 on: January 20, 2022, 11:45:51 AM »
Any chance that having the wires crossing each other and over/around the ESC could cause a glitch? Any way to shield it?

Best,    DennisT

Offline Mark wood

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Re: System cuts to low voltage cut-off?
« Reply #12 on: January 20, 2022, 03:14:22 PM »
Any chance that having the wires crossing each other and over/around the ESC could cause a glitch? Any way to shield it?

Best,    DennisT

EMI generally isn't an issue with the ESC. However if there is a concern braiding the wires will fix it.
Life is good AMA 1488
Why do we fly? We are practicing, you might say, what it means to be alive...  -Richard Bach
“Physics is like sex: sure, it may give some practical results, but that’s not why we do it.” – Richard P. Feynman

Offline John Rist

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Re: System cuts to low voltage cut-off?
« Reply #13 on: January 20, 2022, 10:04:37 PM »
Any chance that having the wires crossing each other and over/around the ESC could cause a glitch? Any way to shield it?

Best,    DennisT
Yes it is possible for the placement of wires to cause a glitch.  Crossing each other is not the problem.  The problem occurs when wires are placed in tightly bound bundles for a long distance.  You can bundled the 3 motor leads by themselves.  You can bundled the two battery leads by themselves.  What you don't want to bundle in with motor or battery leads is the 3 wire control lead to the ESC.  Also you don't want to bundle the extra wire that comes out of the KR timer.  This is the wire that goes from the KR timer to one of the motor leads.  It's purpose is to let the KR timer control RPMs.  This wire will be in proximity of the motor leads.  It should not be laced tightly in with the motor leads.  I did this once and it caused the KR timer to shout down.  Unlacing the bundle and moving the KR timer wire a little solved the problem.   D>K
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Online Dennis Toth

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Re: System cuts to low voltage cut-off?
« Reply #14 on: February 06, 2022, 09:22:17 AM »
Yesterday we had some flyable weather down here in FL. I did a little repositioning of the battery hold down strap to secure the pack a little tighter and keep the wires from having any tension on them. This was the S1 Electric Ringmaster with the #1 battery (same one that stop short of time last session) along with the new FINS 40G, 45LB Test lines. All went well, full flight time and the FINS 40G lines used less battery mah (about 4 - 5%) then the 0.012" stainless steel 7 strand braided cable I had been using and felt the same for control.

I will add an additional strap and maybe a frame where the battery sits on the fuse to make sure it doesn't shift around and move the hookup wires.

Best,    DennisT

Online Dennis Toth

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Re: System cuts to low voltage cut-off?
« Reply #15 on: February 10, 2022, 06:47:54 PM »
I FOUND THE PROBLEM. Today I was adding an additional battery strap to the S1 Ringmaster and noticed the power and ESC wires were very close to the setup button on the ZTron timer. A closer look it seems if the battery moved around in flight the wires could mover over and hit the button and stop the timer. I am pretty sure this is what happen cause I flew the ship with that battery (was careful about the battery strapping) had no problem. I saw a way to secure the loose wires to the gear with a zip tie, looks very neat and secure.

Best,       DennisT

Offline John Rist

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Re: System cuts to low voltage cut-off?
« Reply #16 on: February 11, 2022, 07:25:13 AM »
I FOUND THE PROBLEM. Today I was adding an additional battery strap to the S1 Ringmaster and noticed the power and ESC wires were very close to the setup button on the ZTron timer. A closer look it seems if the battery moved around in flight the wires could mover over and hit the button and stop the timer. I am pretty sure this is what happen cause I flew the ship with that battery (was careful about the battery strapping) had no problem. I saw a way to secure the loose wires to the gear with a zip tie, looks very neat and secure.

Best,       DennisT

Thanks for sharing this info with us.  Electrics can have funny problems.  The more we learn the greater chance we have of avoding them.  Electric flight when working is very reliable and consistent.  When it is flakey it can drive you nunts!  D>K
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Online Dennis Toth

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Re: System cuts to low voltage cut-off?
« Reply #17 on: February 12, 2022, 11:10:06 AM »
After zip tying the lose wires I flew again today with the same #1 battery and had no problems. I believe that it was the wires hitting the setup button that caused the problem. Lesson learned keep hookup wires neat and secure and away from any buttons on the ESC or Timer.

Best,    DennisT


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