Notices
Electric General Discussion General Discussion forum about rc electric related aircraft, accessories, flight, tips, etc.

Voltage limit for Lipo

Old 04-04-2012, 03:39 PM
  #1  
acdii
Thread Starter
 
Join Date: Jan 2011
Location: Capron, IL
Posts: 10,000
Received 97 Likes on 88 Posts
Default Voltage limit for Lipo

What should the cutoff voltage be for a plane just before the ESC cuts power? Ihave a battery alarm that will beep when it reaches a set volt, so Ijust need to know what it should be. Ihave it set to 3.2 at this point and Inoticed it beeps rather quickly when the pack gets warm. It was a shorter flight than I thought it would be, so I am thinking Ihad it set too high.
Old 04-04-2012, 03:43 PM
  #2  
guver
Senior Member
My Feedback: (325)
 
Join Date: Mar 2003
Location: LaGrange, OH
Posts: 14,857
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Voltage limit for Lipo

Since the loaded voltage and resting voltage differential can vary so much it is expressed like this:

It is a cut off voltage that ultimately winds up being a resting voltage of about 3.7 volts per cell. The lvc could vary from 2.5 to 3.5 easily.
Old 04-05-2012, 12:29 PM
  #3  
acdii
Thread Starter
 
Join Date: Jan 2011
Location: Capron, IL
Posts: 10,000
Received 97 Likes on 88 Posts
Default RE: Voltage limit for Lipo

I cant find my book for the ESC so I dont know what the cut off voltage is so I can set the alarm.  The plane is too quiet when a popper is up with it so I can't hear the surging when the limit is reached, but I can hear the beeper.
Old 04-05-2012, 01:14 PM
  #4  
guver
Senior Member
My Feedback: (325)
 
Join Date: Mar 2003
Location: LaGrange, OH
Posts: 14,857
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Voltage limit for Lipo

How about setting the beeper voltage so that the packs rests at 3.7 volts per cell. If your first try as posted above had a lot of remaining capacity then you can probably go ahead and set it lower than it was.
Old 04-05-2012, 03:49 PM
  #5  
acdii
Thread Starter
 
Join Date: Jan 2011
Location: Capron, IL
Posts: 10,000
Received 97 Likes on 88 Posts
Default RE: Voltage limit for Lipo

I had it set to 3.2 and it went off, when I landed the packs were at 3.8. I may have a pack going under though, I was only up a few minutes when it started beeping, but the pack before it I was up 10 minutes and still had plenty left when I landed.
Old 04-05-2012, 04:21 PM
  #6  
guver
Senior Member
My Feedback: (325)
 
Join Date: Mar 2003
Location: LaGrange, OH
Posts: 14,857
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Voltage limit for Lipo

In both cases it sounds like you could set it lower. Maybe you used a pack that wasn't charged?

Probably 3 volts is a good setting and should really be thought of a "insurance" in case one forgets to land in the proper timed window. It shouldn't really be thought of as a device to tell one when to stop. I know I'm guilty of it too , I have one plane that I fly on purpose to lvc because I like to maximise the flight time , it is accurate every time and it is an easy plane for me to dead stick it in every time (GP flylite)

You could also be onto something and be right about a pack getting weak,old,damaged, ect. How is the performance of the pack? Is it a lot worse than other packs? If it was indeed full when starting and the timer went off at 2 minutes then compared to your 10 minute pack it is at best a lower quality,damaged,old,worn, or out-of-balance pack.
Old 04-05-2012, 06:20 PM
  #7  
acdii
Thread Starter
 
Join Date: Jan 2011
Location: Capron, IL
Posts: 10,000
Received 97 Likes on 88 Posts
Default RE: Voltage limit for Lipo

What I noticed was this pack was a lot warmer then the first one, and after it sat for a while the voltage was back up to 3.9. I have 3 of the same types, Gen Ace 25c 3300 packs. The one I flew before it was the same type, bought at the same time and flown the same number of times.  Maybe I hot dogged it more than the first one.
Old 04-06-2012, 01:58 PM
  #8  
guver
Senior Member
My Feedback: (325)
 
Join Date: Mar 2003
Location: LaGrange, OH
Posts: 14,857
Likes: 0
Received 0 Likes on 0 Posts
Default RE: Voltage limit for Lipo

Sounds like it is time to retire it to a less demanding app , or perhaps is best to dispose of it. I have many old used packs that I no longer used have a new lease on life since getting into airplanes. It has allowed me to fly gentle long flights without buying too many packs. I'm happy to put them to good use.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service -

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.