Go Back  R/C Tech Forums > General Forums > Radio and Electronics
Sky lipo problem, please help! >

Sky lipo problem, please help!

Community
Wiki Posts
Search

Sky lipo problem, please help!

Thread Tools
 
Search this Thread
 
Old 01-31-2013 | 01:12 PM
  #1  
Thread Starter
Tech Addict
iTrader: (9)
 
Joined: Apr 2011
Posts: 634
From: Litchfield park, AZ
Default Sky lipo problem, please help!

I have a 2, 2s 5000mah Sky lipo my son was running in my Slash 4x4. He ran the first one for about 25 minutes before the lvc cut in. We let the esc and motor cool (it was already cool to the touch as it was cold outside and geared very low as he's only 4). I put in the second battery and after about a lap he started to complain that the truck was stopping on it's own. I went over to look and once he let it stop and sit for a second, he would floor the throttle and the car would zoom off great then almost immediately after would slow to about 1/3 the normal speed. He could let off, let it sit and the same thing would happen. The LVC doesn't seem to be kicking in and it would make me cycle the esc on/off to reset the LVC. I checked voltage on the battery and it was still just over 4.0v per cell. I've tried this battery on one 80a Hobbyking (in the slash) and a Tekin RX8. Same results. What's going on here? Do I have a bad cell? If so why is the voltage looking normal. He was very sad he couldn't keep playing because of this. Thanks all!!!
jrowles91 is offline  
Old 01-31-2013 | 01:48 PM
  #2  
Tech Master
iTrader: (17)
 
Joined: Jun 2004
Posts: 1,500
From: SoCal
Default

Definitely check if the cells are balanced. Sounds like they're out of balanced.
trigger is offline  
Old 01-31-2013 | 01:55 PM
  #3  
Thread Starter
Tech Addict
iTrader: (9)
 
Joined: Apr 2011
Posts: 634
From: Litchfield park, AZ
Default

Originally Posted by trigger
So you are experiencing this condition with two different batterie? I think it's more esc related than battery issues. What kind of speedo? If its a sensored system, do the routine checks like sensor cable and connections.

Just read the op again and realized that you tried it again with another speedo and the same result. Hmmmm quite possible you have battery woes. Both packs are sky packs? Check the balance of the cells. I'm assuming the cells are out of balanced.
No, only 1 of the 2 batteries is acting like this. That's why I've ruled out speedo, along with trying it on multiple speedo's. The cell's were within .02v of eachother which I'm perfectly fine with. Both over 4v still. Any other thoughts on that? I really don't want to buy another battery although I guess it's given me a long life already...
jrowles91 is offline  
Old 01-31-2013 | 02:14 PM
  #4  
Thread Starter
Tech Addict
iTrader: (9)
 
Joined: Apr 2011
Posts: 634
From: Litchfield park, AZ
Default

Originally Posted by trigger
Definitely check if the cells are balanced. Sounds like they're out of balanced.
They were definatly balanced showing just over 4v each. One was at like 4.03 and the other was 4.01
jrowles91 is offline  
Old 01-31-2013 | 02:17 PM
  #5  
Thread Starter
Tech Addict
iTrader: (9)
 
Joined: Apr 2011
Posts: 634
From: Litchfield park, AZ
Default

And I balance the batteries every time they are charged.
jrowles91 is offline  
Old 02-01-2013 | 07:31 AM
  #6  
Hoese37's Avatar
Tech Elite
iTrader: (5)
 
Joined: Apr 2007
Posts: 3,819
From: Hutchinson, MN
Default

Do you have a charger with a discharge option? If so then setup a discharge and see if the cells go out of balance while discharging.
Hoese37 is offline  
Old 02-01-2013 | 09:41 AM
  #7  
Thread Starter
Tech Addict
iTrader: (9)
 
Joined: Apr 2011
Posts: 634
From: Litchfield park, AZ
Default

Originally Posted by Hoese37
Do you have a charger with a discharge option? If so then setup a discharge and see if the cells go out of balance while discharging.
I do yes, at what amp should the discharge be set at? I always read discharging a lipo on the charger was bad, never knew why as it's discharging on your truck anyway.
jrowles91 is offline  
Old 02-01-2013 | 10:41 AM
  #8  
Hoese37's Avatar
Tech Elite
iTrader: (5)
 
Joined: Apr 2007
Posts: 3,819
From: Hutchinson, MN
Default

as high as it goes. youll notice in the few first moments if it has a weak cell.

Its not that its bad to discharge a lipo on a charger, theres really just no need to do it.
Hoese37 is offline  
Old 02-01-2013 | 11:03 AM
  #9  
Tech Addict
iTrader: (1)
 
Joined: Nov 2008
Posts: 650
From: Tampa, FL.
Default

Originally Posted by jrowles91
I always read discharging a lipo on the charger was bad, never knew why as it's discharging on your truck anyway.
It's easier on the battery to discharge with the charger or other discharge device. Discharging while in the vehicle is hard on batteries.
Johnnysplits is offline  
Old 02-01-2013 | 11:14 AM
  #10  
Thread Starter
Tech Addict
iTrader: (9)
 
Joined: Apr 2011
Posts: 634
From: Litchfield park, AZ
Default

Originally Posted by Hoese37
as high as it goes. youll notice in the few first moments if it has a weak cell.

Its not that its bad to discharge a lipo on a charger, theres really just no need to do it.
Makes perfect sense. I'll give it a shot tonight.
jrowles91 is offline  
Old 02-01-2013 | 11:25 AM
  #11  
Hoese37's Avatar
Tech Elite
iTrader: (5)
 
Joined: Apr 2007
Posts: 3,819
From: Hutchinson, MN
Default

Good luck. If its bad, get a SMC battery.
Hoese37 is offline  
Old 02-01-2013 | 11:32 AM
  #12  
Thread Starter
Tech Addict
iTrader: (9)
 
Joined: Apr 2011
Posts: 634
From: Litchfield park, AZ
Default

Originally Posted by Hoese37
Good luck. If its bad, get a SMC battery.
Thank you! Why is SMC preferred? THey look very reasonable in price.
jrowles91 is offline  
Old 02-01-2013 | 11:38 AM
  #13  
Hoese37's Avatar
Tech Elite
iTrader: (5)
 
Joined: Apr 2007
Posts: 3,819
From: Hutchinson, MN
Default

Very reasonable, great warranty, trade in program, great numbers and specs, awesome price. I plan on getting a few very soon here.
Hoese37 is offline  
Old 02-01-2013 | 02:38 PM
  #14  
Thread Starter
Tech Addict
iTrader: (9)
 
Joined: Apr 2011
Posts: 634
From: Litchfield park, AZ
Default

Just bought SMC 2s 5000mah 30c for $25! Plus shipping of course but whatever $31 total. I'll still check the battery but wanted one anyway!
jrowles91 is offline  
Old 02-01-2013 | 10:05 PM
  #15  
Thread Starter
Tech Addict
iTrader: (9)
 
Joined: Apr 2011
Posts: 634
From: Litchfield park, AZ
Default

Ok Hoese37, I have it currently on a discharge and the highest my charger can go is 5a. It's discharging nicely and evenly. It's now been 10 minutes and both cells are within .01v of eachother. WTH is going on!?!
jrowles91 is offline  


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

Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.