money
RSS Facebook

RCMF

*

RCMF Donations

Enjoy using RCMF? How about a wee donation to help us keep you in the style to which you've become accustomed?

Welcome, Guest. Please login or register.
August 16, 2018, 19:06:38 PM

Login with username, password and session length

Articles

Author Topic: LiPo Standards Dropping?  (Read 385 times)

0 Members and 1 Guest are viewing this topic.

Offline Bad Raven

  • Trade Count: (0)
  • RCMF Ace
  • ******
  • Thank You
  • -Given: 65
  • -Receive: 24
  • Posts: 6,077
  • Liked: 395
  • Country: gb
LiPo Standards Dropping?
« on: May 17, 2018, 07:46:17 AM »

In the last year I have experienced a rising level of LiPo reaching me in unsatisfactory condition. Since 1st Jan 18 EVERY supply received has had some significant issues.

This from UK supplier/brands, Chinese supplier direct and from (different) Chinese supplier with UK warehouse, so it seems not to matter where the final supply comes from.

Purely as an example, yesterday I received four 1300mAh 3S. As usual I test with three differing testers for positive confirmation, but one is an ISDT unit that has been proven to be extremely accurate, so I will only quote its data here.

Pack 1 - 3.75v average per cell with a range of 8mV
Pack 2 - 3.76v average per cell with a range of 11mV
Pack 3 - 3.02v cell one, cells two and three 0v
Pack 4 - 1.82v cell one with tester resistance causing it to slowly drop further, cells two and three 3.6*v

I have charged packs 1 and 2 and they completed charge (on a verified good charger) as follows:-

Pack 1 - 4.191v average per cell dropping after an hour to 4.183v, at that time a 2mV range
Pack 2 - 4.18v average per cell with a range of 12mV, voltage has held overnight.

The previous supply from a different source and brand were three 2200mAh 3S, and briefly one had a shorted cell 2 so pack indicated as 2S, and another was so unbalanced that there was no way I was about to use it. (These were not budget priced items)  When replaced under warranty, one of the two sent was badly out of balance but did balance after a couple of cycles.

SO.............

1. Do you check packs before charging for use?
2. HOW do you check packs?
3. What level of failures are you seeing?
4. Have you had issues getting warranty replacement?  (I have not, which suggests that the suppliers KNOW they are on poor ground!)

What does worry me is that in theory the possibility of a failure to thermal runaway must also be increasing with such erratic supply quality?





The user formerly know as Bravedan........... Well if Prince can do it....................


Offline paulinfrance

  • Trade Count: (0)
  • RCMF Ace
  • ******
  • Thank You
  • -Given: 0
  • -Receive: 23
  • Posts: 1,760
  • Liked: 264
  • Country: fr
  • I'm so new it hurts!
Re: LiPo Standards Dropping?
« Reply #1 on: May 17, 2018, 07:55:11 AM »
Yes,  I have also noticed the quality dropping, when a new 'brand' comes out usually they seem to be good, but
as they bring out more battery's with different capacities the quality seems to drop, this time Turnigy Bolt 'HV',
I bought some 3S 1300 for my drone and after a year they still give me 1000 mah but the second
delivery of my 2200 for my 'other' drone it takes off and within a minute it's back on the ground after 3 flights. and a couple of months. :-X

 Ps the only thing that I have noticed is that when they are on 'promotion' and cheap they are crap !. :-\
Mode 2 THE only way to fly


 

BloQcs design by Bloc
SMF 2.0.2 | SMF © 2011, Simple Machines
SMFAds for Free Forums
TinyPortal © 2005-2012
Page created in 0.197 seconds with 42 queries.