SMALL - espritmodel.com SMALL - Telemetry SMALL - Radio
Reply
Thread Tools
Old Oct 30, 2010, 11:14 AM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,834 Posts
Discussion
Proper (?) LiPoly management.

So this subject comes up often and I wrote this post on another User's group over a year ago.

Note close to 3 year ago now. 2-26-12



The following are my opinions and have worked for myself and many others.

Proper storage :
Approx. 3.85 volts per cell in a cool location. IMO with today's fast charge capable LiPolys and high rate capable chargers there is little sense in leaving LiPolys charged just in case the weather turns nice.



Discharge level:
I have used 80% depth of discharge as my standard for years and it works extremely well. There is mounting evidence that the latest high quality LiPolys can endure deeper discharges much better than prior ones but testing is still limited.

Handling :
LiPolys are fragile. I have been called crazy for suggesting the be handled like an unboiled egg or fine china. Every crease,bing,bump,etc. creates a pressure point which leads to accelerated salt crystals growth.

Cheap chargers :
My advise is not to use them. An accurate high quality charger / balancer will extend the life of your LiPolys and in conjunction with high quality fast charge (3-6C) capable LiPolys will reduce the number of batteries you need,make LiPoly management much simpler and greatly increase your flying time and enjoyment.

High C rate charging:
I have charged at 3C and higher for close to 4 years now. I have proven to myself that quality LiPolys charged and balanced on quality equipment does not adversely reduce their life. I am currently charging at 5C and replacing over 80% capacity in under 15 minutes on many of my LiPolys.

<Added> I keep reading post that charging at greater than 1C reduces life and that the slower charges are always best. I am not going to do extended cycle testing at 1C charge rates but all the proof I need that 5c charging with high quality LiPolys and eauipment is not damaging is right here.

http://www.rcgroups.com/forums/showp...19&postcount=1

Break-in:

I start with 1C charges and moderate max. loads.I try and stay under 60% of claimed max. cont. C rating and keep flight times short to insure not exceeding 80% capacity used.
Example A 20C 2200 is rated for 44 amps. cont . but I would stay under 26A (12C) average. Short burst to 35-40 amp. are fine but the practice of charging a new LiPoly and then seeing how much power it has does a new LiPoly no good.

Added 5-4-12: As noted above I charage at multi C rates routinely however:

I work up to this on a gradual basis.First charge is at 1C perhaps even two at 1C depending on the LiPoly and charger used. Observe the cell's balance and do not charge faster if they are drifting about much.
Next up is 2 or 3 2C charges then a 2 or 3 C rate ones. Once the LiPoly has 10 to 15 charges I have worked up to 5C (for so rated LiPolys) and from then on I charge based on how fast(soon) I will need it charged again.

Post here with fairly detailed charge and discharge cycles working up to 5C charge rate.

http://www.rcgroups.com/forums/showp...1&postcount=10

First sign of a LiPoly going south.

Most often the first signs of a LiPoly starting to go down hill will be cells not staying balanced as well,more time being taken in the CV stage of charging / balancing.
If the battery is marginal to begin with you could also notice a decline in power but often this is so gradual that it is not noticed until it gets really bad or you happen to fly a newer / better battery.


Efficient use of charging time:

This example based on charging 3S3300 at 12.5A (3.78C) and while not linear are representative of other rates. Each person will have to conduct their own equalization as chargers/balancers and LiPolys will vary.

Total charge time 18 min. capacity replaced 2896 for an average of 160.9 mAh per min..
During the first 12:30 while rate was holding at 12.5A
2600 mAh for an average of 208 mAh per minute.
Between 12:30 and 14 min . 200 mAh or 133.3 mAh per minute.

First 12:30 or 69.4% of total time 2600 mAh or 89.8% of capacity achieved.



Added:2-26-2012

C rate in simple terms

OK now C in simple terms.

C rate as used by most is C apacity in Ah times a number.

A 2200 mAh LiPoly is 2.2 Ah as 2200 mAh / 1,000 mAh = 2.2 Ah.

A 1C charge rate is the A rate required to fully charge the battery in one hour.
2.2 Ah to be replaced in 1 hour equals a 2.2A charge rate.

Greater than 1C

If discharged at 10C then 2.2A X 10 = 22Amps.

also 60 min . / 10 = 6 minute fligjht.

If Charged at 3C then 3 X 2.2A = 6.6 Amps.

Charles
everydayflyer is offline Find More Posts by everydayflyer
Last edited by everydayflyer; May 04, 2012 at 07:26 AM.
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 30, 2010, 01:22 PM
Registered User
ggcrandall1's Avatar
USA, GA, Marietta
Joined Aug 2005
5,810 Posts
Well said Charles.

Glen
ggcrandall1 is offline Find More Posts by ggcrandall1
Reply With Quote
Old Oct 30, 2010, 08:35 PM
TJin(Guy + Tech)
tjinguy's Avatar
United States, NM, Socorro
Joined Jun 2008
784 Posts
Lines up with my beliefs pretty much perfectly.
tjinguy is offline Find More Posts by tjinguy
Reply With Quote
Old Oct 31, 2010, 11:20 PM
Registered User
Joined Feb 2010
187 Posts
Normally the battery storage at 40%capacity,however I 've received some batteries from hobbyking-1cell batteries -Turnigy 3,7V-160Mah and from China 3,7V-180mha which are both being storaged at 3,95V???
ndp62 is offline Find More Posts by ndp62
Reply With Quote
Old Oct 31, 2010, 11:30 PM
The 6 P principle works for me
elecfryer's Avatar
Ventura CA
Joined Aug 2007
977 Posts
I agree with what you are saying Charles. For long term storage I have been using 3.7V/cell.

Question, would the 3.85V/cell apply for newer lipo's or for older lipo's as well (I put that not too well, I ment is there a difference in storage voltage for 10C-20C capable lipo's vs 25C and above?)

Michael.
elecfryer is online now Find More Posts by elecfryer
Reply With Quote
Old Nov 20, 2010, 02:25 AM
Registered User
bladefan's Avatar
United States, OR, Portland
Joined Jun 2006
273 Posts
This ought to be a sticky!
bladefan is offline Find More Posts by bladefan
Reply With Quote
Old Nov 20, 2010, 05:23 AM
Registered User
ggcrandall1's Avatar
USA, GA, Marietta
Joined Aug 2005
5,810 Posts
Quote:
Originally Posted by bladefan View Post
This ought to be a sticky!
Yes, but if it was nobody would read it. This info is pretty much covered in the existing stickies and it seems you have to drag newcomers there, kicking and screaming, to get them to read them.

Glen
ggcrandall1 is offline Find More Posts by ggcrandall1
Reply With Quote
Old Nov 23, 2010, 01:38 PM
Registered User
United States, FL, Palm Harbor
Joined Feb 2007
652 Posts
I just got rid of a couple lipos and they seemed to charge ok but in the first place they were slightly puffy. second while the full charge was nearly 4.2 the performance was terrible and I time my flights and at the end of the flight the battery was discharged a little more than usual ..some guys will use them ..I figured given the number of cycles and overasll condition it was a safe bet they needed to go.some of flying buddies laugh at me cause I time my flights.at any rate I decided to drown them in salt water which is good inasmuchas I dont need all that sodium in my diet.

everyday are you saying you can charge a good lipo at higher than a 1c?? they dont necessarily need to be fast charge batteries.??can you clearthat up for me..

I have fast charged nimh and nicads but the chemistry was different.the reason I ask is that I am going to replace much of my inventory and purchase fast charge type lipos like the g3 hyperions and nano techs. whats your best advice?
propnut07 is offline Find More Posts by propnut07
Reply With Quote
Old Nov 23, 2010, 02:02 PM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,834 Posts
Standard 1C charge rate has been around ever since the days of 3C discharge rate Lipolys.

When FMA first introduced the CelPro 4 around 6 or 7 years ago it had the option to set Auto C rate charges of 1,2 or 3C. Many used these to charge 6-15C LiPoly at Auto 3C rates for years and years now and I have not read of any isuues doing so in the past 5 or 6 years. Now the Cell Pro 4(and other FMA chargers set to Auto) will refuse to charge a cell which has very high internal resistence at a high rate.

I have charged Thunder Power Pro lites 13C dsc. rate at 3C for over 5 years. I have charged Hyperion 25 and 35C G3 Lipolys at 5c for over two years and some of the Thunder Power Pro Power series at between 5 and 10C for close to a year.

So what is a good summary? I feel that cells with low internal resistence have no problems being charged at greater than 1C. I feel that any 15C should be fine at 2C charge rates and that 20 C and above should be fine with 3C. This is assuming that a decent balancing charger is used and that the LiPolys are first charged at 1C and that charges are increased gradually and observed for any signs of problems.

Note there is at least on vendor who insist that their LiPolys not be charged at greater than 1C for the first 10 chceged even thought they rate them at up to 8C charge and 65C discharge.

There is another Vendor who says that this whole break-in business is BS and their's can be charged and discharged at the maxes. from the get go.

I tested some LiPolys for on vendor and he clearly stated not to charge at greater tan 3C. Well I charged them at 5C and 200 cycles latter they are stil doing great. Hint, some vendors do not know the products they sell.
everydayflyer is offline Find More Posts by everydayflyer
Reply With Quote
Old Aug 03, 2013, 12:30 PM
Registered User
Joined Aug 2013
13 Posts
What is a sticky

Quote:
Originally Posted by bladefan View Post
This ought to be a sticky!
Hi, What is a sticky ? I assume its a tip or note? If so where and how do I access them?
Corporalcuddles is offline Find More Posts by Corporalcuddles
Reply With Quote
Old Aug 03, 2013, 12:34 PM
Registered User
United States, WI, West Bend
Joined Jun 2013
131 Posts
Quote:
Originally Posted by Corporalcuddles View Post
Hi, What is a sticky ? I assume its a tip or note? If so where and how do I access them?
Sticky's are threads that stay at the top of the forum boards at all times. If you look in all the different forum categories, the first few posts will be sticky's.
Osborn Cox is offline Find More Posts by Osborn Cox
Reply With Quote
Old Aug 07, 2013, 10:06 AM
Me a long time ago
Flypoppa's Avatar
London N.E. UK
Joined Jan 2007
6,107 Posts
Why do lipos puff?
I have quite a few do this. I do not over C discharge them, as the most draw is about 11-15 amp and the lipos have a C rating from 25-35.
I now have a theory that because I store them fully charged, and dont maybe use them for a couple of week, this could be why they puff.
A while ago I bought 2 1300mah 3s Nano tecs for my FPV. They were charged and put in my batt box. When I looked today I noticed that they were slightly puffed.
Thoughts on this please.
Flypoppa is offline Find More Posts by Flypoppa
RCG Plus Member
Old Aug 07, 2013, 12:59 PM
Registered User
ggcrandall1's Avatar
USA, GA, Marietta
Joined Aug 2005
5,810 Posts
Over and over it has been said in these forums not leave LiPo's fully charged. Looks like you have discovered a reason why.

You say you do not over discharge your batteries "C" value. That is not enough. You need to hold the amp draw of the battery to 80% and also not discharge more than 80% of the mah.

Glen
ggcrandall1 is offline Find More Posts by ggcrandall1
Reply With Quote
Old Aug 07, 2013, 05:29 PM
Me a long time ago
Flypoppa's Avatar
London N.E. UK
Joined Jan 2007
6,107 Posts
Thanks for your answer Glen. So my theory was correct. I am at present putting the lipos into 'storage' charge.
Flypoppa is offline Find More Posts by Flypoppa
RCG Plus Member
Old Aug 07, 2013, 09:08 PM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,834 Posts
First suggestion from first post.


Proper storage :
Approx. 3.85 volts per cell in a cool location. IMO with today's fast charge capable LiPolys and high rate capable chargers there is little sense in leaving LiPolys charged just in case the weather turns nice.
everydayflyer is offline Find More Posts by everydayflyer
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Sold Hyperion g3 ex 2600 mah 6s 22.2v 45c/90c lipoly pack HeliPro5 Aircraft - Electric - Batteries & Chargers (FS/W) 1 Mar 17, 2011 04:26 PM
Discussion Proper cabling methods? g00bd0g FPV Talk 2 Oct 21, 2010 05:42 AM
Found Wanted: Dewalt DC9360 Battery Management System 99sh Aircraft - Electric - Batteries & Chargers (FS/W) 2 Sep 19, 2010 03:05 AM
For Sale Litco Alpha4 batter management system Plane Addicted Aircraft - Electric - Batteries & Chargers (FS/W) 0 Sep 03, 2010 06:45 PM