SMALL - Telemetry SMALL - Radio
Thread Tools
Old Jul 12, 2015, 06:12 AM
jj604 is online now
Find More Posts by jj604
ancora imparo
jj604's Avatar
Melbourne, Australia
Joined Jul 2005
8,112 Posts
Discussion
An Introduction to Lithium Polymer Battery Technology - translated into English

Ron van Sommeren recently posted a link to a presentation on “An Introduction to Lithium Polymer Battery Technology” that is on Gerd Giese’s home page.

http://www.rcgroups.com/forums/showthread.php?t=2453532

Herr Giese is an acknowledged expert on LiPos and model electronic matters but unfortunately this particular presentation by Dipl.-Ing. Frank Siegert is only available in German.

It is such a good up to date summary that I was inspired to translate it. Unfortunately this was hampered by the fact that I don’t speak any German.

However I do know a bit about LiPos. Mr Google and Mr Bing know a bit about German translation but nothing about LiPos. Together we attempted an English “transliteration” of this Power Point slide show. In some parts I was confident enough in the intent to translate it into colloquial English, in other parts I left it as a straight translation with the German sentence structure.

Unfortunately German is like English in the sense it has multiple words with similar meaning and the same word can mean many different things. I found the “auto-translate” programs pretty useless and had to resort to comparing several different translation engines to decipher meaning.

In particular, at first I couldn’t find any satisfactory translation of the word Deliithierung. I figured it out by asking Google to translate Lithiation into German. Lithiation isn’t the sort of word that occurs in everyday conversation!

So if anyone who is fluent in both German and English would care to send me any corrections I would be very grateful. I am sure there are a few hilarious mistranslations.

I have formatted it with the original slides followed by an additional one with the translation. This kept the file size down so RCGroups would load it. Easiest way to follow it is to format your screen so the pdf reader shows two pages - one above the other.

It is a most useful summary of LiPo technology if you are interested in how our flight packs work.

It will clarify such questions as:

Why do my LiPos die in the Winter under the same conditions as Summer flying?
Will the new high rate and high voltage LiPos last as long as my current ones?
Is that smell dangerous?

John
jj604 is online now Find More Posts by jj604
Reply With Quote
Sign up now
to remove ads between posts
Old Jul 12, 2015, 08:50 AM
hoppy is offline
Find More Posts by hoppy
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
21,920 Posts
Thanks John,
From just a few hours of looking at ways to translate that document I can appreciate the amount of effort you put into preparing that document.
Thanks again.
hoppy is offline Find More Posts by hoppy
Reply With Quote
Old Jul 12, 2015, 10:13 AM
mrforsyth is offline
Find More Posts by mrforsyth
Registered User
So. Cal.
Joined Oct 2004
8,934 Posts
Outstanding effort John!

I took particular interest detailed explanation of the physical principles and changes in cell chemistry that occur due to usage patterns. These clearly corroborate the empirical observations of hobbyists that have been amassed over the last several years (Winter failure symdrome (W. Giles coined term), effects of storing at full charge, benefits of deliberately undercharging, benefits of gentle 'break-in' cycles, etc.).

Nicely done!

Mark
mrforsyth is offline Find More Posts by mrforsyth
RCG Plus Member
Reply With Quote
Old Jul 12, 2015, 11:10 AM
Wayne Giles is offline
Find More Posts by Wayne Giles
Registered User
Rugby, UK
Joined Feb 2007
995 Posts
John,

Thanks for all your efforts in translating this document. It reveals a lot of electrochemical detail of which most of us are quite ignorant, but now much is revealed if we are prepared to go through it.

To anyone only generally interested I would suggest that they go to the last few pages where most of the practical advice and details are, particularly in relation to maximising lipo life and avoiding cell damage. Eg I have long been aware of the winter failure syndome caused by taking high currents at low temperature, but now we have the explanation and confirmation of its existence.

Wayne
Wayne Giles is offline Find More Posts by Wayne Giles
Reply With Quote
Old Jul 12, 2015, 02:20 PM
JAyThaRevo is offline
Find More Posts by JAyThaRevo
Registered User
Austria, Stmk., Graz
Joined Sep 2013
330 Posts
+1
JAyThaRevo is offline Find More Posts by JAyThaRevo
Reply With Quote
Old Jul 12, 2015, 04:48 PM
OnGuard is offline
Find More Posts by OnGuard
Registered User
Indiana
Joined Nov 2004
646 Posts
Thanks John
OnGuard is offline Find More Posts by OnGuard
Reply With Quote
Old Jul 12, 2015, 06:40 PM
jj604 is online now
Find More Posts by jj604
ancora imparo
jj604's Avatar
Melbourne, Australia
Joined Jul 2005
8,112 Posts
Additional information

The Wikipedia article on Lithium Ion batteries has more information on the chemistry. I found it an interesting parallel read to this slide show.

https://en.wikipedia.org/wiki/Lithium-ion_battery

The Wikipedia article on Lithium Polymer batteries is not very good in my opinion. It is mainly useful for the description of the confusion around the term Lithium Polymer in model markets.

https://en.wikipedia.org/wiki/Lithium_polymer_battery

In fact it reads as though it were written (or at least added to) by a Hyperion salesman/vendor. All battery references are to Hyperion packs and it claims that in the Summer of 2015 Hyperion introduced HV LiPos to the market which is patently untrue. Revolectrix were selling HV LiPos long before Hyperion to my knowledge.

John
jj604 is online now Find More Posts by jj604
Reply With Quote
Old Jul 13, 2015, 02:50 AM
henrtenaitn
A moderator felt this post violated the following rule: Redacted Content.
Old Jul 13, 2015, 07:09 AM
apriliamille is offline
Find More Posts by apriliamille
Registered User
apriliamille's Avatar
United States, UT, American Fork
Joined May 2008
288 Posts
i thought it was interesting about the charge to 4.1 and get double the life. that is really not that much loss in flight time to save some money over the long run

i wonder how much difference over time will there be if stored at 3.7v instead of the 3.85 that i have been using
apriliamille is offline Find More Posts by apriliamille
Reply With Quote
Old Jul 28, 2015, 06:24 AM
frank77433 is offline
Find More Posts by frank77433
Miggy2007
frank77433's Avatar
United States, MN, Burnsville
Joined Jun 2014
5 Posts
Quote:
Originally Posted by mrforsyth View Post
Outstanding effort John!

I took particular interest detailed explanation of the physical principles and changes in cell chemistry that occur due to usage patterns. These clearly corroborate the empirical observations of hobbyists that have been amassed over the last several years (Winter failure symdrome (W. Giles coined term), effects of storing at full charge, benefits of deliberately undercharging, benefits of gentle 'break-in' cycles, etc.).

Nicely done!

Mark
Corroborate, empirical, observations was the only .25 cent word I understood. . I appreciate the thread gentleman, scholars and fellow flyers!
frank77433 is offline Find More Posts by frank77433
Reply With Quote
Old Jul 30, 2015, 01:22 PM
treehog is offline
Find More Posts by treehog
UN Earth peoples true enemy
treehog's Avatar
Euroland
Joined Jan 2004
1,824 Posts
good work OP keep going

Ralf
treehog is offline Find More Posts by treehog
Reply With Quote
Old Jul 30, 2015, 04:46 PM
chuck75 is offline
Find More Posts by chuck75
Registered User
Georgia
Joined Jun 2007
818 Posts
It's interesting that there are some similarities that seem to be common to many rechargeable batteries.
The life vs optimum discharge rates are of interest because model aircraft typically use momentary to semi-continuous high discharge rates.
An area that I felt was not detailed enough has to do with loaded vs unloaded voltage and charge level. Voltage rebound and settled voltage might be a related area of interest.

The tab area explanation of current was interesting, but mechanical construction details might reduce the differences in current density.

We lived in Germany for several years in the 70's, and I struggled with technical German (as well as commonly spoken German)
(The local dialects (low German) were different from Dorf to Dorf in th Eiffel area.)

I completely understand the translation difficulties. French is even worse! One of my then cohorts had to go to a meeting in France concerning
aircraft color weather radar. The meeting was conducted in French, and he was fairly fluent in the common spoken language.
Technical French was as bad or worse to him as German was to me. He was still irritated when he returned from the meeting.
As soon as the non French attendees were excluded from a French only part of the meeting, the French reverted to using many English
technical terms instead of the more obscure French ones! Remember that English is the "official" worldwide aviation standard language.
chuck75 is offline Find More Posts by chuck75
Last edited by chuck75; Jul 30, 2015 at 05:01 PM.
Reply With Quote
Old Jul 30, 2015, 08:29 PM
ignernt_dweeb is offline
Find More Posts by ignernt_dweeb
Registered User
Joined Apr 2015
211 Posts
Does anyone make a device that limits maximum discharge rate? Preferably, it would be digital and adjustable... and very lightweight, of course.
ignernt_dweeb is offline Find More Posts by ignernt_dweeb
Reply With Quote
Old Jul 31, 2015, 06:56 PM
hbollier is online now
Find More Posts by hbollier
Registered User
hbollier's Avatar
United States, LA, Lafayette
Joined May 2013
211 Posts
Quote:
Originally Posted by ignernt_dweeb View Post
Does anyone make a device that limits maximum discharge rate? Preferably, it would be digital and adjustable... and very lightweight, of course.
I believe that would best be done with the choice of prop.
hbollier is online now Find More Posts by hbollier
Reply With Quote
Old Jul 31, 2015, 07:38 PM
jj604 is online now
Find More Posts by jj604
ancora imparo
jj604's Avatar
Melbourne, Australia
Joined Jul 2005
8,112 Posts
If by that you mean a current limiter in the plane, I do not know of a general purpose one. Castle Creations speed controllers have something that sounds like it however.

http://www.rcgroups.com/forums/showthread.php?t=191938

It might be an interesting project. You could take the output of a standard telemetry system that has a current sensor and use it to control the ESC.

I'm guessing you could build it with just the current sensor alone which normally puts out a voltage proportional to current and a small microprocessor that accepts the input of your throttle channel and feeds it to the ESC. By comparing the voltage from the current sensor to your set maximum , it should be possible to control the output of the ESC so as never to exceed that set current. Wouldn't be all that expensive or heavy as the only additional weight is the current sensor and controller - and all the heat dissipation is already happening in the ESC.

As hbollier points out however, the normal way to do it is to adjust the load on the motor for a given cell count by the choice of prop. Unless the air density or the IR of the pack changes dramatically this will set the maximum current you will draw.
Quote:
Originally Posted by ignernt_dweeb View Post
Does anyone make a device that limits maximum discharge rate? Preferably, it would be digital and adjustable... and very lightweight, of course.
jj604 is online now Find More Posts by jj604
Reply With Quote


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Why Don't We use Lithium Polymer Batteries in RC? unknownflier Batteries and Chargers 30 May 14, 2015 07:34 PM
Discussion Why you don't charge an overdischarged lithium polymer battery. Mark Wood Batteries and Chargers 21 Sep 01, 2014 03:26 AM
Sold Turnigy 4x6S Lithium Polymer Battery Pack Charger IntheTubeDeep Aircraft - Electric - Batteries & Chargers (FS/W) 1 Nov 20, 2013 01:19 AM
Sold Turnigy 4x6S 400W Lithium Polymer Battery Charger echeng Aircraft - Electric - Batteries & Chargers (FS/W) 2 Nov 15, 2013 09:27 AM