HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Sep 15, 2006, 06:58 PM
Registered User
United States, CA
Joined Dec 2001
416 Posts
Discussion
LiPo Temperature

Hi all,

After overheating and ruining a 4300 mAh LiPo pack, I will be monitoring pack temperature in real-time from now on.

A couple questions:

1. What is the maximum safe temperature that LiPo's can be repeatedly (every flight) subjected to w/o damage?

2. I'm assuming that LiPo's are encased in thermally-conductive material to dissipate heat, but don't know this - Anyone know otherwise? If the material is insulative, then monitoring surface temperature will be pointless.
green66 is offline Find More Posts by green66
Reply With Quote
Sign up now
to remove ads between posts
Old Sep 15, 2006, 07:12 PM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,512 Posts
The cells are aluminum and copper so yes very heat conductive. Inner cells will be slightly hotter than outside ones but not an issue unless pushed to upper limits. I stay at 70% of rated max. cont. C for the most part and have no problems staying below 130 F in flight.
How hot is to hot? 125 F or below is great. 140 F is OK and brief excursions to higher temperatures can be tolerated by some quality LiPolys.
A look in the Battery Graph Vault of some of RD B's test will show what some cells have survived.

Charles
everydayflyer is online now Find More Posts by everydayflyer
Reply With Quote
Old Sep 15, 2006, 07:14 PM
Permanently Banned
San Jose Ca / RSA flyer
Joined May 2003
8,030 Posts
If U gotta worry about temperature, then U R overloading them and the lipo casing is not thermal conductive, they just have to be in a vented compartment
hall woo is offline Find More Posts by hall woo
Reply With Quote
Old Sep 15, 2006, 07:28 PM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,512 Posts
hall ,just how much thermal insulation do you think that very thin plastic film provides?

http://www.rcgroups.com/forums/showp...54&postcount=1
everydayflyer is online now Find More Posts by everydayflyer
Reply With Quote
Old Sep 15, 2006, 07:43 PM
Permanently Banned
San Jose Ca / RSA flyer
Joined May 2003
8,030 Posts
have U ever worn a thin vinyl jacket on the lake while boating ?
hall woo is offline Find More Posts by hall woo
Reply With Quote
Old Sep 15, 2006, 07:44 PM
Registered User
United States, CA
Joined Dec 2001
416 Posts
Charles,

Thanks - The thermally-conductive Al/Cu materials relieves my anxiety as to whether measured surface temperature would be indicative of internal temperature or not.

I'll probably bond a small temperature sensor between cells with thermally-conductive epoxy - Any problems foreseen?

TIA
green66 is offline Find More Posts by green66
Reply With Quote
Old Sep 15, 2006, 07:46 PM
Southern Pride
everydayflyer's Avatar
Haralson County GA. USA
Joined Oct 2004
34,512 Posts
Have you ever held a piece of aluminum in your hands while grinding on it?

IMO is the inside of LiPoly cells got as much hotter than the outside as some seem to believe the plastic film would melt and the cell would short.


Charles
everydayflyer is online now Find More Posts by everydayflyer
Reply With Quote
Old Sep 15, 2006, 09:34 PM
Space Coast USA
hoppy's Avatar
Space Coast
Joined Oct 2000
20,657 Posts
Side temperatures are ~10F hotter for me then top/bottom temps in 3s packs. It's probably the hotter middle cell causing the temperature difference.

The cells are mainly inorganic/organic compounds with about 25% metal content.
http://app.rayovac.com/cm/groups/pub...sds/007125.pdf
http://www.ulbi.com/documents/msdshe...14-Polymer.pdf
hoppy is offline Find More Posts by hoppy
Reply With Quote
Reply


Thread Tools