LiPo Battery Life

[Dean Pappas]

Hi Richard,

Hopefully, we can all get a little smarter, after your unfortunate experience. 
First, what was the setup?
1)Batteries? 
2)Motor? 
3)Prop static current at full throttle?
4)voltage on tha batteries under that condition?
5)after flight battery temperatures?
6)after flight motor temps?
7)capacity used per flight?
8)after flight voltages?
9)Do you know if you ever drove any individual cell below 3.0V?


Right now, I am flying a testbed. I don't anticipate flying the E-setup competitively until 2007, at least.
My post flight battery temps are about 25F above ambient, until it gets colder than 80F: below that they always seem to be at 100 to 105F, which probably shows that the batteries get resistive at low temps, and then self-heat to 100F.
I try to limit the battery to no more load than will allow me to maintain 35V (right at the battery) when checking the current at fresh charge and W.O.T.
I am limiting myself to 65A on the 4 A-H Kokams that FMA sell, and so far, I haven't measurably lost any battery capacity.
I cycled them when they were just a few cycles old, and just recently re-ran the test, this week. 
I did fly a couple of short flights at over 70A, just to see what the performance might be like, with batteries like the TP5200. I am impressed.
By the way, FMA sell a stick-on thermometer label that you can put on your batteries, in several places: Great item.

For now, I suspect the secret is in measuring the battery temps and the cell voltages, every flight, to make sure you aren't damaging them.

later,
Dean

  

Dean Pappas
Sr. Design Engineer
Kodeos Communications
111 Corporate Blvd.
South Plainfield, N.J. 07080
(908) 222-7817 phone
(908) 222-2392 fax
d.pappas at kodeos.com

 
 
-----Original Message-----
From: discussion-request at nsrca.org [mailto:discussion-request at nsrca.org] On
Behalf Of Richard Strickland
Sent: Thursday, November 17, 2005 3:40 PM
To: discussion at nsrca.org
Subject: Re: Discussion List (Batteries)

OK, how's this:  I got seriously involved in electric power until my three
sets of batteries shot craps after about 25 cycles each, was going to go
back to IC for a while until it looked liked the batteries were going to
hold up better, but my source for the interim airplane and power unit got
later and later so I was effectively out of the loop for the season.  I've
kept myself busy with other stuff(good and bad)--and don't know what the
latest skinny is on batteries.  Anyone?

Richard

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