[NSRCA-discussion] batteries?

Fri Apr 17 08:05:43 AKDT 2009

Oh yeah. ALL batteries should  be considered somewhat dangerous. They ALL have a lot of stored energy. When I used to race R/C cars we only had NiCd's. One time when we were getting ready to head to the track for practice, my friend noticed smoke coming from his racing box. When we opened it up we saw that the wire supports for a rear wing had come in contact with the connector on one of his 7-cell packs. The 1/16" wire was glowing red and it had melted the Lexan wing. The wire actually fused (melted) and that took care of the short circuit problem. The wing was ruined and  the battery was HOT! I had a lot of respect for the amount of energy that one of those packs could deliver after that. VBG

John Pavlick

--- On Fri, 4/17/09, James Oddino <joddino at socal.rr.com> wrote:

From: James Oddino <joddino at socal.rr.com>
Subject: Re: [NSRCA-discussion] batteries?
To: "General pattern discussion" <nsrca-discussion at lists.nsrca.org>
Date: Friday, April 17, 2009, 3:37 PM

I don't agree John.  Write a spec for your batteries.  When you get to the user friendly section, state of charge is the most important parameter.  How do you determine when it is charged (when to terminate charging) and how do you know when it needs to be charged.  Safe fast charging is also a desirable feature.  LiXX wins.  It is very difficult to determine the state of charge of NiXX batteries.  You'd never specify a battery that you need to overcharge to make sure it is charged and that is the case with NiXX.  Lithium also wins if you want small batteries.  If it is safety that you alluding to, it is important to know what you are doing with any kind of battery.  NiCds can deliver a lot of energy in a very short time too. 

Jim O

On Apr 17, 2009, at 6:52 AM, John Ferrell wrote:

I believe the market has confirmed your choice. The availability of NiCads seems to be shrinking. The latest crop of NiMh (Eneloop, Sanyo) looks to me like it will have own the entire market place soon. LiPo's still seem to be the best power/weight ratio for those who need big batteries but remain less user friendly.

John Ferrell  W8CCW

"All that is necessary for the triumph of evil is for good men to do nothing." -- Edmund Burke
...."The problem with socialism is that you eventually run out of other people's money."  
   MARGARET THATCHER 
http://DixieNC.US

----- Original Message -----
From: George W.Kennie
To: NSRCA Mailing List
Sent: Thursday, April 16, 2009 3:12 PM
Subject: [NSRCA-discussion] batteries?

TOO COTTON-PICKIN' QUIET on here so I thought I'd stir the waters a little.

I remember, several times hearing on this forum that Nickel Metal Hydride batteries were not all that desirable of a choice
when making the decision to make up a pak due to their tendency to self-discharge and other erratic anomolies.

I feel compelled to relate my experience. I put a set of 2500 ma cells in my Txmitter a little over a year ago.

When I take this unit off of charge, many times it has indicated a voltage of 12 Volts (usually 11.9). My previous charge
was done last September and even though we are located in the N.E. where we sometimes fly in temps ranging into
the low 20's, we do get out quite a few weekends throughout the winter. Despite the fact that I never take my Txmitter
out of the car all winter long and it's subjected to 5 degree nites, which I'm told is not good for batteries, I charged it
about a week and a half ago and since September it had finally dropped to 10.5 Volts.

Special Paks?, you ask?  I go to Best Buy and pick 'em up and solder up my own. They're not significantly cheaper
than commercially available stuff I could buy, but when the impulse strikes, I conveniently go and get 'em. Nice !

Since a week and a half ago I've only flown about 3 times, but the thing is still reading 11.5 !

Now I do have to admit that they like a slow charge better than fast, but I never slow charge the flight paks I wire up
for my planes and I don't own any planes with commercial flight paks and some of them have more years on them than
I would dare to mention in this group.

Soooo, If you've been considering a NMH pak and you have doubts or concerns, take my experience for what it's worth !?!

G.

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