[Elecraft] [K2] Has the k2 a future - not if you use Li-Po cells!

2009-10-20 Thread Greg Williams
Hi Guys
I have a mate, Ian VK3FFLY, who is into flying radio controlled models 
using Li-Po cells and they are very careful about the way they charge 
them - always in a metal box (not the radio cabinet!). Several of them 
have had fires from charging these cells. Ian suggests you have a look 
at http://www.rcgroups.com/forums/showthread.php?t=209187

Ian's son-in-law had a house fire in the last couple of months from a 
charging Li-Po - luckily he was home and the smoke alarm worked so he 
just had damage to the one room.

Greg VK3VT


Subject:
Re: [Elecraft] [K2] Re: has the k2 a future?
From:
Leigh L. Klotz Jr WA5ZNU le...@wa5znu.org
Date:
Fri, 16 Oct 2009 11:15:58 -0700 (PDT)

To:
elecraft@mailman.qth.net


Johnny,
Do you have pictures posted?   I remember when you started this project and
I'd like to see how it worked out.

Presonally I lean more toward LiFePO4; although they have a lower energy
density than the Li-Po (though higher power density) they reportedly are
safer in conditions of over/under charge and mechanical stress.

Leigh/WA5ZNU

Johnny Siu wrote:

 
 Hello Wayne,
 
 Yes, K2 is still my favourite field day and QRP rig and no others can bit
 it.
 
 I now have 3 x 3.7v 3300mAH Li-Po cells in the KBT2 and they work very
 well.
 
 73
 
 Johnny VR2XMC
 



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[Elecraft] [K2] Has the k2 a future - not if you use Li-Po cells!

2009-10-20 Thread Greg Williams

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Re: [Elecraft] [K2] Has the k2 a future - not if you use Li-Po cells!

2009-10-20 Thread AD6XY

This is why I eventually decided to use AA NiMH cells instead when replacing
the lead acid battery in my K2. 

I use 10 AAs in a pack, this gives me 2.5AH vs ~3AH for a small LiPo pack of
similar mass. The LiPOs are fine but I will keep them outside the case so I
can throw them somewhere if a fault occurs. I am sure computer packs are
fine but I am wary of the RC type packs. The advantage of NiMH is they are
easy to charge. They may fail faster but they are very cheap to replace.

Mike
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Re: [Elecraft] [K2] Has the k2 a future - not if you use Li-Po cells!

2009-10-20 Thread Julian, G4ILO



AD6XY wrote:
 
 This is why I eventually decided to use AA NiMH cells instead when
 replacing the lead acid battery in my K2. 
 
 I use 10 AAs in a pack, this gives me 2.5AH vs ~3AH for a small LiPo pack
 of similar mass. The LiPOs are fine but I will keep them outside the case
 so I can throw them somewhere if a fault occurs. I am sure computer packs
 are fine but I am wary of the RC type packs. The advantage of NiMH is they
 are easy to charge. They may fail faster but they are very cheap to
 replace.
 
Why didn't Elecraft choose NiMH cells for the KBT2 in the first place? There
must have been a reason.

-
Julian, G4ILO. K2 #392  K3 #222.
* G4ILO's Shack - http://www.g4ilo.com
* KComm - http://www.g4ilo.com/kcomm.html
* KTune - http://www.g4ilo.com/ktune.html

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Re: [Elecraft] [K2] Has the k2 a future - not if you use Li-Po cells!

2009-10-20 Thread Leigh L. Klotz Jr WA5ZNU


Julian, G4ILO wrote:
 
 Why didn't Elecraft choose NiMH cells for the KBT2 in the first place?
 There must have been a reason.
 
One reason might be self discharge; SLA stay charged longer than NiMH. 
There are new longer-life NiMH cells these days, though.  And the LiFePO4
and Lithium nano-phosphate cells as well.
Leigh/WA5ZNU
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