[Elecraft] Portable Battery tests

[Fred Jensen]

The issue is discharge curve.  A very good LiFePO4, LiIon, or Lipoly 
battery will have a very flat discharge curve, maintaining its terminal 
voltage under load right up to near total discharge.  At that point, the 
terminal voltage will adopt the glide angle of a brick at which point my 
K2 conveniently shuts down.  I get around 90% of the rated capacity of 
the battery.  The "really good deals" on eBay exhibit a discharge curve 
that continually decreases, and will fall below the value usable by your 
radio much more quickly.  The energy [or most of it] is still there, you 
just have to find a transceiver that will run on less than 8 volts.

Shrink-wrapped Li<mumbles> almost always come from 'you know where' and 
employ cells rejected by real battery makers.

73,

Fred ["Skip"] K6DGW
Sparks NV DM09dn
Washoe County

On 8/17/2018 3:35 PM, Al Lorona wrote:
> Howie this is excellent data. Thank you for your work in this area.
>
> The table really clearly shows the tradeoffs between cost, weight, volume, capacity and everything else. Alkaline batteries do pretty well for themselves, although I'm not sure why the voltage for 8 cells is listed at only 9.6 V. Is that the ending voltage after the discharge tests?
>
> The measurement that caught my eye is the third-to-the-last column, "MAH ACTUAL % OF ADVERTISED" because I abhor false advertising and go out of my way to boycott it. I'd say those at 0.90 and above are acceptable, while the ones at the bottom should be ashamed of themselves. QuickCable at 11% of advertised? Really?
>
> Al  W6LX
>