[Elecraft] What battery to use?

[Bill NY9H]

i also used a 84 ah,,,, for field day  k2/100...  with a 50 watt solar panel...

at night it dropped to 11.4 before the panel brought it back to 12.4 the 
next morning after the sun hit the panel for a few hours...
it was slowing climbing up....

this was a gota station,.,,,so xmt duty cycle was slow...

bill.



At 09:19 AM 7/15/2005, Mike Morrow wrote:

>Mark wrote:
>
> >I am gearing up for a portable station for emergency
> >communications and have decided to use my K2/100 and
> >KAT100 combo.  I want to be able to power it with
> >batteries, if the need arises...I've been thinking about using
> >something on the order of a 50-60 Ahr size.
>
>
>I've been playing around with portable HF gear at campsites for 25 years.
>My only QRO rig for such use is a TS-50S running about the same power as the
>K2/100.
>
>I won't speculate on other battery technologies, but I'll just say I've
>found deep-discharge batteries to work fine as long as they are periodically
>well discharged and re-charged (about every 90 days or so).  At the very
>least, they need to be put on charge once or more during the same interval
>even if they've been sitting unconnected.
>
>Even for short camping trips less than a week long with casual HF
>operations, I've found it best to choose the highest amp-hour capacity
>battery that you can find and easily move around (something about 100
>amp-hours or better).  I think you'll find the 50 to 60 amp-hour capacity
>you mention to be too low, even for short trips portable, but especially for
>stationary emergency use.
>
>I don't know how the K2 is, but for many solid state QRO rigs the various
>bandswitch and control relay switching circuits are the first things to
>falter as the battery voltage drops from the 12.6 vdc max that you'll have
>when the battery is at full charge.   Low source voltage combined with
>voltage drop in the solid-state relay coil switching circuits (at least 0.7
>vdc) can result in coil voltage that is too low  to reliably operate the
>relays.   I had one rig that wouldn't function much below about 11.0 volts
>due to that effect.  Under transmit loads on the battery and with the
>voltage drop in the power cables, 11 vdc at the rig happens a lot sooner
>than you'd think for a QRO rig.  Since you'll be starting with a relatively
>low 12.6 vdc, you'll want to use the shortest and heaviest wire that's
>practical for the power cables.
>
>I think you've got a great idea about preparing your station to operate at a
>power output level that is conducive to reliable communications.  Any HF
>station truely intended to function for emergency communications should be
>capable of 100 watts output at least.  QRP is a great hobby mode that tests
>the proficiency and equipment of the operator at the other end, but it has
>no place in serious emergency communications planning except as a very last
>resort.
>
>BTW, I've been able to operate for a week a 100 watt HF rig (SSB and CW) a
>few hours a day, and as a shortwave receiver for several times that, while
>camping in the boonies.  I still had plenty of energy left in the
>deep-discharge battery I took, which was rated for 105 amp-hours.  I also
>was using that battery to feed a 50 watt 2m FM rig and a scanner radio, and
>to feed a small electric light.  It's really surprising how much service can
>be gotten from one charge from a decent-sized battery.  I've had a 400 watt
>12vdc/120vac portable gas-powered generator for 20 years but I've never
>needed to run it to re-charge the battery on any trip.
>
>The nice thing about these high capacity deep discharge batteries is that,
>compared to the price of typical handy-talkie battery packs, they are dirt
>cheap.  I keep a couple charged at all times.
>
>73,
>Mike / KK5F
>
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