[Elecraft] K2 qrp battery drain estimation

[Robert G Strickland]

Most folks point out that SLA batteries are best *not* drawn down to 
their bottom. I'm thinking of using newer LiFePO4 batteries. What's the 
draw-down limit, if any, on these items?
...robert

On 6/15/2013 14:06, Michael Babineau wrote:
> *Robert : *
> *
> *
> *If you are planning to use Lead-Acid technology (SLA or wet-cell )*
> *then, as others have suggested, you should double your calculated
> capacity, as you never want*
> *to drain a Lead-Acid battery by more than 50% ..*
> *
> *
> *so *
> *
> *
> *10 hr requires 7 Ah*
> *20 hr requires 15 Ah *
> *etc.*
> *
> *
> *The reality is that you will probably spend somewhat more than 50% of
> the time listening and tuning around*
> *for stations when you are S&P so the real split may be more like 30% TX
> and 70% RX, but 50/50 is probably*
> *a good guess. *
> *
> *
> *One further point .. don't discharge a Lead acid battery below 10.5 v.
> Repeatedly doing this will shorten*
> *its lifespan.  Don's suggestion of setting the low voltage indication
> on the K2 to 11v is a good idea.*
> *
> *
> *For picnic-table-portable operations, battery booster packs (intended
> to jump-start cars) work very well*
> *and it is easy to find one with an SLA in the 10Ah to 20Ah range, often
> on sale. You can take the plastic*
> *case apart to install some fusing and even powerpole connectors to
> customize it for your application*
> *(I also removed the jumper cables from mine).  Some of these packs now
> even come with USB ports to allow for impromptu *
> *powering/charging of i-Devices.  It is often cheaper to buy one of
> these than to purchase just the equivalent capacity SLA*
> *battery .. so you get a nice carrying case with a handle and other
> goodies for free. *
> *
> *
> *Best of luck ...*
> *
> *
> *Michael VE3WMB *
>
-- 
Robert G Strickland, PhD ABPH - KE2WY
rcrgs at verizon.net.usa
Syracuse, New York, USA