Re: A&A Engineering Charger + KBT2

Posted by Don Wilhelm-4 on May 09, 2011; 6:16pm
URL: http://elecraft.85.s1.nabble.com/A-A-Engineering-Charger-KBT2-tp6342835p6345226.html

  Brian,

The consideration over the bulk charge rate is still valid - if the
charger goes into bulk charge state the voltage is higher - AND, if the
receive current is much lower than the bulk charge current, the battery
can be over-charged.  To prevent that condition, the bulk charge rate
should be lower than the receive current (it does not have to be matched
to the receive current - just lower).

What will happen is that part of the receive current will come from the
charger and some from the battery - all is well as long as your
operating times are only for a few hours, the battery will provide
plenty of "juice".  The switchable Smartcharger is a real help here, but
I would suggest using 1 amp for the higher current rate - provided you
resolve to leave it at the low current rate until your operating session
exceeds 2 or 3 hours, and at that time, switch the charger to the 1 amp
rate.  If you cannot make that resolution, then I would suggest your
proposed 250/500 ma combination would be better.

73,
Don W3FPR

On 5/8/2011 8:02 PM, Brian - N5BCN wrote:

> Hi all,
>
> A&A Engineering's "QRP Smart Charger" has the option to be built using two
> of the four charging rates: 0.250 A, 0.500 A, 0.750 A, and 1.00 A.  I plan
> to run my K2 using a KBT2 + Charger combo.
>
> Which two charging rates would be suit this setup?  My K2 has a number of
> options and draws about 380 mA right now on receive, considerably more when
> the remoted KPA100 goes into high power mode (remoted KPA100 obviously runs
> on a different power source).
>
> I've read W3FPR's Smart Charger Mod and he's using 250 mA, so I'm leaning
> towards the 250 mA/500 mA combo, however, I don't think his mod is used in
> conjunction with a remoted KPA100.
>
> 73
>
> N5BCN - Brian
>
> -----
> K2 #6800 KPA100/KAT100-2, KSB2, KAT2, KIO2, K160RX, KNB2, KAF2, LP-PAN/K2 w/ Pre-amp, SignaLink USB
> --
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