[Elecraft] Solar battery charger

[Don Brown]

Hi

The Pc board is 1 7/8" X 2 7/8" X ~1/2"

It works the same as the Micro M+ but uses a different circuit that is mu=
ch simpler. The circuit is made up of 8-resistors 1-8 pin IC 1-power FET =
1-Shottkey diode 1-led  and 3-capacitors. A terminal block connects to th=
e battery and solar panel.

The design is for a 12 volt SLA gelcell or wet cell battery I have used t=
he charger with a 2.8 amp battery and 5 watt charger and a 70 watt solar =
panel with a 35 amp SLA battery.

I haven't researched this but it may work with NiMH or NiCads with some r=
esistor changes

There are no rf generating circuits. The charger operates as a switch app=
lying the full power from the solar panel to the battery until the termin=
al voltage reaches the trip point then the current is switched off. Once =
off there is a 4 second delay before the current can switch back on. When=
 the battery is fully charged a very short pulse of current is applied to=
 the battery every 4 seconds to keep the battery toped off as long as the=
 solar panel output is above the battery voltage.

The power FET is rated at 64 amps so with the proper heat sink the contro=
ller will handle just about any solar panel. The limiting component is th=
e Shottky diode in series with the battery. The diode is rated at 8 amps =
so the max power is about 75-85 watts. The power FET and a larger diode c=
ould be mounted off board on a heat sink for a larger solar panel.

The board is small enough to mount inside the K2 with KBT2 or it will fit=
 in an EC-1 enclosure with a 2.8 amp 12 volt SLA battery. You can also us=
e a 1 amp 15-18 volt wall wart power supply with a 5-10 ohm 5 watt resist=
or in series in place of the solar panel to keep the battery charged from=
 the mains.

Don Brown
KD5NDB

K1 #542
K1 #1000 sold
K2 #1808
K2 #2174
K2 #2468 For Sale
----- Original Message -----
From: Steve Lawrence
Sent: Wednesday, March 27, 2002 10:27 AM
To: Don Brown
Subject: Re: [Elecraft] Solar battery charger

Interesting...
Don,
How big is the charge controller?  (what is the approximate cube size tha=
t
it would fit in?)  How does it compare to the Micro M+?  Can the
controller charge NiMH or NiCads?  Does the controller emit any hash
noise?  What is the range of battery capacities will it handle?

Inquiring minds want to know...

Thanks!
Steve
aa8af


Hi All

I have been working on a little project for the Elecraft EC-1 Project box
that matches the K1.

Powersonic has a gelcell battery (#PS-1228) that fits into the box with
room for a small circuit board to control charging with a solar panel. I
have come up with a design, a PC board and a kit of parts for the
controller. The Powersonic battery is 12 volts at 2.8 amp hours so a K1 o=
r
K2 can run at full power from this battery for many hours. A small 12"X12=
"
solar panel rated a 5 watts will recharge the battery in a few hours or
run the radio at the same time with reduced charging of the battery. The
controller can handle up to a 90 watt panel so it is possible to run a
K2-100 with a much larger battery and solar array. The EC-1 setup with a
K1 or K2 would be great for portable or field day. You could also mount
the controller inside a K2 to charge the internal SLA battery from a sola=
r
panel or a wall wart power supply.

The PC board, instructions and kit of all parts on the board $25 shipped
con US (check or money order)
I still have plenty of the noise generator kits also used to align a K1/K=
2
$15


Don Brown
KD5NDB
19132 Falls Creek Drive
Flint, Texas 75762


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