[Elecraft] Battery Charging with DC Power Supply

[Matt Zilmer]

I just have to chime in on this one.

I run my K3/100-based station on solar photovoltaic power, with a 100
AH SLA battery for storage.  Quick description of this installation is
that I use a charge controller to regulate battery charging.  It's a
Micro M+ c/c and can put out 4A for a 12VDC system.
http://edge.rit.edu/content/P07308/public/Custom%20Charge%20controller
The article is from October, 2001 QST.

As others have stated, you should not charge *any* battery directly
from an uncontrolled source like a power supply.  If you want to use
the battery as the main power source and recharge it periodically (or
whenever the sun shines), you have to regulate the charge rate and
voltage level presented to the battery.  The Micro M+ does a fine job
for smaller installations, and its max charge rate of 4A is adequate
for topping a battery in the 100AH class.  The Micro M+ uses pulse
width to control the charge rate, and this is suggested for FLA and
SLA battery types - others work with this method too (AGM, etc.).

You can use the Micro M+ or its equivalent for any type of source -
power supply, solar PV, bicycle generator, etc.  When the weather is
cloudy, I use a little Tektronics 3A AC/DC power supply and just run
it full bore into the c/c.  This works fine too.

<Details are below for those that are insomniacs>

Near the _big_ PV panels on the roof are the two Siemens SR50's, which
are rated 50W each, and they are in parallel for the 12VDC system. The
feed to the shack travels through a weatherproof enclosure that has a
10A fuse and GFP circuit breaker.  This might be overkill. Together
the two Siemens 50W panels are nameplate rated at around 6A. In
practice, maximum output is a little over 5A on a really good sun day.

The feed down to the shack is 8AWG THHN wire, about 30 feet of it, in
flexible NMT.  The 8AWG is to minimize the voltage drop to the charge
circuitry.

Both the battery and charge controller are here in the shack.

73,
matt zilmer W6NIA
K3 #24, K2 #2810


On Sun, 07 Jun 2009 21:17:17 -0700 (PDT), you wrote:

><I am using an Alinco DM-330M power supply. Across the output of the <power supply I have a 26 AH battery. If the AC power quits I have <many hours to shut down the K3.
> 
>Charging a battery with a DC supply not meant for that purpose is a very BAD idea.
> 
>In the case of Astron supplies it can damage parts of the DC regulator.  If there is a "Crow Bar" circuit that operates with a battery connected to the power supply output it will ruin your day or even burn your house down!
> 
>Bill - K6WLM
>
>
>      
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