[Elecraft] Battery Charging with DC Power Supply

[dave]

I'm not quite sure what is meant by the term 'uncontrolled source'. A 
regulated power supply makes a fine battery charger. Review the 
charging recommendations at the various battery manufacturer sites 
such as here:

<http://www.power-sonic.com/index.php?doc_id=116>

or here:

<http://www.powerstream.com/SLA.htm>

and you will see that constant voltage charging is one of several 
recommended charging methods.

The charge voltage needs to be carefully regulated, which Aston and 
other power supplies should do, and it is certainly a very good idea 
to put a fuse in line with each battery to protect against the unknown.

But there is absolutely nothing wrong with constant voltage float 
charging. At the phone co. we kept batteries on float charge for 20 to 
25 years and they were instantly ready, indeed constantly on line, and 
fully charged.

Keep the charge voltage set correctly, use proper safety precautions, 
follow the battery manufacturer's recommendations, and you should be fine.

The recommended charge voltage varies by the type of battery. Flooded 
batteries require a somewhat lower voltage than do SLA or AGM types. 
For flooded cells the usual recommendation is about 13.5 to 13.6, but 
some manufacturers are lower than this, and for AGM it is usually a 
bit higher at 13.6 to 13.8. Check with the battery manufacturer to be 
sure.

What you are trying to do is keep the battery fully charged but yet 
not burn off the water nor damage the plates.


73 de dave
ab9ca/4





Matt Zilmer wrote:
> 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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