Harbor Freight Charge Controller Problems

 Recently I purchases two of Harbor Freight's 45 watt solar kits.  Both
charge controllers failed after working fine the first day and the next
mornig both were down around 2.5 V output.  They were on sale and I
purchased two more kits.  I am an engineer and was mainly interested in
getting the panels, the controllers and other gear were just icing on
the cake.  I returned one of the failed controllers for a replacement,
right in the store, and brought the other failed unit to my lab to
evaluate the failure.  Previously I had read some posts that there was
or wasn't a blocking diode or that the controllers did or didn't
regulate the battery charge.  Harbor won't release the schematic of the
circuit, because it's "proprietary".  It could best be described as
coming from the "crazy quilt" school of electonic design.  I had a hard
time tracing the circuit until I made a list of components and realized
there were only 2 transistors, an inverter IC, and a bunch of diodes.
Off their little circuit board are FET switches, and voltage regulators
to provide the 6V and 9V services.  A 9V regulator is used on the
board, floating on a reference gound, to provide the 12V regulation for
the battery charge.  It looks like the circuit implodes when the
battery is disconnected while the 24V panels are still connected.
Alternately, the circuit may fail due to shunt regulation dumping
continuous DC throught one of the FET switches.  I have one of the
controllers operating now for a few weeks and it hasn't failed yet.  4
failures and one that has continued without failure.  It looks like the
optimum operating mode for this controller is to keep the 12V battery
on line and provide enough of a load that there is a drain when the
controller shunts the voltage.  When that happens, the buzzer cycles on
and the FET begins conducting the panels to ground.  When the 12V reg
circuit drops due to a load, the buzzer will cycle off and FET shuts
off.  The diodes on the board are drops that provide trigger to the
inverter (6 channels) to turn on the voltage indicator LED's.  Hope
this helps others cope with this fragile circuit.

  I wouldn't lose any sleep over those HF charge controllers.  You are
lucky they didn't ruin your battery.

Get yourself a good charge controller.  I am using a BZ 20+ pwm
controller on my two HF kits.

 
My impression from reading this newsgroup is that the optimum
operating mode for this controller is to throw it in the trash and get
a real one.

 Actually, I am using one of the HF charge controller for a dc
distribution panel by connecting it to the batteries.  In that respect
its a handy device for the 12 lights you get with the kit and the
mutiple adaptors for 9 and 6 volts outlets.  I even hooked up a 12
cigarette lighter socket to it.   I think that Max suggested that one
time in one of his posts.

Larry

 The connections in most HF kit controllers are bad. Remove the cover,
check all connections (pay attention to the "solar panel" and "battery"
connectors). I had to solder all the connections in both of mine. And
like Larry, I only use them to distribute 12 volts.

Photos are at my site at this URL:

http://www.kitcar.dynip.com/solarpower/installation.htm

Photos of the guts of the things are at the bottom of the page. I'll
add some bits about what to look for in the descriptions.

BTW, Canweb (my dynamic redirection service) has been bouncing up and
down. Might take a few tries to get on the server.

Max