"Larry Jaques" wrote in message
...
On Thu, 12 Sep 2013 11:15:21 -0400, "Jim Wilkins"
wrote:

"Larry Jaques" wrote in message
. ..

You bought the HF solar panel kit, right? One of the Schottkys that
blocks reverse leakage out to the panels failed short on mine. I
replaced both with one 10A 50V Schottky diode. A temporary silicon
diode's higher voltage drop cost about 0.1A at 2A.

Yeah. A tenth amp drop beats zero output, huh?

Here's a link to a schematic which nearly matches the charger in my
two-year-old aluminum-framed panel kit:
http://solarpanelkitatharborfreight....eight-charge-1
The Schottkys are D1 and D2, in series between the panel and battery
on the positive side. When one failed short the charger kept working
normally. Q6 connects the negative side.

I use a separate double-pole toggle switch to isolate the battery from
the charger when it's not in use, since I don't leave Harbor Freight
electronics powered up when unattended*, so I hadn't noticed if the
panels discharge the battery at night. I found the problem during
inspection of the wiring.

F1 and F2 are swapped on the schematic vs the circuit board. The UF400
current limiter is F1, the 4A ATC fuse on the back panel is F2. The
output jacks show PCB pin numbers but not the connectors or silkscreen
labels. Mine turns off at 14.4V, back on at 13.1V to restrict battery
overcharge and water loss.

I wired a separate lighter outlet to the battery terminals because the
front panel one won't supply the full bootup current to a laptop
auto-air power adapter. I saw the voltage drop rather than the fuse
blow so perhaps Q6 hit its limit.


What's your max wattage now from a set of HF panels?


The nominal output is 0.86A at 17.5V, or 15W per panel. The current
isn't much higher into a 12V battery which means the power you
actually get is lower. The kit can just about keep up with my laptop's
20W-35W demand.

When they were new I think I saw as much as 0.9A per panel, but after
two years I rarely see much over 0.7A, 2.1A total, on the analog
(unpowered) ammeter I added before the controller input, the safer
side. A meter on the battery side needs to tolerate more current in
either direction. http://www.futurlec.com/Panel_Meters.shtml
Amazon delivers them faster.
http://www.amazon.com/Amico-Class-An...analog+ammeter
They are NOT precision instruments, but are good enough to detect
problems and cheap enough to leave outdoors.

*Testing a cigarette-lighter DC-to-AC inverter of Chinese origin
showed it would happily drain the battery down to 7V though it claimed
to have a low battery shutoff.

jsw