On Saturday, 15 July 2017 21:19:12 UTC+1, wrote:
About 5 years ago, I bought a solar charger for charging cell phones. It
seemed like a great idea, and worked fine for a year at most. Then it
would charge for a minute or so, and shut itself off. It could also be
charged by hooking it to a USB port on a computer or use a phone
charger. It had 4 blue LEDs that were supposed to indicate the amount of
charge it contained. Even after charging form a USB, it did not charge a
phone anymore.

It's been sitting in a box ever since. I just connected it to a USB
charger and it would not even take a charge anymore. I took it apart and
was expecting to find some AA or AAA NiCd batteries, similar to the ones
that are inside of those sidewalk solar lights. My plan was to replace
those batteries with NiCd cells, the same way I change them in those
solar lights that quit working.

When I opened it, I was shocked. Instead of AA or AAA batteries, I found
two square "pouches". Sort of like tin foil covered bags that are
labeled as batteries. They are flexible, squishy, and just have two
contacts labeled + and - (there are two of them). I have never seen
batteries like this.

Besides those weird batteries, I found a small circuit board with 6 or 7
very small IC chips. One with 16 pins, and the rest have 6 pins each.
Plus an electrolytic cap, and a small coil which is probably some sort
of choke, and several surface mounted things which I assume are
resistors. Also the USB plugs and those 4 LEDs are connected to that
board. All of this seems very complex for such a small charger, and
those chips are so small I can barely see the leads on them, much less
try to repair this thing. Heck, I need a magnifying glass just to see
the solder joints on this thing.

The plan is to salvage the solar panel, and trash the rest of it. The
solar panel is a lot bigger than the ones on those solar lights, (about
4 x 5 inches). I'm suspecting the solar panel is still good, (I will
have to test it to be sure, by hooking a volt meter to it when it's in
the sun).

My question is whether I can connect this solar panel directly to a
rechargable battery, or do I need some sort of diode or other components
between it, and the battery(s). (I know those solar lights have very
minimal components). But it seems to me that there probably needs to be
some sort of component (at least a diode) to protect the battery current
from back-flowing into the solar panel. In the end, this will just
become a solar charger for NiCd or NiMh rechargable batteries, or I
might even turn it into a solar light sort of thing.

Anyhow, what is needed to attach this solar panel to a common
rechargable AA or AAA battery?


Thanks!

Likely the fault is with the squishy lithium batteries.

If you want to use just the panel, some allow dark current leakage, some don't. Hook it to a battery, put it in darkness and measure. If it leaks add a diode.

Charge control depends on battery chemistry & size. NiCd & NiMH can be charged by just limiting current delivery to C/16, so measure your panel output current in full sun as well as offload voltage. Lithium is much more fussy, hence some of the circuitry.


NT