On Sunday, 16 July 2017 02:24:07 UTC+1, Jeff Liebermann wrote:
On Sat, 15 Jul 2017 17:58:46 -0700 (PDT), tabbypurr wrote:

Likely the fault is with the squishy lithium batteries.

The first step to solving a problem is to blame someone or something.
However, in this case, you're probably right.

If the OP had the skill to fault find I'd think they''d already have tried to

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.

Unless the solar cells (or panel) have built in diodes, most
everything I've seen exhibits dark current (leakage).

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.

I beg to differ. You might be able to trickle charge NiCd, but NiMH
is considerably more picky:
http://batteryuniversity.com/learn/article/charging_nickel_metal_hydride
"It is difficult, if not impossible, to slow charge a NiMH
battery. At a C rate of 0.1C to 0.3C, the voltage and
temperature profiles do not exhibit defined characteristics
to trigger full-charge detection, and the charger must
depend on a timer. Harmful overcharge can occur when
charging partially or fully charged batteries, even if the
battery remains cold."

In other words, C/16 or 0.06C charge rate for NiMH screws up the NVD
(negative voltage detection) mechanism used to detect EoC
(end-o-charge), which can easily overcharge a NiMH cell or battery.

My cordless phones use NiMH with no charge control. They get charged or discharged all the time. Last set of cheap cells lasted at least 1500 cycles. So you can do it.


NT