it cost TOOO much
originally they were surplus cells from some failed laptop project, and it only cost about 300$ (hey this will be cheap , , ,NOT)
but then these started failing after ABOUT a year and a half, and i replaced the ones with high self discharge, about 1/3 of the originals are working good, it costs some 300-400$ more to replace the bad ones.
the originals are still dying, the replacements have worked great for years, i wont know more till they also start going bad.
yes it is all parellel, definatly.
i want to replace the little cells with a few mondo AUTO sized lithium, but the INITIAL cost is prohibitive, even though auto ones would handle many more short cycles.
all the "electronics" had to be redone about 3 times, till they worked continuously and correctally, and didnt WASTE stuff so fast.
first the solar cell was regulated with a 317 (type) adjustable regulator in the high temp package t-220 or something? anyways the voltage regulation suffered from huge losses, that 1.5v drop across it was killing the efficiency.
then i tried to make a relayed protection curcuit, because HIGH AMP power protection was not easily available. the relay would disconnect the rack when the voltage went to about 4.15. the problem with that is the relay wouldnt reset untill it was way low again, a cheap 555 timer curcuit would attempt the reset, and it required power to run the curcuit and relay.
after that they made available these 8amp protection curcuits, WHICH i discovered were only good for 4 amps :-( so 2 of them do the job. again they do not reset till the next day, or if i manually trip it.
it is Rare (but it occurs) that it reaches full charge, because of the self regulation, the charging voltage (vrses max voltage) of the solar pannel is very close to the max voltage, when the voltage differential between them is low, the charge is slow. so it tapers itself off. for example when its around 4.1volts the charge tapers to about 3-5amps depending on sun.
low voltage cutoff, which again rarely occurs , is the power relay that switches the LEDs on, it just wont work at around 3+V
so the thing just quits working if the battery goes to low. mostly the leds going low draw so little power, that solves the cutoff all by itself.
it might sound like i know what i am doing, but if i did
it might have some microcontroller in it that did everything and took only little power to do so. it was just a test.
every possible loss or drain was attempted to be removed, an original setup has SOOO many losses down each chain of items it really ammounted to neer 50%. losses start adding up quick.
so even the diode protection for the solar pannel was replaced with something that has very low resistance.
