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Amazon Basics 9V Cell Rechargeable Batteries 200mAh Ni-MH, 4-Pack
I presumed that It was a simple process- the folly of presumption,,
Any 9v battery will do the trick
Thanks
I presumed that It was a simple process- the folly of presumption,,
Any 9v battery will do the trick
Thanks
Last edited by a moderator:
The "9V" battery is more likely 8.4V (seven 1.2V cells in series), so at mid-day with a cloudless sky a "9V" solar panel might just about provide some charge via a Schottky diode and current-limiting resistor. A 200mAh battery charging at C/10 draws 20mA, so almost any Schottky diode could handle that.
Based on one review (if they have not changed the supplier since then, which is something amazon has done from time to time with their basics NiMH cells), this has 7 cells in it for a nominal 8.4V, BUT to reach full charge you're going to need closer to 1.45V/cell for a total of 10.15V after the diode forward drop loss.
You should hook the panel up with a diode and see if it can finish charging at all, monitoring it the whole time to terminate the charge before it reaches an overcharge state if it ever will.
Ideally you would use a pair of these solar cells or some other combination, to arrive at 12V or more, for example a panel designed to trickle charge an automotive battery, then you have some headroom to put a charge controller circuit in series. That could be some existing product designed to recharge faux-9V NiMH batteries, or it could be something you build from components, maybe something like an MC33340 based design.
If you wanted to do it cheap and crude, you could just set an LM317 to 9.8V output, current limiting resistor in series, then you'd never get them fully charged, but be close and shouldn't be able to overcharge... but again you should monitor it the first time to verify it works as intended, and this assumes what amazon sold to you is a 7 cell battery, not 6 or 8 cells.
You should hook the panel up with a diode and see if it can finish charging at all, monitoring it the whole time to terminate the charge before it reaches an overcharge state if it ever will.
Ideally you would use a pair of these solar cells or some other combination, to arrive at 12V or more, for example a panel designed to trickle charge an automotive battery, then you have some headroom to put a charge controller circuit in series. That could be some existing product designed to recharge faux-9V NiMH batteries, or it could be something you build from components, maybe something like an MC33340 based design.
If you wanted to do it cheap and crude, you could just set an LM317 to 9.8V output, current limiting resistor in series, then you'd never get them fully charged, but be close and shouldn't be able to overcharge... but again you should monitor it the first time to verify it works as intended, and this assumes what amazon sold to you is a 7 cell battery, not 6 or 8 cells.
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