I am very keen to start a project to make a solar recharger that i can use to recharge my PDA whilst out hiking, i have done some research but have a few questions i need answered, hopefully someone will be able to help me out, as though i am very keen to get in and make it myself, my knowledge is (at the moment) quite limited in this field.
Here goes:
My device uses a battery that is 3.7v 1350mAh (PA16A)
While i understand that the voltage of the solar panel must be higher than that of the battery i am charging, what is considered to be a safe voltage to go over when considering this? (for charging a PDA through a USB cable)
When looking at the specs of a solar panel, is the mA and mAh rating considered to be one and the same (i understand that mAh = mA/hour?) and what relation will the mA (and/or) mAh rating of a given solar panel have to do with the project? does more current mean a faster charge?
does wattage come into the equation at any point?
How do i tell if my Li-ion polymer batteries have cut off to prevent overcharging ? (aside from the obvious destructive answer of 'burst into flames') or is this feature built into the device not the battery
Would using more than one solar panel mean quicker charging, taking into consideration that there is more surface to capture sunlight (even on days of less light)
And with this in mind, i am guessing that i would probably then need to reduce the output voltage of the solar panels (if they are bringing over 5v to the circuit) somehow to suit the 5v input required for the PDA (a LM2937?)
And if this is the case, then how would (if they would) the inclusion of more panels make it more effective (is then just the increase of the mA and/or mAh) and if so, is there a maximum/optimum figure of current that i should be looking at attaining?
should i consider looking at putting something into the circuit to prevent the circuit from draining the battery in times of low light, and is this something i only need to consider if i am charging the device with the battery in it (instead of just charging the battery standalone)
Here goes:
My device uses a battery that is 3.7v 1350mAh (PA16A)
While i understand that the voltage of the solar panel must be higher than that of the battery i am charging, what is considered to be a safe voltage to go over when considering this? (for charging a PDA through a USB cable)
When looking at the specs of a solar panel, is the mA and mAh rating considered to be one and the same (i understand that mAh = mA/hour?) and what relation will the mA (and/or) mAh rating of a given solar panel have to do with the project? does more current mean a faster charge?
does wattage come into the equation at any point?
How do i tell if my Li-ion polymer batteries have cut off to prevent overcharging ? (aside from the obvious destructive answer of 'burst into flames') or is this feature built into the device not the battery
Would using more than one solar panel mean quicker charging, taking into consideration that there is more surface to capture sunlight (even on days of less light)
And with this in mind, i am guessing that i would probably then need to reduce the output voltage of the solar panels (if they are bringing over 5v to the circuit) somehow to suit the 5v input required for the PDA (a LM2937?)
And if this is the case, then how would (if they would) the inclusion of more panels make it more effective (is then just the increase of the mA and/or mAh) and if so, is there a maximum/optimum figure of current that i should be looking at attaining?
should i consider looking at putting something into the circuit to prevent the circuit from draining the battery in times of low light, and is this something i only need to consider if i am charging the device with the battery in it (instead of just charging the battery standalone)