I assume you mean charge batteries, as you can't "charge electronics".
Modern batteries are very difficult to charge correctly, which is why most appliances that have a rechargeable battery have special electronics that monitor the batteries state as the charge progresses, and control the charge rate to avoid damage.
If the charge controller is inside the appliance (cell phone, PC, camera, etc) then you can safely apply the voltage that the charge controller requires. Frequently this is 5 volts at 1/2 amp (USB chargers) but for something like a PC it can be a lot higher. My PC supply generates 18.5 volts at 4.6 amps and 16.5 volts at 3.6 amps, for example. You would have to supply those voltages.
My camera, on the other hand, has removable batteries that I plug into a special charger that plugs into the AC line. Here, the charge controller is in the charger box, and you could not safely try to charge the batteries with some external power source.
So, no, you do not need to keep the current low, you just need to supply the proper voltage with enough current capability to match the requirements, in some cases. In other cases, you should not make the attempt.
altogether, this can be risky. Calculate the cost of using utility power before you proceed, so you can see what your possible gains are.
A USB charger, 5 volts at 1/2 amp, for example, is 2.5 watts. If you charge something for 5 hours, that is 7.5 watt-hours. If you do this every day for a month, that is 225 watt-hours. At typical utility rates, that is 2¢ per month. So you can save 2¢ a month, is it worth it?
edit: bottom line, you have to examine each appliance separately to see what is possible and what is not, they are all different.
one easy solution, if you have enough power, is to use an inverter to convert your source to 120 volts AC and then you can plug in your standard chargers.