I have been using NiCd batteries in my solar garden lamps . Of late when those batteries did not perform well, I started using ordinary electrically rechargeable batteries which automatically get charged under the sun light. Is it OK or will it reduce the lifespan of the solar light bulbs? Also can I electrically recharge NiCd batteries?

Your "ordinary electrically rechargeable batteries" will probably work fine. You can check it with a voltmeter. Test the voltage at the bulb. If it's the same or less than the voltage that the NiCd was rated at (or preferably the voltage measured when a charged NiCd was in the circuit), the lifetime of the bulbs will not be affected. If it's high, it's possible the lifetime of the bulb will be limited. You can also look up the nominal cell voltage of the batteries you're using - multiply that by the number of cells in the battery arrangement, and compare that with the product of the nominal cell voltage of a NiCd battery and the number of those cells in the battery arrangement.

Nominal Cell voltages:
1. Standard alkaline batteries - 1.24 V
2. NiCd - 1.24 V
3. Nickel-metal hydride - 1.2 V
4. Lead-Acid - 2.105 V
5. Lithium ion - 3.6-3.7 V

Usually you want to be within 10% of the original design voltage.

You can electrically recharge NiCd batteries. You must use a charger intended to recharge that type of battery! There are a number of commonly-rechargeable battery types. NiCd, Nickel-Metal hydride batteries, Lithium iron batteries, and Lead-Acid batteries (the oldest rechargeable). There are a few more exotic types also.

Eventually, all rechargeable batteries will fail to hold a charge or fail to recharge. When that happens, you recycle them (there are now laws in many places, that don't permit you to simply throw them away) and get new batteries.

When charging batteries, you must use a charger intended for charging that type of battery. The chargers are built to recognize the voltage behavior of the particular battery. They shut themselves off when the battery is fully charged. If you attempt to use a charger designed for a lithium ion battery with a NiCd battery (or vice versa), it is conceivable that you may cause a fire -- or worse.

Hi Perito
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