Hello All
from my understanding on the construction of the 18650 lithium ion battery is this, the 18 indicates the diameter of the battery-- -18 mm, and the 650 is the length. 65 mm, some batteries are fraction longer because they have a protective circuit built into the positive end to prevent rapid discharge, thus causing overheating and perhaps fire or worse exploding, thats why some are a tight fit into the battery charger.
The voltage is supposed to be 3.7 volts, and they are available in a variety of milliamphour capacities, my blue are 2400, red are 3000 and now there are 4000 and 5000 mah on the market, I have quite a few of both the 2400 an 3000 amh and chargers all left overs from my LED torch days. so these were going to replace the dead 1.2volt nicad batteries in my panasonic 15.6 volt drill.
I have yet to experience overheating or fire with any of the batteries I have charged, had a few battery charger failures though from the wrong voltage regulator fitted 110 volt and sent to me as a 240 volt charger.
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I had a battery charger system set up for the 18650's so they would be fully charged when I sold them , they do take some time to charge up and I used to check the voltage , 3.7 to 4.1 volts, when fully charged. I also had the bike helmet light that had a removable 4 x 18650 battery pack but the pack had a circuit in it, probably to regulate the charging, that unit was very good as a pawning light, run time was about 2 hours .
I am particularly interested in how you fit the 18650 batteries into the SDC 2300 , mine came with rechargeable batteries and a charger, but I always carry a few ALDI c type alkaline batteries when I go out.
Any advice on how its done will be appreciated