I wanted a rechargeable alternative to the cr123a batteries, so I ordered some 18650's and a charger. Unfortunately I didn't read the forum before placing this order and it now seems that I'm in over my head
Now I need a digital multimeter and a discharger too? Everything I've read makes these things sound like ticking timebombs that you have to always check voltages on. I'm going to have a light in my car, can I not use an 18650 in it because of the heat? Is there a battery that I can just plug in until it's charged and use until it dies?
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If you want a battery that you can just plug in until it's charged and use until it dies then the nearest to that would be a low self discharge AA battery.
If on the other hand you want a battery that has lots of power for its size , then the 18650 is the one to go for ... I was a bit worried about Li-Ions when I first started , but with a little bit of care they pose no significant problems ... Bear in mind that there are posts on CPF that report explosions in torches that use ordinary everyday AA and AAA batteries , so problems are not just limited to Li-Ions ... Nobody writes in to say that their torch hasn't exploded ... It's like the Doctors Surgery ... People don't queue up to tell him that they are well !
Certainly if you are just now getting into 18650s , you would be initially better off with the protected ones ...Don't rely implicitly on the protection ... It is there as a last line of defence ... Treat them as you would an unprotected battery and you will be OK.
More care is needed in the charging and discharging of the Li-Ions ... After all , a highly tuned Ferrari needs more care than a VW Beetle or similar car but it's worth it in the end ... A digital voltmeter capable of reading 4.20 volts is handy as the amount of charge in a Li-Ion can be predicted by just measuring the open circuit battery voltage ... 4.20 volts is 100% full , 3.6 volts is empty , 3.85 volts is about 50% ... So a simple digital meter is all you need ... No need to mess about with the Amps or the Ohms ranges for the simple checks needed.
You do have to take care more with the charging of Li-Ions ... I check the voltage of the batteries every half hour or so ... Simply switch off the charger and remove the cells ... Check their open circuit volts are below (not above) 4.20 volts then put them back and switch the charger on again ... Eventually the chargers LEDs will tell you that the batteries are charged ... Check the batteries voltages again and put aside for an hour or so ... Check voltages again and this should be below 4.20 volts , say 4.18 or 4.19 volts ... That is perfect ... You can of course remove the batteries before the end of charge ... At 4.10 volts they will be about 90% full ... After a while it will become really easy !
Don't leave the charging process completely unattended for hours ... I do my checks ever half hour or so ... Don't forget and leave them charging overnight ... Chances are that they will be OK , but it is better to play safe.
You will find that multiple battery systems give the majority of the problems ... The reasons why are in other threads on CPF ... A single 18650 in a torch is much less dangerous.
Even with a protected battery , don't let the voltage go below 3.6 volts ... I tend to recharge when the voltage gets to 3.7 or even 3.8 volts ... I can go down to the 3.6 volts , but it doesn't matter as long as you don't over-discharge the battery ... You can top-up the charge whenever you want because the batteries don't really have a memory as some others do ... When you think that you have used your torch for a long time , just check the battery voltage when you get home to see how much charge you have left ... If it reads 3.80 volts for example , you know that there is still 40% left ... Please yourself whether you use it a bit more or top-up the charge again ... Your choice.
It isn't (as they say) rocket science , it is common sense.
I leave a 18650 torch in my car glove box and a 3AAA in the car too ... I also carry a very small (iTP A2) single AA torch in my pocket all the time ... If it is a boiling hot day , I would possibly leave the the car in the shade or maybe remove the torches , but being a bit lazy I tend to forget ... Most of the time , even in the cold weather , the torches stay in the car ... I top up the batteries before the Winter starts and again later in the Spring if I remember ... I do tend to rely on my every day carry torch though.
I hope that you don't get too paranoid about "time-bombs" etc. but it is worth the little bit of extra care to end up with a "brilliant" torch battery.
Sorry about the longish post.
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...any suggestions regarding hit and go care and feeding of 18650's or any other rechargeables such as rechargeable 123's. Or should I just have my battery charging license revoked and stick with disposables?
