[hyudryu]

I bought 4 CR123 batteries for around 2$ each and they arent protected. I want to make a protection circuitry myself. I know a store around my house that sells electrical components as well as surface mount. Can someone give me a schematic?

 

[(*steve*)]

The easiest way is to purchase protection circuitry already made up. It's probably cheaper than building it yourself. You do have to ensure that the protection circuitry protects against what you want it to protect, and for the appropriate values.

There are three big ones: maximum charge, minimum charge, and maximum current.

Here, here, and here are some options to consider.

I would be very surprised if you could build them cheaper.

Also note that these are not a panacea. They may help in preventing gross overcharge or discharge, and prevent prolonged exposure to short circuit conditions for the cell, but they do not ensure that the cell is not subject to conditions that are beyond its nominal ratings.

As for schematics, I couldn't quickly find any, but this would probably be of interest. Note that many battery protection circuits (especially those in laptop battery packs) track charge and cycles, and are considerably more complex beasts.

 

[neon]

I agree with steve buy don't make it save cost and trouble . just a $4 timer can do it charge it for a time and it will recharge to your desires

 

[55pilot]

just a $4 timer can do it charge it for a time and it will recharge to your desires

REALLY BAD ADVISE.

NEVER CHARGE A LITHIUM BATTERY BASED ON TIME ALONE.

Even in the presence of a safety circuit, a lithium battery has to be charged with a proper voltage/current limited charger. The safety circuit is designed to offer you a level of safety against unintended abuse. It is not designed or able to protect you against intentional abuse like charging based on time with no regard to termination voltage and charging current limit.

---55p