Samsung 21700 / 40T Batteries

• Model: 40T
• Size: 21700
• Nominal Capacity: 4000mAh
• Nominal Voltage: 3.6V
• Maximum Voltage: 4.2V
• Discharge Current: 30A Maximum Continuous

Battery Safety Basics

Do not overcharge or over-discharge.

To combat this, do not leave your batteries in any charger without supervision. Make sure that you are able to see or check on the charger every 15-30 minutes. This way when the charger indicates that the batteries have been fully charged, you can remove them from the charger. Leaving batteries in a charger all night long or longer can cause them to be overcharged, which can result in battery failure. Charging your battery over 4.25 volts can shorten its life-cycle and going over 4.5 volts can cause it to burst. Cease using your charger if this ever happens.

Recharge batteries with a resting voltage below 3.6V as soon as possible.

Leaving LiIon batteries in a discharged state will incur irreversible damage – creating a loss in capacity and a loss in cycles.

Determining the exact voltage can be tricky, unless you have a multimeter. If you are delving into the world of mechanical mods and RBAs (ReBuildable Atomizers), or making your own coils, a multimeter is a must have device because you can use it to test your coils and your batteries. Sure, you can always use a battery tester, but the majority of battery testers are not equipped for the types of batteries that are used in mods, or even test batteries under load condition.

Do not short circuit your batteries.

Short circuiting can cause a huge surge of current that will potentially burn out your battery, damage your mod, or even your face!