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Battery Safety & Ohm's Law

Information on Ohm's Law

Vaping Calculators

 

BATTERY SAFETY


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.

Get a good charger: Nitecore i2 Charger (2 Bay) or Nitecore i4 Charger (4 Bay)

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!

Short circuits happen when the voltage from a battery is discharged through a low resistance wire at a discharge rate that exceeds the battery’s upper amp limit. Short circuiting a battery is very close to what a mechanical mod with a sub-ohm coil is doing, except you are trying to keep the resistance under the upper amp limit – there’s a fine line that you have to be careful of when sub-ohming.

Do not let your batteries touch each other or other metallic items

Keeping your batteries loose, such as in your pockets, is a good way to have your batteries fail and seriously harm you. There are battery holders and covers to keep your batteries safe. Get some – now.

Do not dispose any battery in a fire

This is just common sense people. There are dangerous chemicals in batteries. If you try to burn your batteries they’ll release dangerous fumes and will probably explode. Do yourself, and the rest of the world, a favor by taking your old batteries to a battery recycling center.


Let’s take a look at the specifications of AW IMR batteries for a moment:

IMR16340 Specifications:

Nominal Voltage : 3.7V
Capacity : 550mAH
Lowest Discharge Voltage : 2.50V
Standard Charge : CC/CV ( max. charging rate 1.5A )
Cycle Life : > 500 cycles
Max. continuous discharge rate : 4A
Operating Discharge Temperature : -10 – 60 Degree Celsius

IMR14500 Specifications:

Nominal Voltage : 3.7V
Capacity : 600mAH
Lowest Discharge Voltage : 2.50V
Standard Charge : CC/CV ( max. charging rate 1.5A )
Cycle Life : > 500 cycles
Max. continuous discharge rate : 4A
Operating Discharge Temperature : -10 – 60 Degree Celsius

IMR18350 Specifications:

Nominal Voltage : 3.7V
Capacity : 700mAH
Lowest Discharge Voltage : 2.50V
Standard Charge : CC/CV ( max. charging rate 2A )
Cycle Life : > 500 cycles
Max. continuous discharge rate : 6A
Operating Discharge Temperature : -10 – 60 Degree Celsius

IMR18490 Specifications:

Nominal Voltage : 3.7V
Capacity : 1100mAH
Lowest Discharge Voltage : 2.50V
Standard Charge : CC/CV ( max. charging rate 3A )
Cycle Life : > 500 cycles
Max. continuous discharge rate : 15C
Operating Discharge Temperature : -10 – 60 Degree Celsius

IMR18650-1600 Specifications:

Nominal Voltage : 3.7V
Capacity : 1600mAH
Lowest Discharge Voltage : 2.50V
Standard Charge : CC/CV ( max. charging rate 4.5A )
Cycle Life : > 500 cycles
Max. continuous discharge rate : 15C
Operating Discharge Temperature : -10 – 60 Degree Celsius

IMR18650 -2000 Specifications:

Nominal Voltage : 3.7V
Capacity : 2000mAH
Lowest Discharge Voltage : 2.50V
Standard Charge : CC/CV ( max. charging rate 2A )
Cycle Life : > 500 cycles
Max. continuous discharge rate : 10A
Operating Discharge Temperature : -10 – 60 Degree Celsius

Determining Your Maximum Discharge Rate

The most important specification to pay attention to is the “Max. continuous discharge rate” for each battery. Each battery has a number and a letter, either measured as A or C (30 Amps or 15C). Look at the IMR18650-1600 for example. If your battery has a maximum continuous discharge rate of 15C, this means the battery is rated for 15 times the capacity of the battery measured in amps. So a battery that sits at 1600mAh, which equals 1.6Ah will have a max continuous discharge rate of 15 X 1.6 = 24A. There is a chart below which has the max continuous discharge rate in Amps of some common batteries.

You should always determine what your max continuous discharge rate is in Amps (which many of the new and popular batteries have already) to keep your math consistent and mind at ease.

How To Use This Information Effectively

Knowing the max discharge rate in amps is only half the battle.

How do you know if your coil or atomizer/clearomizer/cartomizer won’t short circuit your battery? Simple, use this equation: battery volts / the ohms resistance of your coil = your actual discharge rate.

If your actual discharge rate is less than the maximum discharge rate you calculated earlier, you’re in the clear. If it’s not, you need to suck it up and rebuild a higher resistance coil.

Let’s take a closer look using the 18650 1600mAh battery again (for the sake of continuity). If you took a freshly charged 18650 1600mAh battery and tossed it in your mechanical mod with a very limited voltage drop, and put a .2 Ohm coil on top, you’d be running at 20 amps. To figure out this math you take the voltage running to your coil from your battery, which lets say after a full charge, the multimeter shows that the battery is sitting at 4 volts. Now, divide by the ohms of your coil. The number you get is your total amps. In this case our math is 4/0.2 = 20. So we now know that running this exact setup will push our battery to 20 amps, just 4 amps under its max discharge rate. If you were using a different battery capable of less power under the same circumstances, you would be asking for complete battery failure and the chance of possibly hurting yourself.

Safety PSA: Resistance in coils can have a variance of 0.2 Ohms in either direction, or +/- .2 Ohms. This means that if you build a 0.2 Ohm coil, you have to account for that +/- 0.2 Ohm variance. The coil in the above example at .2 Ohms is an incredibly unsafe coil, and I would not use nor suggest that anyone use such a coil. Because of this, I would not recommend anything lower than a 0.4 Ohm coil for 18650 1600mAh battery.

Equation Recap

Let’s take a look at everything you’ll have to calculate in order to determine your coils safety in order.

1. Calculate your battery’s capacity in amps: capacity in mAh / 1000 = capacity in amps

2. Calculate the maximum discharge rate if measured in C: maximum discharge rate = (battery capacity in amps) x (continuous discharge rate)

2. Measure your battery’s volts with a multimeter.

3. Measure the Ohms of your coil and subtract .2 to account for the +/- .2 variance.

3. Calculate the discharge rate you’ll have with the coil you’ve built: battery volts / Ohms = your actual discharge rate

4. Check to make sure that the actual discharge rate is LOWER than your battery’s maximum discharge rate.