Measuring the discharge rate of a 18650 lithium-ion battery involves monitoring the rate at which the battery releases energy during use. Here's a general guide on how you can measure the discharge rate:

Equipment and Tools Needed:

1. Multimeter:
   • Use a multimeter capable of measuring current (amperes) in the range of the expected discharge current.
2. Resistor (Optional):
   • A known resistor can be used to create a simple load for the battery.
3. Load Tester (Optional):
   • A specialized battery load tester can provide a controlled and constant load for accurate measurements.

Steps to Measure Discharge Rate:

1. Select Load (if using a resistor or load tester):
   • Choose a load that corresponds to the discharge rate you want to measure. Ensure it is within the safe operating range of the battery.
2. Connect the Load:
   • Connect the load to the positive and negative terminals of the 18650 battery. If using a resistor, create a circuit with the resistor in series with the battery.
3. Use a Multimeter:
   • Set your multimeter to measure current (amperes) and connect it in series with the battery or load.
   • Connect the positive lead of the multimeter to the positive terminal of the battery or load, and the negative lead to the negative terminal.
4. Monitor Current:
   • Start the discharge process and monitor the current reading on the multimeter.
   • The discharge rate is the current flowing out of the battery, measured in amperes (A).
5. Record Readings:
   • Record the current readings at regular intervals to observe any fluctuations.
   • Note the discharge current over time.
6. Calculate Discharge Rate:
   • The discharge rate can be calculated using the formula: Discharge Rate (in watts) = Voltage × Current.
   • Ensure to use consistent units (e.g., volts and amperes).
7. Maintain Safe Limits:
   • Avoid discharging the battery beyond its specified safe limits.
   • Monitor the battery temperature during the discharge to ensure it stays within safe operating temperatures.
8. Use a Load Tester (Alternative):
   • If using a load tester, follow the manufacturer's instructions for setting the desired load.
   • The load tester may provide more accurate and controlled discharge conditions.
9. End the Discharge Test:
   • Stop the discharge test when you have gathered sufficient data or when the battery reaches a predetermined voltage level.
10. Analyze Results:
    • Analyze the recorded data to understand the battery's discharge characteristics.
    • Look for any voltage drops, fluctuations, or anomalies in the discharge curve.

Always prioritize safety when working with lithium-ion batteries. Ensure that your equipment and procedures are in line with safety guidelines, and avoid discharging the battery beyond its specified limits to prevent damage or safety hazards. If you are unsure or lack experience, consider seeking assistance from professionals.

I connected a charged battery + to +, - to -  for about 40 seconds. This brought the voltage up enough to get the charger to enguage. after the charge the volts are as pictured, running the load test resulted in as pictured

WOW This battery is super strong and it was ready for the Bin!

note: This battery showed 1.1 v and not zero, so far zero batteries have not worked

The 18650 Cell belongs to the Lithium Ion type chemistry, very high care has to be taken while using it. This includes while both charging and discharging the batteries. While discharging the battery, care should be taken that we never consume more current than the  C rating and also the battery should never be discharged below 3.0V. Normally a circuit will be employed to monitor the discharge current and under voltage value to cut off the battery from the load if anything goes wrong. Also care should be taken that the battery never experiences a short circuit or reverse polarity. 

mAh is a measure of battery capacity, and it utilizes all three concepts (electric charge, current, and time) to estimate how much electricity the battery can hold. For example, a capacity rating of 1,000mAh on a battery means that once fully charged, it can sustain an electric flow of 1,000mA for one hour.

The ENE is Watt hours 

Wh is short for Watt Hours.

The energy capacity or capacity to do useful work stored in the battery.

The maximum electric current a battery can output depends on the battery's structure and is measured as the discharge rating.

We are using different methods to better understand the discharge and capacity of LiPo batteries

This is some actual testing now we have figured out a system. Battery #2

After 1amp discharge.  The dl24 is setup to stop at 2.7. the batteries bounce back after removing them to 3.12

Beginning Test 2 on battery #2

after testing 

Batteries are a big part of my learning sessions. I try to inform about the technology, the dangers of LiPo and how to get the best performance from your battery tools and systems that use batteries. This is not a learn once and move on technoligies, the pace of development in batteries is even faster than computer chips.

Step one was getting a battery resistance tester labled peacefair. It didn't do condition tests, it measured resistance in the battery, The unit stopped working on the 3rd battery (china)

Step 2 is where we are. This is the DL24 condition tester. There is some real awesome forums that cover this product, even with it having several manufactures the forums are very detailed. This unit is the 180watt unit.

Here Goes:

The 18650 Cell belongs to the Lithium Ion type chemistry and hence very high care has to be taken while using it. This includes while both charging and discharging the batteries. While discharging the battery, care should be taken that we never consume more current the C rating and also the battery should never be discharged below 3.0V. Normally a circuit will be employed to monitor the discharge current and under voltage value to cut off the battery from the load if anything goes wrong. Also care should be taken that the battery never experiences a short circuit or reverse polarity. 

Disclaimer: 18650 batteries can short out and catch fire. You got that! Use caution when working with and using lithium ion batteries as they are very sensitive to charging characteristics and may explode, burn, or cause a fire if misused or mishandled. Always charge in or on a fire-proof surface. Never leave batteries charging unattended.

Charge only with a smart charger designed for this specific type of lithium ion battery.

OK so some regulators got into the mix and endorsed a solution to a problem that doesn't really cover much but we will look at that first

PRBA –The Rechargeable Battery Association applauds the Safety Warning issued today by the U.S. Consumer Product Safety Commission (CPSC) regarding the safe use of 18650 lithium ion battery cells.  PRBA's policy on the use of these and other cylindrical lithium ion battery cells explains how manufacturers of these products  never intended them to be sold to consumers as loose, replaceable power sources without the necessary safety protection features.

Ok Great, so don't buy loose 18650 batteries because they don't have electronic circuitry to protect from overheat, overcharge and short circuit. Yeah but they don't explain the battery and the manufacturing process and manufacture certification process.

Why did this come up, because I purchased a head lamp from Amazon and the batteries had no labeling, no identification and no traceability. They had caps like a battery that has electronic protection but how could you know?

Good Bet these are not protected just on cost. Quality protected ones are around 10 bucks

Button Top--Flat Top Electronics ?

There are button tops with protection, and without. There are flat tops with protection, and without. The button, or lack thereof, does not indicate whether a cell is protected. There is no difference in risk between button top and flat top cells, all else equal. The main thing is to make sure the cell fits well and makes good contact - some lights work better with one type or the other.

Button tops are just that, a button or nipple looking thing on the end of the battery.

Protected and non protected Li-ion has nothing to do with the physical + end contact. Although you may find a trend that more protected batteries are button top and more non protected are flats

Going through my inventory of misc recovered batteries It became evident that alot had no identification and even removing the blue plastic cover revealed no traceability

Good practice:

Constantly topping off charge for hours, days and weeks is abuse and will only result in a reduction of cell capacity, current, and ability to hold charge. Over-discharged cells below 2.5V for Li-ion (which with LiCo chemistry can cause them to explode or catch on fire if charging is subsequently attempted).

Do not mix and match old and new, used and unused batteries.

This is a comparison of protected and unprotected by price

Samsung 25R 18650 2500mAh 20A Battery

Sale price$4.99

Protected 9.99

A great follow up read is protective circuits

• MISUSING OR MISHANDLING LITHIUM ION BATTERIES CAN POSE A SERIOUS RISK OF PERSONAL INJURY, PROPERTY DAMAGE, OR DEATH
• BATTERIES MAY EXPLODE, BURN, OR CAUSE A FIRE IF MISUSED OR MISHANDLED
• ONLY USE WITH PROPER CIRCUITRY IN A PROTECTED BATTERY PACK
• ONLY USE WITHIN MANUFACTURER LISTED SPECIFICATIONS
• DO NOT STORE LOOSE BATTERY IN A POCKET, PURSE ETC. - ALWAYS USE A PROTECTIVE CASE OR BOX
• KEEP AWAY from metal objects to prevent short circuiting
• DO NOT short circuit
• DO NOT use if wrapper or insulator is damaged or torn
• DO NOT use if damaged in any way
• DO NOT overcharge or over-discharge
• DO NOT modify, disassemble, puncture, cut, crush, or incinerate
• DO NOT expose to liquids or high temperatures
• DO NOT solder, spot weld only
• User must be familiar with handling lithium ion batteries before purchase
• Usage of batteries is AT YOUR OWN RISK
• ALWAYS charge in or on a fire-proof surface and never leave charging batteries unattended

This post moves from just trying to get voltage from a 18650 to building a DL24 capacity tester

this simple 3d print battery holder works great , use alligator clips on the probe ends