Awesome Batteries Part 2 - Inspecting the Samsung 25R January 13 2015, 7 Comments
Table of Contents
- Official Data Sheet
- Visual Inspection & Measurements
- Technical Discharge Test
- Checking Resistance
- E-cigarettes, Vapes, and Mods
The Battery Bro team recently went to Shenzhen, China and inspected the most recent (Oct, Nov, Dec) production run of the powerful Samsung 25R batteries. We tested multiple cells and ran a series of tests. There will be a few more updates to this post as we discharge a larger machine and then deconstruct the cells.
Official Data Sheet
Please contact us for the Samsung 25R data sheet.
Visual Inspection & Measurements
The numbers on the Samsung 25R vary with each shipment. This is because they indicate the country of origin, the factory, and even which production line inside of the factory.
Take a close look at the top cap and positive terminal. These are often not totally centered on 18650 cells, which is normal.
The weight of this cell is 43.56g. There is a slight variability of.05 grams in the batteries I tested.
Checking a length of 64.7mm with the digital calipers.
And a width of 18.7mm.
Technical Discharge Test
Using a Soshine universal charger which has not failed me yet. You can see the full 2542 mAh was put into the cell, and we are at a maximum voltage of 4.2 volts when charging finishes.
This is a custom-built lithium-ion discharging tool used for the low-amp testing. It's small and portable and can be used to verify batteries in under an hour when visiting assembly lines. However as it draws power from the USB, the maximum ampere discharge is locked at 2.5A. Even if it can not do the full 20A, it can still verify a battery's specifications very accurately.
I did a minimum of five tests for each cell and came with very similar results. It's important to do several charge/recharge cycles until the cell is at maximum efficiency. There is a very flat discharge curve which is an advantage of lithium-ion. There is about a 100mAh variability between the cells I tested. Temperature, start voltage, and end voltage are all things that must be very accurate or they will skew your results. End voltage is especially important to get right. The Samsung spec sheet officially uses 2.5V as a cut-off which is lower than Panasonic uses. Keep this in mind, because the last few volts can still hold a lot of power. This is because Samsung has a special chemistry at the positive pole which is more efficient at lower voltages.
The temperature during testing should be conditioned to match the spec environments. It should be close to 25 degrees Celsius. If too hot or too cold you will not get the capacity to match the specs.
There are several standard ways to measure resistance for 18650 cells. This particular test sends a short pulse of current through the cell, and is most relative resistance measure for vapes and mods. This is a very low resistance, and one of the lowest I have tested.
E-cigarettes, Vapes, and Mods
This is the ideal battery for vapes and mods right now. It is the perfect balance of capacity and maximum continuous discharge, and has a higher cycle life than its cousin the LG HE2.
This is Samsung's second-most powerful 18650 - rated at a continuous discharge or 20 amps. The Samsung 20R is rated for up to 22 amps but the capacity falls short by 500mAh. Note: LG has a 30A cell but it can only store 1500mAh. So you can see what a nice balance the 25R has.
This is the best cell on the market for e-cigarettes and mods as of January 2015. Battery bro is in-stock now. Be sure to contact us if you want wholesale Samsung 25R batteries.