Awesome Batteries Part 2 - Inspecting the Samsung 25R January 13 2015, 8 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.
hleduc on July 05 2019 at 03:00AM
Thanks for the article.
Where can I find a full spec sheet of the Samsung 25R?
Brent Wissenback on February 12 2017 at 02:33PM
I have sent both Tesla Panasonic and Samsung an 18650 revolutionary design. I have written a paper on surface to volume relationships in both Physics and Biology, all of science for that matter. I have designed an electrode perforator to increase S/V. All of these things are available.
Lewis Balentine on December 28 2016 at 08:25PM
“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. "
Pray tell what is a ‘mR’ unit ?
ibrahim on March 09 2016 at 02:43PM
Please mention if someone want to measure his battery, the clapier ends must be in plastic like in the pic so he doesn’t short the battery while measuring
Anton on August 04 2015 at 11:52AM
@David You are right to question their function. One criteria for replacement is if they do not charge in their normal charging time. Have you tried another charger to rule that out? Otherwise yes, you should return them to the vendor you bought them from (not directly to Samsung).
@Artem Thanks for the suggestion. I would also like to do this but have a difficult time getting a safe spot within reasonable budget. I could always bring them to the middle of a field but there are still a few safety considerations ;)
@Ulf Hey that sounds like a very cool project. 18650 cells are commonly used in e-bikes, and many are using the 25R so you are on the right path. When talking about 18650 battery packs – the whole pack becomes the battery (nomenclature)… and the cells become each individual 18650. So when describing packs, the battery is the pack.
To put something like this together safely (instead of just creating a bomb) you will need a BMS (battery management system). This will regulate the cells, for example shunting current around a cell with a higher relevant voltage to actively balance the overall charge and prevent overcharge.
The Panasonic B series is also a good choice, especially if it is capacity (more travel distance before charge). If you want more help with packs, just shoot us an email.
David sandall on August 02 2015 at 05:42AM
Hi I’ve bought 2 samsung 18650 batteries and I’ve been told that there could be something wrong with them because after 7 hours they are not fully charged I only use them on my ecig box mod the place I bought them ain’t interested in my complaint can you help me I was even thinking of sending them no to samsung ….yours Dave
Artem on June 08 2015 at 05:32PM
Hi! Very good review, thank you!
How about safety tests? Something like shorting it and watch the result, to be sure in its safety.
Ulf Anderö on June 08 2015 at 04:40AM
I’am sending this from Sweden I really like your blogg and I think todays Lithium cells are great
and it will be intersting to see whats going to happen in the future.
I have an ongoing projekt togehter with a friend we are uppgrading 2 old swedish elektro mopeds from the
early 1980 they only made about 200 of theme.
One of the thing we focus on is uppgrading the battery to 18650 battery’s in orignial it was lead.
I have tested a lot of batterys so i’am quit sure what i want but there are something else that i think is importent
that are not so much to read about, And that is how connect to the battery.
When we are talking about a couple of amps there isn’t really a problem but when you have a battery like the samsung
that could deliver 20 amps how do you connect to the cell? could you wrigt something about that!
I know a good way is to weld but I’am going to use 18650 battery holders from Fastech.
And put 24 panasonic 18650B in papralell, then the cells are eayse to exchange if something goes wrong or if you want to lend them in another projekt.
I’am only going to draw 2-3 amps per cell at most.
Once again thanks for a nice blogg.