Sanyo UR18650FM still best 4.2V cell at keeping up voltage during discharge?

Batteries and Chargers Rechargeable Batteries
1

I have 8 Sanyo UR18650FM cells pulled from a low cycle count 2008 Lenovo laptop battery. They still have 80-90% original capacity and work fine.
Still I was looking to upgrade so I compared some discharge curves and it seems those Sanyos are still the best 4.2V cells at keeping up voltage during discharge (up to 2A). I was expecting that current cells would blow those 13yo Sanyos out of the water in every regard.

https://lygte-info.dk/review/batteries2012/Common18650comparator.php

They are the first Sanyos in the list. The latest Sanyo GA or Samsung 35E / 30Q still lose out in terms of voltage from 1,5 Ah onwards. (While they certainly win when it comes to overall capacity.)

So eg. for a single 18650 direct drive UV light with its high Vf and not pulling too much current (1 and 1.7A are common depending on the emitter), there would be no benefit in using any of the latest type cells instead of those 2600mAh Sanyo FM (that can still be bought new). What do you guys think?

2

I’m not sure how you read the curve but at 2A 35E beats FM over almost the whole curve.
You are not better off with the FM battery.

3

So I guess there’s really just a benefit for a UV emitter that can’t make use of voltages below ~3.35V and theres only some added output in the last 1/4 (2A) to 1/3 (1A) of charge it can use.

I’ll keep using my old FMs in the UV light and put something more recent into the regular (visible) light. No use in buying brand new FMs.

4

It still seems you can get 2.5Ah from the 35E vs 2.3Ah from the FM at 2A if 3.35V is the limit.
At 3.5V it has a slight edge in runtime though.

If you already have the FM cells, I see no reason to replace them in the UV-light though.

5

For the price of free, keep what you have. I always liked the LG D1 charged up to 4.35 (or 4.4 if you don’t care about cycle life) for capacity above 3.5V and rates below C/2 and especially C/4.

The balancing act here is really won out by cells like the Sony VTC6 and Samsung 30Q. Still on top after all these years.

6

Welcome IDDQD!

Your name is the invulnerability cheat code from the original Doom. Brings back memories. :innocent:

7

It's a pleasure to have you onboard, IDDQD!

8

Thanks, for the welcome.

Yeah good old Doom. You can still play the original (with some minor improvements) on Windows / Mac / Linux with a free port called “gzdoom”. Great for 10 minutes of fun and blowing off some steam every now and then.

Absolutely. I have pulls from 3 different Thinkpad T60 batteries all roughly the same age (2008) and the cells are all specced 2550 to 2600mAh, cycle counts on the packs were different:

#Sanyo UR18650FM are hands down the best. Lowest internal resistance and highest remaining capacity of 2200 to 2400mAh after 13 years. Plus they have this more horizontal discharge curve.
#Panasonic CGR18650E are doing ok at 2050 to 2200mAh.
#Sony US18650GR are practically dead. Capacity is way down and they warm up more. They will go into safe disposal.