How trustworthy are Sofirn batteries?

What are you using for testing the resistance? Which Sofirn battery is it?

I’ve seen button tops in general really mess up charger measuring devices. The results would be all over the place even exceeding the max resistance of the display. I removed the button top and added a solder blob and that fixed it (30Q). Other button tops would be fine and show what they should. So it could be the button top. It depends on how it was attached, the amount of power used and the pulse time to weld it together.

Sorry, I don’t have any Sofirn 18650 button tops.

LittoKala LI 500 Engineer charger/tester. Black 18650 3000 mah button top rechargeable 3.7v that came with a sofirn SP31 V2.

You can’t trust the resistance reading then, most chargers aren’t an accurate measurement.

I have the same charger and can get 125 and others 35 using the same battery.

Button tops also raise the resistance, some more than others. Last year I purchased 120pcs Sofirn 18650’s to find the buttons could easily flick off with a knife. Very poor soldering job. The batteries are almost as good as a Sanyo NCR18650GA with the button removed.

Liitokala Lii-500 Engineer doesn’t show precise mR values (values will change even for other batteries).

However, the button on the button-top does add resistance for such kinds of chargers.

I just orded two samsung 40t batteries I do not trust the battery that they offer the sofirn c8g with.

Why?

I don’t know suppose I just think of them as being a rewrap batt.

Besides I had a better deal ordering two legitimate cells for a little more for what sofin wanted for one battery

They are a rewrapped cell because Sofirn is not a battery manufacturer. This does not mean it’s bad, though. It comes from a chinese battery manufacturer and generally speaking their chemical mixes tend to be slightly not as good as a company like Samsung.

The 40T is a top notch cell, but it’s usually more expensive than a chinese battery. The cheapest I’ve seen the 40T is about $7-$8 each plus shipping. If you paid noticable less than that, I would be suspicious if it’s a real 40T.

I paid 6.99 a cell on 18650batterystore but with a coupon code it came out to 20 bucks shipped sofirn wants 9.99 for one cell that shyed me away lol

If you get a Sofirn battery bundled with the flashlight I find it’s much cheaper on Ali or their website

That sounds legit.

Here’s my discharge test of the PLB 26650 5000mAh 10A cell Sofirn now stock.

The datasheet shows a maximum discharge temp of 60 degrees Celsius. Though the 20A discharge performs well, it exceeds the max temp at 74 degrees.

Keep in mind the results are slightly lower on the graph than the actual voltage due to resistance

5A - 0.01v
10A - 0.02v
15A - 0.03v
20A - 0.04v

Here’s a comparison vs the Sofirn 26650 HD 5000mAh

Can you add a picture of each cell? I didn’t know Sofirn sold a PLB cell. The common PLB cell most are familiar with is the 5750mah. Pictures might help to clear things up.

The Sofirn PLB 5000mah is this one, right?

The High Drain you tested was this one that says 25A on the label?

Even though the older PLB 5750mah (Shockli 5500mah, etc…) was better than this new one (higher continous amps 20 vs 10-15, plus higher capacity) this newer 5000mah is still beating the cells Sofirn uses in their HD version? Man, that’s high praise to PLB. I wish they hadn’t discontinued the older, better cell.

Yes, that’s the correct PLB cell I tested

Also the same Sofirn 25A HD button top

I was rather disappointed the older cell had been discontinued as I had placed a bulk order from my supplier. I had to then change to these PLB 5000mAh but I’m not disappointed.

I’ll run another discharge at 15A to check the temp. Pretty certain it was around 50 degrees Celsius

Okay, I ran another discharge test at 15A and the temp reached 62 degrees Celsius. Slightly exceeding the max of 60. I reckon 14A continuous would be fine

I wonder what the ideal room temp is meant to be for an accurate test. Room temp tonight is 20C.

I’m not sure what’s up with this cell on capacity as almost every discharge shows a different result. Then again my charger hasn’t got a reliable cut off, sometimes 4.20v and others up to 4.25v.

This test at 15A got just over 5400mAh and battery was 4.23v

I received four button top 18650’s in a BLF LT1.

Sofirn 18650 3000mAh Test #1 (2020-11-06)
Room temp: 17C
Capacity (mAh):
3060, 3071, 3051, 3091
Internal Resistance (mOhm):
51, 59, 53, 46

Measured with a Vapcell S4+.

Is 2A continuous charge ok for these when around 3.8V?

i have similar findings with their 18650, all measured just a tad over the rated 3000, but their 26650, which is supposedly PLB re-wrapped, rated at 5500, one of them measured at 5480, which is close enough ill let it slide, but the other is 5331, a bit disappointed with that. the no brand 26650 that came with my ft03 was over 5500, but it was only rated 5000