Just thought I’d link the datasheet for anyone interested since it’s not available on their websites.
Here’s the most important specs:
Rated capacity: 1100mAh
Typical: 1050mAh
Minimum: 1050mAh
Discharge Cut-Off: 2.75v
Standard Charging Current: 0.55A
Max Charging Current: 1.1A
Standard Discharge Current: 0.55A
Max Discharge Current: 1.1A
Max Temp: 60°C
The Wurkkos TD07 charges this cell at 2A, is that a safety concern?
It’s certainly not good for the battery. Likely not a safety problem (check the temperature), but the battery will degrade quickly.
That’s good to hear, but could it potentially become a concern as the cell degrades and resistance increases?
From what you’re saying, charging current is only a concern if the cell gets hot? I’m always a bit nervous exceeding datasheet specs when it comes to lithium cells and all the horror stories. At 22°C ambient temp the cell reached almost 40°C (I received it to review). 1Lumen’s review said it gets a bit hot, but still safe for an 18350. I just needed help in knowing whether this was indeed an accurate statement for my own review as well.
I’m really trying to decide whether selling the TD07 is wise or whether I should avoid it in my store. Maybe I should wait for Wurkkos to sell an 18650 tube and caution customers about the charging, should they choose to charge the 18350.
It’s disappointing since It’s quite an enjoyable model.
Edit: Correction, 1Lumen said 2A is a bit hot. My mistake.
1lumen said
“…2 amps at 5 volts which is a bit hot, but still safe for the 18350”.
That’s different than saying it gets hot.
All batteries are going to have a rise in temperature while charging. If you charge it in the light it’s going to get hotter than if you were to charge it externally. Is charging it at 2 amps inside the light at high ambient temperatures good for a long battery life? No.
Are you exceeding the discharge current while on turbo or high?
Yes.
I don’t know why people keep saying s&w use good batteries.
After charging it inside the flashlight it’s now reading very high resistance in my Vapcell S4+, took a few attempts to get it to 4.20v. It’s very likely damaging the cell already. Had no issues before I used the onboard charging. Perhaps I’ll just sell the Sofirn SK1 instead.
1C max discharge? That doesn’t sound particularly useful for flashlight applications… Wonder why they used these cells.
It’s not the first time they ignore specs. The Sofirn IF30 bundles a 32650 rated at 6.5A max discharge, the IF30 draws 37A. It was proven that every turbo activation was damaging the cell because turbo measured less lumens each time on a full charge. Barry from Sofirn said they tested it and it was safe for 30A, I then replied saying but it’s drawing 37A, I was ignored from then on. Using a 21700 cell performed so much better. It’s a shame they have this attitude.
In my testing, the battery tube got warm, but not alarmingly so, and never hot. I think the charge current is safe in that respect as it doesn’t keep it at 2A long enough to hurt the battery. I hadn’t charged it outside the flashlight though to evaluate whether it is sustaining any damage.
Same with HD15 wurkkos. It gets close to two amps for a while depending on what the voltage is at when you start charging but it doesn’t stay up there.
I find this discrepancy with Sofirn’s 18350 1100mAh cells quite concerning.
The product listing clearly advertises the battery as 1100mAh:
Sofirn 1100mAh 18350 Cells
However, the table on the same page states Nominal Capacity: 850mAh and Max Discharge: 5C. If we calculate 5C for the stated 1100mAh capacity, that would be 5.5A. For the 850mAh capacity, it would be around 4A. This is already a bit inconsistent.
To make matters worse, the datasheet you linked specifies Max Discharge Current: 1.1A (Standard Discharge Current: 0.55A )
This is a massive difference! A 1.1A max discharge current would make these cells unsuitable (and potentially dangerous) for many flashlights, especially high-drain models. Failing to prominently disclose such critical specifications on the product listing feels irresponsible and undermines trust in Sofirn as a brand. It’s essential for Li-Ion batteries to have accurate and detailed specs, as using them beyond their limits could result in overheating or even catastrophic failure.
Sofirn really needs to provide consistent, transparent, and accurate information about their batteries to avoid putting users at risk. For now, this discrepancy makes me question their reliability.
I personally wouldn’t charge any 18350 battery at 2A
Those specs are for their old 900mAh 18350 cells that they no longer sell. I received two datasheets for both 900mAh and 1100mAh.
I had a chat just now with Mooch and this is his response. This relates more to me selling the TD07, but you just can’t state something is safe with thorough cycle testing. As a reviewer myself, I would caution you to stating “safe” in a review when we actually have no clue over time how that cell will behave.
Personally, I’ll be cautioning my viewers to the onboard charging, and even using the bundled cell with a 1C discharge rating.
If reviewers don’t start complaining about this then Sofirn and Wurkkos will continue to bundle crap cells that aren’t up to the job.
That very clearly answers my question. I’ll grab the Sofirn SK1 instead with the 18650 cell.
Thank you, @PiercingTheDarkness, for your reply. Unfortunately, this further highlights Sofirn’s shortcomings. They not only neglected to disclose the critical (and low) max discharge rate of 1.1A for their new 1100mAh battery, but also left outdated specifications for the discontinued 900mAh version on their product page. This mix of omissions and inaccurate information raises serious concerns about their commitment to transparency and safety, especially when dealing with Li-Ion cells where proper handling is crucial.
I agree! I think that manufacturers need to be careful here, and most higher end brands package protected batteries for this reason. I also don’t think Wurkkos or Sofirn package the best quality batteries either (have they ever?). However, the charge current doesn’t stay at 2 amps for too long. It decreases to a safe level after a short time. The total charge time tells me that the cell isn’t being abused, and the fact it doesn’t heat up excessively during charging. I think you’d have to cycle test the battery and charging system with other cells to properly adjudicate that and compare it to other charging systems which have lower input current.
Safe is what I’d consider 1C though and it remains around 1.5-1.6A, surely you can understand that we have no knowledge of this particular cell and how it’ll behave over time. It’s not from a known reputable brand. Also, the fact the max discharge is also 1C is probably even more concerning. Charge and discharge abuse in this case.
The head of my unit reached 37°C at 22°C ambient, that’s within the 0 - 45 temp range in the datasheet, but what about countries with much higher temperatures, will it still be within range, even as it ages and resistance increases?
Back when the C8F was released it was thought to be a rewrapped 30Q because of how well it performed. Not long after they changed to low drain cells.
I’ve not seen much in the way of testing of fast charging cylindrical batteries. Many EVS have multiple charging speed options. Some high-end phones have regular charging and then fast charging AND super fast charging. I believe most/all of them. (cars and phones) slow things down when they get to 80 or 85%. Most cars and some phones have the option to limit the full charge to 85 or 90%. I’ve read plenty of experts who claimed that there’s not really much of a problem to fast charge in the middle range from 30 to 80%. Cars and phones do have more protection built-in in the form of temperature sensors and cooling. Yes some phones actually have little cooling tubes inside.
How does all of this relate to flashlight batteries?
When I’m charging in a light or externally in a charger I almost always use a USB tester to be able to periodically look at amps. I also periodically check the temperature with the back of some fingers whether I’m charging in a light or externally in a charger. These steps are especially important for new lights or new batteries.
Is everybody going to go out and buy a USB tester? No.
Charging a battery externally will cause less temperature rise versus charging inside the light assuming the same charging voltage and amperage. Does that mean everybody is better off charging a battery externally? Not necessarily. Does that mean that it is ”safer"? Not necessarily. How are you going to charge your olight battery externally? If LG had their way consumers would not be able to remove batteries from flashlights or other devices. It’s likely that LG had a hand in Korea essentially banning consumers from purchasing single cells. A few years back LG also promoted the idea to the US government that consumers should be banned from handling single cells. Not everybody should be handling them. Flashlight batteries are going to last longer if you don’t charge them to 100% and don’t store them at 100%. It doesn’t appear that most people here worry about that. Does that mean it’s unsafe to charge to100%? Not necessarily.
This specific data sheet referenced above has a cycle life of > or= to 250. That tells me everything I need to know about this battery. It’s not going to last very long. Does that mean it’s unsafe to charge it at 2 amps in a light or to discharge it at 2- 4 amps for short periods? Who knows without testing? My guess is you won’t get that 250 cycles while maintaining 80% capacity. Some Chinese battery makers have come a long way. Some I wouldn’t trust. Some flashlight manufacturers choose their batteries very carefully. Some would rather that you don’t take the batteries out to charge them. Some don’t want to sell batteries with their lights. Some only sell batteries with protection circuits added. Some are buying 18350 batteries at 60 cents a pop a thousand at a time. You don’t have to use that battery.
As someone who has just bought a Wurkkos TD07 (and loves it) this thread makes me a bit uneasy. It made me realize that I have never seen a 18350 rated for charging at 2 amps, do they even exist? As long as it only shortens the life expectancy of the battery I don’t really care - an 18350 is not exactly expensive. But if it potentially shortens my life expectancy, that’s a different story.
I’d say there’d be an extremely small chance anything goes wrong, but no one here can 100% guarantee that chance is small haha, that doesn’t help. Looks like Jinba picked up a cheap cell and sent it off for testing, then completely ignored the datasheet report.
I’d recommend grabbing an 18350 that is rated for 10A discharge, then decide whether you want to use the onboard charging or use an external charger.
I’ve heard of too many horror stories to take risks with lithium cells. One old post on here or Candle Light Forum, was a quad 18650 model that exploded and blew out the guy’s windows leaving shrapnel in the walls. The cause was cheap Chinese cells that were bundled with the flashlight.
