I’m devastated. I plugged in my sp36 pro and a it was blinking blue. After a few minutes a smelt something bad and there was smoke coming out of the usb socket on the torch. I immediately took it off and took out the batteries. There was some kind of brown sticky liquid on the batteries and one of them especially was a bit melted at the top. The flashlight is also burnt on the main board a bit. What do you guys think happened?
Checked for continuity between positive and negative rings on the flashlight but there was none. If something shorted inside wouldn’t there be continuity? Also checked all voltages of batteries all the same 4.06v. except there is a brown sticky fluid on one of them especially and it has melted at the top.
I wouldn’t describe it as a sweet smell, no. More like a bitter burnt smell. The smoke coming out was a dark grey smoke. The smell is still lingering on my fingers.
I don’t get any voltage reading when I measure at the brass rings when plugged in the charger. The charger was a 5v Samsung phone charger with original sofirn usb c cable.
Thanks for your reply. Yes I double checked the cells when I opened the flashlight to take out the battery tab. I was using the original batteries the flashlight came with.ive attached a picture, hope it helps.
Looks like the charging controller or a related component overheated and melted the solder mask (which is what you find on the battery). The batteries might still be fine, even the dirty one. But you definitely need a new driver (or flashlight if you can’t solder everything back together).
The dirty one got it’s insulation melted. Do you think the smoke could have been the battery venting?
When you say driver you mean the led driver right? So that means the flashlight wouldn’t work anymore. I know there is no charge voltage when I plug it in the usb without batteries. But I haven’t dared to try it with batteries.
I think the battery is fine, maybe got a bit hot, maybe needs a new wrapper. I’m pretty sure the LT1 doesn’t work anymore, you will need a replacement (driver or flashlight).
I’d be willing to bet those batteries weren’t matched up well enough to be put into parallel.
If there’s nothing in the manual about it then it’s not your fault.
When batteries are put in parallel the higher voltage cells charge the lower voltage ones and balance each other out, which is why all of them are 4.06V now. That’s never supposed to happen. Before pulling that plastic tab and putting cells in parallel you need to be sure they are all nearly identical to each other in every way you can measure, or as near as you can possibly get. Resistance should be in the same range, capacity should be identical or within the margin of error, and all within 100mV of each other at the most but preferably much less. If you had checked each cell voltage and resistance, maybe even a capacity test, before you took off the plastic tab and put them in parallel I bet one of the been way off. A high resistance, or
voltage way off the others or something.
But again, not your fault. Not saying you did anything wrong, just advising on how others can avoid this.
Its Sofirn’s responsibility to make sure the batteries sent out with the light match up, but it’s possible it was damaged in shipping or something. Usually cells in parallel are spot welded together from the factory and can’t be seperated, so this doesn’t happen, but flashlight people would just rip them apart anyways. I’m glad they have it setup like it is…They could maybe include a warning I guess. But they assume most people understand the risk I suppose. Any flashlight with loose cells in parallel could have this happen. But this one in particular, the way that flashlight is setup, so little resistance between the 18650s. If one of them was defective, say it was at 3V, and it was connected to two other batteries at 4.2V it just got super fast charged and the other two got pretty quickly discharged, lotta heat, lotta swelling, this is the result.
Series cells are more dependent on being balanced than parallel cells. One cell would have to be dead to be a problem with parallel cells. That’s my understanding anyway.
Sorry to hear about what happened to the OP.
But after reading some posts here discussing the weaknesses of built-in charging and risk of charging imbalanced batteries together, I have a question. Is it advisable, for newly purchased batteries, to charge them one by one inside the light (in this case SP36 Pro with its parallel cells arrangement) so as to eliminate the risk from initial imbalance voltage?
I’m no battery expert so please bear with me if it’s such a noob question.
Thankfully my brand new SP36 Pro and stock batteries did not suffer from the same problem as the OP. I hope he can get replacement/refund from Sofirn.
It is extremely dangerous to allow putting raw lithium ion cells especially the really powerful ones we can buy one, in series or parallel, with different protection required and strict cell balancing. I do not understand why flashlight manufacturers allow this because it is very irresponsible. In practice most of the time you are ‘ok’ but when things go wrong they can cause very dangerous fires. Built in charging is also not a problem if designed correctly but it is disappointing that many corners are usually cut.
Jeffgoldblum also describes it correctly. I also love your movies by the way As a result of this kind of implementation from my experience in electronics engineering, I unfortunately have to be cautious about any flashlight manufacturer who produces flashlight that allow multiple loose cells because it is a safety responsibility issue. This is also why proper battery packs like the one found in power tools are so expensive even though the cells are cheap, because a lot of additional safety circuit is required.
To OP, I am glad that you did not get hurt. From the photograph it looks like probably some component around the part where the black solder mask burned off must have been damaged. It could be a unfortunate shorted capacitor that started burning, or it could be an IC that somehow got shorted. Sadly it is most likely it is unlikely that the driver is still working. Even if it is the burn marks will leave carbon soot behind which is a future shorting concern. I hope you are able to find a good replacement or be able to repair the flashlight. The issue is likely not your fault and if I was you I will contact Sofirn for a refund or replacement.
What do you mean with “bad”? If the internal resistance increases, other batteries in the pack will see a higher load. But usually all should age similarly.
As a result of this kind of implementation from my experience in electronics engineering, I unfortunately have to be cautious about any flashlight manufacturer who produces flashlight that allow multiple loose cells because it is a safety responsibility issue. This is also why proper battery packs like the one found in power tools are so expensive even though the cells are cheap, because a lot of additional safety circuit is required.