A bizzare incident - explosion and fire - Opus Battery Charger

I’m just glad that you and Mr Pipes are OK.
As you say it is quite bizarre, but of course it is always a possibility with our batteries.
What battery was it, and how old was it?


Damn bro, I’m glad you’re both all right. I’ve been playing with the idea of putting my charger in a cool-box that I have, just to be on the safe side.
I get paranoid ideas sometimes :sweat_smile:
Till now I’ve been too lazy to clear out the flavours I’ve been keeping in it, but now you’ve given me an incentive. I also own an Opus for my 21700’s :scream_cat:


I have never used an Opus, so have no first hand knowledge of them.
I only have eFest Luc V4 and Nitecore I2 which thus far have been fine.
The Samsung 25R’s are well regarded batteries so they should have been fine, I’m running about 30 of them myself, some married and some individuals.
It will be interesting as to whether anyone else may be able to shed any light on this.


Wow, glad you are ok, was there a battery in bay 3 by chance? It looks like thats where all the damage is concentrated, only thing I can think of is a short in the charger, I have a Nitecore D4 EU edition, this has certainly made me think twice about leaving my charger on when im out, thanks for sharing


Wow this make me re access my battery charging methods - I know if it was posted elsewhere the know all brigade would come out with a barrage of BS.

I am glad Mr Pipes is ok and the damage was contained to carpet and paint.

I doubt you will ever find the actual cause but is sure as shit a wake up for me.

Thank you for posting and making us all think about it.


On a side note the Nitecore D4 supposedly stops trying to charge the battery once it is full, does the Opus have that?? I know some will continue trickle charging


I’m amazed (and thankful) that you guys escaped without serious injury. I also want to add my thanks for sharing the situation.

As you mentioned, I too have long thought highly of both components (Opus and Samsung) involved in the incident. Talk about a serious reminder that nothing is infallible (or beyond reproach) when it comes to dealing with Lithium-Ion technology… :flushed:

/my speculation from observations

Agreed, and good eye.

I’m strongly inclined to believe that the battery that exploded (and there was ‘nothing left of’) had to have been in bay 3. As judging by the pattern left by shrapnel, and knowing that the charging position of the battery is positive to the top, it is logical that it vented in an almost 360° pattern which radiated from the top of the battery (away from the side of the battery). The bottom being a single, solid ‘plate’ did similarly, but with marginally less force, thanks to its construction (which I can only assume directed the majority of the force to the top).

It’s interesting to note though, that there doesn’t seem to be much damage at all to the underside of where the battery is assumed to have been in bay 3.

The above is what leads me to believe that the battery was at fault, and shorted/exploded faster than what the charger could react to.

That last sentence though is what really throws me though. I strongly agree with @anon96069639 that one would think (hope) that the monitoring circuitry would catch whatever ‘condition(s)’ were encountered BEFORE things escalate to a full on venting condition.

It also reminds me that I am curious about a couple of things.

What version of the Opus did you own? 1.x, 2.0, 2.1?

Did you ever test the batteries in the charger (regularly or otherwise)? Meaning, to not just charge them, but to get the overall condition (such as resistance, max capacity, etc)?

I’ve got some 25r5’s here that are approaching 3 years old (if not already that old), and while the max capacity has dropped off to an average of around 1800mah… I’m overdue to test them again for the resistance measurements.
Fortunately, I have replaced the majority of them (in daily use) with newer 30Q’s. (But OTOH, that only means increased reserve potential at hand to vent [God forbid]).

My line of thinking is…
I’m wondering if the internal resistance of the battery falls too far outside of spec (for the charger to ‘safely calculate’ or measure), then a window of ‘fail condition’ could open up…and you’d get what we see here?

/my speculation from observations OFF

Knowing full well that there’s really no way to know exactly what happened, in what order, I am still inclined to believe that the more info we can piece together, might help for future knowledge. (Better to have extra details, and not be useful [now], than to not have them, and learn they could have been important [down the road])

/random thoughts I haven’t had time to process yet

  • how can a battery seemingly explode in place, leaving no remnants embedded in the charger (adjacent to the side of the battery, underneath the battery)?
  • IF the battery started to vent (blowing both ends off of the charger where the battery was) from the ends first, was there then a further degradation of conditions which expelled the battery before it “exploded into nothingness”? (Which could explain there not being any shrapnel embedded in the ‘side wall’ of the chassis underneath the battery. But then proposes another question of “in order to eject the battery, one would think there would have to have been force exerted from the bottom side of the battery” [between the battery and charger] which again implies there should be shrapnel embedded in the area of bay 3)

So many questions… Such limited information out there (not pointing at you Dan, just touching on Li-ion venting conditions testing that’s in the public domain).

/parting thought
Times like this make me wish Mooch was able to run a series of venting tests in a controlled environment using a high speed camera (with varying chargers and batteries).

Sad day. But invaluable reminder.
Thank you again.


Considering that both batteries were red hot, one exploding and the other splitting, makes me think that it is the charger. To me both batteries failing at the same time seems highly unlikely.
However maybe the battery in bay 3 overheated the battery in bay 2 causing a chain reaction.
Would it be worth reaching out to Opus for their opinion?


Thanks for the heads up. Information is always a good thing. I haven’t had any irregularities with mine but I may replace it anyways. $30 isn’t worth risking disaster. A general search of " opus battery charger problems" turned up a few results like this:


Good to know.
While it may be a false sense of “added safety”, the whole reason I’m not nearly as comfortable charging at 1A, is that the time or two that I did test that level of charging, I noticed a distinct rise in the temperature of the batteries while being charged at that rate.

/EDIT: I neglected to mention that I only charge at the 500ma setting. /edit

I figured I’d rather have to wait a little longer (or buy additionally sets for rotation) than to shorten the lifespan (which I assume has to be a side effect of the increased temp cycling, which I would also believe to have a cumulative effect on the internal resistance).

Again, I’m not anywhere near as versed as Mooch or others… But this is from my understanding, and my approach as a result of my understanding.

I understand, and I think that’s probably what most people do.

What I’d really like to see is Mooch (or someone with similar knowledge) weigh in, and see if anyone has any kind of concrete data on the upper limit of the safe margin of internal resistance to operate in.
(EG: Properly discard your “brand x, model y” battery if the measured internal resistance meets/rises above ‘xx’ reading. Of course, this would be expected to vary from brand and model of battery… So a load of further testing for the most commonly used variables alone would be in order.)

At least, that could add one more layer of safety between the user and the Li-Ion technology.

As do I, but, it’s probably for the best that you didn’t. I know while my curiosity is at a peak, the risk of handling/exposure to certain chemicals (as a general rule) can have long term consequences. And knowing enough to realize that I don’t have the necessary information about the ‘raw goo’ inside tells me I have no business handling the exposed insides of one. So I damned sure wouldn’t ask/expect someone else (with the same level or less) to.

@Steampugs @mjag @woftam or whomever…
Could I ask one of you gents to request Mooch’s presence (or at least ‘eyes on’) to this thread?
I’m sure he doesn’t know me from Adam…
Even if he replied elsewhere, I’d simply be grateful for his thoughts.

And like @anon96069639, I’m also very interested to hear @SmilingOgre’s thoughts. :slight_smile:


Thank you for sharing this video (and your thoughts of course).

I have been hesitant to add (before now in this conversation) that just within the last 24 hours, my BT-C3100 v2.1
<EDIT for accuracy: just double checked mine, and it’s actually a v2.2>
has just started to exhibit some of the symptoms shown in the video (specifically the unit on the left) that you just shared. It’s at least two years old (and probably older, but I’d have to check)

I took immediate notice of it, and DID NOT dismiss it… But haven’t had a chance to look into it further yet.

I instantly thought, “ok, time to start thinking about replacing it.” But this just took that thought to Priority 1.

As you say, the risk FAR outweighs the cost.

I will also note, that the conditions are persistent, and the monitoring appears compromised until the unit is unplugged and self-resets.
HOWEVER, just like with the digital thermostat I just replaced for my mom’s AC unit (days ago), once a device has been exposed to a power surge (not saying his nor mine has with any guarantee), it’s never trustworthy again IME.
And I’d be far more inclined to think that that’s what might have corrupted the charger (if the charger were to blame). Again, just supposition and educated guessing going on here…


First off @anon96069639 I am glad to hear everyone is ok, second off that is some seriously scary stuff.

Like many here I am going to think of ways to improve the safety if my charging. I charge in a room with tile floors and the chargers sit in granite but now I know that is not enough if something like this happens. I am going to look into that box with computer fan venting you mentioned. I know they make boxes for safely charging Lipo’s in, never researched were to get them though.

Thank you for bringing this to our attention and sorry it happened to you but thank God everyone is Ok.

@Sprkslfly I have only spoken to Mooch once but will reach out to a friend who may know him better and see if he can weigh in.

Edit: Contacting VapeyMcGyver from reddit as well, he might be able to help. If not then I can just post this over on reddit with @anon96069639 permission, Mooch tends to hang out there.


Here is something for the Lipo user’s, I don’t think you can put your charger in it though, anything similar for a charger?

They have a bag at Amazon too for Lipo, something like $14 but my mobile just keeps opening the amazon app so can’t post a link.


Wow! @anon96069639, I am so thankful you and your’s were not hurt. You have a lot of great input already here and I doubt I have anything to add. @Mjag, Not sure about the Bat-Safe. Does it provide cooling? The bags and such will contain a thermal runaway reaction but often also promote it allowing internal temperatures to rise more than they would in open air. Having said that, the amount of effect is dubious as the chemical reaction initiating thermal runaway starts from within. As to the causation, I have no idea. Faulty battery, sure. Faulty charger is possible too. I don’t have enough information on the charger to assess if a failure mode could be placing an shunt across the terminals of the battery or under what circumstances a battery could go into thermal runaway as a result of overcharging. As per others, I would defer the evaluation to Mooch. I have had little formal education on batteries themselves.

Again, just glad you weren’t hurt.


Got a response from VapeMcGyver over on reddit, he said he will let me know if he can think of anything else:

from VapeyMcGyver sent 12 minutes ago
Thanks for linking me the post! Always interested in failures and safety related stuff.

I’ve seen a fair number of external chargers have melt downs but explosions are fairly rare. Goes to show it can unfortunately happen to anything we use. I haven’t got any personal experience with Opus brand but I’ve heard they’re good quality.

So I’m already thinking about causes but it’s hard to tell. Especially as he mentioned both cells got red hot, that complicates things a bit. Generally for a cell to go full thermal runaway before it can vent it requires a hard short. It’s gotta be able to hit the runaway temp before the burst disc ruptures and that requires very rapid heating. This wasn’t just venting, this was rapid disassembly. I would have first thought an actual explosion in a charger would be due to a damaged wrap enabling the cell to short on the positive end against the contact… but then it wouldn’t make sense for both cells to be hot. One cell shorting shouldn’t affect the other. Overcharge is a possibility… but to be honest there is very limited information out there regarding what happens to a lithium cell with degrees of overcharge. So I’m not entirely sure what conditions would need to be met to cause a thermal runaway situation in regards to abnormal charging. I have some plans to do controlled overcharge tests to see what happens. Interestingly I have seen factory testing information showing cells withstanding a 20V overcharge without even venting. Still absolutely wouldn’t rule it out, I’d say a huge overcharge situation is probably the most likely cause so far.

I’m not sure if an electronics fault could produce a hard enough short, normally these cells have such a high current output that they’ll vapourise a failed component right off the board before sustaining too much damage themselves. But could happen. Possibly a mechanical fault inside the charger with the sprung metal contacts and sliders inside?

The charger is supplied with 12V 3A so that rules out mains voltage somehow getting through to the batteries. I’m sure there would be big problems of the 12V got connected to the cells though. Again I don’t know if this would cause thermal runaway or just damage and venting.

Because of both cells getting hot we could probably rule out one battery being factory defective or previously damaged by use. Unless of course they were both heavily abused… but I’d really struggle to think they’d both fail at the same time. Extremely unlikely.

Obviously just throwing ideas around! Would be very interesting to get hold of the charger and try to do an autopsy on it. Or see if it could be pieced back together enough to be working in the condition it was when the cells popped.

Cheers for the link!


@anon96069639, do you still have the charger? He did mention doing an autopsy on it.


Sent a PM to Mooch too, will let you all know


That sounds like a real possibility then, maybe the spring broke and caused a short?


Well. There’s a new wrinkle. chuckles
I wonder if there was corrosion in areas that weren’t readily visible?

That caught my eye before as well. But I just attributed it being missing by having been forcibly blown through the bottom of the charging bay. I also noted that the two switches (Bay 3 and 4) were ripped off (presumably by the shrapnel passing by) as well.

Thanks for reaching out, and relaying!!


Yeah they do!

Ok, now that a little humor has been injected into the thread, I feel slightly more comfortable…

I think you’re going to need a new fan bud. :crazy_face:


Just got a response from Mooch, thankful he responded and @anon96069639, check your PM :


I recently finished testing two of those chargers, V3.1, for my patrons and they did not overheat when charging. Certain components reached 130°C when discharging though and the circuit board material under and nearby was too damn hot for its max temp rating. But if the unit was charging then that’s not an issue.

Some questions… - Were the batteries being charged or were they being tested when they blew?

How long had they been in the charger?

Have the batteries ever run hot before when being charged?

Were the battery wraps in PERFECT condition or could they have been beat up a bit?

Were the batteries ever accidentally short-circuited, even for a split-second?

Do you use the batteries until they get hot, chain vaping, and then stop for a bit before vaping again?

Have you ever charged those batteries when they were below 0°C?

Were those batteries ever brought down to below 2.5V?

Samsung batteries spray out through three slots under the top contact when in thermal runaway. The ejecta leaves the battery perpendicular to the long axis of the battery (“sideways”) at several hundred degrees-C. This hot material can easily bring adjacent batteries also into thermal runaway. It’s how the failure of one cell can spread throughout an entire battery pack, destroying every cell in it.

The top contact can eventually melt though, allowing the ejecta to spray “up” and out of the battery too.

Sometimes the shifting contents of a battery can clog the top venting holes, resulting in increased internal pressure. This can literally stretch the battery and undo the top crimp that holds everything inside. The battery then undergoes what is often called “rapid disassembly”. We call it exploding. :slight_smile:

Depending on the location of the fault in the battery it can also burst through the side of the metal can. This can very easily send the adjacent battery into thermal runaway too.

The internal resistance of a battery doesn’t go up much as the battery ages unless it has been badly damaged from severe abuse during charging or discharging. This means there isn’t much of an increase in the heating of the battery as it’s being charged or used.

Charging a 25R at 1A when new creates 1A * 1A * 25mOhms of internal resistance = 0.025W of heat. Even if the internal resisted tripled it would create less than 1/10th of a watt of heat…insignificant. After a couple hundred cycles the internal resistance often has only increased by about 15%-20% though.

If the cells were becoming more and more damaged internally from something the increase in heat would be VERY noticeable. The external temperature of the battery needs to be way over 100°C before it approaches the point where it might go into thermal runaway and burst. A short-circuit though can cause the internal temp to skyrocket almost instantly.

I often see references to “faulty” batteries. But the most often quoted spec for the internal failure rate of batteries from the major manufacturers is one in one million batteries. So, while it’s not impossible that a Samsung battery was faulty the odds that it was are astoundingly low.

Recovering that charger is critical, though I realize it will be unpleasant. Remove the four screws from the back and take close up, very well lit, in perfect focus, shots of the circuit board.

Then remove the bunch of screws holding the circuit board down, many screws are hard to see, rotate the board out of the unit, and photo the other side.

Let’s see if we can spot any obvious failure points internally or if we might just be talking about an external-only failure, i.e., one only involving the battery.

The protection circuitry in the Opus, if functioning properly, can only stop the charging if the outside of the cell reaches about 60°C before the inside of the cell goes into thermal runaway. And that’s only after waiting several seconds for that 60°C temp to work it’s way through to the unit’s temp sensor. A short circuit can blow a cell in almost instantly.

Whew…okay, that’s enough to get us started. So sorry to hear about this but I am glad it wasn’t any worse. Hopefully we can find the cause.

Regards, Mooch