BUDDY must be a rocket scientist. NOT
Hold it right there.
These products are easily available to ordinary consumers who have no technical knowledge and no idea that this sort of thing can happen.
Just as an example, I looked at my Fenix UC35 manual - I believe that Fenix lights are available over the counter in the US - and the only safety warning I can see is about shining the light in someone's eyes. From the manual:
When powered by two CR123A batteries, the Turbo output will be around 1000 lumens for the first couple of minutes.
That light must be drawing at least 2A from those CR123As. It comes with an 18650, it has a Li-Ion charger built in, but people can still buy it over the counter, run out of power one day and buy a couple of CR123As from a nearby store to keep them going until they get home to charge the 18650. At that point, you have a consumer carrying and using an unsafe system.
Fair dues to Fenix, they have a five-minute turbo stepdown, but that wouldn't have prevented the failure in the original post, which happened after a mere 90 seconds.
The onus is on the cell and flashlight manufacturers to:
- make sure these failures can't happen, by design;
- restrict sales to people who can show they know what they're doing;
- or plaster dire warnings all over the product.
Right now, as a group, they do practically none of the above.
Has Titanium Innovations published a datasheet for its CR123A battery? All I can find is the
spec published at Battery Junction. According to it, max. constant current is 1500mA. If that is right, then 3A is not 50% over max. It is 100% over max.
According to Battery Junction,
"Every Titanium CR123A battery incorporates PTC protection (a type of thermal fuse) and the PTC threshold is set at 5AMPS."
Setting the PTC threshold at more than three times the constant current rating is just
asking for trouble.
Perhaps the cell has a higher burst current rating that the PTC setting needs to accommodate, but then we're back to the onus being on the cell and flashlight manufacturers to make sure that their products will be safe under all conditions, or to make sure that every single user knows what not to do.
The reason Selfbuilt only uses CR123A batteries that are made in the USA is because they have a PTC that trips at lower levels. Selfbuilt will not use CR123A batteries sold under the Titanium Innovations label.
I don't blame him. I wouldn't use those cells either.
This doesn't need to happen, folks.
Precisely.
I know it's difficult to design around - if you want to build a powerful light that needs to draw 3A, support 18650 and 2x CR123A *and also* reduce current consumption to 1.5A when you are not using a 18650 cell.... difficult. There are some possible tricks (voltage checking?) that might work but it wouldn't be reliable enough in my opinion.
For a single 18650 light, it's not quite so bad. Most modern lights already step down to a lower mode when they detect a low cell voltage, so the capability is already built in. Admittedly, bigger lights that take more cells might be more awkward, depending on the exact cell combinations they support.
A fully charged 18650 can hit a maximum of 4.4V (4.35V ± 0.05V), which would be 2.2V each for 2xCR123A, so the CR123As would be virtually dead at that point. There's no reason why the light firmware shouldn't be programmed to disable high current modes if it detects a voltage over about 4.5V.
Although that would let the light try to draw full current from a pair of CR123As at less than 2.25V each, I suspect that the voltage sag on those near-dead cells would self-regulate the current in fairly short order.
Even if it is still dangerous to try and draw 3A from CR123As at 2.2V each, the voltage check would nonetheless eliminate most of the potential failures, and that's better than nothing.
You could reduce the chances of failure still further by setting a flag in the driver's memory whenever it detected a voltage over 4.5V, so that it would stay in the low current mode even after the voltage dropped below that level. The flag could be reset whenever the voltage was removed, i.e. when the cells were changed.
You'd still be vulnerable if your two CR123A cells dropped below 4.5V and you physically locked out your light, because that would look like a cell change, but once again, some attempt to implement safeguards is better than nothing.
When selfbuilt recently tested the popular Nitecore MH20, turbo mode tripped the PTC protection on his CR123A batteries. Why do flashlight manufacturers design lights that do that?
I have no idea.
The thing is, many of them also sell own-brand CR123As. Those are just rewraps of ordinary CR123As from the original battery manufacturers, which means that the flashlight manufacturers' own lights can overload their own CR123As.
Sooner or later, we're going to see a case where someone loads their light with the light manufacturer's own-brand CR123As, then the light pipe bombs in the user's hand 90 seconds later. That flashlight manufacturer is going to get sued.
I really wouldn't want to be defending that case.
Thinking about it, I actually find myself wondering whether those flashlight manufacturers even bother to do risk assessments, because this scenario would be a big flashing red warning on any risk assessment of mine.
