>>>>>a charging box build it from wood. A 5/8” or 3/4” plywood floor and walls should be plenty.
>>>>>>Make the box about 1’ cube with no cover
Now that sounds like a good idea! All this stuff about sealed boxes. Like I said, I myself won’t be putting a a stick of dynamite in a sealed ammo box inside my house to see how well that controls the explosion. I wouldn’t put explosives in a sealed anything to control it. Of course, the box lid may pop off from the explosion and vent some of the force. But it’s like a battery PCB, I wouldn’t trust it to actually do that.
I’ll just skip all the contraptions and charge ’em outside, away from the house. If anything happens, no appreciable damage except to the charger and battery, PLUS minimal clean up.
I can’t stress enough, you DO NOT want to clean up that black gooey stuff. It is NASTY.
I like using the LiIon bags that are designed to handle a LiIon explosion:
They are frequently used by RC people, when charging their batteries.
But do not use them if you charger gets hot in open air.
I do not use these bags for regular LiIon charging, but in my battery testing, where I have been charging and discharging 24/7 for more than 1/2 year (I have never had any venting from the tested batteries or from any other LiIon battery).
I just got the temperature probe for my Turnigy Accucel 6 hobby charger and I think that might have prevented something like this (assuming the battery was getting hot before the explosion; this could still easily be a charger issue). The hobby charger can also be set to time out after some number of minutes and to only add a certain number of mAh to avoid overcharging as well. And it tells you the voltage and current the whole time it is charging. Maybe it’s not fool proof (you have to enter all those limits and change them for different types of batteries), but there are a lot of levels of protection that most chargers don’t have.
The problem with “Ultrafire” is that it is so commonly faked. PCB protection that doesn’t actually do anything is another problem with budget batteries. I like the idea of shorting a battery to test the PCB, but it kind of scares me, so I’ve never tried it.
The metal ammo boxes scare me because it seems like you’re asking for a short. Also I don’t have a secure battery holder for my hobby charger, just magnets holding alligator clips in place, so I want to be able to see what is going on and what is touching or not touching.
After reading instances where these type of failures have occurred I’m almost at the stage of thinking people using cheap chargers with *fire batteries deserve to have a scare! Now I know the possible outcome could be far more severe so of course I don’t actually wish that on anyone.
What is it going to take tho? A family burned to death in their house? That’s a very sobering thought and I really hope this makes people throw away any cheap cells, stick to the Panasonic/Sanyos etc and maintain safe practices.
It really is a shame as I believe good cells, well respected are very safe, the crap that people buy is going to lead to more and more restrictions
This is kind of off topic here but all this talk about explosions and crap got me questioning my li on batteries.
I periodically discharge my batteries about once every 3 months to about 2.5v to check the capacity on the hobby charger. Most of my batteries are unprotected. Is that too low to discharge the cells? I didn't think it was but since there's so many of you experts here, I thought I'd ask. Maybe I should be taking them down to 2.8v like HKJ's tests or even as high as 3.0v?
It depends on the batteries, NCR18650A go down to 2.5 but the sanyo 2600 go down to 2.8. As a general rule discharge them to 3 unless you read that you can discharge them further.
It was mentioned earlier in the thread. Given the number of sellers that advertise protected cells and then send unprotected cells, it doesn’t surprise me. I don’t know of any like that.
Thanks. That makes sense. I sorta knew that but I've been draining them all to 2.5v due to laziness. I'll start taking them down to 3v going forward just to be safe.
I got those figures i think from trooplewis, he was charging some stuff in the garage for a few days (forgot about it) and he did measure, believe it was the less branded cells. I’ll do a search, maybe i am wrong with some of the details….and i think it did not vent at all though the unloaded voltage was quite high @ ~ 4.3V when he pulled them and the cell looks messed up.
As mentioned it depends on the cells (we are using xxxfire cells and recycled cells here in BLF). We have so many factors involving the quality in manufacturing that it is mind boogling to say the least, it’s good to be careful.
Here’s a Li Po (ok so different chem but it’s definitely far from 12V) exploding at low 5V under charging load.
I’d definitely never put it as 10-12V as the ballpark, definitely not over here at budgetlightforums.
In an overcharged condition, the cell expands.
BTW one thing i have experienced also is that if you have a hobby charger, do take care. Some chargers do auto detection of cells and it just might charge a 1 x 18650 in 2S mode. It actually killed the PCB of my PAlight 18650, but that’s good coz the PCB cut and charger gave me a connection break error. If it’s unprotected, good luck bros! The charger are programmed with protection conditions, but nothing is foolproof unless yours is an extremely advanced charger (higher-end RC etc).
Yep, no protection. It was a recycled cell and the placed a sheet of aluminum over the negative end to make it look like it was protected. It was from dx.com.
The charger are programmed with protection conditions, but nothing is foolproof unless yours is an extremely advanced charger (higher-end RC etc).