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  • Battery charging and fires

    There was a letter in (I think) our HSM magazine telling about a fire in a garage, traced to portable tool batteries being charged. This was a worry of mine several years ago, so I installed a special outlet with one of those wind-up timers similar to this one: https://www.amazon.com/Tork-Springwo...%2C390&sr=8-21

    Mine is 12 hours instead of 6 but I normally set mine to 2 hours anyway. A power strip is plugged into the "timed" outlet, and all the chargers are plugged into that. I always make sure that only the charger that's in use has a battery in it.

    FWIW:

  • #2
    Originally posted by jdunmyer View Post
    There was a letter in (I think) our HSM magazine telling about a fire in a garage, traced to portable tool batteries being charged. This was a worry of mine several years ago, so I installed a special outlet with one of those wind-up timers similar to this one: https://www.amazon.com/Tork-Springwo...%2C390&sr=8-21

    Mine is 12 hours instead of 6 but I normally set mine to 2 hours anyway. A power strip is plugged into the "timed" outlet, and all the chargers are plugged into that. I always make sure that only the charger that's in use has a battery in it.

    FWIW:
    That’s a great idea I have heard of Chargers causing fires,a friend had large New Farm Shop burn to the ground.It was not 100% confirmed that was the cause but most likely investigators thought.

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    • #3
      Good practice JD, I don't keep my battery's in them Im aware when I want them charged and don't just leave them but that's an extra step cuz sometimes we all forget...

      one of my late great mechanic buddies had his shop go up overnight due to a car battery charger that he had connected in auto ramp down mode...

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      • #4
        Are we talking about battery fires here? Any specific type batteries? Or is it the chargers that seem to have been the culprit?

        One thing you can do, is to make the charging area on a metal shelf that has a continuous rim around it like a tray, with non-burnable materials on the wall and nothing flammable above or close on the sides. Then, even if one did go up, it would be very likely to simply burn up, and you would find the remains the next day. Ground the metal shelf, and the electrical portion is likely to short an blow the breaker, so arcing does not prolong a fire.

        I'm not very optimistic about made-in-china UL ratings.... The US UL HQ is obligated to respect them, but I know a little something about that, and know of some products that appeared to have gone through with non-passing features, some of which might have caused a fire. The products are long-gone I suspect, and even the company has changed, but I'm still not naming names.

        I don't leave too much "on" overnight or if I am not somewhere nearby.
        Last edited by J Tiers; 02-17-2021, 08:27 PM.
        2801 3147 6749 8779 4900 4900 4900

        Keep eye on ball.
        Hashim Khan


        It's just a box of rain, I don't know who put it there.

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        • #5
          Originally posted by J Tiers View Post
          The products are long-gone I suspect, and even the company has changed, but I'm still not naming names.

          .
          Perhaps the products your thinking about are, but I can assure you for everyone your thinking about there's about a half dozen stepping in line and in use right now to fill their shoes... hey in a somewhat related topic, wanna buy an N-95 mask lol

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          • #6
            I wonder what the incidence rate is? If only 1 in a million chargers catches fire, I'm not going to worry about it. It's all about the numbers.

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            • #7
              J Tiers,
              I assume that it's the batteries that catch fire, it's well-known that LiIon batteries can become a bit unstable when they're fully charged, and that's exacerbated by leaving the charger "on". Doesn't really matter, it's just a good idea to shut off the charger when the charge cycle is complete.

              Your ideas on a metal bench and "surround" are very good; perhaps a metal box of some sort would do as well. Of course, you'd want it ventilated to a degree.

              Bob, I don't think that the incident rate is all that high, but if it happens to you...... An inexpensive timer can help alleviate the risk. Also, most power tools that I'm familiar with have instructions that recommend you remove the battery from the charger when the charge is complete.

              Also, it's a good idea to not leave a LiIon battery in a fully charged state, and of course you don't want to run it completely dead. The BMS (battery management system) in the tool and/or battery should help protect the battery, but...

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              • #8
                If you are really concerned about it you can built a metal enclosure with a door and put a thermal link on it (like those on parts washers and old school fire doors) so if it gets hot it slams shut. However I would have to question the effectiveness as I've seen a lithium battery fire demonstrated and its pretty much like a thermite charge. If a cell burns for any reason it gets hot and cooks off the next cell and keeps repeating.
                Last edited by Ohio Mike; 02-18-2021, 10:41 AM. Reason: typo
                Mike
                Central Ohio, USA

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                • #9
                  Originally posted by Ohio Mike View Post
                  [snip]
                  its pretty much like a termite charge. ...
                  A termite charge? Is that an army of termites charging, or is it the amount of electrical charge that a termite can hold, or what a termite charges for a service? Curious minds want to know.😁

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                  • #10
                    Originally posted by Bob Engelhardt View Post

                    A termite charge? Is that an army of termites charging, or is it the amount of electrical charge that a termite can hold, or what a termite charges for a service? Curious minds want to know.😁
                    That's funny, fixed it 😂
                    Mike
                    Central Ohio, USA

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                    • #11
                      One of my colleagues started a fire in his garage from charging LiPo drone batteries. The fire gutted the garage and got into his attic. He had insurance, but had to vacate for a long time while they rebuilt his house. Another colleague now charges his LiPo batteries in his fireplace as a result.

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                      • #12
                        My run of the mill charger has a trickle down mode from about 8 amps down to 1 or 2, its automatic - if the battery's hungry it will take all 8 amps and then some but this creates heat withing the charger but it's thermally protected, it's not unusual for it to cycle dozens of times off and back on when this happens, there is a red flag within that,

                        if your leaving your battery unattended after just connecting the charger make sure you have VERY good connections to the terminals from the clamps, in a way it's the perfect storm because the battery can build up gasses all around it when charging --- if you have a half arssed connection and the charger kicked off -- when it kicks back on it could give a spark right at the terminal, kaboom...

                        I always try to clamp at the large lead boss of the terminal and "rock" the clamp back and forth to set it in a little cleaned groove...

                        I will add - place the charger away from the battery too - due to it's cycling - there are contacts within it that are sparking every time that happens...
                        Last edited by A.K. Boomer; 02-18-2021, 11:25 AM.

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                        • #13
                          I have used my 20V batteries at the museum a lot, they last longer if they get used regularly, and the battery vacuum uses them up in 6 to 12 minutes, depending on their size. I would not dream of leaving a battery on charge unattended and if one needs charging I would rather take it home than leave it charging at the museum. The chargers do stop charging when the battery is full, and the whole lot cools down to ambient even if left powered on.
                          The only charger that is designed to be on all the time is for the scissor lift which uses lead acid batteries, the charger is built into the machine.

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                          • #14
                            It takes electronic technology to properly control the charge of batteries. Particularly important for LI batteries that become unstable if over charged, allowed to go below a threshold of discharge, or are physically damaged. In videos of LI battery fires, they aren't passively burning in place. They tend to "burst" and toss burning matter around.

                            I would be as much or more concerned with the design and quality of the components used in the controller boards contained in the chargers. Failures there can cause an otherwise stable LI battery to become unstable.

                            Underwriters Labs has a comment on LI technology:

                            “Lithium-ion battery technology is

                            not intrinsically safe. Short circuit,

                            overcharge, over-discharge, crush,

                            and high temperature can lead to

                            thermal runaway, fire, and

                            explosion” - UL Laboratories
                            S E Michigan

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                            • #15
                              It's not only high temperature that's important, charging below 32 degrees or so can be bad news as well. If the BMS control's the charging current they can be charged at colder temps. Without specific directions from the battery manufacturer, this would not be a good idea
                              See here: https://www.grepow.com/blog/lifepo4-...-consequences/
                              paul
                              ARS W9PCS

                              Esto Vigilans

                              Remember, just because you can doesn't mean you should...
                              but you may have to

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