"observe the battery while charging ... if it gets hot ...."

It’s all very well to say keep an eye on the charger while it’s working, but — stuff happens.

Has anyone got a heat sensor — something with say a 9v battery — that can be set over a charger to start beeping loudly?
I know there are temperature sensors available for hobby chargers, but I don’t know how the circuits work.

I mean something other than the usual smoke/ionization sensor that I’m sure we all have (cough) ….

Something along the lines of the piss-light — battery pack, detector, and output signal.

maybe something like that?

Link

-> just desolder the temp sensor and use a wire to get it attachable on the battery (with plastic clip / rubber band)

I charge mine in the garage… meh if its going t pop, Id prefer it did it in the garage/outside where I can leave it air and cool off than me try to prevent it with heat alarms etc and have to go near it to pull the battery, plug or whatever, or worse still pick it up and toss it outside etc. How long do you have from the point an alarm will sound, and it going nuclear? Is it well mannered and gives you as long as you need, or is it a tad unpredictable? A decent charger already has systems built in to stop that cascade state, if they are insufficient then I dont want to play the hero with it.

I don’t want to get into an exchange of “I don’t care why should you” on this.
Consider it a technical question please, assuming someone wants to do this, how might it be accomplished.

Whether on the porch or in the garage, venting a cloud of hydrogen fluoride is no joke and should be detected as early as possible.
Or that’s just what I think anyhow.

Help me out here if you can.

Hank,

Maybe this can help?:
http://www.aliexpress.com/item/Measuring-Range-50-to-300-Celsius-Digital-LCD-Screen-Thermometer-with-17cm-Stainless-Probe/1319827666.html?s=p
It’s possible you can somehow modify the probe of this thermometer and fix it to one of the charger contacts?

On another note, all this talk about 18650 batteries going nuclear is scaring me! I just received my first 18650 flashlight today, a Convoy C8 and was looking to buy a charger also. But now I am thinking to just toss it in the bin and get me a multiple 14500 flashlight instead :frowning:

Check out electronic kitchen thermometers. They are fairly cheap.

I don’t think you mean 14500… those will go just as nuclear… maybe you mean NiMH AA?

The kitchen thermometer w/ alarm links sound like a nice solution.

I had a channel on a high-current NiMH charger go bad and cook the heck out of an AA cell recently. I was sitting nearby and heard it start to sizzle. I was dumb enough to burn my finger a little when removing the battery.

A lot of multimeters come with a temp probe ...

So one would could make a plastic clip that attaches the probe to the battery but does not get in the way of fitting into the charger ...

+ Those infra red temp probes ( hand held ) , that you point at an object for a temp read out , there cheap enough now ...

Point shoot , get a reading !

http://www.ebay.com/itm/LCD-Digital-Thermometer-Temperature-Display-Embedded-PC-MOD-Probe-Gauge-Temp-HHO-/271275617388?pt=LH_DefaultDomain_0&hash=item3f29496c6c Cheap

http://www.ebay.com/itm/gib-Digital-Blue-LCD-Thermometer-Temperature-Panel-Meter-With-Probe-Sensor-/191243173557?pt=LH_DefaultDomain_0&hash=item2c86fb3eb5 Cheap

http://www.ebay.com/itm/LCD-IR-Laser-Non-Contact-Infrared-Digital-Thermometer-Probe-Temperature-Sensor-/181464396459?pt=LH_DefaultDomain_2&hash=item2a401ef2ab ????????? Cheap

http://www.ebay.com/itm/LCD-IR-Laser-Non-Contact-Infrared-Digital-Thermometer-Probe-Temperature-Sensor-/181464396459?pt=LH_DefaultDomain_2&hash=item2a401ef2ab

With alarm ( For Beer ) Got to look after the beer !

http://www.ebay.com/itm/Digital-Alarm-Temperature-Thermometer-For-Kitchen-Bbq-Meat-food-Lab-With-Probe-/161471530014?pt=LH_DefaultDomain_0&hash=item259874041e

Sais Alarm ???

http://www.ebay.com/itm/12V-Red-Digital-Thermometer-High-Low-Alarm-Temperature-2m-Stainless-Steel-Probe-/251721641618?pt=LH_DefaultDomain_0&hash=item3a9bc76e92

?????????????????????? 12v

http://www.ebay.com/itm/Digital-Indoor-Outdoor-Thermometer-Clock-Temperature-Alarm-1-4m-Probe-50-C-F-/321202597337?pt=LH_DefaultDomain_0&hash=item4ac92aadd9

Just check Flea bay , if its not on flebay ....

How about using a small resettable temperature fuse and wire it to either the supply feed positive or negative and run it over the charger and sit it or tape it on the charging batteries.
you can buy them I’m a wide range of preset temperatures to match the maximum temperature your comfortable with, and if you daisy chain them you can have one for each battery for added safety.
If the temperature of any charging battery goes above your chosen temperature, the power is instantly disconnected

I have used then on charging battery’s and on 50 watt resistors, to cut the power in the event of one over heating

Obviously your charger needs to be able to take a 12 volt feed, but lots do, I.e nitecore or bt3100

Probably not wise to use on a 110/240VAC supply cable though for obvious reasons, although it would work the same if you applied proper safe guards to prevent electrocution

Regards

The chargers are out on the back porch right now, charging six Panasonic cells I salvaged from an old HP battery pack.
So it’s an attention-getter I mostly want.

Good idea about the IR thermometer though, I do have one of those and will go check each cell and see if there’s any noticeable variation.
EDIT. Oops, forgot these are shiny enough to confuse the sensor; need to put a square of matte black tape on each one, or something like that.

I do have a temperature probe for my Accucel 6 charger; wish that my other chargers had that port.

But maybe I could use that probe with some homemade or repurposed heat alarm.

Heck, if this approach works, I’ll want one over the stove, to catch me if I forget and boil a pan dry ….

Buy good 18650, then you do not need to worry. Today many cells mas a HRL (Heat Resistant Layer) that will prevent the battery from getting to hot. Cells do also usual have a PTC (Kind of thermo fuse) and a pressure vent.

For HRL see here: http://industrial.panasonic.com/www-data/pdf2/ACI4000/ACI4000CE17.pdf

I understand I can avoid the problem by buying brand-name genuine new cells from a reliable source.

I understand Panasonic cells are using “spinel” chemistry, which is somewhat safer.

But the Panasonic website makes clear they don’t sell single cells because they don’t consider them safe as single cells. So, they’re being conservative.

My question here is whether there’s any way to tell that a cell did ever get overdischarged and “rescued” — if I have a cell and am not absolutely sure.

I understand some chargers do something to test cells — but I don’t know what they do to test them.

There are some boards on FT, BG and Ali that have a temperature sensor and a relay, I think you could program the event you want to happen when X°C/F is reached.
I’d just connect a bell or cut the supply voltage of the charger, maybe both.
I’m in the train right now so no link, maybe tonight.

Perfect answer except for
“I think you could program …”
which I can’t — but this sounds like the right answer,

to take the action needed (alert and disconnect) when something overheats.

I can think of quite a few places that would be useful, especially in houses with children or elderly people.

Thanks for the idea; I’ll keep looking and perhaps someone will build it or set out a guide to how to do it.

I think it’s ‘program’ as in “program my VCR”.

Maybe tryps will provide a link or two. I assume that the programming is as simple as twiddling a knob or two.

I don’t know if you’re scrounging laptop packs or not, but most of them (what I get) come with thermistors/thermocouples you could use.

IIRC you have some wirehead cred, so maybe you could use this:

Obviously YMMV, and I’d use an annunciator or relay->horn instead of a light, but this seems pretty simple if it works.

Maybe you could use the thermistor to turn the transistor OFF which would be used to turn OFF the charger via a relay… You could even make it turn back ON after the thermistor cools…

But mostly, scrounging laptop packs leads to a “so what, who cares” attitude where I charge new (to me) cells outdoors & don’t think twice about it.

But that’s just me, and I’m just

Dim

EDIT: Maybe you could use these:

or this, if you just want the process to stop:

I see I’m late to the dance again… You already have lots of good suggestions!