Battery question

[geoscash1]

I am trying to find out what this little "thingamajigy" is or what it does. I am assuming it is some sort of charge control??? to keep the battery from over charging which is what happened here, over charge and battery melt down. I have purchased a couple new batteries and am ready to replace but need to know what this is so I don't end up with more melt downs.

So anyone have any ideas or is my thought correct, if it is correct what is it, where can I find something to replace it.

Thanks in advance.

p.s. The battery is a bp1.2 12volt and used with a minelab detector. I have searched high and low and cannot find any info as to what this little part is so any help would be appreciated. I also tried searching the part number on the little clear plastic cover over the part but to no avail.




Edit - found a link to what it is, thermal overload switch.. Obviously, it didn't work on mine.. .. now just need to find what exact part number and where to pick it up.
http://www.billandlindaprospecting.c...ttery-new.html

[IBGold]

Hi the thermal overload switches are available from most electronic supply houses just match the Voltage and the maximum amps of the old one and you should be good to go I make my own 6V and 12V battery tops and buy the thermal cut outs from a local electronics house.

Regards, Ian.

[geoscash1]

thank you Ian

Hi Ian,

Thank you for that info, that's perfect and very much appreciated. I'll go see what I can dig up.

I did read in a couple of places that the wall charger never seems to work right and melts most batteries if left on the
charger, although, it tells you straight out to keep the battery on the charger when not in use.

It looks like to me (now that I know what the part is) that the thick plastic shrink sleeve they use to cover the switch, then hot glued to
the top of the battery may actually impede what it is suppose to do in the first place.

My theory is when the battery reaches a certain temperature the thermal switch is supposed to read that temp and then
"open" to stop the charge process but with that thick plastic shrink cover on top of heavy hot glue, it cant read/feel the proper temp
and the switch doesn't open and close properly like it should, then ends up cooking batteries in which the wall charger is then blamed.

I am going try it different, I'll leave the bottom of the thermal switch uncovered and hot glued directly to the top of the battery
and see if that helps or corrects the issue. In my mind, it seems that that may be the age old problem and should be a simple fix.

Anyway, thanks for the reply and the info, much appreciated.

EDIT - p.s. I wonder if something like this would work better??
http://www.ebay.com/itm/DC-12V-Thermal-Relay-Control-Sensor-Module-Temperature-Switch-/261255575739?hash=item3cd40bb8bb:g:thEAAOSw9N1VoI9 A

EDIT - p.s.s. Not having much luck with the part number that is on my switch - thermal cutoff switch #17AM203A5-8

[kt315]

i am not able to understand what you need, as mine english is very poor, but simple primitive thermal fuse is very spreaded in power supplies.
i meet those '130 grad' everywhere in my repair practic
http://www.ebay.com/itm/10-Pcs-New-L...-/181048791721

[geoscash1]

Hi kt315,

I guess it depends on what is typed into search, I searched the part number and "thermal cutoff switch" so I assume the link to the part
you added will work just fine. Thanks for the help. you can see the one I was looking for in the first post image but it probably doesn't matter
what it looks like as long as the temperature/amp rating is the same.

I'll order some of those and try them out, thanks for the link...

[homefire]

http://wuyuetech.company.weiku.com/item/thermal-battery-protector-smallest-size-2mm-thick-5717008.html


http://www.digikey.com/en/pdf/t/te-c...lyswitch-strap

[IBGold]

Hi Geoscash1,

What I am using is Positive Temperature Coefficient (PTC) Fuses Altronics Part Number R4553A or R4555A I have been using them with no problems for about 10 years Hope this helps.

Regards, Ian.

[Mechanic]

Hi Geoscash,

The thermal fuse heats up when too much current flows through it, causing the bi-metallic strip to break contact. Then after a bit, it cools down again and closes the cct once again. It is more for short cct protection or reverse polarity protection. It won't shut off charge to the battery unless the charge current it too high.
The wall chargers are crap, throw it in the bin with your old battery! If you have the 12v car charger, use that instead as it shuts off charge when the battery is full, unlike the wall unit..

Cheers Mick

[geoscash1]

Awesome, thanks Ian and Mick. I had heard the wall chargers are crap so I will heed you advice..

Thanks for all the responses.
Geo

[Tim]

If you have Li-ions you can charge safely by using this: search 3s 8a li-ion on ebay.$6.40 Just turf your ML battery(except the plug) and set up a "black DIY ABS Storage Box Holder Case For 1/2/3/4 Li-ion" $1.99-18650 holder and this circuit in a same sized or smaller box. Put a 5.5x1.3 socket on it and use ANY auxiliary 12v input or your car cig lighter with no additional expensive BS.
Hell, why not set up a 1.5-3 watt solar panel on it as well? Never charge again, just leave it in the sun for a half hour!!

Stuff the money-grubbing Aussie/any/all corporates and their bludging, lying CRAP! Patronage deserves some recognition, and we get FA, just more money-grubbing.
They buy the same stuff from the same factory and mark it up 3000% F-'em!

[Mechanic]

If you have Li-ions you can charge safely by using this: search 3s 8a li-ion on ebay.$6.40 Just turf your ML battery(except the plug) and set up a "black DIY ABS Storage Box Holder Case For 1/2/3/4 Li-ion" $1.99-18650 holder and this circuit in a same sized or smaller box. Put a 5.5x1.3 socket on it and use ANY auxiliary 12v input or your car cig lighter with no additional expensive BS.
Hell, why not set up a 1.5-3 watt solar panel on it as well? Never charge again, just leave it in the sun for a half hour!!

Stuff the money-grubbing Aussie/any/all corporates and their bludging, lying CRAP! Patronage deserves some recognition, and we get FA, just more money-grubbing.
They buy the same stuff from the same factory and mark it up 3000% F-'em!

Tim, you really need to loose the chip you have on your shoulder. You could always set yourself up as a charity, selling items at cost price! Heck, you could pop down there and offer your services for free! Nobody is forcing anybody to buy their products. Besides, without them we would still be fumbling around with old vlf and bfo machines.

Now, lets take a look at your recommendations for an alternative power source before someone blows up their detector and or themselves...
For a start, the battery the OP has is 6v, not 12v, and depending what detector he is running it on, might need to be closer to 6v than even 8.4v.
The circuit you recommend is a pcm, not a charger. You cannot apply 12v to this and expect it to charge your cells. Further its output overload protection current is 8A, which is more than enough to make a lot of damage if hooked up in reverse polarity or an internal fault develops with the device it is hooked up to.

"Hell, why not set up a 1.5-3 watt solar panel on it as well? Never charge again, just leave it in the sun for a half hour!!"

Lithium batteries really love heat NOT. Do not leave lithium batteries in the sun, especially when charging them!

Mick

[Tim]

That charge regulator will do 1,2,3 or 4 Li-ions. You would just need a blocking diode and a fuse on + to detector to avoid reversing or surges. If it's a 6volt, use a 6 volt solar panel. I did not mean let it cook in the sun. Merely if the batteries were flat they could be briefly charged this way. Only the panel would need to be in the sun, and not necessarily directly either. The idea of the solar panel on the detector was so it was charging as it was being used. I have an adjustable i-phone holder for bike handlebars(less than $5) that expands enough to fit a small (120mm width) panel. It will mount on the detector shaft. This would only be useful for onboard battery systems. But for external carried batteries your panel could be on your backpack(or your hat for that matter). The constant recharging would mean a lighter battery pack could be used. Unless you're a moonlighter, of course.
The said item is over-charge, over discharge, over current and short circuit protection. It can be configured for 10.8-12.6 volts. However many li-ions are seriesed will define output voltage, but if you are in doubt a similar circuit is available for other voltages.

A chip on my shoulder? Bloody oath I have! A BIG chip, and it's getting bigger every time i discover another corporate lie. By suggesting low cost alternatives I suppose that does make me a charity, or worse in some capitalistic eyes.
Since I am a dumb hick, I had to look up pcm. Is that pulse code modulation? Wikipedia gives no mention of this as relative to charging, nor does this items ebay description.

[greylourie]

Hello Tim,

PCM maybe stands for protection circuit module. Guess like what is found in laptop and similar battery packs that are charged by a "dumb" charger/power source. As opposed to say, a RC/Hobby smart charger to both supply charge and monitor/regulate individual cells that make up the pack ?

Geocash wanted to know what the part was, and where to find a suitable replacement (thermal cut-off fuse). Guess he wants to build a new lead acid pack ? Suggesting lighter battery type alternatives is good. But the OP simply wanted to replace his old one.

Mechanic pointed out that a 3S lipo would be unwise, and even 2S might need down regulating. The old 6v lead acid battery simply works, and is cheap. Always good to look for newer alternatives, but can add complexity and potential pitfalls. And when it comes to fixing models from this particular manufacturer, Mechanic has devoted much time on these forums to helping owners understand how to get them going again. So good to heed any cautionary note from him.

[geoscash1]

Hi guys,

I did fail to mention in my op, the unit is a minelab goldenhawk, which uses the 12v bp1.2ah battery.
Understandably, I know a lot of people here dislike the company but this forum is a great place for diverse knowledge so I had hoped it wouldn't come to bashing, just some clear info on what the individual part that's used inside the plastic cover.

I just replaced the batt and will use a cigg lighter charger for now. I ended up reinstalling the old thermal shutoff, if it doesn't work, I'll just get a complete different charge system for the SLA 12v batts.

I appreciate all the answers,replies and links, very useful info to add to my archive of geotech info..

Thanks again,
Geo