Melting Batteries

[travelinbeat]

So I bought a 9.6v from a place called Hobbytown USA here in my neighborhood.  I made an adapter to take the Tamiya power plug and spit out a 1/8" mono in order to power my Denecke PS2 (discussion on that process over here).  I plugged in the battery and the little red power light on the denecke popped on and off (as it should) and the battery pack instantly got very very hot.  I unplugged it, cooled it down, tried again, same thing.  I hooked up mic's and saw that it was working, it was just getting VERY hot, VERY fast.  So I took it all apart, cooled the battery again, then charged it (first ever charge), plugged it in again and within about 10 seconds it was smoking and the plastic was melting away from the batteries!! 

Question is basically wtf.  Bad batteries?  Bad solder work on my part somewhere?  I mean, I'm pretty confident that I did everything right (the successful powering of the mics I think attest to that), but it's certainly possible that I made a mistake.  Any input?

Thanks

[bhtoque]

That's a short somewhere. I had the same problem with a ni-cd pack once. Mine shorted between the cells in the pack, but I can't say you are having the same issue.

I'd check your cable with a multi-meter then you'll know where the problem is.

JAson

[travelinbeat]

no short on the cable (yay I made it right!), guess the problem is / was the battery.... strange that a brand new battery would do that though 

[Brian Skalinder]

That -is- strange.  How did you test the cable?  Did you test all the cables and connection points (sounds like you have at least battery cable + Tamiya connector, adapter Tamiya connector + cable + 1/8" connector)?  Are you sure nothing's cross-wired?  Are you certain the 1/8" plug seats fully into the PS2 (if memory serves, the PS2 briefly shorts the 1/8" connector during insertion; once fully seated, it doesn't short)?

[travelinbeat]

Brian-- 

The testing I did was pretty simple, just tested the cable I built to make sure that positive on one end was positive on the other end (and that negative was not getting any positive signal) and visa-versa.  I also tested the load it was carrying an it didn't seem to be "leaking" power anywhere.  The 1/8" does feel a little "soft" when plugged in all the way, it doesn't really give that nice SNAP, but rather a sort of soft cushiony feeling.  I still am not really sure how / why the deice would've worked during that one mic test too.  I've also heard strange things about the order in which people should power the PS2 / plug in mics / blah blah blah, but I really can't remember the details of it or why they are important.  I'd love to get a little more clarity on what's going on here, so thanks again to everyone following this thread.

[rowjimmytour]

Brian-- 

The testing I did was pretty simple, just tested the cable I built to make sure that positive on one end was positive on the other (and that negative was not getting any positive signal) and visa-versa.  I also tested the load it was carrying an dit didn't seem to be "leaking" power anywhere.  The 1/8" does feel a little "soft" when plugged in all the way, it doesn't really give that nice SNAP, but rather a sort of soft cushiony feeling.  I still am not really sure how / why the deice would've worked during that one mic test too.  I've also heard strange things about the order in which people should power the PS2 / plug in mics / blah blah blah, but I really can't remember the details of it or why they are important.  I'd love to get a little more clarity on what's going on here, so thanks again to everyone following this thread.

Could the short be in the connection between Battery>cable (cross current)? Regardless its always a good idea to add a quick blow fuse in line on the + side of cable

[travelinbeat]

Brian-- 

The testing I did was pretty simple, just tested the cable I built to make sure that positive on one end was positive on the other (and that negative was not getting any positive signal) and visa-versa.  I also tested the load it was carrying an dit didn't seem to be "leaking" power anywhere.  The 1/8" does feel a little "soft" when plugged in all the way, it doesn't really give that nice SNAP, but rather a sort of soft cushiony feeling.  I still am not really sure how / why the deice would've worked during that one mic test too.  I've also heard strange things about the order in which people should power the PS2 / plug in mics / blah blah blah, but I really can't remember the details of it or why they are important.  I'd love to get a little more clarity on what's going on here, so thanks again to everyone following this thread.

Could the short be in the connection between Battery>cable (cross current)? Regardless its always a good idea to add a quick blow fuse in line on the + side of cable

To make this whole situation a little more confusing, I have virtually no familiarity with the in's and out's of power and fuses and the like.  I basically just saw what Tim Brown was running at a show a while ago (the 9.6V RC battery > 1/8" > PS2), did some research on the polarity, then got to it.  I know my polarity is right, and I know that the positive on my Tamiya connector is the positive on the 1/8", and the negative is the negative, and that there is no signal getting from one to the other.  I also know that the polarity on the 1/8" is wiring according to the Denecke's requirements.  Aside from those things, there is little, if anything, else that I know.  I understand that it seems far more likely for me to have made a mistake with my wiring somewhere than for a brand new battery to spontaneously crap out like that, but my tests seem to indicate that my end is looking good.  So unless the Denecke is doing weird things to the battery, I just don't know what, outside of having a bad battery, could be causing this.

Also-- what is this quick blow fuse you speak of? How does that work, what does it look like, how do I install one, where do I get one, and what does it do? 

[rowjimmytour]

Go to ratshack and buy a inline fuse holder:
http://www.radioshack.com/search/index.jsp?kwCatId=&kw=in%20line%20fuse%20holder&origkw=in%20line%20fuse%20holder&sr=1
And pick up some quick blow fuses .25.
Wire fuse holder on + side of cable inline near battery source and you should be good to go
Are you sure inside the plug the sleeve and ring are not crossing wires? You can check by setting your multimeter to continuity and placing one  probe at each end of + side and you should hear a beep. Then do the same for - and try mixing + and - and see if you get a beep then you know you have short. I have had this problem w/ rca connectors so using a little electric tape around the sleeve>cable solder helps.

[travelinbeat]

Are you sure inside the plug the sleeve and ring are not crossing wires? You can check by setting your multimeter to continuity and placing one  probe at each end of + side and you should hear a beep. Then do the same for - and try mixing + and - and see if you get a beep then you know you have short. I have had this problem w/ rca connectors so using a little electric tape around the sleeve>cable solder helps.

This is exactly how I tested the cable I made and it is solid.  Thanks for the info on the fuses-- is a 10-Amp sufficient?  The battery is 9.6v, but I don't know what it is in Amps or anything.  Also, exactly what will this fuse do for me?

[bhtoque]

Brian-- 

The testing I did was pretty simple, just tested the cable I built to make sure that positive on one end was positive on the other end (and that negative was not getting any positive signal) and visa-versa.  I also tested the load it was carrying an it didn't seem to be "leaking" power anywhere.  The 1/8" does feel a little "soft" when plugged in all the way, it doesn't really give that nice SNAP, but rather a sort of soft cushiony feeling.  I still am not really sure how / why the deice would've worked during that one mic test too.  I've also heard strange things about the order in which people should power the PS2 / plug in mics / blah blah blah, but I really can't remember the details of it or why they are important.  I'd love to get a little more clarity on what's going on here, so thanks again to everyone following this thread.

Brian's point about the PS2 connection is spot on. I always connected the cable then plugged the battery into the tamia end. You'll occasionally see sparks if you plug a live cable into it.

Couple other bits about the PS2. It will hold a charge sufficient to power a set of mics for a minute or two after power is removed. It allows you to swap out batteries without losing signal. Also means that you should not pull mic connections from it right after unplugging.

Not sure about the time frame in your scenario, but it might explain why the gear ran after the battery started to go.

JAson

[rowjimmytour]

Are you sure inside the plug the sleeve and ring are not crossing wires? You can check by setting your multimeter to continuity and placing one  probe at each end of + side and you should hear a beep. Then do the same for - and try mixing + and - and see if you get a beep then you know you have short. I have had this problem w/ rca connectors so using a little electric tape around the sleeve>cable solder helps.

This is exactly how I tested the cable I made and it is solid.  Thanks for the info on the fuses-- is a 10-Amp sufficient?  The battery is 9.6v, but I don't know what it is in Amps or anything.  Also, exactly what will this fuse do for me?

10 amp is overkill and if I remember right I always used .50 or .25 amp fuses. The in line fuse will save your gear and batteries from being damaged if you have a short.

[travelinbeat]

So the idea then is once the fuse pops the circuit is cut?

[Brian Skalinder]

So the idea then is once the fuse pops the circuit is cut?

Yup.

I'm putting my money on the plug not seating completely.  Try this:

• Unplug the 1/8" / Tamiya connector from the battery and test continuity across the Tamiya and 1/8" connector's (+) and (-) terminals.  If there's no continuity across (+) and (-) terminals, the short isn't in the cable/connectors.  If there is continuity, the problem lies in the cable/connectors.  (I think you already did this test.)
  
• Plug the 1/8" connector into the PS2, as before, but with no battery connected to the Tamiya connector.  Test continuity across the Tamiya connector's (+) and (-) terminals.  If there's no continuity, then the short is not in the cable/connectors (already confirmed in the first bullet) or the PS2 (which we just confirmed).  This suggests the problem lay elsewhere (with the battery or battery cable).  If there is continuity, then the problem is the PS2 shorting the 1/8" connector when it's plugged in.

[travelinbeat]

Am I right to assume that the second test would involve opening up the PS2?

[Brian Skalinder]

Am I right to assume that the second test would involve opening up the PS2?

Nope, not necessary.  Let me explain visually.  See attached for what I understand is your battery setup.  I didn't bother labeling, but in case it isn't obvious:  brown box = RC battery and maroon connector = Tamiya male.

The others are all labelled and hopefully make sense.  When you run this test, if there is continuity, then you've found the short.  If there is not continuity, then we have to keep digging.