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Confused... Batteries shorting out for no reason? Host issue...

ElectricPlasma

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Here's the issue;

My recent host with the 520nm module takes 7.4v (two 18350s/16350s, this issue happens with both) It will work perfectly with the batteries, as long as I keep the end cap loose enough. But, if I tighten the end cap (to where it's supposed to be), the laser is not functional, and I'm guessing it's a short. But another issue, I have left the laser unattended with the batteries still within the host, and the tail cap still loosened, it shorts and my batteries die. I have lost basically three pairs of batteries because of this issue, feeling extremely lucky that none of them vented in the process. I'm on my last pair, and now I keep them out of the host whenever not in use.

I cannot find the short for the life of me. I tried wrapping the batteries in a layer of electrical tape, nothing... Wrapping the connecting between the batteries in electrical tape, nothing... Whatever I do, it ends up shorting out. Any ideas.. anyone? :undecided:
 

RedCowboy

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When you tighten the tail cap something is shorting, if both batteries get hot then it's in your wiring or the spring board.

I have had several of the old ZERO lasers round spring boards short out, when you solder you have to be careful not to get them too hot, it may be your spring board shorting when you put pressure on it. You are lucky you haven't burned out your tail cap switch, your batteries must not be IMR ?

Sometimes your batteries can short through the plastic wrapper on a sharp solder blob or against the case if there's a worn through spot, but it sounds like your spring board or a pinched wire behind it because it is pressure related...my bet is it's your spring board.
 
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ElectricPlasma

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When you tighten the tail cap something is shorting, if both batteries get hot then it's in your wiring or the spring board.

I have had several of the old ZERO lasers round spring boards short out, when you solder you have to be careful not to get them too hot, it may be your spring board shorting when you put pressure on it. You are lucky you haven't burned out your tail cap switch, your batteries must not be IMR ?

Sometimes your batteries can short through the plastic wrapper on a sharp solder blob or against the case if there's a worn through spot, but it sounds like your spring board or a pinched wire behind it because it is pressure related...my bet is it's your spring board.
Thanks for the feedback Red. I don't have a switch on the tailcap, the switch is on the side. The tailcap is metal with a blob of solder on it to connect the batteries to the host and complete the circuit, no tailcap switch. Thinking it may be the fact that theres no spring, but still should work fine if theres a good connection, not a reason for a short?

Also, when I tested things, the battery towards the diode got noticebly more hot, but in the long run both batteries were dead.

Man, I have no luck with batteries :crackup:
 

paul1598419

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Is this host one of those made from a flashlight body? I've had trouble with the side switch on those sliding a bit and causing problems as well. It's difficult to troubleshoot the laser without even a picture of it. Obviously there is a current path even with the laser off. You may, or may not, be able to measure this with an ohmmeter.
 

ElectricPlasma

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It's difficult to troubleshoot the laser without even a picture of it. Obviously there is a current path even with the laser off. You may, or may not, be able to measure this with an ohmmeter.
picture of the contact board please? time for An engineer to fix something....
Here are the pics:





 
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paul1598419

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The contact board would not be the tail cap, but the contact for the positive battery connection.
 
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alright i see the problem.... the solder blob is the issue ( it oversize and make contact with the side from the inside ) from what i can see... try to minimize the blob size. and can we have a picture of how you assembled the module at the front end.......
 

paul1598419

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I saw that blob of solder and it looks sloppy, but not so bad as to cause the laser to override the side switch and cause conduction. Of course, that is just my opinion.
 

paul1598419

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Yeah, I asked to see the front end, but he said he got it that way and can't access the contact board. I assumed the switch is on the positive side of the input to the driver.
I could be wrong, but if that is the case, wouldn't the laser fire if the tail cap was shorting out the switch?
 
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i meant the picture of how he solder the module to the host front end...

what battery that he use as well....
 
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Based on the picture, if the positive end of the battery is going toward the front of the laser, it would short out the battery. That little solder "tail" is long enough to make contact to the center post positive and the case of the battery (the negative). I would normally suggest to get a small little neodymium battery and stick it to the positive end of the battery and insert it, but you already have the issue of the host being to tight.
 
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