Keeppower Protection Circuit Issue

md17

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So, here is the scenario…Malkoff MD3 body, 2 brand new protected Keeppower 18500 with a hound dog, m61 hot and m61…

When the flashlight is on and hit slightly, the light shuts off and will not turn back on without taking the head off and back on again.

I tried new tail switch as well. The odd thing is that it's only with this set of batteries. I'm wondering if it could be a faulty protection circuit that somehow gets activated. Thoughts?
 

vicv

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I'm not sure. But I can't see taking the head off and putting it back on resetting the protection circuit. Usually the only way those can be reset is by putting them on a charger. That being said, I don't use protected cells so I could be talking out of my behind.
 

F89

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Sounds like a contact issue with that light and battery combination.

I agree with Vic, I don't think the protection circuit is activating.

Hopefully with some tinkering you can work it out.
 

md17

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It's a very well used combo, so I don't know what the issue could be, but possibly a faulty switch. It is actually having issues with another set of batteries now also.
 

F89

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Start by cleaning all the contact surfaces on the body, tail cap, and heads.
That might do the trick on its own?
 

md17

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I did that. Used acetone and even a small piece of steel wool. If I got the bottom of the light it'll shut off and if I click the switch it occasionally flashes then shuts off and won't respond. Does it with multiple light heads
 

F89

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Sounds like you checked the switch also?

Do the heads function with another body?

Perhaps it's a contact issue simply due to the length of the batteries/contact springs?
The head and/or switch spring may need to be stretched a little?
 

F89

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Try bypassing the tail cap and using something to make contact while pushing the batteries down firmly towards the head and positive spring. Give it a good shake while doing it and you shouldn't get any flicker or shut off unless you've broken contact with your bypass.
 

thermal guy

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I did that. Used acetone and even a small piece of steel wool. If I got the bottom of the light it'll shut off and if I click the switch it occasionally flashes then shuts off and won't respond. Does it with multiple light heads
Give the spring in the head a pull. Stretch it out then try it. I had one that did the same thing
 

md17

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the odd thing is the batteries sit flush just like the md4 body, which has no issue. Could it possibly be an issue with the body or the threads?
 

F89

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I don't think so, particularly considering you cleaned it.
 

md17

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So, after a lot more overthinking and trouble shooting…I might have a defective battery charger. Relatively new xtar VC4SL. It may be that the batteries are not charged enough causing issues, despite the chargers showing adequate capacity. I have a new charger coming tomorrow.
 

F89

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Well, there you go. Always start with the basics.

I have a cheap multimeter that I use for stuff here and there that I usually have handy around batteries and chargers.
 

knucklegary

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Mtn Electronics use to sell these mini DC voltmeters inexpensive. Easy to solder a couple wires to magnets.. Great for checking voltage when in field

IMG_20231121_204956363_HDR.jpg
 

vicv

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So, after a lot more overthinking and trouble shooting…I might have a defective battery charger. Relatively new xtar VC4SL. It may be that the batteries are not charged enough causing issues, despite the chargers showing adequate capacity. I have a new charger coming tomorrow.
What makes you believe it's the charger? If you don't have a multimeter
 
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