A Fuse Saved My Hot Wire! (PICTURE!)

Northern Lights

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Jan 17, 2006
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I was carrying my Mag Charger 61 to the car, it was not turned on, it had a cool bulb and I dropped it on the sidewalk. The shock broke the bulb at the pins. I did not know that and I turned it on and nothing happened. I changed the bulb and found a twisted pin in the socket. The new bulb did not illuminate. I found the fuse had been blown. After the fall the bent pin somehow was grounded. The fuse at least saved some wear and tear on the battery pack and maybe some burned out wiring! I have room in the tail for a spare fuse and bulb. I was back in business very quickly.
One Mag Charger, a MC61, that is a 900 Torch-Lumen light, Phillips 5761 on 7.2 volts, 5.4 Ah, 12X Sanyo 2700s in the pack has the pack soldered and wired by leads directly to the positive contact and to a ground screw. (see pict.) The ground lead has the mini fuse in it on the pack side of the connector. When I built this light and was working on the 4x boring I had a similar pack and I twisted it some. The wrappers were damaged. After a half-hour after setting it aside and there must have been some contraction due to cooling, the pack shorted while it was on the desk and nearly caused a fire. That inspired me. I fused the light and got a new battery pack and that was an expensive lesson.

I have built several basic hot wires now. And I fused some of them. I added an automotive mini fuse, 10 amps to the tail cap ground.

For an ROP I isolated the ground on the spring by placing a plastic cap on the spring and then put a contact, a U.S. penny, on the plastic and wired it to ground where the spring contacts the tail cap. In that circuit I put a mini fuse.

Isolating a ground wire to many types of packs, holders and tail caps does not appear to be too difficult and these could be easily fused in a number of designs. I will continue to do this after seeing the success.

http://img479.imageshack.us/img479/7578/fusesa9.jpg
fusesa9.jpg
 

paulr

Flashaholic
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Mar 29, 2003
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10,832
Good plan with these high current lights. Should become a standard feature.
 

benighted

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Feb 13, 2006
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Grays Harbor, WA
That just gave me an idea to design a fuse that is flat and attaches to the bottom of a battery pack with a magnet. It would look something like a coin cell but there would be an automotive fuse soldered in-between the contacts... I think I might be on to something.
 

Northern Lights

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Jan 17, 2006
Messages
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Location
Southwest
benighted said:
That just gave me an idea to design a fuse that is flat and attaches to the bottom of a battery pack with a magnet. It would look something like a coin cell but there would be an automotive fuse soldered in-between the contacts... I think I might be on to something.

You are onto something! A flat mini or standard fuse with a contact on top and bottom would do the trick, drop right inbetween the bottom of the battery and spring.

In my hot wires I always wire the spring and switches for a low resistance fix. But your idea would still work and drop in. Shorts usually go to ground so that is why I put mine on the battery ground side. I may make a version. If I do I will PM you. You need to build one and post it, you first!
 
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