Can a P60 drop-in short out batteries?

[jimbo231]

I was wondering if its possible or common for the middle spring on a p60 drop-in to bend when batteries are put in and short on the flashlight body when the flashlight is turned on?

 

[gswitter]

Don't know how common it is, but it happens. It's been reported and discussed in a few threads. One general recommendation that's come from previous discussions is to remove the battery(ies) before inserting the drop-in - i.e. shorting seems to be more common when installing drop-ins without removing the cell(s) and tailcap.

It's happened to be once, with a pair of IMR cells, and the tailcap spring immediately overheated and fatigued. Whee!

Edit: ...and I should clarify, this was an aftermarket P60 drop-in with both inner and outer springs.

 

[hoongern]

You should always remove your cells before changing drop ins.

It happened to me just a couple months back (I have a thread on it), although again that was not a P60, but a different module with a pretty long spring. Melted both that spring, plus the tailcap spring, as well as rendering both my cells useless.

So yes, it happens.. but I'm not sure how often. Best to just remove those cells first!

 

[kramer5150]

Yes.
Al though I don't think its possible for a Malkoff M60. His springs are stiff, flat on theend and inverted so the wide flat part is against the cell.

 

[jimbo231]

Thanks I'll avoid the L2 I wanted to buy since I don't want the li ions going The one I have now just uses aa's.

 

[mfm]

Thanks I'll avoid the L2 I wanted to buy since I don't want the li ions going The one I have now just uses aa's.

People answered if it was possible to short it by inserting the drop-in with the battery in it, not if it was possible to short it when inserting the battery with the drop-in in it. The latter isn't more likely than with non-p60 lights.

 

[march.brown]

.
I have two L2 5 modes and a L2i single mode and all are using 18650s ... So far, I haven't had any trouble, but do what others have already said ... Remove the cells first and leave the tailcap off before replacing the drop-in ... Then put the cells back in and put the tailcap back on.

I love my Solarforces especially in the Sand colour as my three are.
.

 

[Benson]

There are P60 flashlights (such as the Ultrafire WF-501B) with a spacer in the top of the battery tube, which isolates the battery from the drop-in.

 

[AnAppleSnail]

Summary: remove your batteries when replacing your light engine.

 

[jimbo231]

Why do they need a spring in the center? Why don;t they just use a flat contact point? That would be a lot safer and easier.

 

[Benson]

Why do they need a spring in the center? Why don;t they just use a flat contact point? That would be a lot safer and easier.

To start with, because that would be incompatible with the Surefire P60 lamp assembly that they're meant as a drop-in replacement for.

Other reasons (some of which may be related to why Surefire designed the P60 and similar with a center spring):

• Because you want extra float to allow variations in battery length. (Especially for 3 and 4 cells arrangements, and/or protected/unprotected Li-ion cells.)
• Because you don't want shocks causing the light to flicker, and in multi-mode drop-ins, to change modes.
• Because, with the outer spring being present, hosts have developed considerable variation in where the drop-in actually sits relative to the cells -- the center spring accomodates this.
• Because the contact point would change if you unscrew the pill a half turn to adjust focus.
• Because a flat contact point won't hit flat-top cells.

 

[gswitter]

People answered if it was possible to short it by inserting the drop-in with the battery in it, not if it was possible to short it when inserting the battery with the drop-in in it. The latter isn't more likely than with non-p60 lights.

You still have a center spring, and by design, it has to deflect. Most lights don't have exposed contacts that the deflected spring can short against, and that's unfortunately inherent in the P60 design.

The cases of shorts don't appear to be all that common, but it's better to be aware of the risk.