C8+ build spring bypass necessary/worth it?

Hey all!

I just completed my first flashlight builds. :smiley: Two C8+s with XPL-HI V2 5D emitters and QLITE REV.A 3.04A drivers with guppydrv. I will be gifting them with NCR18650GA cells to people who I didn’t want to gift a super high powered pants-burnkngw light to.

On second thought, I probably should gift them different batteries for that purpose, right?

Anyway, my real question is: should I bother doing a tail cap spring bypass on these lights? Will I notice a difference in brightness at all by doing this?

I’m aware a spring bypass would usually only be necessary for a multi-emitter build that will draw high amps to avoid melting the tail cap components, and to increase the power draw. So I’m wondering whether I should bother to do so with these lights.

Thanks!

With that regulated driver, it wouldn’t make a noticable difference in output. It will only put out as much as the 7135’s allow. 3A is pretty tame for an xp-l.

Cool that’s what I guessed. Thanks for the info.

I thought about giving them a FET+1 driver to show them some real lumens but I really don’t want to give them something I’ll worry about them misusing…

Smart since if you d9nt ha e a thermally regulated driver with lvp it can drain the cell too low amd possibly overheat.

According to others, spring bypasses are always beneficial even with regulated lights. They are able to stay in regulation longer due to less voltage drop due to spring resistance. This is my understanding anyway.

Haha, ya. I am still new to the hot rodded flashlight game. But I know enough that I don’t want to hand one over to my Dad and let him accidentally start a fire with one!

Interesting… I was thinking of doing a bypass just to practice it, anyway. So in this case it wouldn’t be brighter, but would be more efficient?

I think. Hopefully other experts here will comment soon.

Well I appreciate your input too! Thanks.

Any time you reduce resistance it can be good thing up to a point. Experience has shown me that bypasses in my lights is really only beneficial/noticable for higher currents. I bypass all my springs anyways, even if I only see a negligible difference or only measurable with a luxmeter or multimeter.

I had a surprise moment this week while adding bypasses to my Sofirn SP33 V2. It was always losing turbo at about 4 volts so I thought I would try to eliminate some resistance. Applying very little heat just tinning the point of the driver spring caused it to fall off. It was only held on by a small amount of what looked like under heated solder. While I am still testing it, it now seems to lose turbo at 3.7 volts where it should be. This of course is a higher current light than a S2+.

Rad. I appreciate your experience. I probably won’t bother on this one because it will be negligible. But in the future…

Huh. That’s interesting. Going over everything with a fine tooth comb never hurt!

Ah cold solder joint probably. It’s well known that the SP33 needs bypasses to reach full brightness, or upgraded springs. The xhp50.2 3v can pull huge current in low resistance setups.

For a buck, boost or buck-boost driver, it always makes sense to minimize resistance when possible.

For a linear driver, and at low current like 3A, I would prefer not having spring bypasses for reliability reasons.

Thanks, Tater Tot, that makes sense.

Every 18650 light I own is bypassed. From the tip of the spring to the switch itself. Why?
On arriving every light is disassembled, cleaned, adjusted, greased and put together again.
Adding a tailswitch bypass is a little effort. If it does not help (much), it does not hurt either.
And if you decide to hotrod your light in the future, there’s already one thing finished.

As for the batteries: it would not be my first choice.
You may have chosen a 3 Amp light, those are still 10Amp batteries.
It’s like giving your 3yr old daughter her “First Ferrari” even before she can ride a bike.
There are very nice AA lights out there, that you can eventually “upgrade” with a 14500.
A bigger light does not always make a better gift.

Just for the record, the regulated SP33 V2 uses the xhp50.2 6 volt.

All valid points. I am giving him a C8+ to use for boating in the dark, though. It is small, compact, and throws very far with bright light. I can’t think of a 14500 or AA light that will be comparably useful at such distances for this purpose. I am fully confident he can take care of the batteries properly (he’s a gadget freak) but I didn’t want to give him something that can get really hot during use. I will surely remind him of li ion battery safety when I gift him the light.

What batteries would you use? I will buy some different ones and keep the 10A batteries for my own hotrod C8+ build. No loss!

Thanks for your advice.

Im learning from your thread, thanks. Im not a turbo user, so extending turbo runtime would not be a reason to bypass for me… but thanks to Penzy, I learned something new

your dad probably will use turbo, if you give him a light that can. Note Turbo = potential for burning pants

I only have one light with a bypass but it makes less than 400 lumens maximum (I seldom use half that).

It is only 3% brighter than without bypass. I like being able to brag that I have a light with a bypass, but for practical purposes in my case, unnecessary.

If you want a bypass, it does not need to be practical, just fun to know you have one :wink:

I do not understand why a bypass is considered less reliable… seems like redundancy to me… (thats a good thing)… even if unnecessary…