PT surge vs PT 40 with surge bulb

I have heard that you can modify the surge bi pin bulb to fit into a pr base and then plug it in to a pt 40 and get the same brightness as the surge in a smaller package.
If i am correct the brightness is the same but runtime will suffer because of not having the added benefit of running 8AA in series/parallel. is this true?

If so does anybody have instructions on modifying the surge bulb?

I don't know about the mod, but running the Surge on only 4 cells is noticably dimmer then on all eight. So it would probably be brighter then the Tec 40, but dimmer then the Surge. Now if you put 4 lithiums in there it is very close to 8 alkalines, but costs more to fill That would probably be the brightest, lightest 4 AA light.

Well if you run 8 of them in the surge, the lamp will be running at to high of a voltage, but with 4 of them it is about the same as the 8 alkalines. So 4 are fine, 8 is pushing it, but it is nice and bright that way.

Actualy, Brock, wouldn't the un-loaded voltage be the same for 4 or 8 in the Surge, since it's a series-parallel arrangement? Of course, 8 would provide more amperage which might produce less voltage drop under load, so in essence what you say may be correct under real-world conditions.

Yes, the unloaded voltage would be the same (or very close) on 4 or 8 cells. The 8 cells do provide more amperage, but that is due the batteries not dropping as much under load since each battery has only 1/2 the load in the 8 cell configuration. As the voltage to the lamp drops it pulls less power, the more voltage the more power it will draw. Does that make sense?

Bushman,

I suppose you read about this bulb "mod" in some of my posts. I've mentioned it a number of times, and no one ever seemed to care. I hope this situation changes, though, because I know of no other way to get as much light out of a Tec 40.

The thing is, I haven't done a professional enough mod on the PR base to warrant posting any instructions. All I've done so far is solder the bulb with wire to the base. I've gotten numerous little aluminum parts and screwed around with them to try to make a permanent socket, but I'm not yet satisfied, and it's something I keep in the back of my mind as an unfinished project. It's not that it's that hard, but it does require being able to get certain parts. For example, I can't even find a simple solid aluminum billet!

Now for the beam results:

First of all, I only use rechargeables. I can't tell the difference between a Surge on 4 or 8 NiMHs, although Brock is right about the difference using alkalines.

As for the beam differences, the Surge has an overall smoother beam, both at the central bright spot, and the peripheral beam. The Tec 40 has a pretty smooth central beam, but there's a sort of small (dim) splotch off to one side in the peripheral area. I notice this with an overdriven 3 cell bulb too. It's really not a big deal, though. The Tec 40 has a broader peripheral beam, which is less bright, but still bright enough to light up a whole field. I've grown to prefer the broader peripheral beam on the Tec 40 because it also lets you see the ground close to your feet with the light pointed straight ahead. With the Surge, you can't see closer than about 3 feet.

It's my intention to get around to making this a permanent mod, and replacing my Surge altogether. The compactness of the Tec 40 outweighs the slightly smoother beam of the Surge, in my opinion.

One other thing. If you use the narrow beam reflector with the Surge bulb, you'll get a laser like spotlight that will blow you away! I plan on having two Tec 40s with Surge bulbs - one with each style reflector.

If anyone else wants to do this PR base mod be my guest, and by all means let me know how it works out.

ps. I forgot to compare the Surge bulb to an overdriven 3 cell bulb, maybe because there's no real comparison. The peripheral beams aren't terribly different, but the Surge bulb produces a MUCH brighter central beam. It "punches through" far better than any overdriven 3 cell bulb. This is with the broad beam reflector.

About runtimes. I haven't tested the Tec 40, but I have been getting about 2:55 with the Surge on 8 Powerex NiMHs, so I would safely guess about an hour and a half. These particular batteries have a little more charge capacity than all the others, though.

brock would the li+ cells hurt the bulb any?