ROP voltage issues?

[think2x]

Well I've finally decided to try an ROP as a first "real" mod after playing with my maglites for a while. To get the feel for it I started with a 2D maglite, swapped in a 4 cell whitestar, ordered a modamag 6AA/2D adapter and went out and bought some duraloops. I assembled the light and it made a nice difference.......until I charged the duraloops! When new out of package they were about 1.23V and ran GREAT but after I charged them they went to 1.46V and the whitestar went Oops...hot off the charger. I waited until the next night, still 1.4V each 8.4V total (8.7V pack hot) thought WTH and put in another 4 cell whitestar again!
My charger is a kodak K6600 FWIW. Am I right that the pelican bulbs used for the ROP are rated for for approximately the same input voltage as the 4 cell bulb? Is 1.4V after 48 hours rest too high for duraloops? I just don't want to oder the wrong bulbs and waste time and $$.
Any input on the situation will be greatly appreciated.

 

[Sgt. LED]

Those Pelican bulbs for the lead acid battery (3854) are plenty more robust.
You need to get a set of the proper bulbs is all.

 

[mdhammack]

I thought the whitestars were actually rated for 4.8v that's why a 4 cell already overdrives them slightly and the 6 aa's way overdrive it.

 

[Howecollc]

think2x

The 4 cell WhiteStar bulbs are designed to work at 4.8 volts "under load". The "resting voltage" of 4 alkaline D cells is around 6 volts. When you provide a load by turning the light on, their voltage drops to around 4.8 volts under load. 4 of your Eneloops, while having a slightly lower resting voltage of around 5.6 volts, have the same 4.8v when under load as the alkalines. You can overdrive the 4 cell WhiteStars by adding one additional cell to the mix, thereby creating 6.0 volts under load. Using 6 cells as you have done, provides 7.2 volts, which is too much overdrive. The 3854 Pelican bulbs are designed for use with an SLA rechargeable battery which provides 6.0 volts under load. Therefore, when using it with 6 cells providing 7.2 volts under load, you are within safe overdrive parameters.

 

[Kestrel]

Sorry to interject with a quick question, regarding that Whitestar 4.8v bulb, I gather that this is the Xenon 4-cell bulb from Mag, can someone post with its amperage? A quick search resulted in many posts about overdriving it with 5 cells, but didn't come across what amps it's rated for with four cells.
Thx,
K

 

[Howecollc]

The MagnumStar is the Xenon filled bulb. The WhiteStar is the Krypton filled standard bulb that comes installed from the factory in new Mags.

I have found that all of the Krypton bulbs (2-6 cell versions) pull right at .82 amps when driven at spec voltage. The few Xenon bulbs I have tested pulled a hair more at .84 amps at spec voltage.

So the 4 cell WhiteStar pulls .82 amps at 4.8 volts under load for a wattage of 3.94 watts. I use this exact bulb in a 3D Mag with a MagCharger battery pack (which is comprised of 5 shortened 1/2 D ni-cad cells putting out slightly better than 6 volts when under load). The now overdriven bulb pulls .94 amps at 6.17 volts for a wattage of 5.80 watts.

As a sidenote, a while back I tested a few very old but new spare bulbs from the tailcaps of a couple of my older 3D Mags. These bulbs were from the days before Mag began putting the new and improved WhiteStar lamps in all their new lights. The old bulbs tested anywhere from .70 to .72 amps at spec voltage of 3.6 volts under load.

 

[Kestrel]

Thanks for the info, what is the amperage of the 4-cell 'Magnumstar' for comparison then?

 

[Howecollc]

I've only tested the MagnumStars in 3 cell and 5 cell versions. They both pulled .84 amps at spec, so I'm inclined to think the 4 cell will as well; especially when considering the consistent .82 amp draw of all the WhiteStars.

 

[lctorana]

Thanks for the info, what is the amperage of the 4-cell 'Magnumstar' for comparison then?

0.79A at the rated 5.3V

 

[Kestrel]

Thank you both for the info. Interesting that the amp draw is basically the same across their entire PR-base line then.

 

[fivemega]

Interesting that the amp draw is basically the same across their entire PR-base line then.

This is because "C" and "D" size alkalines perform well under 0.8A~1.0A

Manufacturers add number of cells to increase wattage while current is just about same.

Carley has variety of PR based bulbs for rechargeable batteries up to 1.7 Amp.