Surefire 8NX help?

[dano101]

A buddy of mine owns a stock 8NX with the standard surefire B90 rechargeable battery stick and X80 lamp assembly. Any ideas how to increase performance out of this unit without going to some turbohead conversion? It has to be used in the duty belt holster he already has so i was hoping to just help with alternate lamp and/or batteries etc.

Thanks a bunch,

Dano

 

[bones_708]

If you did a search for b90 you would of found this thread http://www.candlepowerforums.com/vb/showthread.php?t=107901
Unless someone does another run of battery sticks you're out of luck. No real upgrades without serious custom work.

 

[SilverFox]

Hello Dano,

Welcome to CPF.

An improved battery pack does wonders for the 8NX. I am in the middle of testing some new cells. I am still in the prototype stage, but if things work out, I will offer another limited run of NiMh B90 replacement packs.

Tom

 

[yellow]

*get some 7.2 Volts battery packs from the remote-controlled crowd, one with 2 rows of 3 cells each.
(its best when they are mounted together to act as sticks already - if the space between the cells is very small, the chance is good)
* cut the pack into the 2 sticks.
* bend the metal at the positive end round and to a size that the total is like Your original B90 sticks
* solder this round part to improve strengh
* cut some metal strip for the connection to the negative end
* remove plastic halfway at last cell
* glue some isolation disc at the positive end, put the connector on, glue it in
* bend the metal strip along the cells and solder to last cell (quick!)
* put heat shrinking tube over everything and heat it.

TRY NOT TO SHORT THE CELLS WHILE DOING THIS!

gives my 9N at least 1:30 hours at high

 

[dano]

I've made a bunch of custom B90's over the years, starting with 300MAH NiMH's and progressing to 4200's (Sub-C's are now approaching 4600MAH capacity).

The capacity and chemistry of the cells limit charging options with a B90 style battery stick. I'm using a R/C charger made by Integy and another one made by Duratrax in a modified cradle I scavanged from a Streamlight "piggyback" charger.

Dummy chargers will work, but have to be monitored so the cells don't over heat. Surefire's charger is NOT compatible with NIMH or hi-cap. cells, and some SF chargers were over-charging the cells, causing the cells to vent.

A higher capacity cell won't give you a more intense beam, though, and I'm not too sure how a non-hobby type will like the extra attention needed for a custom piece of hardware.

As far as I know, there's no other bulb option for a 8NX.

--dan

 

[SilverFox]

Hello Dan,

I think you need to qualify your statement to say that not all B90 chargers are compatible with NiMh chemistry...

During the development of the NiMh B90 replacement pack we discovered that the new style of charger for the B90 batteries had a switch that selected between NiCd and NiMh packs. Further investigation revealed that in later chargers the switch was removed and the NiMh side of the circuit was being used.

The older chargers cooked NiCd packs and would certainly cook NiMh cells, but the newer chargers seem to be able to handle NiMh charging without problems. The timer on the charger is set for 1800 mAh cells, so it shuts down too early. This requires a double charge, but other than that, it works very well with NiMh high capacity packs. Of course there is always the caution that you should not leave battery packs on charge all the time.

The problem we ran into with the high capacity sub C cells was their size. It seems that in order to get higher capacities, they have increased the diameter of the cells, and, in some cases, the length as well. The increase in length makes charging in the SureFire charger impossible, because the pack won't fit. The increase in diameter makes for a very snug fit.

What the high capacities sub C cells offer is a higher mid point voltage, and a higher voltage throughout the entire discharge cycle. As you know, my goal was twice the run time and brighter. Because of the higher voltage, I was unable to get twice the run time, but I came very close. I was able to get a much brighter output.

Depending on where you are in the discharge cycle, the NiMh B90 pack was running at from 0.15 - 0.5 volts higher than the original NiCd pack. With the 8NX, that voltage difference makes for a brighter and whiter beam.

My prototype run of NiMh B90 packs had venting problems. I believe you tried out one of those venting packs. We discovered that the venting was not due to charging issues, but due to too high a setting used during spot welding. The initial run has had 3 packs develop venting problems. As far as I know, the other 72 packs from that initial run are all still working great, and I believe most of them have been charged on the stock SureFire new style charger.

While there is no lamp improvement for the 8NX, a battery pack capable of maintaining a higher voltage during discharge gives you a very noticeable improvement over the stock pack.

Tom