ROP 2D to 6AA with Nickel Zinc AA's?

[Joshz]

I am a total newbie. After doing lots of reading on these forums I ordered all the parts to do a 2D to 6AA ROP and the final parts should arrive today. (Yay!) I already have the Pelican 3854 set of high and low bulbs. The only thing I still need to buy are AA rechargeables. I heard about the new Nickel Zinc AA batteries that are 1.6 volt each. Can I use them in the ROP? The potential problem I see is that since the Nickel Zinc are 1.6 volt each, using 6 of them makes a total of 9.6 volts, versus regular Nimh that are 1.2 volt each, making a total of 7.2 volts. Can the 3854 bulbs be run at 9.6 volts?

If I can't use the the 3854 at 9.6 volts, would it gain me any lumens to use a different bulb that can run at 9.6 volts? My huge preference would be to use a potted bulb that I can just drop in, since I have never done this before. If I have no choice, and it is really really easy, I guess I can try some sort of bi-pin holder.

 

[Kestrel]

First (detailed) post lost due to server issues...

Shorter answer,
I'm not that familiar with NiZn chemistry,
If NiZn cells are 1.6v under load, yes, voltage could be an issue
If NiZn cells drop from 1.6 to 1.x under high current loads, things should be fine.

You might want to use the 3853-H instead of the 3854-H, that bulb is better for slightly higher voltages per ElectronGuru

I definitely understand your desire to say with PR-base bulbs, that is always my consideration as well.

Hope this helps,
K

 

[mdhammack]

The 9.6 volts will be too much for the ROP setup. Stick with the tested and proven Sanyo Eneloop batteries. They are one of the best, if not THE best choice for the ROP lights.

 

[Mjolnir]

It seems like NiZN batteries actually are about 1.6 volts under load, so they are probably too high for an ROP. You could try using 5 cells, which would get you about 8 volts maximum (the voltage at the bulb will be lower because of resistance in the maglite). This might work with a 3853H bulb, but probably not a 3854H bulb (this voltage would be very close to blowing a 3854H bulb, so it won't have a very long life).

 

[KiwiMark]

Voltage at the battery of 9.6V under load?

3854-L or 3853-H should be impressively bright from that kind of voltage!

3854-H or 3853-L will most definitely go . There is no way there will be enough voltage drop between the battery at bulb to let these bulbs live for even a second!

Lux Luthor has tested these bulbs and his results can be found here: http://candlepowerforums.com/vb/showthread.php?t=179748
The 3854-H bulb blew at 8.6V
The 3853-L bulb blew at 8.1V
There may be some variation from bulb to bulb, but 9.6V at the battery = over 9V at the bulb =

 

[Joshz]

So I guess I won't be using NiZN batteries with 3854 or 3853 bulbs. But there must be another drop-in bulb out there that can use the extra 2.4 volts to give more lumens compared to the 3854 or 3853. It seems a shame to waste the extra 2.4 volts that the new AA batteries could provide. Can anyone recommend another bulb to try?

 

[RaVeN38571]

Don't forget that by using the NiZN batteries you will be giving up some precious runtime. I think the NiZN's only have around 1500mah, and an eneloop has 2000mah.

 

[Bullet Bob]

I have the ROP low setup in a bored out 2D mag with a 8 pack battery holder from FM with one dummy cell and 7 eneloops. I just got the extra deep reflector from FM and now this is one of the best lights I own.

 

[TheInvader]

3854L flashes at around 9.2+ volts, with around 800 torch lumens (1000 bulb). Use exactly 6 NiZi cells.

3854H flashes at 8.4+ volts, with around 1300 torch lumens (1500 bulb). Use 3 NiZi and 3 Eneloops (1.6*3+1.2*3=8.4 volts) Make sure the Eneloops are really 1.3 and under, that bulb is very sensitive. Discharge slightly with a resistor if necessary.

 

[xenonk]

Don't forget that by using the NiZN batteries you will be giving up some precious runtime. I think the NiZN's only have around 1500mah, and an eneloop has 2000mah.

1500mAh @ 1.6V = 2.4Wh
2000mAh @ 1.2V = 2.4Wh

Mind you going brighter will reduce runtime anyway, but it won't be because the cells contain less energy.

 

[LumenHound]

Use 3 NiZi and 3 Eneloops (1.6*3+1.2*3=8.4 volts) Make sure the Eneloops are really 1.3 and under, that bulb is very sensitive. Discharge slightly with a resistor if necessary.

Mixing batteries of different chemistries (even if they are only slightly different chemistries) in a multi cell light is not a great idea. Proceed with caution.

 

[Bullet Bob]

Just did my second ROP low with a Fulton anglehead and an FM 8aa to 2 d holder and seven eneloops and one dummy and the pack measures at 9.8 volts and the rop low runs fine. So I think the 9.6 ni/zn should do just as well.:thumbsup: