What NIMH battery config will roughly equal my 2C mods?

Okay I have a 2C with a 5 cell mag and 3 CR123 and a 2D with a KPR118 with 4 CR123.

How many nimh cells would I run each bulb with in a 2D to replicate the performance I am getting now.

I assume 6 cells with the 5 cell mag bulb and 7 cells with the KPR.

I plan to get modamag holders.

NiMH's are slightly less voltage than Alkalines so you could keep that in mind. If the 5-cell bulb is made for 5 x 1.5V, then 6 NiMH's are not quite enough.

I've been running the KPR118 with 7 Alkaline AA's. My 8AA-2D with a dummy AA measures barely under 10.0v with a lot of use on the batteries. The fun of running these types of setups is overdriving the bulbs so you might even try 8- NiMH's with this bulb.

bjn70 said:

NiMH's are slightly less voltage than Alkalines so you could keep that in mind. If the 5-cell bulb is made for 5 x 1.5V, then 6 NiMH's are not quite enough.

I've been running the KPR118 with 7 Alkaline AA's. My 8AA-2D with a dummy AA measures barely under 10.0v with a lot of use on the batteries. The fun of running these types of setups is overdriving the bulbs so you might even try 8- NiMH's with this bulb.

Click to expand...

Perhaps the 9.6v RC car battery pack?

Just to throw out there... you know you can build the ROP Low LE in the 2C host with just a bulb change if you're willing to use LiON cells.

I used to sell a lot of the KPR112+3x123 cells and a few of the KPR118+4x123 cells and finally built the ROP LE Low which is where you take a totally stock 2C host, replace the bulb with the Pelican Big D low bulb and run it on 2 18650 cells. You need to remove spring and remove the anodize from inside the tailcap so you can make contact with the negative end of the back cell.

It's an 11 watt bulb so it is a SERIOUS upgrade over either of the KPR bulb builds. I've gone through probably 5 or 6 charge cycles on my light and there's zero damage to the reflector or lens. Actually, I only used the stock lens for the first 2 or 3 charge cycles then replaced it with a USL because I just prefer them. I used a stock reflector with a heavy sputter and just love the light to pieces.

The bulbs are $8 for a 2 pack which comes with highs and lows. The highs need an aluminum reflector and a glass lens.

I think alkalines sag below the 7.5 spec we would expect for the 5 cell bulb.

I was going for the "overdrive by one cell" rule.

As for the ROP I am well aware of the possibilities but I am waiting to see how AW's C size cells work out.

I need to replace the power source for one of these two lights.

An ROP will be my glory light but the overdriven 5 cell or overdriven KPR is as bright as I want to go for this application. I need more runtime as well.

Ahh... I see. Well, I never tried any NiMHs with the KPR bulbs... mostly because since

3x123 = 9 volts with some sag
7xNiMH = 8.4V with, I assume, less sag

Though I'm not 100% sure why I never even tried, it always seemed that you'd either be giving up some brightness, or more likely to flash the bulbs. Having said that, if the 7 cells don't flash the bulb, it should give MUCH better runtime!

I use a MAG118 8xAA 2D. Certainly, it's no ROP, but with 1800mAh NiMH batts, it still produces about about 150 lumens for 2 hours with a KPR118 7.2V bulb drawing about 700mA.

The 8xAA NiMH drives the KPR118 very well without "over over" driving it to produce a good shade of "incandescent white" over several battery cycles for a guestimated 5-10 hours of bulb life. YMMV. I do not use the batteries "hot off the charger", letting them cool before using them.

In this configuration, I've used my MAG118 turned on for about 20-30 minutes at a time and for a cumulative hour over a period of 1.5 hours with no heat or melting issues with stock MAG parts.

Simple, bright and safe with good runtime.

I've flashed a KPR118 on eight alkalines. On seven alkies, I've had to constantly downgrade bulbs from a KPR118 to a KPR112, then a KPR104 just to maintain color and some semblance of brightness.

73
dim

dim said:

I use a MAG118 8xAA 2D. Certainly, it's no ROP, but with 1800mAh NiMH batts, it still produces about about 150 lumens for 2 hours with a KPR118 7.2V bulb drawing about 700mA.

The 8xAA NiMH drives the KPR118 very well without "over over" driving it to produce a good shade of "incandescent white" over several battery cycles for a guestimated 5-10 hours of bulb life. YMMV. I do not use the batteries "hot off the charger", letting them cool before using them.

In this configuration, I've used my MAG118 turned on for about 20-30 minutes at a time and for a cumulative hour over a period of 1.5 hours with no heat or melting issues with stock MAG parts.

Simple, bright and safe with good runtime.

I've flashed a KPR118 on eight alkalines. On seven alkies, I've had to constantly downgrade bulbs from a KPR118 to a KPR112, then a KPR104 just to maintain color and some semblance of brightness.

73
dim

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Thanks dim.

At least I have one known good config tied down.

I also use Scotch Satin tape, Rommul, to smooth out the beam. It's not perfect and it does rob just a few lumens and some lux, but overall, I think that the tape does a good job improving the beam. I've not had any heat related problems with the tape.

73
dim

Rommul said:

Okay I have a 2C with a 5 cell mag and 3 CR123 and a 2D with a KPR118 with 4 CR123.

How many nimh cells would I run each bulb with in a 2D to replicate the performance I am getting now.

I assume 6 cells with the 5 cell mag bulb and 7 cells with the KPR.

Click to expand...

I believe the 5 cell Mag bulb is made for 6v input so it should run very well with 6 NiMh AAs (7.2v nominal). This would be equivalent to running the bulb on 2 rechargeable LiIons (R123s, 18500s or 18650s) which is what I do all the time on my 2C.

If your KPR118 is currently running on 4 123s (12v nominal), then 7 NiMh AAs would be under-driving it. 8 would be a better fit.

lexina said:

I believe the 5 cell Mag bulb is made for 6v input so it should run very well with 6 NiMh AAs (7.2v nominal). This would be equivalent to running the bulb on 2 rechargeable LiIons (R123s, 18500s or 18650s) which is what I do all the time on my 2C.

If your KPR118 is currently running on 4 123s (12v nominal), then 7 NiMh AAs would be under-driving it. 8 would be a better fit.

Click to expand...

Yeah I believe Carley makes the stock bulbs for maglite.

http://www.carleylamps.com/star.htm

Apparently the stock 5 cell is a 6.3 volt 700ma bulb so 7.2 V should be appropriate (nimh will not sag as much as lithium primaries).