P7 Maglight NiMH vs P7 Maglight Li-ons?

Assuming both P7 Mags have a 3amp draw initially on Direct Drive.

I see some bored 1D Maglight P7 with 3 17670's (parallel). 4.2v and up to 3000mAh.

VS.

A 2D Maglight P7 DD running 3 NiMH (in series). 4-4.5v with each cell at 5000mAh. I know you do not add up the mAh, but you do add up the voltage. Yet because there are 3 cells don't they share the current?

What are the pros and cons of each?
I like the NiMH version better because it's not much bigger, but offers many times over more runtime.

bigchelis said:

Assuming both P7 Mags have a 3amp draw initially on Direct Drive.

I see some bored 1D Maglight P7 with 3 17670's (parallel). 4.2v and up to 3000mAh.

VS.

A 2D Maglight P7 DD running 3 NiMH (in series). 4-4.5v with each cell at 5000mAh. I know you do not add up the mAh, but you do add up the voltage. Yet because there are 3 cells don't they share the current?

Click to expand...

No, they're in series, so they all have the same current.

What are the pros and cons of each?
I like the NiMH version better because it's not much bigger, but offers many times over more runtime.

Click to expand...

The NiMH version should be cheaper (no boring, just a little tailcap modding), uses cheaper/more available cells and chargers, and can fall back on KOH cells in a pinch (with poor output). It has worse runtime if you're correct about the capacity, but I think it's the same or slightly better. NiMH are much safer if you don't know what you're doing, and slightly safer if you do; they should also get longer life, for whatever that's worth.

I'm not aware of any 3Ah 17650s; in fact, I'm not sure there are even 18650s making that, yet (there's some rated as such, but not sure how they test in reality). The best I know of (but there may be better) are around 1.5Ah, so you'd get 4.5Ah. Since it's DD, you're going to have a hard time getting it to work off any primary cells -- Lithiums are the wrong voltage, and you'd need a special series adapter to run on 3 AAs (and get very poor output), so you basically can't use it if you run out of charged 18650s.


I don't really like either of those options, but especially not the 1D/3x17650 -- it seems like too much hassle to save a couple inches, and I'd rather make a 2D with a 3x25500 parallel adapter (inspiration here; I think I could squeeze 3x25500 in a 2D...) for about 9 Ah, if I wanted a compact P7.

I am not sure what you are exactly building, but the 26700 emolie, is 3.7 volts at 2950 mAh. They have one of the flattest discharge curves, the run looks as if the P7 was on a regulator when direct drive. On a P7 D bin-J Bin, 800-900 lumens at Vf 3.7, they are the exact Vf. They can be charged at 5 amps too so a recharge is just minutes.
The size is C, 26 mm diameter, 70 mm long. Since you are writing about 1 D obvioulsy you can cut a tube.
Wonderful for direct drive, obviously brighter for the P7 of those bins than Liions. The D,J bin P7 is a perfect match for the emolie which also come in 18650s but less Ah obviously.

I have run several P7 on this. My favorite is a 2C with a charging jack and D2FLEX for three modes, an always on LED under the GID cap for light locator in the dark and thermal management. I have a1D P7 in C bin which if Vf 3.5 on a c lion, 3000 mAh, and those of course are 700-800 lumens. It too is direct drive on a D2DIM for modes otherwise it is like the 2C seen here. It is not as bright as the D bin on the emolie.


1D with a 3D 7x Q5 and TM-800x3 in P4

I am having Nailbender build me a P7 Maglight. I finally decided on a P7 Maglight build around a 2D body. Using 3 NiMH cells and d2Flex switch. UCL lens and a metal smooth reflector plus custom touches on the stock one VLOP like.

I wish I could make my own, but right now my skills are limited to Surefire Lego.

I just want a somewhat thrower P7 with more than 2 hours runtime and in a 2D or shorter hosts.

Thank you all,
Jose

bigchelis said:

I am having Nailbender build me a P7 Maglight. I finally decided on a P7 Maglight build around a 2D body. Using 3 NiMH cells and d2Flex switch. UCL lens and a metal smooth reflector plus custom touches on the stock one VLOP like.

I wish I could make my own, but right now my skills are limited to Surefire Lego.

I just want a somewhat thrower P7 with more than 2 hours runtime and in a 2D or shorter hosts.

Thank you all,
Jose

Click to expand...

Lets, see, P7 D bin runs at 2.8 amps at 3.7 Vf by spec. Consumes just over 10 watts. C bins also run at 2.8 amps.
On direct drive you need 3.6 volts at 5.6 Ah battery pack to get your 2 hour run.
I have found from experimenting that the D bin, J bin Vf is brighter than the C bin I bin Vf on 3.6 volts although the D bin will not reach its full potential of available lumens until you get the Vf up to 3.7 and thus the amperage 2.8-3.1. In simpler terms the correct voltage for D bin is 3.7 volts but at 3.6 volts, that of 3x NiMh it still is brighter than the C bin which is meant to run on the 3.5-3.6 volts. So go with at least the D bin luminousity, which usually has the J bin Forward Voltage requirement of 3.7 volts, it will be the brightest between the two no matter the voltage.

Now how are you going to get all those mAh into a 2D with NiMh?

Powerex 2700 AA was the highest capacity AA until the Belkin 2900 came out. Most other manufacturers over rate their AA, in this case these guys under rate theirs.

You can get 6 AA into a 2D so you can get 5.8 Ah with that at 3.6 volts, 3S2P configuration.

I really do not see any other way to get the capacity you want in NiMh.
I would like to know what you finally decide on. Have fun and good luck! :twothumbs

From what's been said, I think he's talking 3xC cells. I know there's 6Ah C cells available; I'm not sure how accurate that rating is, but getting 5.6Ah out of them at 0.5C seems plausible.

Benson said:

From what's been said, I think he's talking 3xC cells. I know there's 6Ah C cells available; I'm not sure how accurate that rating is, but getting 5.6Ah out of them at 0.5C seems plausible.

Click to expand...

Yes,
3 NiMH cells in a 2D hosts.

"Black 2D P7 Maglite adapted to 3C nimh with D2flex dimming. Smooth reflector and stock reflector I lightly sputter making almost a LOP, UCL glass, 3 - 5000mah Tenergy NIMH C Cells, tail piece mod, momentary switch and pvc Dcell to C cell holder" nailbender

bigchelis said:

Yes,
3 NiMH cells in a 2D hosts.

"Black 2D P7 Maglite adapted to 3C nimh with D2flex dimming. Smooth reflector and stock reflector I lightly sputter making almost a LOP, UCL glass, 3 - 5000mah Tenergy NIMH C Cells, tail piece mod, momentary switch and pvc Dcell to C cell holder" nailbender

Click to expand...

Now I follow, yep, should work. I did some testing of sputtered v. $5 DX and KD reflectors. NO comparison the Chinese reflectors in 52mm LOP made for the P7 were about 1/3 better in performance! I would use the sputtered reflector until my other came in! Why for $5 would you cut that much light from something you have invested all that time and money! Well worth buying.
I also used UCL or its equivalent. It helps.