2D ROP: 6 eneloop or 2 18650?

[smopoim86]

I got a 2D mag today (I saw it and couldn't stop myself). Anyway, Would I be better off with 6 eneloop or 2 18650. Battery holders are not an issue, wither is fine. I'm just wondering if output or runtime would be different. Just from manu. ratings I should get more runtime out of a pair of 18650 @ 2400mah, right? Would 2 18650 be too much for the rop bulb fully charged at 8.4v (vs around 7.5 for the eneloops) ?

Daniel

 

[jasonck08]

Well, lets see here. 6xAA eneloop's would be 1.2x2ah=2.4whr's per cell. 6 cells would be 14.4 watt hours.

2x18650's would be like 3.7x2.4Ah=8.88Whr's per cell. 2 cells would be 17.76 watt hours.

Both calculations are optimistic calculations. But the 18650's should last a tad longer and will be lighter than 6XAA. Just be sure your 18650's can handle the current draw of your ROP.

I'm not sure about 8.4v being too much for the ROP, I haven't built one yet...

 

[Gunner12]

Factoring in resistance from contact points, 8.4v should be fine.

The runtime will be similar with either battery, in this case the 18650 should have longer runtime.

There are also Li-ion D cells.

 

[2xTrinity]

Factoring in resistance from contact points, 8.4v should be fine.'

Yes it will. Note also that 6 fully charged NiMH cells also reach 8.4V, and some have even run the ROP on 7 NiMH.

There are also Li-ion D cells.

The kaidomain cells require a soft starter to light the ROP. And they actually don't offer much benefit over AW C Cells for ROP high as the light would get too hot to handle long before the runtime difference would matter. If the concern is taking the light on vacation and not wanting to recharge, it's possible to buy a spare set of C-Cells, or even 18650s as backups, C's as your "main" battery.

Id' suggest if you want to run LiIons you buy a 2C. It will be a lot smaller and lighter weight, and offer you more runtime than the 2D NiMH setup.

 

[Misterbean]

I am definitely a newbie but I have recently built a ROP with eneloops in a modded 8AA holder from radioshack(note it will not fit in a D sized M*g). In my experience 7 eneloops with a litte resistance will power a ROP Hi and Low very well as will 6 eneloops. 7 is obviously very very white and bright with both bulbs but six will impress you. I have done some stuff with 18650s with a similiar set up. 8 eneloops will absolutely blow an ROP hi or low(i have done it on accident...i forgot to take one of the batteries out). to answer your question in short though 6 eneloops is a great option.

 

[smopoim86]

Well, the reason I was saying 18650 or AA was because I already have the batteries and i'm on a very tight budget for this light. Eventually I may get a set of D liion, or maybe a 2c with a set of aw c cells. Right now I'm just wanting a cheap ROP(I'm planning to build a superlight out of a 4d once i get the money to quad bore it and buy a battery pack).

 

[Misterbean]

what kind of 18650s are you using. protected/unprotected. like i said in my previous post the eneloops work great. they are cheap too if you can get to circuit city and find some on clearence. i got 8 for under 8$.

 

[smopoim86]

The 18650 are cheap dx batts(trustfire protected 2400mah).

I'm guessing it's much safer to use the eneloops?

 

[Misterbean]

since they are protected i would think it would be safe enough. i have heard of some protected 18650s not powering the rop but it depends on the batteries i think(don't quote me on this). i love protected lithium-ions but i still prefer ni-mh for cheapness and ease of care.

 

[smopoim86]

I may testfire it on a set of 18650, but may build a batt holder as well. Who knows. I came to this forum looking for a decne t led and now i'm a friggin flosholic with plans to build an 7500 lumen mag mod. YOU PPL ARE MAKIN ME CRAZY

Thanks for the advice

 

[Misterbean]

i know i pretty much did the same thing. i was looking around for flashlight reviews and now i'm spending every spare dollar trying to make my lights just a little brighter.

 

[2xTrinity]

If you already have a charger, the 18650s will be your cheapest option ($10/pair, vs more like $15 for the eneloops + >$25 for a good adapter) The only reason I dislike the NiMH for hotwires is that adapters that are high enough quality to not suck the life out of your ROP due to excessive resistance are pretty expensive.

What are you doing for reflector/glass etc?

You can get plainglass for <$1, or AR coated for $5 from Kai or DX. You can get reflectors from Kai for $15. If you buy two of each, you can make two ROPs down the road if you get more money. One for a ROP-Hi, and one for ROP-Lo (perhaps the 2c?).

 

[smopoim86]

Got the reflectors and glass from Kai. I'll prolly use the 18650 for now since that will be the easiest adapter to make. I could make the AA adapter but don't feel like spending the time right now, although it's going to be a while till my reflector comes. I may rob the MOP from my 3c p7 (also running on 2 18650, in parallel though). I'm trying to standardize my batteries to eneloop and 18650.

random thought: I wish i could find another 8 pack of eneloop for 6.50

 

[FILIPPO]

I think with 4,5Ah of drow you may have some problems with protection circuit...:thinking:

if you don't want to build a new adapter for eneloops you can contact LuxLutor and order a 6 cells battery pack that will fit in an unbored mag...:thumbsup:

 

[MikeSalt]

I built my ROP using AA Eneloops, simply for the reason of safety. When driving cells so hard, I would rather be playing with the safer chemistry. Also, I can use the FiveMega charging plug adapter to fast-charge the cells with ease.

 

[Illum]

I built my ROP using AA Eneloops, simply for the reason of safety. When driving cells so hard, I would rather be playing with the safer chemistry. Also, I can use the FiveMega charging plug adapter to fast-charge the cells with ease.

the "on board" rechargeable option is definitely a plus, playing with hotwires is fun, until you get to the point where you must disassemble cell holders to extract and charge the cells. that is, if you plan on using AAs.

Mike, Im using the same config as yours
FM 6AA to 2D holder
6 eneloops
Tenergy universal smart charger:naughty:

I haven't given a thought on feeding my ROP 18650s...
alright, thats what I'll do for my second ROP:twothumbs

 

[Mark620]

FM 6AA to 2D holder
6 eneloops
Tenergy universal smart charger:naughty:

Dang, that sounds familiar....:nana:

 

[2xTrinity]

If you're worried about safety of the 18650s, another option is Emoli cells from the Milwaukee drill packs. Two will fit in a 3C, or a 2D, and it's an inheretnyl safe chemistry. It's also particularlyl suited for high drain, so will run whiter and brighter than any of the already mentioned options (NiMH/18650) and will provide you with more runtime (~3Ah).

They won't break the bank either at ~$16/each.

 

[Misterbean]

which drill pack has those batteries in it and how large are the cells exactly.

 

[2xTrinity]

which drill pack has those batteries in it and how large are the cells exactly.

Milwaukee 28V. They are 26700, which means 26mm diameter (like a C-Cell) 70mm length (20mm longer than a C-cell) Though there is a vendor on CPF who sells them if you search for Emoli.