My dad gave me a 4 D cell lantern that I want to modify. What cells can I use in place of the D cells? I plan on putting in a circuit board and probably a xm-l emitter depending on how I’m able to configure the battery voltage.
Thanks
Why change the d-cells?
You could use 32650s lions or Dcell NiMh
I have a both 3D and 4D LED lanterns and use NiMH cells in both. Easy to use and great capacity.
I have modded lots of lanterns, even converted some gas & oil laps LED and still look & light up like original. 
The reason I want to modify the lantern is that I need long runtimes, different modes (hi,med, low) and rechargability. I was disappointed that I went throught a 20 bucks worth of duracells on my three day camping trip. My kids are young and need the lantern on in the tent at night. I was going to just mod the incandescent to led and add a board but I thought why stop there?
If its an Incadesent that would explain why it eats batteries. a LED mod would make it much better run times and even brighter. For lantern use, i would go with either a Warm white LED or Neutral White LED to offer better ambience with a lantern.
I modded a couple D-Cell lanterns with this WarmWhite generic with a built in driver and they worked very good > https://www.fasttech.com/products/1134701
and then for low mode i placed a 47 ohm 1/4 watt resistor in line with a two-way switch. on high/direct it gets about 12 hours on 3 D cells, and on the low mode it runs for a full week continous ! ( and the Low mode is still brighter than the incadesent hi mode previously, which gave only a 3 - 4 hour run time on high.
Thanks for the link! Fastech always has the coolest stuff. :-). Yeah, incandescent eats batteries. As much as I think just nodding the emitter will do the trick, I think I need to mod the batteries as well. I like having all my batteries the same type so that they are interchagable. I’m thinking is should be able to use 18650’s if I use a sleeve to drop them into the lantern. I need to take it apart and see how I can mod it. Hell, even if I mod it with that emitter/driver that you linked and used it with an 18650 it would probably be much better than it is now.
a single 18650 runs that emitter/driver unit perfectly.
One of these will run approximately forever on 3 NiMh D cells: http://www.amazon.com/dp/B0018S4XIS
edit: And the 3 batteries are in series, so you could swap in a bunch of LiIons in parallel for close to the same total voltage and have it run for approximately an infinite number of forevers.
here's my 4D lantern mod. It was quite involved, but I'm sure you could do it more simply.
I second the NW/WW and high CRI options. CW LEDs really make you all look like zombies. I like mine much better now with the Nichia 219 in it. It's had a bunch of use and the only thing I'd do would be to add a velcro strap to the battery holder as sometimes cells will fall out if it's dropped or jolted. You could easily add a multimode driver in there too, but I've never felt the need.
That’s a really sweet mod. I was thinking I wanted to do that but then figured I’d be better off being able to swap batteries out if needed. Really nice though. I’m thinking I’m going to run two 18650’s in parallel and an xp-g with a nice 3 mode driver to give me super run times and enough light when I really need to light stuff up.
For their tent hang something like an E01 with a chap stick diffuser on it, you can also hang another one or two in the camp area outside their tent, use the lantern as a central family light that stays in place and can be turned off when not needed for cooking or eating or family card games.
Diffusers and long run time AA or AAA flashlights or head lamps, can replace most lanterns, and be much more practical and versatile, and given to the kids as they grow.
thanks! You can swap batteries out in this as it uses a 3 cell Digikey 18650 holder wired in parallel. I usually have only a couple of cells in there (~5h runtime), but when I’m going on a longer trip where I’m not sure there’s electricity I stuff it full of cells. If I use some salvaged parallel pairs from laptop batteries I can fit 6 in there (15h?) but the weight tends to make them fall out more easily.
2 18650 in parallel will be awesome and a 1 or 1.4A 3 mode driver would be awesome. I’d really recommend a high CRI emitter, like a Nichia 219 or 80+CRI XP-G2, as the difference in light quality is huge. It might not sound much, but when you’re cooking food or hunting for a particular piece of clothing, cool white LEDs are terrible. There’s little difference in cost and at that output, not much difference in output either.