Looking for a compact, rechargeable 36V battery

Hello,

I may want to build a high powered flashlight using one of my Bridgelux emitters. However, they have a very high forward voltage in the 30's. Normally I use them with one of the Meanwell LDD constant current drivers, which can also give me PWM dimming. However, I'd need 36+ V to drive it. Ideally the battery should be compact enough to fit in the handle of a C-cell flashlight, and also be rechargeable. I'm assuming there is some kind of a lithium battery + recharger that is like that?

LiFePO4s have a nominal voltage of 3.2v and Li-hybrids have a nominal voltage of 3.6v/3.7v.

10 in series would get you there, even 9 at 4.2v hot off the charger, but you're not packing them into C size MagLite, I don't think. And forget the charging board, even if you could shoehorn some custom battery cradle that holds 10 cells into the available space.

Something like 10 18650s in series is kind of scary stuff, if you ask me, even with protected cells.

I don't know what other chemistries, or form factors, are out there in a small package.

What kind of current is that sucker pulling, on high?

Chris

You're going to need a handle type light that takes a lantern battery to fit all the cells and make your own battery pack. Or a d cell size light and a custom welded 16340 pack like the 2/3A packs of incan fame. But then how are you going to charge it? I've only seen hobby chargers go up to 8s and as mentioned you'll need 10s. Plus look at $400+ for a charger if one is even made that can do it

600 mA

Edit: ok ok maybe 300 mA <30V

There are all these "little" battery packs that go up to 18V or so that fit in the handle of a cordless drill, so I figured there must be something similar?

you'll need a 10-series battery pack. use high-quality japanese/korean cells only. that rules out 16340 size. try sanyo UR14500.

there are very few 10-series hobby chargers. try the turnigy reaktor 1000w

Curious. At that draw that's only 18w. That's easily doable with an XML and a single cell or an xhp led and two cells. Is this just for fun or is there an advantage to a 36v led?

A couple of 5S Lithium Polymer hobby packs ran in series(10S - 37V nominal)would work perfectly but, I doubt you are going to get anything with a half decent capacity to fit in a C cell flashlight. Two 5S packs can be charged easily by most hobby chargers as well. They can handle up to 75C too so you can push them pretty much as hard as you want.

Here is a 1350mAh example...

https://www.pulsebattery.com/pulse-1350mah-5s-18-5v-75c-fpv-racing-series-lipo-battery.html

And, here is a much larger 4500mAh example...

https://www.pulsebattery.com/plu45-45005-pulse-lipo-4500mah-18-5v-45c-ultra-power-series.html

10s will be too much. When fully charged that will be providing 42V which will definitely fry the emitter.
8s will do almost 34v when fully charged, so 9s would be ideal.

However, since current increases exponentially, you need something to regulate the current or voltage because the emitter might be fine at 37v and then die at 37.5 because of how fast the current increases.

Just saying "36v+" is not specific enough.
This is why there are voltage-current graphs for every emitter.

He also stated a current t draw of 500ma so I'm sure he has a driver.
16340s will be fine. They don't need to be Korean or Japanese cells. I'd personally use aw or efest IMR cells. 16340 if 18350 won't fit. Much safer in 9-10s

Then he should get as many batteries as the driver allows, if it can do 42V then sure do 10 cells.

The reason for the high voltage is that I already have a few of the Bridgelux Decor 97+ CRI 2000lm emitters that I use in my overhead lighting, plus I already have 600mA PWM dimmable drivers for them. But hey, if there is a super high CRI ~3500-4000K LED that can put out 1000+ lumens that only takes 12V to drive, then I'd like to know.

OK, I see that there is the Cree XHP, which makes life easier at ~12V 1A, although the CRI is "only" 90, and it costs more, and they don't already come in an easy-to-solder-and-heatsink disc.

There are many places like mountain electronics that sell it already mounted on a copper star.
The XHP70 can do 5000+ lumens at high currents, if you drive it low at ~1000-2000lm it won't get that hot.
But if you already have the driver and want 97CRI then you're going to need to go with many cells to power it, or a boost converter, that could work too.

In your search, these candidates below won't work :/

• 12V A23 battery. If it could work, you could fit 3 in a 2xAAA host, like a AAA Mini Mag, and get pretty close to your voltage requirements. That would be insanely great to clip to your shirt pocket! But current and capacity will prevent much, if any, functionality for you.
  
• 15V Neda 220 battery / A220 / 504A. With 2 of these and a boost driver you might be able to use a stock Surefire 6P or E2E host, handsome and very bright! But even if it could match your current requirements, 60mAh of capacity won't get you very far.

Also, these are primary batteries and not rechargeable. Why did I bother to post? Someone was going to eventually suggest these, and then the replies would stack up explaining why they'll never work. I saved everyone the effort!