High voltage on rcr123?

[mr.squatch]

Trying to come up with the next big project, been doing some brainstorming. Curious how much voltage one could build from 3.0 or 3.7v rechargeable 123's. I have a couple big hosts dying for a mod, and a big bag with various 35, 50 and 65w 2 pin bulbs that need a workout. The scarcity of big LithIon batts these days has me getting creative. What kind of limitations am I going to run into? Could I get to 18-21v with the little guys?


2nd idea completely separate from the first... How bout 18650's? How many of these could I stack up?

Thanks for any insight, still years worth of learning yet to do I'm sure.

G

 

[SilverFox]

Hello Mr Squatch,

I am not sure if I understand your question, but if you put the cells in series, the voltage adds up.

A 3.7 volt Li-Ion cell starts off at 4.2 volts and reaches 3.7 volts about half way through its discharge. If you put 10 of those cells in series, you would start off at 42 volts and end up with a mid point voltage of 37 volts.

The same goes for the 18650 cells.

Did I answer the right question?

Tom

 

[VidPro]

i think if you want high voltages, a good way to get them is to start with a cell that uses them to begin with
often the 3.6v li-ion is easier to work with than 3 ni-mhy which is about the same voltage and potentials for total power.
the only conciderations are the SPECS for the li-ion are more pickey than the ni-mhy, needing protection and balancing and all.

i have made 12 24 and 36volt packs with 18650s and (again) the only problems were that overcharging and overdischarging specs stuff, the protection and balancing.
in some electric car models or conversions or alterations they use Li-Ion to get to huge voltages (over100), and again the issues they faced were the protection.

yes did i mention protection and balancing do that and the possibilities are endless.

 

[mr.squatch]

I think maybe my late night post wasn't exactly clear what info I was seeking, but I got some good info anyways. I have several AA projects that range upto (sofar) 12v. I'm interested in going higher, like maybe overdriving a 50w bulb in a 6c or 6d host. I've yet to add more than 3 lith ion 123's together, so I was wondering what kind of characteristics it'd cause, like say as opposed to bigger c or d cells. Whether it's a viable/reasonable thing to even attempt I guess. I have and love plenty of my 123's. If they have enough umph to run a monster light, that'd be really cool. Sounds like it may work, I was really just hoping to not get "they can't handle the amp draw" type answers to my question

g

 

[VidPro]

ohh, to bad, they cant handle the amps

check out the stickeys on the li-ion shootout thing in the stickey in this forum. then try to stay reasonable with the rate of discharge.
like if you can stay below 2C or 1/2 hour runtime, then the cells will last much longer.
but i know you wont so you do get into heat issues and voltage depression from load that will disconnect it , trigger the built in protection and all, you know cause a thermal overload and blow the whole thing up, stuff like that


http://www.candlepowerforums.com/vb/showthread.php?t=117117
look for the 123 charts Here , in the li-ion thread for RCRs.

see the poor things cant even handle 2C very well. and you want to rate your 2C discharge rate off of the actual capacity of some 600-750ma not the claimed magic 900ma that none of them actually have.

So taking a wild stab at it, which is all i can do (due to cell differences), mabey about 2amps, then you blow up
i have some good RCR123s and they work ok at about 1.5amps , and about the max i would want to push the little suckers. i have some cheap ones , and they handle about 1amp just fine.
so use about 31 of them and drive that 110V ac halogen bulb at 100 watts that should be what your looking for .

How bout 18650's? yes much better choice, handle a lot more power , have a lot more real capacity at even easy 5+ amp discharges.
for C and D sized li-ion they are more for better runtimes, than for more amps, a great 18650 would be the "best" choice for "amps vses size" , and there are more brands of them with high amperage protection curcuits .

so then it comes down to FIT, wedged into a D item :-(
3 of the rcr123s will fit in a Boored out D thing, or one that is big enough.
and 10 rcr123s would fit lengthwise into a 6D (i just checked).
so potentially you could get 30 (holy cow) wedged into a 6D , and really run a AC 50W halogen bulb. hmmm sounds crasy enough to try.

 

[mr.squatch]

This has me thinking... that's not good. haha. I'm thinking 3x rcr 123 3.7v wide x 2high in a shortened 2d mag at 22.2v overdriving a 50w 64440 to just under 7000 lumens Hmmm.............. I'll keep you posted


g


edit: or six 18650's in a similar config in a 4d mag. Hmmmmmmmm

 

[mr.squatch]

Or how bout six 18650's two wide in a 6d mag? hmmm...... I have a 6d host that's dying for something more than her current rophi mod, dunno if anyone could 2bore something that long. Time to do some shoppin :twothumbs

g

 

[VidPro]

i think it would be difficult to wedge 18650s side by side
but 17650s piece of cake
4x 14500s works good, and is less total length than a D. but they dont have so much total energy.

 

[mr.squatch]

i think it would be difficult to wedge 18650s side by side
but 17650s piece of cake
4x 14500s works good, and is less total length than a D. but they dont have so much total energy.

Jesus Hernandez says he can do a dualbore 18650 mag. That'd be sweet. Six 3.7's side by side in a 4d mag at 22.2v I can make one heck of a mess with something like that. That'd make a heck of a long running 11.1v light too. Hmmm.... For now I've ditched the 18650s for something that can draw out more power faster. Haven't given up on this project just yet tho.

g

 

[mdocod]

RCR123s aren't the answer to high power modifications in any way. Way too much current limitation, have to use way to many cells to be practical, not worth the effort at all, use lower voltage higher current bulbs instead and you'll have much better results.

Lets say you did have a tri-bore 4D mag and a carrier that could load up RCR123s, You could theoretically fit 21 RCR123s in there. Realistically 18 cells is more like it since you would need a carrier and that takes up some length.

What would this equate to? In terms of maximum safe output, you could deliver about 3.7V per cell at about 1.1Al, or a ~75-85W mag mod that would run for about 20-30 minutes. That's really not all that impressive at all compared to other options. A set of just 6 18650 cells in a 4D duelbore mag can power up to a ~90W mag for 20-30 minutes, that's 1/3rd the number of cells required, which makes charging and safety and resistance issues and everything about 3X easier to deal with.