Planning a new hotwire build

[TigerhawkT3]

I was looking into superbulbs, and I found an interesting one that I thought might be fun to play with. It's the Philips 23177, rated at 36V/400W and 16,625 lumens. I'm hoping the filament will be relatively compact, and focusable by a a reasonably-sized reflector. I'm planning a power pack of 35 Titanium high-discharge 1.8Ah AA NiMHs, assembled as five 7-cell hex bundles stacked end-to-end. I'll run taps from each bundle down the length of the pack, for easier charging.

According to SilverFox's NiMH Shootout thread, these cells start at about 1.2V at a 10A draw, and this bulb should pull about 11-12A, so I'm guessing it'll basically start at around 1.17V per cell, giving a total pack voltage of ~41V, which is about 14% overdrive. I'm hoping that the bulb will be able to handle that, because removing a 7-cell hex bundle to get 28 cells would give a voltage of 1.17*28=32.76 and a drive ratio of only 91%.

So, any suggestions?

 

[mdocod]

well.. here's what I come up with...

if you could get 40V at the bulb after resistance (it will probably be less that this)... then you could get almost 20-24K bulb lumens with a re-rated life of about 15 hours or so.


.. after looking at a few spec pages and various "cross-reference" lamps... it appears that it might be a 14,500 lumen lamp.... either way, it's a lot, and the efficiancy looks pretty good.. that's why I'm saying "20-24 thousand" lumens up there... because it depends on which lamp spec is right, lol.

the only specification I was able to find that seems to stay consistant from one source to another is the lamp life of 50 hours at 36V..

I *think* it's supposed to be about 3450K at 36V... but I found one site with it listed as 3200K.. (which would not make any since for a lamp driven to this low a life and this high an efficiancy)... Rerated CCT could be as high as 3570K... hard to say...


anyways.. in conclusion.. I think the bulb will handle 35 cells. After all the resistance from that large of a pack configuration, I'd suspect you'll get more like 38V at the bulb on rested cells, which would be fine... I think this setup could probably handle being turned on pretty fresh off the charger. Depends how warm the cells are I suppose... since heated cells tend to deliver more oomf.


Most places that sell the lamp suggest proper ventalation... obviously, you probably won't have that but probably won't be running it realy long either...
I was wondering... what host are you putting this in? Might be pretty cool in a spotlight host (thor type thing).

 

[mdocod]

jus found something really weird..
http://www.1000bulbs.com/product.php?product=7482

~400watts... 750s hours... but it claims 75lm/w, 30,000 lumens... just have to come up with more volts for it, lol.

 

[BigusLightus]

Geez, 75 lumens per watt. Wow!

 

[Aircraft800]

jus found something really weird..
http://www.1000bulbs.com/product.php?product=7482

~400watts... 750s hours... but it claims 75lm/w, 30,000 lumens... just have to come up with more volts for it, lol.

Wow! At $243.25 Each bulb, that would be a expensive evperiment!

 

[TigerhawkT3]

Great! Thanks, mdocod. Glad to hear that I won't be pushing that bulb TOO hard.

Total runtime for that batt pack will probably be at most 10min or so, so I should be fine as far as ventilation goes, letting it cool between short runs.

The body I'm thinking of is an aluminum tube, so that it can actually be handled like an ordinary flashlight. I've already got an LK12 in a spotlight host, so I wanted to shoot for something different.

I hope it'll be able to start a fire quicker than the LK12.

 

[mdocod]

it'll be interesting to see if it works... the problem I see... is... lets say you were able to get resistance WAY down (more than I'm expecting) and you tried to run it with "hot" off the charger packs.. Lets say each cell is above 1.4V resting "hot" and yearning to go.. If somehow, the bulb were to see more than ~42V for some reason... then you'd be itching on instaflash territory....

Like I said, doubt it's going to happen.. but if you do built it.. rest the cells for the first run and try to take V-Bulb readings if possible.

 

[TigerhawkT3]

Sounds good; I'll let the cells rest after charging.

Well, newspaper ignition time for the LarryK12 is one minute. I wonder how well this new build will do...

 

[DM51]

Following this with GREAT interest. Can't wait to see some pics!

 

[TigerhawkT3]

So, 5 cells in each of 7 sticks grouped into one long hex, or 7 cells in each of 5 hexes stacked end-to-end? For the former, it'll be harder to bundle the sticks into a tight hex, but for the latter, I'll have to use more battery bars and isolate each hex from the next while needing fewer charging taps.

Button top, or flat top?

 

[mdocod]

7 cells per pack will make the best use of space... (just experimented with this)

1 in the middle and 6 around the outside of it fills the space up and makes a nice perfect cicrle of cells, 5 cells, no matter how you arrange them, is pretty lousy

 

[TigerhawkT3]

No no, what I meant was if I should make seven sticks, each one being 5 cells long, and then bundle them into a hex configuration, basically meaning a bunch of end-to-end soldering with a few bars as opposed to just a bit of end-to-end soldering with a bunch of bars. I think that's what I'll do.

Here's my favorite setup so far:

 

[mdocod]

ah, that makes more sense now, lol (i'm a visual understander, not a reader understander when it comes to describing objects in space, LOL)

, I think I like the "sticks" idea as well.

 

[TigerhawkT3]

Cool.

So, button top, or flat top? I'll to need to end-to-end solder them, as well as solder on battery bars and charging taps.

 

[mdocod]

no clue there to be honest. I have very limited experience soldering cells together into packs... (if you saw the results of my attempts at pack building, you wouldn't take advice from me!< lol)

 

[DM51]

Cool.

So, button top, or flat top? I'll to need to end-to-end solder them, as well as solder on battery bars and charging taps.

You definitely need to get cells with tabs on if you are going to solder them. You don't want to be soldering direct onto the end of a cell.

 

[TigerhawkT3]

I've ordered the cells, but the site where I bought the batt bars and silver solder doesn't take credit cards or PayPal. All payment is finalized by phone... I think I'll have to send them a check or something. Weird.

 

[LuxLuthor]

Cool.

So, button top, or flat top? I'll to need to end-to-end solder them, as well as solder on battery bars and charging taps.

Make sure you get flat top for soldering end to end. You don't need tabs with NiMH cells. Just follow that video that goes through the steps. It works perfectly, and I have done a number of cells using the hamnmerhead tip from CBP's site.

Tabs are only for Li-Ion cells where you cannot apply the heat directly to the terminals....also the Li_ion cells don't have the current output to work for these high power hotwires. Their PCB shuts off at 5A, unlike the NiMH high current cells with the Elite or Titanium 1800 High current AA's.

I think you are going to face a risk of instaflashing with the very high startup voltage spike.

 

[TigerhawkT3]

Yep, ordered the flat tops. We'll just see about the instaflashing when I actually receive the bulb, batteries, battery bars, etc., because right now I don't have ANY of the parts yet. :candle: I'm probably going to cancel that battery bar order from that one store and just order some from Tower Hobbies.

 

[LuxLuthor]

What light (tube) are you using for that many?