# Amature trying to build HID flashlight



## transparent101 (Sep 19, 2009)

My dad's got an automotive hid conversion kit laying around so I thought I' try to build a HID flashlight. Problem is, I used two lantern battery and the light flickers then dies. I tried the kit using the power from my car and it worked. Any ideas?


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## Norm (Sep 19, 2009)

:welcome:
Two lantern batteries in series positive to the other batteries negative 6V + 6V = 12V ? if you tried it this the the batteries are probably to flat to supply the starting current.
Two lantern batteries in parallel positive to positive negative to negative =6V voltage is too low.
Google search of HID builds
How to SEARCH CPF?


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## lctorana (Sep 19, 2009)

Believe it or not, lantern batteries, even when fresh, won't have enough kick in them to power a HID. Their internal resistance is too high. They are designed for incan bulbs in the 0.5-1.25A range, and in this service, they excel. A HID draws a lot more than that. A car battery can supply this easily.

You need a different type of battery. A 12V SLA might do, or a string of rechargeable cells, if you can afford them.


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## Norm (Sep 19, 2009)

lctorana said:


> Believe it or not, lantern batteries, even when fresh, won't have enough kick in them to power a HID. Their internal resistance is too high. They are designed for incan bulbs in the 0.5-1.25A range, and in this service, they excel. A HID draws a lot more than that. A car battery can supply this easily.
> 
> You need a different type of battery. A 12V SLA might do, or a string of rechargeable cells, if you can afford them.


Thanks Bruce I thought they'd be able to handle at least 5 or 6 amps 
I bow down to your superior knowledge in the area of lantern batteries. 
Norm


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## Flashanator (Sep 19, 2009)

No way in hell those lantern batteries could run a HID setup.

As mentioned a 12v lead acid battery.


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## lctorana (Sep 19, 2009)

Norm said:


> Thanks Bruce I thought they'd be able to handle at least 5 or 6 amps


Alkaline ones might, but only for a little while. I just got the impression the OP was using ZnC or ZnCl ones, though.

The good thing is that F cells bounce back like new after being punished. His lantern batteries will be no worse for the experience to play with other things.


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## transparent101 (Sep 19, 2009)

How about using 4 cr123a batteries? Would it work? How long will it last? I want it to be compact so that it can fit in a flashlight housing


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## BVH (Sep 19, 2009)

I wouldn't even think of trying CR123's. IIRC, they are around 750 mah and are good for maybe 1.5C meaning 1 Amp each approx. You might have some fireworks that you really don't want to have.

You really need a 4 Amp SLA minimum to be effective. Unless you plan a 3 Serial, 2 Parallel setup with some high power 18650 Lithiums, (2900 mah) there are no cylindrical cells that are going to work in a flashlight body.


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## RyanA (Sep 19, 2009)

RCR's are 750 mah, most primaries come in around the 1400-1500mah mark.


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## Patriot (Sep 19, 2009)

....BVH's point being, *do not try to use 123s.*


You cant pick up a 7A SLA at a hobby store for around $22 bucks and it will work beautifully. Fully charged they're about 14V.


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## RyanA (Sep 19, 2009)

Eh, depending on the draw rate it could be made to work. Over 2 amps, I'd say no. More than 4 in series would be a no as well. But yes SLA is probably easiest.


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## Norm (Sep 19, 2009)

This is the sort of build you need to be looking at Aldi HID conversion.
Norm


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## BVH (Sep 19, 2009)

RyanA said:


> Eh, depending on the draw rate it could be made to work. Over 2 amps, I'd say no. More than 4 in series would be a no as well. But yes SLA is probably easiest.



Draw rate is going to be at a minimum, 5-6 Amps for starting cycle, maybe more.


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## transparent101 (Sep 20, 2009)

Havent had the tome to source a SLA batt. Anyway, out of curiosity, I tried this battery configuration, 8x1.5V(in series)x3(in parallel). So 24 AA batteries in total. The light fired up straight away with no flickering. Is this dangerous in anyway? How long will this last? (man, i really need to gain more knowledge about these stuffs!)


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## Patriot (Sep 20, 2009)

No, that's not dangerous but alkaline chemistry performs pitifully under any type of high draw demand. You're run-time will be very short especially since your starting point is 12V. Running 9s3p would be slightly better than 8s3p because you'll remain above ballast low voltage cut off longer with a starting voltage of 13.5V. Starting at 12V they're probably sagging to 10V the instant you switch the light on. Also, keep a close eye out for leaks...

NiMH will perform far better under load and you could even run 11s with short run-time. 11s2p would provide decent run-time . It's just that it's a lot of batteries and not ideal. 

I think BVH mentioned this before but if you have 18650 cells you could run them 3s2p.


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## [email protected] (Sep 20, 2009)

Patriot said:


> You cant pick up a 7A SLA at a hobby store for around $22 bucks and it will work beautifully. Fully charged they're about 14V.



*+1* :thumbsup:


Depending on which wattage kit you're using you should enjoy 40 minutes + of HID goodness!


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## transparent101 (Sep 20, 2009)

Must.. get... SLA....
Anyway, would 10s3p be going over board with regular AAs? That would be 15V, the ballast say that it could handle 16V. Also, how hot would the bulb be, enough to melt a plastic reflector? I tried it with some plastic reflector, and damn these things are bright!!(being an amateur to bright lights XD)


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## [email protected] (Sep 21, 2009)

People do use high current drain capable AA NiMH cells for their [email protected] projects but I'd never use (quick to sag in voltage) Alkalines to power anything... except maybe a direct drive P7 Magmod 

Get the SLA :thumbsup:


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## Patriot (Sep 21, 2009)

transparent101 said:


> Must.. get... SLA....
> Anyway, would 10s3p be going over board with regular AAs? That would be 15V, the ballast say that it could handle 16V. Also, how hot would the bulb be, enough to melt a plastic reflector? I tried it with some plastic reflector, and damn these things are bright!!(being an amateur to bright lights XD)




10x in series wouldn't be to much voltage as they would sag terribly under load. It would turn the light on and run fine for a short time and you'd needlessly be out 30 AA's a short time later. If you just want to see it run, hook it up to your car battery. 

HID will melt plastic reflectors so use metal. If the lens is high temp plastic, it should be fine.


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## transparent101 (Sep 21, 2009)

Hmm, I'll just stick with AAs for this project. I'll use SLA and a better flashlight housing for my next project since the hid kit comes in a set of 2 bulb and ballasts. Time for more parts shopping!


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## Patriot (Sep 21, 2009)

transparent101 said:


> Hmm, I'll just stick with AAs for this project.




Just to clarify, you'll want to use NiMH rechargeables. 12 in series for your application.


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