24v hid balast to 12v please help

[ashbilt]

i have just got a second hand ballast to suit my ralle 4000 preditor (thanks to some light figered so an so who decided to cut the cord then find they had no hope of actually removing the light) problem is that i've now dicovered that its a 24v ballast does anyone know if or how to convert it to 12v

any help or info would be greatly appreciated

cheers

[ashbilt]

err who ever sent me a pm i may have accidently erased it before i read it a resend would be appriciated sorry mate hehe

[want33s]

AFAIK its not possible, but I might be wrong.
Unless..... you run an inverter to convert 12V to 240V and then a transformer to convert 240V back to 24V. Would work but would use a lot of power.

[ashbilt]

err anyone wanna buy a cheap balast lol

[DamTriton]

Have you actually tried to fire them up on 12 volts??? Might be worth a go, given you have nothing to lose. May well be that the circuitry in them is optimised for 24 volts, but may allow a large range of voltages to drive it, possibly down to 12 volts.

[ausoops]

ill buy it

[DamTriton]

Laptop voltage converter each side and you're done. Most of them will step up to 24V with about 90% efficiency.

[ausoops]

don't do what he said... you really need to sell it to me instead...

seriously though that is a good idea, after all the current draw on a hid ballast is bugger all so more than likely it will work.

[ashbilt]

oh yea so whats a lap top thingo your suggesting gonna cost me (ballpark figure be fine)

cheers

[DamTriton]

oh yea so whats a lap top thingo your suggesting gonna cost me (ballpark figure be fine)

cheers

Big W (50-70 watt) about $50-70 each, or buy one of the larger ones (90 watt) for about $100.

Assuming you are running 35 watt lamps....still cheaper than new ballasts.

[ashbilt]

bloody oath, cheers mate ay. so obviously the 90 watt gonna be the go ay? bigger always better in my book

[Shadow]

any DC-DC converter will do the trick

have a look at jaycar, i thaught theyd be closer to $50 for a 100watt but i could be very wrong.

[ashbilt]

cool cheers guys, i guess i'l do some searcking then.

[1MadEngineer]

run the globes in series off 1 balast?? half the input voltage, half the load = same output. ??

[DamTriton]

run the globes in series off 1 balast?? half the input voltage, half the load = same output. ??

Won't work at all.

[1MadEngineer]

run the globes in series off 1 balast?? half the input voltage, half the load = same output. ??

Won't work at all.

why??

[Shadow]

run the globes in series off 1 balast?? half the input voltage, half the load = same output. ??

Won't work at all.

why??

the output of the ballast is high voltage, not sure exaclt what but thaught it was about 1KV

the input of the ballast is 24volt.

[bushy555]

Each bulb requires one ballast. (Unless of course your an electronics engineer and can design up your ballast to supply enough grunt for X number of bulbs.) Each bulb requires a startup voltage of around 22 to 23kv in order to ignite the arc that passes through the xenon gas in order to do its thang with the salts inside. Once the salts dissolve and the arc is stabilised, the ballasts fancy electronics within can somehow (?) detect this (internal resistance of the bulb perhaps?), and then drops the running voltage to around 80 to 90 volts which is what normal xenon flash bulb runs at.
Two bulbs in series on the one ballast wont ignite... certainly the ballast will have a crack at it, but theoretically it would require two ballasts in series as well to produce 45,000 volts to ignite the two bulbs in series. But even so, this wont work due to the frequencies and phases and fancy techy stuff involved with the initial pulse of doof doof voltage.

Running two bulbs in parallel on the one ballast would most likely work for the first, second and maybe third time that you turn them on. But would kill the ballast internal electronics very quickly since you'd be pulling in around 16 to 20 amps at the initial turn on, and the internals wouldn't take the extra strain required to produce the current drawn by the bulbs.

Bit Dizzo who used to sell Xtec kits were at one stage selling two bulb to one ballast kits. However these kits were designed for twin headlamp housings (Late cruiser 60 series, Cruiser 80 series, Subaru EA81's etc) and were designed so that only one bulb was on at one time. Ie, Low beam would have been the outside headlamp housing, and when you switched to high beam, lo-beam would switch off, the innner headlamp highbeam would ignite.
Saved from having four ballasts for the four bulbs.

Interestingly I read somewhere where the Hella HIDs (28 watts each) startup is only around 5000 volts, hence the life time of the Hella ballast and bulb is ten times that of standard HID stuff.
Never knew that.

[on4tou]

I sell a balast that will run 2 globes at the same time or you can just have one of the globe running at a time. the balast is about the size 132mmx76mmx34mm and it will run 2 35w globes all day and all night and come with a 18 month warrant
Steve

[bushy555]

I sell a balast that will run 2 globes at the same time the balast is about the size 132mmx76mmx34mm and it will run 2 35w globes all day and all night and come with a 18 month warrant
Steve

Ok, they exist. I am wrong.

[1MadEngineer]

I sell a balast that will run 2 globes at the same time the balast is about the size 132mmx76mmx34mm and it will run 2 35w globes all day and all night and come with a 18 month warrant
Steve

Ok, they exist. I am wrong.

i was asking a serious question, i cant remember but i thought the input voltage specs on some of these ran from 14-28vdc.

[ausoops]

I sell a balast that will run 2 globes at the same time the balast is about the size 132mmx76mmx34mm and it will run 2 35w globes all day and all night and come with a 18 month warrant
Steve

Ok, they exist. I am wrong.

but it wont run them in series.

[-Scott-]

I would expect it's more getting both to strike at the same time.

As ausoops explained, initially the ballast applies a high voltage to create the arc, but once the arc is struck (and current flows) the voltage drops back to something much lower (sort of like fluro tube ballasts, I suppose.)

If you wire two bulbs in series, once one arcs and attempts to draw current, will there be sufficient voltage left to strike the second bulb? If the second bulb doesn't strike, how can enough current flow to sustain the arc in the first bulb - because the second bulb won't have significant current through it.

There probably are ways around running two bulbs in series, but I doubt that the average "standard" ballast will do it. I would guess that on4tou's double ballast is designed to run the two bulbs in parallel - but I could be wrong.

[Shadow]

I would expect it's more getting both to strike at the same time.

As ausoops explained, initially the ballast applies a high voltage to create the arc, but once the arc is struck (and current flows) the voltage drops back to something much lower (sort of like fluro tube ballasts, I suppose.)

If you wire two bulbs in series, once one arcs and attempts to draw current, will there be sufficient voltage left to strike the second bulb? If the second bulb doesn't strike, how can enough current flow to sustain the arc in the first bulb - because the second bulb won't have significant current through it.

There probably are ways around running two bulbs in series, but I doubt that the average "standard" ballast will do it. I would guess that on4tou's double ballast is designed to run the two bulbs in parallel - but I could be wrong.

current wont flow until both builbs arc, the ballast will not sense the massive drop in resistance until both bulbs have arced.

[ashbilt]

you blokes gettin al a git tech for me ay

[DamTriton]

I would expect it's more getting both to strike at the same time.

As ausoops explained, initially the ballast applies a high voltage to create the arc, but once the arc is struck (and current flows) the voltage drops back to something much lower (sort of like fluro tube ballasts, I suppose.)

If you wire two bulbs in series, once one arcs and attempts to draw current, will there be sufficient voltage left to strike the second bulb? If the second bulb doesn't strike, how can enough current flow to sustain the arc in the first bulb - because the second bulb won't have significant current through it.

There probably are ways around running two bulbs in series, but I doubt that the average "standard" ballast will do it. I would guess that on4tou's double ballast is designed to run the two bulbs in parallel - but I could be wrong.

current wont flow until both builbs arc, the ballast will not sense the massive drop in resistance until both bulbs have arced.

Actually in series with 45 KV applied one will probably arc up long enough (ie effectivly "dead short") to dump 45 KV across the remaining one, thus shortening its life dramatically and somewhat spectacularly....

[clm434]

Doesn't it use a big arsed capacitor to arc the bulbs? Therefore the high voltage output would only be momentary, wouldn't it? So you'd be arcing both bulbs within a heartbeat, provided it could do both in one hit. Also would that mean parrallel would be better or series?

I could be wrong but I thought thats how it works. If it is right then how's it going to shorten the bulb life?

[ausoops]

because if they are wired in series neither bulb will have a potential difference across it as the hid's are in effect an open circuit until the arc strikes.

[-Scott-]

because if they are wired in series neither bulb will have a potential difference across it as the hid's are in effect an open circuit until the arc strikes.

Well, sort of. There's a potential difference across the two of them combined, but it's difficult to say what voltage is across each bulb - the joint in the middle is "floating" somewhere in between.

Theoretically, if both bulbs are identical, they'll have identical capacitance, and each will have exactly half the voltage. In reality? Who knows? And if/when one bulb arcs?

Somebody must have tried this! Who wants to google it?

[bushy555]

As ausoops explained, initially the ballast applies a high voltage

erm... you sure?


>Doesn't it use a big arsed capacitor to arc the bulbs?
>Therefore the high voltage output would only be momentary, wouldn't it

Not quite. There are no big caps within these metal halide ballasts. Fluro's yes, some 240v metal halides - yes. 12-36v automotive halides - no. Or at least nothing that you would consider 'big' with the fancified electronics.
The ballasts sends out high frequency high voltage pulsed DC to fire the ballasts, of which it can take anywhere between 0.01 to up to around two seconds before the bulbs does its initial arc, which then disolves the metal salts to create the stablised arc. Then it drops to the 85-90 odd volts with around the 2 to 5 amp current draw depending on the pressure of the gas, amount of metal salts within the bulb, and distance of the arc. (35 to 55 watt kits)

I could be wrong but.




>Somebody must have tried this!
I'd do it right now, except that all of my 4 spare bulbs are glued to a Blitz light.
http://www.outerlimits4x4.com/phpBB2/vi ... p?t=131040

Will try it after I light the blitz up. And if it does ARC up with two bulbs in both parallel and or series, can measure the stablised voltage and current draw.

Would be interested to see how it goes...