# Is it possible to parallel two HID ballast?



## ma_sha1 (Oct 15, 2010)

What if wire two 35W HID slim ballast in parallel connect to one igniter one lamp?

would that make a 70W HID?


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## XeRay (Oct 15, 2010)

ma_sha1 said:


> What if wire two 35W HID slim ballast in parallel connect to one igniter one lamp?
> 
> would that make a 70W HID?


 
No you cannot do that.


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## ma_sha1 (Oct 15, 2010)

Thanks, can you explain the reasons?


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## richardcpf (Oct 16, 2010)

It is possible but that would damage/greatly shorten the life of the ballast and bulb, because the supplied voltage is not always constant. dont know if that would make it 70w bright...


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## jh333233 (Oct 16, 2010)

If i get 2 li-ion cell in parallel to push 1 lamp,is it ok?
No, it will get over drived by the current
or even it dont get burn, over driving will GREATLY decrease the lifetime

1 ballast is danger enough
2 in parallel, not to think


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## XeRay (Oct 16, 2010)

ma_sha1 said:


> Thanks, can you explain the reasons?


 

The ballast is not a passive device, it is an active device which maintains constant power. 2 ballasts together would create chaos.


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## lucca brassi (Oct 17, 2010)

> The ballast is not a passive device, it is an active device which maintains constant power. 2 ballasts together would create chaos.


Nice explanation!

Well problem is that ballast AC (voltage go through O from +95V to - 95V ) or DC ( is for lower power normaly for example 24W HID from +65V to O and back ) at frequency cca 250 Hz . 
You must sychronize frequencies at the same clock , otherwise for example if one balast is on +95V and other on -95V result is zero
Simpler is to have one ballast but you doubled power IGBT transistors conected in H bridge or switch them for more powerfull. You must also sychornize ignition period which is harder because new ballast are normaly digital (and you can do that ) old are analog resonant btw , but ignitior is still analog made from coil winded like autotransformer and powerfull capacitor which stores energy and that part must be literaly equal . That on short 
if you want more you can read for example about electronics

http://focus.ti.com/lit/ds/slusa23/slusa23.pdf


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## richardcpf (Oct 17, 2010)

lucca brassi said:


> Well problem is that ballast AC (voltage go through O from +95V to - 95V ) or DC ( is for lower power normaly for example 24W HID from +65V to O and back ) at frequency cca 250 Hz .
> You must sychronize frequencies at the same clock , otherwise for example if one balast is on +95V and other on -95V result is zero
> Simpler is to have one ballast but you doubled power IGBT transistors conected in H bridge or switch them for more powerfull. You must also sychornize ignition period which is harder because new ballast are normaly digital (and you can do that ) old are analog resonant btw , but ignitior is still analog made from coil winded like autotransformer and powerfull capacitor which stores energy and that part must be literaly equal . That on short .


 
No one would believe this was quoted from a* flashlight forum*.


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## lucca brassi (Oct 18, 2010)

so ... what is not correct ?


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## jh333233 (Oct 18, 2010)

It is not the problem of the net voltage
it should be the stability of the current
you will have to maintain the stable arc


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## ma_sha1 (Oct 18, 2010)

By far the best explanation, still not based on facts but it's got some good logics. 

The way I see it, short of actually doing it & see, there are possibly three outcomes (Parallel ballast only, use one Igniter)

1, Two Ballast exactly in sync. So they go positive & negative together, end up with 2x AMP, 2x Power.

2, They are in Sync negatively, I.E. +95 & -95 always cancel each other
Net result, no power, nothing lit up

3, They are completely out of Syn. I.E, each ballast powering the lamp at 
different times. Because the +95 & -95 are applied at different clock, they do not cancel each other. Because no cancellation effect, it'll still be 2x the AMP & 2x the power

Think about PWM dimming (reduce power), except that this is like PWM boosting to increase power. 

Looks like there still a good chance this might work, 
now just a matter of who wants to try it first? :devil:

Because the two ballasts from a kit will operate by the same frequency, 
they could only be either in Sync. ( positively or negatively) or Out of Sync., 
Not possible to be a chaos, ie. some times in Sync & some times out of Sync. They are either in our out of Sync completely. 




lucca brassi said:


> Nice explanation!
> 
> Well problem is that ballast AC (voltage go through O from +95V to - 95V ) or DC ( is for lower power normaly for example 24W HID from +65V to O and back ) at frequency cca 250 Hz .
> You must sychronize frequencies at the same clock , otherwise for example if one balast is on +95V and other on -95V result is zero
> ...


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## HKJ (Oct 18, 2010)

ma_sha1 said:


> 2, They are in Sync negatively, I.E. +95 & -95 always cancel each other
> Net result, no power, nothing lit up



No, the 2xXX watt will not just disappear, probably the ballast will lit up!



ma_sha1 said:


> Because the two ballasts from a kit will operate by the same frequency,
> they could only be either in Sync. ( positively or negatively) or Out of Sync.,
> Not possible to be a chaos, ie. some times in Sync & some times out of Sync. They are either in our out of Sync completely.



No, they will not operate at exactly the same frequency, there might easily be a few percent difference.


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## get-lit (Oct 18, 2010)

There are special current regulating power supplies that are made to be capable of being paired up by synching their timings, but ballasts also have an ignition and boost phase, so I'm not sure how often you'd come across what you're looking for, if ever.

Also, be sure to never operate an HID ballast outside of it's documented methods. They are way too dangerous to mess around with. An acquaintance of mine was just killed by a similar device just a few days ago.


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## ma_sha1 (Oct 18, 2010)

get-lit said:


> Also, be sure to never operate an HID ballast outside of it's documented methods. They are way too dangerous to mess around with. An acquaintance of mine was just killed by a similar device just a few days ago.




Sorry to hear that, that's terrible news. 

Although it's tempting, I am *Not* going to try it.


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## Ra (Oct 18, 2010)

XeRay said:


> The ballast is not a passive device, it is an active device which maintains constant power. 2 ballasts together would create chaos.



No offence, but I'm a little surprised that this discussion is still going on..

No, I'm not going to say those three. very well known words.. (TJS..)

Ra.


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## 06yfz450ridr (Jun 28, 2012)

I know this thread is old but i stumbled across this. Supp there are 2 35w ballasts hooked to one bulb and you can clearly see and hear the two ballasts. Hopefully this is real

http://www.youtube.com/watch?v=Sag9LC6uhZY&feature=youtube_gdata_player


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## XeRay (Jun 29, 2012)

06yfz450ridr said:


> I know this thread is old but i stumbled across this. Supp there are 2 35w ballasts hooked to one bulb and you can clearly see and hear the two ballasts. Hopefully this is real
> 
> http://www.youtube.com/watch?v=Sag9LC6uhZY&feature=youtube_gdata_player



Must have 2 stupid (rather than smart) ballasts.


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## mvyrmnd (Jun 29, 2012)

I was hoping for a more classic YouTube video where it exploded violently 

So it would appear that it can work, sometimes, maybe.

I wouldn't be brave enough to try it myself...


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## ma_sha1 (Jun 29, 2012)

Wow, didn't think this would really happen, the youtube guy got some big balls


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## mvyrmnd (Jun 30, 2012)

The video ends after only a few seconds of runtime. Maybe it did explode and that was all the footage recoverable from his torched camcorder!


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## XeRay (Jun 30, 2012)

They must be DC output ballasts for this to work, no way they are exactly synchronized if the were at 400 Hz or other AC frequency.


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## dan13l (Oct 15, 2013)

XeRay said:


> They must be DC output ballasts for this to work, no way they are exactly synchronized if the were at 400 Hz or other AC frequency.



I'm probably in the wrong forum but I have 35w morimoto ballast connected to my car, I wanted to test out a 55w morimito ballast that I have. I accidentally connected the 55w plugs that go to the bulbs into the plugs of the 35w ballast by mistake thinking they were the bulb plugs. I turned on the lights but quickly turned them off when I noticed the one bulb didnt turn on. After, I checked both ballast and they both worked fine. What kind of damage would I have caused? They may work now but how about down the road?


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## broadgage (Oct 16, 2013)

It depends on the type of ballast.
Electronic ballasts can not be parraleled for various reasons.

The old type of copper/iron ballasts most certainly CAN be parralled, indeed some high power discharge lamp circuits are intended to consist of two ballasts wired in parralel. This is common practice for very large discharge lamps that are not used in large numbers. It is much cheaper and simpler to to use a couple of "off the shelf" ballasts than to custom manufacture small numbers of specials.

As the O/P refers to 2 ballasts, one lamp, and ONE IGNITOR, that suggests that old type copper iron ballasts are being considered since most types of electronic ballast do not use a seperate ignitor.

A pair of 35 watt copper/iron ballasts in parralel WILL work a single 70 watt lamp at ABOUT the correct power input. Lamp operation may be non optimum though, because it assumes that a 70 watt lamp operates at exactly the SAME voltage and exactly TWICE the current of a 35 watt lamp.
This is not the case, but the difference is small and the lamp will work at least reasonably, but light output, life, colour rendering, or efficiency may be poorer than intended.

Take great care if experimenting with HID lamps and circuits, not only is line voltage potentialy fatal, but the high starting voltage is even more dangerous.
HID lamps can burst or shatter with great violence even if operated correctly. The risk is potentialy increased by operation otherwise than as instructed by the manufacturers.


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## XeRay (Oct 16, 2013)

broadgage said:


> It depends on the type of ballast. Electronic ballasts can not be paralleled for various reasons.
> As the O/P refers to 2 ballasts, one lamp, and ONE IGNITOR, that suggests that old type copper iron ballasts are being considered since most types of electronic ballast do not use a seperate ignitor.



Automotive ballasts (he is asking about) are electronic ballasts. The vast majority of modern automotive ballasts in fact do have the igniter seperated from the ballast. The igniter is either attached to the bulb or very close to the bulb.


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