Author Topic: Running a 50w mv lamp off a car ballast.  (Read 193 times)
xelareverse
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Running a 50w mv lamp off a car ballast. « on: August 28, 2019, 09:04:41 PM » Author: xelareverse
Is it possible to run a 50w mv lamp off a 12v car HID headlight ballast ?  I'm putting in a solar thing in my shed and I want to cut out whatever unnecessary loss as I can so I don't want to use an inverter.
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Medved
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Re: Running a 50w mv lamp off a car ballast. « Reply #1 on: August 28, 2019, 11:40:33 PM » Author: Medved
It will run, but some time after powerup the ballast will overpower the lamp (this is designed to counter the lack of efficacy when the halides are not yet evaporated so when it has to rely on Xenon alone; the automotive standard requires full output after two seconds, way sooner than the halides could evaporate).
Second problem is, the auto MH are pulse start, moreover with teally high voltage (>25kV) ignition pulse requirement. So mainly during hot restart, the lam will be exposed to this high voltage and as MV are not designed for that, they may get destroyed (an arc may ignite in the outer, or in case of vacuum outer it may emit X-rays till the arc ignites).
The second problem could be solved by using D2S ballast - D2S are lamps with the igniter integrated in their base, so the corresponding ballast does not generate the high voltage, so it will be safe with probe lamps. But these are far from common and so very likely wont be available from the usual cheepee sources, only as car spare parts. And because tgese were only in more expensive cars, those spares will be likely more expensive too...
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Re: Running a 50w mv lamp off a car ballast. « Reply #2 on: August 29, 2019, 11:35:09 AM » Author: xelareverse
Ok. I'll have the inverters shut off when not in use so I don't think a hot restart will be an issue. Will the quick power on just shorten the life of the lamp?
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Re: Running a 50w mv lamp off a car ballast. « Reply #3 on: August 29, 2019, 12:53:20 PM » Author: Medved
It overloads the electrodes,the ballasts start at about 90W, then during 10..20s the power is gradually reduced to the final 35W.
Better count on possible damage andso first try it on some not so rare lamp.
Because MV are not that much efficient anyway, so I would expect the power input is not the main thing in the given application (otherwise I would not use MV in the first place), so safer would be to use some decent ballast and a sinewave inverter.

Otherwise when the power demand is a prime factor, way better service you will get from LEDs (they are directly low voltage dc devices, as the solar batteries are).
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Re: Running a 50w mv lamp off a car ballast. « Reply #4 on: August 29, 2019, 03:16:44 PM » Author: Lumex120
Your best option would be to use a magnetic ballast with a pure sine inverter. Smaller ones that could handle a 50w mercury ballast can be had for under $75. I wouldn't recommend using a modified sine inverter, in my experience ballasts don't seem to work as well on them and will get really hot.
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Re: Running a 50w mv lamp off a car ballast. « Reply #5 on: September 02, 2019, 09:00:36 AM » Author: Fluorescent05
Your best option would be to use a magnetic ballast with a pure sine inverter. Smaller ones that could handle a 50w mercury ballast can be had for under $75. I wouldn't recommend using a modified sine inverter, in my experience ballasts don't seem to work as well on them and will get really hot.
Modified sine wave inverters can damage capacitors.
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Re: Running a 50w mv lamp off a car ballast. « Reply #6 on: September 02, 2019, 11:30:37 PM » Author: Medved
Some years ago this circuit was published. It is not that efficient and does not offer as good voltage regulation as the car HID ballasts (well, hard to compete using just two bipolars and a bunch of passives against dedicated circuit using 100+k transistors in the control part within those ICs), but it is simple enough to be built at home.
For MV you just wont use the multiplier chain (that is just the ignitor).

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