I think I have seen people proving compatibility between automotive XMH lamps and PSMH lamps (with appropriate ignitor change if necessary). Specifically, I would like to see the specs of a 35W XMH lamp (cause thats what I got), but seeing a datasheet with all of them would be nice.

Obviously there are ignition differences, with PSMH lamps needing ~5kV to ignite and XMH lamps needing 15kV or more. But I am talking about the running specs. Anybody know of any good resources (or just know them off the top of their head)?

Thanks!

Automotive MH lamps with mercury, are 35W, and have the same specs as 35W CMH lamps. Only the starting voltage is very high at 30KV.

D2 Xenon MH lamps:
35W 85V 0,45A

35W CMH lamp:
39W 85V 0,50 to 0,53 A depending in exact lamp type and ballast sollution

So the previous comment is not correct. I would politely ask the author to refrain from commenting when he is not certain that what he sais is correct…

About the effects on compatibility I need to think a wile.

Well, generic 35(39)W MH lamp is specified assuming sinewave current at line frequency. It is a little known that MH lamps need some ~10% less current at the same power when running on squarewave electronic ballast due to power factor now essentially becoming 1 instead of ~0.9 when on line frequency sinewave.

Automotive lamp was for sure never meant to be run on the ballast choke, so may be Dor was not that much off the truth... )

I forgot to say XMH lamps can work on 35W CMH electronic ballast.
Or I am confused and the opposite is true that 35W CMH lamps can work on XMH ballasts?

Well, generic 35(39)W MH lamp is specified assuming sinewave current at line frequency. It is a little known that MH lamps need some ~10% less current at the same power when running on squarewave electronic ballast due to power factor now essentially becoming 1 instead of ~0.9 when on line frequency sinewave.

Automotive lamp was for sure never meant to be run on the ballast choke, so may be Dor was not that much off the truth... )

Yes indeed I am aware of that. The current figure come from Osram datasheets, with 0.5A for an lamp exclusive for electronic ballast and the 0.53A for a lamp with choke. However I have looked at IEC 61167:2018 and there the following is specified:
With a choke: 0,53A
With an electronic Ballast: 0,46A.

So if we take ground on the IEC standard -what we should-, dor123 is correct and i apologise. However I find it strange that Osram lists other currents for their electroic only lamps.

Regarding interoperability:
D2 lamp on choke: Might work, however may have reduced lamp life as a choke has a higher current crest factor ans therfore more wear on the elctrode. Also the 15-25kV Ignition pulses may damage choke isolation.

Running a D2 lamp on 35W electronic ballast-does not work, no ignition, I have alredy tried that.

Running a 35W CMH on D2 gear, possible, maybe slightly underdriven, but that would need to be checked. However there may be problem when these lamps are tried to be hot restricken as they are not made to whithstand the ignition voltage.

When I am back home i would do some experiments with that. I have philips Prima vioson elctronic gear for CMH and two D2 lamp contrrolla, one BMW branded (Most likely made by Hella) and one chinese and see how they perform. 

What I am also not sure, how exactly the D2 lamp ballast drives the lamp. When the lamp is first inited the ballast "overloads" The lamp in order to get it warmed up quickly.

Given the arc voltage tolerance and so the range of the corresponding actual arc current variation any arguing whether the "correct current" is 0.45 vs 0.5A is rather moot, it is just arguing what "nominal current" label should be placed for the whole range the things operate.

More important is the exact power tolerance, mainly including factors like mains voltage sensitivity of the magnetic ballast, plus the current crest factor.

And also do not forget the auto MH do not anticipate anything but square wave LFAC feed, the mains zero crossing reignition characteristics is just a completely unpredictable huge unknown, could be OK for one lamp and a complete disaster for other even when both are the same formal specs.

And obviously the mentioned ignition/startup problems.

May be ignitor-integrated D1 lamp or D2 combined with an ignitor socket will have a chance. Don't know exact ignitor schematic though, so no idea if it really needs a DC phase of lamp voltage present with automotive ballast at start to generate ignition pulsed successfully.

Most important here is the power difference, and operating frequency. 

The XMH lamps have rod electrodes often with balled ends, whereas CMH usually have a heat radiator coil on the tip.  If you run an automotive lamp at low frequency, the cyclic current variation causes overheating of the electrode tip with irreversible damage during life - and on average too much heat loss via the rod to the seal.  These electrodes can only survive on the long term at higher frequencies : the design was optimised for use at 400Hz.  You can usually hear this while they are operating on the correct ballast.  Use at 50/60Hz will destroy them rather quickly.

Moreover, general lighting lamps are actually rated 39W, not 35W.  Even if you use a higher frequency CMH ballasts the RMS power is higher, and likely to accelerate not only electrode damage but also quartz corrosion.

By the way, the actual ignition voltage of regular automotive XMH lamps is rather low - its only for hot restrike that very high voltages are required.

@James: What is the pressure of xenon inside XMH lamps, that they provides instant light during starting?
As far as I know, only in the US, 35W MH lamps are rated 39W, not at the EU and other territories.

that is not correct. IEC 61167 rates these lamps at 39W as well.
The german DIN standard is the same as the IEC for these lamps as well as most other european national standards. If you look at datasheets, from example from Osram, these are also rated 39W

Correct, as far as I know all “35W” metal halide lamps except the automotive type are actually 39W.  Same as the 70W are actually usually somewhere closer to 75W, and the Philips 20W PGJ5 capped types are actually 22W.  The reason is in part because they were developed to run on HPS standard ballasts, but due to the very different power factor of the metal halide discharge their actual power dissipation is rather higher, despite having tried to limit that by reducing the arc voltage vs HPS.  Electronic ballasts will however often run the metal halide lamps at lower RMS power, due to the power factor of the discharge approaching unity at higher frequencies.