Just did this a while ago...
TK70 - 218
OTF (out the front). Sustainable for quite a while. 2200L ANSI
DRY triple XM-L direct drive, Sky Ray SR3800 drive drive - 250
OTF after 5 seconds, and very slowly sliding down
Ebay 65W with about 5300k bulb - 389
OTF (3" reflector) (takes at least 5 mins to slowly warm up to this level, initial about 330 only after 20 seconds). Aluminum mirror (whatever that means) has a theorectical max reflectivity of 91%, i learnt this from Discovery channel on a show "World's Toughest Fixes" on a repair job on one of the world's biggest telescope on Mauna Kea on Hawaii called the Keck telescope (there are 2 of them). I think with the reflector which is not great it would reflect like say 82%? The lens takes away 7%. So prob about 5100 lumens at the bulb. I have another copy of the 65W and it's 362 OTF
. I am not sure if you are talking about me, but if we apply 1.2 x 389 it would be about 4600L.
Amondotech 3152 (6" reflector) 55W ballast measured at 58W input (not to the bulb) and the same 35W 4300k bulb which was provided with the light back in 2006 by bro mtbkndad who sold a few batches i think (Philips?) - 380
We can back calculate. Take 85% for reflector and 7% for glass. So 3800L OTF would be 4600L at the bulb. 58W to the ballast means 46W to the bulb (take 80% eff). So that's 100 lumens per watt.
-Sanmak SM5200 with 100W ballast (measured 98W in) with 55W 4300k bulb - 545 OTF
This bulb is deformed though, and this is a Chinese bulb purchased from an aliexpress vendor. 5400L OTF = 6600L at the bulb.
98W input means 78W to the bulb. So that is 84W/lm efficacy.
-Changed out to the 100W bulb (it states 100W, not 75W, but same white ceramic base), got 660
That's approx 6600 lumens OTF from just a 12V 5.5AH SLA. As expected the longer arc length increases efficiency somewhat.
- Used a 7AH battery to power. Got 681
- Used 2 x 7AH @ 24V to power, got 718
I think with correct wattage bulbs it would be brighter. But less throw due to longer arc length.