Paul C. Buff, Inc. Technical Forum

I've been shooting today with 3 ABs and when I turned them on, they started popping almost every 10 seconds. I use homemade battery packs, but I had no problems with them before, and when I plugged the PWs to flash units, everything worked fine.

But it's still interesting, is it possible that passing cars or traffic light would trigger the flash unit? Cause I had never had a similar issue before, but I've never shot near the crossroad in a busy part of the city either. Or maybe low batteries could be an issue?

Thanks

It is possible passing car headlights could trigger the units. Additionally, odd grounding in the battery packs could do this as well.

thanks. wouldn't the odd grounding trigger the units when the PWs are plugged to the units also?

probably, as well you would likely have seen it before as well. However, it is still a possibility, though more likely the headlights.

It's very unlikely for car headlights to set off a tripper - they don't have enough intensity. What can do this is rapid glints of sun reflecting from mirror-like surfaces.

thanks! that makes perfect sense, since the sun was shining just to the backs of 2 units, and the third one could get reflected from the glass building.

EDIT. I was wrong. I've tried it at home now, and it still fires the flashes when after ~10 seconds when the flash is fully charged. I don't know what is the problem, maybe grounding as you said, cause I didn't even ground the inverter. But I have never had similar problems before. I am charging the batteries now, so I will let you know if the problem will be solved when the batteries are fully charged.

Sorry, i assumed with headlights being an issue, it was night time. Sun light would be far more likely in the daytime. Are teh lights 120 or 220V versions? Are you using 240V to 120V converters, or is the native power from the battery packs the same as the lights? Does the same thing happen if you run them off mains power (assuming mains power is the same as the lights' required power source)?

it's 220V lights. They work fine plugged to the outlet in a studio or at home. I am using the 12V battery and 12-220 inverter(200W), and a light bulb in serial connection, because without it the inverter shuts down when the flash unit is recharging, since it's not current controlled.

And I use separate battery packs for every flash unit, and somehow they all started doing this at the same time. And they work fine when I plug the PWs to the units. I can't understand what could possibly be the problem

For them all to do it at the same time when using optical slaves is not surprising. If you have one renegade light, it can fire the others at the same time, giving the illusion of all of them having a problem. Inserting a plug into the sync jack disables the slave eyes. So iff all of them started working ok after that, then there is likely a slave eye issue, but probably only on one light, the others are just following orders.

no, it's not like that. They didn't fire at the same time, it was just like a cycle. The one head popped, then after about 1sec. the second, and a few seconds later the third one.. And I was shooting outside in the open space, and the flashes didn't trigger the optical slaves.