PSA: Check your star tracker batteries before a long session

I spent 3 nights at Cherry Springs last month shooting the Veil Nebula, thinking my exposures looked fine on the back of the camera. When I stacked everything at home, the stars were all trailing just slightly, like 3 or 4 arcseconds. Turns out my iOptron mount's battery was dropping below 11V after 2 hours, so the tracking was glitching without any warning on the hand controller. I replaced the battery with a fresh one and re-shot the same target in one clear hour, and the difference was night and day. Anyone else had a mount silently fail like that and blame their polar alignment first?

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1 Comment

angela_grant6h ago

Ha, funny you blame polar alignment first. That low voltage sag is a real killer, but your hand controller usually blinks a battery icon before it fully gives up. Both my mounts did that and I ignored it for weeks.