Instructions for Pro 12v 20A lifepo4 battery charger

[seiran5x5]

I just purchased the Pro 12v 20A lifepo4 battery charger to charge my Sok 206ah battery and the instructions are very lacking, The little pamphlet said to plug the charger into ac power first which goes against everything I've been told so I didn't plug it in before connecting the clips. I connected the positive Aligator clip first, but when I went to connect the negative I got a spark. I immediately stopped and started searching for better instructions but can't find any, any help with instructions would be very appreciated.
Thanks, R.H

 

[sunshine_eggo]

By plugging it in first, you've energized it to ~14V. Thus when you connect it to a 12V battery, there is only a small voltage difference.

When you connect it with the PS unenergized, you have a ~12V difference in voltage. Hello spark.

Did you try following the directions?

 

[seiran5x5]

I'm charging right now, and like you said no more sparks.
Thanks for the help, I truly appreciate it.

 

[sunshine_eggo]

FWIW, there is nothing inherently wrong with energizing a power supply or charger prior to connecting unless they explicitly prohibit it.

Many "intelligent" chargers benefit as they have additional protection/features if energized when the battery is connected.