12V 17Ah Lead Acid Battery

Hello,

I recently replaced a UPS battery and have the old one to use for some projects. The unit is actually made from 2 smaller batteries that I have now separated.

Each battery is 12 volts, 17Ah
Standby Use: 13.5 - 13.8V
Cycle Use: 14.4 - 15.0V
Initial current: 5.1A Max

I don't want to burn out or overheat my Arduino board so should I use a 5V regulator + heatsink before connecting this to my Arduino?

Is there a better solution?

Thanks,
Alex

You could use a 9V regulator to drop the voltage going into the power jack of the arduino, or connect it directly.
Depending on how much extra stuff you want to power from the 5V line it might not be an issue. A total extra load of another 150mA should be fine.