Finally got my ticket and planning my first Parks on the Air activation with a KX2 and EFHW antenna. I keep seeing folks mention LiFePO4 batteries but man, the prices are steep! Currently looking at a Bioenno 12V 9Ah for around $180.

For QRP operation (5-10W), would this be overkill? I've read that a 6 Ah LiFePO4 is a good starting point and will keep you going most of the day but wondering if anyone has experience with smaller capacity options.

Also considering just grabbing a cheap SLA from the auto parts store to start - terrible idea or acceptable for getting my feet wet?

Skip the SLA if you're planning to hike anywhere! Lead acid batteries are approximately 3 to 5 times as heavy as an equivalent lithium battery, and if you've had to carry a battery for any appreciable distance, you don't want it to be a lead acid battery.

The 9Ah will serve you well and give you room to grow when you inevitably want more power.

I started with a cheaper 12V 7Ah SLA just to try POTA and it worked fine for my first few activations from drive-up locations. But once I wanted to hike to more remote spots, the weight became a real problem.

The weight difference is immediately noticeable - you can carry twice the usable capacity at half the weight compared to old SLA batteries.

For QRP work, that 9Ah Bioenno is perfect. Having a stable power source that will keep your gear running for hours allows you to focus on making contacts and enjoying the scenery rather than constantly checking voltage levels.

The investment is worth it - these batteries last for years with proper care.