I didn't think I needed a bench tester I had contemplated doing it, but I'm just using it in vehicle with PCM Hammer, I unplugged most of my other module relays. I read a few guys doing it in vehicle, now correct me if I'm wrong is that not a positive way to do it? I watched a few vids "FixedUntilBroken" on YouTube, he said you can do it in vehicle unless doing multiple is why most people use bench, and I had it hooked to a battery charger while loading it, and I keep it on 14v, and I believe lowest setting was 4amps.