LPHUS TONWON Car Battery Tester, Bluetooth Wireless Automotive 12V Battery Load Tester Charging System Diagnostic Analyzer Monitor for Android & iOS Device

I use this to repair RV's and be able to monitor if the batteries are charging, their rate of discharge and as it monitors the batteries, I can walk away and get other work done and come back days later if I want to see what the batteries have been doing. Saves me a ton of time and tools not having to sit there and watch the batteries as this device does it all for me.