Reddit reviews DROK Precision Variable 2 Wires 3 Digits Digital Voltmeter DC3.5-30V Voltage Meter Tester 12V/24V Volt Gauge Panel Power Supply Detector Monitor with Bright Red Display and Black shell for Car Vehicle Solar Boat Battery Monitoring
We found 1 Reddit comments about DROK Precision Variable 2 Wires 3 Digits Digital Voltmeter DC3.5-30V Voltage Meter Tester 12V/24V Volt Gauge Panel Power Supply Detector Monitor with Bright Red Display and Black shell for Car Vehicle Solar Boat Battery Monitoring. Here are the top ones, ranked by their Reddit score.
Small size (48 x 29 x 21.5 mm) and wide voltage measuring range (DC3.5-30V).Two- wire connection, simple and convenient. High accuracy: +/- (0.5% + 2 Digit).The meter requires no extra power supply, meaning the tested voltage could work as a power supply.This module is not fit for 24V truck for the voltage of a fully-charged truck battery is above 28V.With anti-reversed connection protection prevents the meter from burning, hence safe to use.
If it's useful, I too just got started, and built a similar drone. When it came to charging, I had to read a ton of stuff. Here's what I did (all non-referral Amazon links. you may find cheaper on banggood if you want to wait forever):
ISDT Charger
12v Power Supply
Balance Charger
To connect these up, it may be useful to have some extra XT60 plugs since the power supply won't have XT60, and neither does the balance charger.
With these optional parts, I was able to make a nice looking (and more safe) charger from the power supply, along with a 3d print available here
Voltmeter
Power plug
I found this to be a pretty fun project, and wasn't as expensive as some options I saw on HobbyKing or everywhere else. To be fair, it wasn't the cheapest option either.