No insulator. When a battery in the system reaches 13.3 volts, it completes the circuit. This means that attempting to charge the vehicle will drain your auxiliary battery when it is fully charged.
Xiaomi 70mai Jump Starter Midrive PS01
120 Review
CARKU Pro-10 black/red
91 Review
Keep Your Battery Fully Charged With A Smart 12V Charger/Maintainer Featuring Winter Mode
28 Review
Mroinge Automatic 6V/12V Trickle Charger For Vehicles, Motorcycles, Boats And More - Maintain Your Batteries With Ease!
29 Review