Review on 🔌 Battery Tender USB Charger Adaptor: Charge Mobile Devices on the Go with 12V Vehicle Battery - 081-0158 by Joseph Scalea

Usually remove the seat. Get my multimeter from my tool kit and measure the voltage. Now I just plug this amazing gauge into the pigtail socket and it tells me what I want to know without removing the seat. For most cars/trucks/motorcycles you need at least 12.5V when idle. When idle means the car was NOT started for at least 12 hours before you took the reading. The reason is that when you start and run your car, the alternator is charging the battery and the reading will be higher because the battery has a new surface charge. So remember to plug it in after 12 hours of battery inactivity for accurate readings. Anything below 12.5V means your battery is dead. This is a must for your motorcycle!