I have a voltmeter / usb / inside temp gauge plugged into mine. The voltmeter is useful; last month it let me know that the generator was dying before I ran my battery down.

https://www.amazon.com/RKURCK-Universal-Cigarette-Thermometer-Temperature/dp/B07GDHQR8Q/ref=sr_1_6?crid=2X05P4XQRLA1Q&keywords=cigar+lighter+voltage+meter&qid=1661273897&sprefix=cigar+lighter+volta%2Caps%2C154&sr=8-6


Gord 🇨🇦
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1954 1/2 ton 235 4 speed