12v car outlet to 5v USB adapter w/ voltage and current monitoring displays (display voltage drop on crank!) $4 shipped
- Deal Link:
- https://www.aliexpress.com/item/4000003 ... 76%232711%
- Price:
- $4.00
- Retailer:
- AliExpress
Not documented but its monitoring is fast enough to capture voltage drop on crank. It uses ~20 mA when plugged in (leds/monitoring). Note that car battery voltage readings from the interior car outlet are ~0.2v lower than at the battery.



