12v Solar Charger Work?

Earplug

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Trickle charging via the OBD-II port is a convenient method for maintaining 12V batteries, as pin 16 provides constant power. It is commonly used for solar panels or low-amp tenders to prevent parasitic drain, especially during long-term storage. Generally considered safe with low-power chargers, it is recommended to keep charging rates below 3 amps to avoid damaging the vehicle's electronic modules.
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Key Considerations for OBD-II Charging:
  • Always-On Power: The OBD2 port's 16th pin is connected directly to the battery, allowing charging even with the ignition off.
  • Recommended Chargers: Low-wattage devices, such as the Sunforce 3.5W OBD-II Charger or ECO-WORTHY 10W OBDII Solar Charger, are suitable for this method.
  • Safety Limits: While some argue it is unsafe, others suggest that low-current solar trickle chargers (under 5W) pose little risk and are effective.
  • Use Cases: Ideal for maintaining battery charge when parking at airports, shipping vehicles, or in storage.
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Best Practices:
  • Avoid High Amps: Do not use high-amperage smart chargers through the OBD port, as it is not designed to handle high-current charging.
  • Monitor System: If you have concerns, refer to specific advice on using an OBD-II Solar Trickle Charger or discuss with your local RX-8 owners club to learn from others' experiences, according to user Reddit posts.
  • Connection Check: Ensure the adapter is properly seated; the constant power (pin 16) and ground (pins 4/5) are the only ones necessary, as detailed in this DIY article.
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You could also use the port in the front bumper and run a wire pair externally through a door that would go to your solar panel inside the car. The only problem with this is that those connectors are dead until the voltage drops below some point.
I run a scan gauge off the OB2 port. If I do not unplug it at night the voltage will be just below 12v and the alarm to take my car to the dealer is in. When charging the car the 12v system stays charged up, but the 12v charging goes away when the charging stops. Someone came up with this info below if it helps.
 

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You could also use the port in the front bumper and run a wire pair externally through a door that would go to your solar panel inside the car. The only problem with this is that those connectors are dead until the voltage drops below some point.
I run a scan gauge off the OB2 port. If I do not unplug it at night the voltage will be just below 12v and the alarm to take my car to the dealer is in. When charging the car the 12v system stays charged up, but the 12v charging goes away when the charging stops. Someone came up with this info below if it helps.
The port in the front bumper does not supply power to the 12V battery. It only works to pop the frunk when the 12V battery has actually died.

I had a ScanGauge always hooked up to my 2005 Prius and 2012 Plug-in Prius and they never had a problem with the 12V battery drained. Unclear why the Mach-E would be different, unless the ScanGauge is keeping the various system modules active even after powering off the car and waiting 12-minutes.
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