You can use an Ignition On input in place of the Alternator D+ feed.
Yes, in many cases, an ignition-switched 12V feed can be used as a substitute for the alternator's D+ signal to activate a DC-to-DC charger. The D+ signal is traditionally used to indicate that the engine is running and the alternator is charging, but a switched ignition feed provides a similar function, ensuring the charger only operates when the vehicle's engine is running.
Here's a more detailed explanation:
- D+ and Ignition Feed:
Both the alternator's D+ terminal and a switched ignition feed provide a voltage signal when the engine is running (or the ignition is on).
- DC-DC Charger Activation:
DC-DC chargers typically require a signal to indicate when the engine is running, so they can safely charge the leisure battery from the starter battery.
- Using Ignition Feed:
If you can't easily access the D+ signal on your vehicle (which can sometimes be difficult), using a switched ignition feed is a viable alternative.
- Considerations:
Some DC-DC chargers are designed to work with a switched ignition feed directly, while others might require a relay to handle the current draw from the charger.
- Smart Alternators:
Some newer vehicles have "smart alternators" that regulate voltage more dynamically. In these cases, using a relay and potentially a voltage sensing relay is recommended to ensure proper charging.
- Benefits of Ignition Feed:
Using a switched ignition feed can be easier than finding and connecting to the D+ wire, especially if you are not familiar with your vehicle's wiring diagram.
- Installation:
When using an ignition feed, it's crucial to ensure it's a reliable and switched source that only provides power when the engine is running.
