Lithium batteries do have different charging characteristics than lead-acid batteries, and it’s important to use the correct charging method to ensure safe and efficient charging. While an Automatic Charge Relay (ACR) can work well for charging AGM batteries, it’s not always the best option for charging lithium batteries.
Lithium batteries can indeed draw higher charging currents, especially during the initial charging stage. This means that if you were to use an ACR to charge a lithium battery from an alternator, it could potentially overload the alternator and cause damage.
A DC-DC charger is a better option for charging a lithium battery from an alternator as it can regulate the charging current and voltage to prevent overloading. However, it’s important to choose a DC-DC charger that is compatible with your alternator’s output and the capacity of your lithium battery.
Regarding your specific setup, if you’re concerned about the 18A Victron charger overloading your alternator, you could look for a smaller DC-DC charger that’s designed for your particular alternator and lithium battery setup. Alternatively, you could consider a Lithium-specific alternator regulator, which can regulate the output of the alternator to match the charging requirements of the lithium battery.
As for a suggestion, Redway Power offers a range of LiFePO4 batteries and battery management systems that can be easily charged with a DC-DC charger. We recommend consulting with a professional to determine the best charging solution for your specific setup.