Need help/information for setup!

FrankL

Hello everyone I’m new to the whole Lithium crowd and have a few questions and looking for advice.

Previously I had my boat (with smaller outboard engine and a 18amp alternator) set up that the main engine battery (24 series 850CCA) would recharge 1× 27 series AGM used for the trolling motor when the motor was running via Automatic charging relay (ACR) and it worked very well on long extended trips away from a power source to recharge.

I’m looking to now replace the AGM with a Lithium to save weight and I’d also gain a bit of capacity. But here’s the question. I read online that Lithium batteries take lots of amperage vs AGM and some state that a Automatic charge relay is a bad idea for the alternator and to use a DC-DC charger. The problem is that the smallest dc-dc charger I can find is a victron smart 12-12 /18amps. Wouldn’t this burn out my alternator? What other options do I have? Am I stuck and should keep original set-up with Lead acid and AGM?

Thanks

ahmadraza

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.