Protecting your boat from overcharging

A properly set up system can prevent damage to electrical components possible with LiFePO4 batteries

- Rebecca Childress

Earlier this year, I finally upgraded from lead acid batteries to lithium iron phosphate (LiFePo4) batteries on my Valiant 40, Brick House. I’d researched for at least a year and South Africa, with its great tech base and good exchange rate, was the place to do it.

Lithium batteries favor the inclusion of a battery management system (BMS) in most applications on boats. The BMS ensures that the battery is not over or undercharged, and that it doesn’t overheat, freeze, or have to deal with oversized currents. Most people understand that a lithium battery BMS is the brains of the charging/power storage operation and will protect the batteries and everything else in the system. But what many fail to understand is that the BMS is not perfected to protect much more than just the batteries. Further measures must be taken to protect both the batteries and the surrounding components.

Many battery manufacturers will tell you that the charging sources installed on your boat will work perfectly with their batteries. In reality, they know your charging sources won’t damage their batteries because ultimately the BMS will be programmed to shut down charging or discharging of the batteries before damage can be done. The BMS, on the other hand, does very little to protect your charging sources, such as your alternator, solar or wind chargers, wiring, or electronics. Whether in the middle of the ocean or anchored in a remote location, a cruising yacht is almost entirely dependent on alternative energy to run important life-supporting systems. It cannot undergo a failure of the energy storage system and still remain safe.

Protecting your sources