How to Monitor a Deep Cycle Battery
To know when a deep cycle or marine battery needs charging you first need to know how much charge it has. To accurately check this, you can use a battery monitor.
Battery monitors can tell you how much charge a battery has left and sometimes even more. The ANCEL BA101 Professional 12V Digital Analyzer can tell you how much charge the battery has, the health, cranking power, voltage, and more. There are even Bluetooth versions you just connect to your battery then use the app on your phone to see the charge of the battery.
When Does a Deep Cycle Battery Need to Be Charged?
Deep cycle batteries are made to withstand being discharged to 50% over and over again and take minimal damage. If you want your deep cycle batteries to last for years to come with zero damage then charging them before they go below 50% discharge is the optimal way to go.
That being said it can be very difficult to stop a battery from going below 50% especially if it’s what’s running the lights in your trailer. The damage when the battery goes below 50% is minimal and as long as you never let it go below 30% the battery will still be able to hold a decent amount of charge for a long time.
AGM batteries are better than gel or wet lead-acid deep-cycle batteries when it comes to discharging damage and Lithium-ion is even better than AGM. If you are planning on draining your battery to 20% over and over again getting a deep cycle Lithium-ion battery is a good idea.
Long story short if you have any kind of lead-acid deep cycle battery then charge it when it gets to 50%. If you have a Lithium-ion deep-cycle battery charge it before it goes below 20% and your batteries will last for years to come.