Choosing the Right Battery Charger

Choosing the Right Battery Charger

Purchasing the right battery charger for your marine battery can be a confusing process if you do not know what to look for. This post aims to guide you in selecting the correct battery charger and explain a couple of technical terms.

When purchasing a battery charger, you need to take several factors into account, including your battery type, battery size and the ideal charging time.

Battery Type

First, we need to know what type of battery you have installed, as not every battery charger will work with all battery types. Some battery chargers will be able to charge most or all of these, but it is worth checking the specifications before purchase.
Common battery types include:

  • Gel Cell
  • AGM (Absorbed Glass Mat)
  • Wet Cell (Flooded)

Battery Voltage & Capacity

It is essential to match the voltage of the battery charger to your battery. For example, a 12V battery will need a 12V charger. However, if you have two 12V batteries wired in series, the effective voltage is 24V, meaning that you need a 24 volt charger. If you use a 6V charger on a 12V battery, you will end up discharging it. On the other hand, using a 12V charger on a 6V battery will end badly.

With regards to battery capacity, we mean the amp hour rating of your battery. If your battery charger is too powerful for your battery, it can easily overcharge the battery reducing your battery’s life expectancy. Charging a battery too fast may also result in Thermal Runaway, a dangerous condition where the battery heats up, causing the hydrogen produced to explode.

On the other hand, if the charger is not powerful enough, it will struggle to fully charge your battery, regardless of how long you charge it for.

A safe charging rate is to have a charger with amp rating from 10-30% of the battery’s capacity. For example, a 10amp battery charger will take about 10-11 hours to charge a 100Ah rated battery. A 20amp charger will charge it in half the time.

Unless you have a microprocessor-controlled charger, slow charging will be the best way to charge your battery. When you slow charge a battery, the current has time to distribute evenly throughout the plates and electrolyte, resulting in a fully charged battery.

Smart Chargers vs Trickle Chargers

Also known as Float Charger, Storage Charger and Maintenance Charger, a smart charger is designed to charge a battery as it self-discharges. In other words, a smart charger will keep the battery at full capacity, without over-charging it.

A smart charger relies on receiving a current from the battery to recognize that it is a battery. Hence, it will not be able to charge a fully depleted battery

A trickle charger will keep charging the battery regardless whether it is fully charged or not. A trickle charger will need to be manually connected and disconnected periodically. If left on too long, the trickle charger will boil the electrolyte out of the plates in the battery or damage the plates.

Microprocessor Controlled Charging

Microprocessor controlled chargers provide the most efficient method of charging your battery. The charger collects information from the battery and adjusts the current and voltage based on the battery’s needs. This allows the battery to be charged quickly without effecting the capacity or battery life. These chargers can be connected to the battery indefinitely without risking overcharging or damaging it.

Boating and RV recommend the Schumacher battery charger range, as it ticks all the boxes at a reasonable price. The Schumacher battery chargers feature microprocessor controlled charging, and can charge most battery types. 

17th Oct 2018