What charger do I need for a deep cycle battery?
Tom Vondrasek | 6th May 2023 | 5 minutes to read
Deep cycle batteries are used as an auxiliary battery in your vehicle to run a winch or fridge and are extremely popular in caravans and campervans to provide power for lighting and power points. They are also used in golf carts, mobility scooters and wheelchairs. They are designed to provide constant power — unlike start batteries that provide a burst of power to fire up an engine. Because of this, deep cycle batteries are rated in amperes per hour (Ah).
Assessing the correct type of charger for your battery is important, so here is some crucial information to help you figure out which is best for you:
Types of Deep Cycle Batteries
Deep cycle batteries come in all types of lead-acid batteries, including Flooded (old fashioned wet cell or electrolyte, vented, require maintenance), Gel (Maintenance-free, spill proof Gel), AGM (Absorbed Glass Mat – Maintenance-free, spill proof). There are also lithium deep cycle batteries which are more expensive and lighter than their lead-acid counterparts.
You can get a deep cycle battery that performs both roles, a start battery and a normal deep cycle to run a fridge or winch. These are used where space is limited and there is no room for an additional auxiliary battery.
The important thing when choosing a deep cycle battery is getting one that suits the current draw of the items you are intending to use.
Battery Chargers for Deep Cycle Batteries
Deep cycle batteries are designed to be drained and recharged as that is how they provide power. It is never a good idea to drain them completely. It is recommended to take all lead acid deep cycle batteries down to 50% then recharging to get the most life out of the battery. You can go deeper but you then reduce the number of times you can recharge the battery.
For Lithium deep cycle batteries, it is recommended you can discharge them by 80% before recharging them. This will have no impact on the number of times you can recharge it.
The good news here is that most battery chargers that charge a lead acid battery will work on deep cycle batteries. It is recommended that you use a 9-stage battery for deep cycle batteries as they are a lot better for those battery types than a standard battery charger. The expense is initially higher though, but the payoff is that it will extend your battery life.
They can also sit across the battery and monitor its charge. If the voltage drops below a certain threshold, it will automatically charge up the battery. This is good to have if your item is stored in a shed and you want to have it ready to go at a moment’s notice. The standard no frills charger also works and will charge a flooded, gel, or AGM battery, however it does not do things like desulphation or monitor the battery.
Some modern battery chargers will struggle to charge a dead flat battery if the voltage in it is too low. With all their smarts they still need a certain voltage to tell the charger it has a battery on the end of its leads. You can trick it by putting a small 9V battery across the terminals (positive to positive, negative to negative) and once it kicks off, you can remove it. The 9 Volts is enough to trick the charger into starting off its charge cycle.
Lithium batteries require their own special charger. Do not use a lead acid battery charger on lithium batteries unless it is dual action and has a lithium setting on the battery charger.
What Is Battery Desulphation?
Sulpahtion is where crystalline sulphate builds up on the lead plates of the battery. The more this builds up on the lead plates, the less charge a battery can store. Flooded and AGM batteries are prone to sulation where Gel batteries resist sulation. Battery chargers that have desulphation send out a high voltage and frequency, low amperage pulse designed to knock the sulphate build up off the lead plates. This then dissolves back into the sulphuric acid in the battery. The charger may send out a number of these pulses to try and clear the sulphate. If the sulphate is bad enough, the charger may not be able to fix it.
Buying a Battery Charger
It is always good to know the capacity of the battery in Ah (Amps per hour) and the battery type before purchasing a battery charger. If you have multiple vehicles, you need to check all the batteries and see if you can get a charger to work on all of them. It is also a good idea to get one that maintains batteries so you can move it around vehicles that are not used that often. It may be more expensive though the benefit of being able to start your vehicles when you need them is a real bonus.
If you’re looking to get things moving again, whether it’s the family car, a motorcycle, or even your caravan’s deep cycle battery, head into your local Repco store or shop our range of battery chargers online.
