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Battery & battery charger terminology explained

Tom Vondrasek | 28th Aug 2023 | 5 minutes to read

With the push to make ever more efficient and better batteries for vehicles or a trailered mobile home with all the creature comforts found in a house, battery technology has gotten complex. Battery charges have gone from providing a single stage charge to up to 9 individual stages including monitoring the battery.

Keeping up with this is no easy feat as companies can muddy the waters by coming up with their own terminology for a device or features. I am only going to cover batteries found in a vehicle with a petrol or diesel engine or a caravan or campervan. Electric vehicles — popularly known as EV’s — are a different thing again and not covered. I will cover the chargers for these batteries as EV’s need to be plugged into a serious power point; standard chargers just won’t cut it.

Here are the some of the main topics we’ll be looking at in this article:

  1. Batteries
  2. Maintenance & Maintenance Free Batteries
  3. Lithium Battery Types
  4. Battery Chargers
  5. Common Vehicle Batteries — Lead Acid or Lithium?

Different Types of Batteries

I need to cover batteries first as the changes to these devices dictates the type of charger you need to keep them working at their best.

Batteries Used for Starting Engines

The most common battery found in your vehicle is the battery used to start the engine. There are 2 types. They are commonly known as a start battery or a stop/start battery.

Start Battery

These have not changed in decades. A start battery is needed to crank over your engine (petrol or diesel) and start it. That is its main role. Once the engine starts, the vehicle’s charging uses the alternator to keep the vehicle running. The alternator is an electrical generator that provides power when the engine is on, as well as recharging the start battery for your next start. Start batteries are rated in CCA (Cold Cranking Amps) or the electric current required to start the engine.

Stop/Start Battery

Newer technology designed to save fuel and emissions. It cranks over your engine (petrol or diesel) to start it, the same as the start battery. Its additional role is to provide electric power when the vehicle is stationary at traffic lights or in a queue.

Vehicles equipped with this technology stop their engines when the vehicle being driven is stationary. This means the alternator in the charging system stops and cannot provide power until the engine comes back to life. The stop/start battery provides electric power while stationary and restarts the engine when you move off.

To allow for this, stop/start batteries are much bigger and more powerful than a start battery for a vehicle with the same engine capacity. They are also rated in CCA (Cold Cranking Amps).

Auxiliary or Deep Cycle Batteries

These batteries power caravans and campervans as well as fridges and winches in a vehicle. They differ from engine start batteries as they are designed to be drained and recharged and provide constant power. They run 12 Volt and 240V (via an inverter) appliances and are heavy duty batteries. They are not normally used for starting engines.

Auxiliary and deep cycle batteries are rated in Ah (Amperes per hour) or how much electric current in Amps the battery can constantly produce in an hour.

Maintenance & Maintenance Free Batteries

A basic battery consists of lead plates in an acid bath (electrolyte) to provide electrical power. For a 12V battery it is normally divided into 6 separate sections called cells which contain lead plates in electrolyte. The cells are internally connected to two battery posts (negative & positive) at the top of the battery on either end. These posts connect the battery to the vehicle.

The electrolyte is liquid like water and with use, this acid level can decrease and needs to be topped up. The battery needs to be vented to the open air as they build up gasses when being used. It is mainly the water content in the acid that slowly escapes in this process.

All batteries either require maintenance or are maintenance free when it comes to managing electrolyte levels.

Maintenance Battery

These batteries need to have their electrolyte levels checked. They are easy to pick as they have 6 screw-in caps across the top of the battery, one for each separate cell.  These can be opened to check electrolyte levels and be topped up as required.

Some very important points

  • Wear safety gear including glasses as battery acid burns.
  • Top up with distilled water and not tap water. Distilled water is cheap and available at Auto parts stores.
  • Do not overfill the cells! Most batteries have internal level indicators, and these must be respected. If not, just make sure the electrolyte is just covering the lead plates.

Maintenance Free Batteries

Popular acronym is MF (Maintenance Free) or SMF (Sealed Maintenance Free)

Extremely common and easy to identify as there are no screw-in caps across the top of the battery. They still have 6 cells with lead plates in an electrolyte bath. While still vented they use a clever, propriety recirculation system to keep the electrolyte in the battery so there is no need to top it up. They are usually labelled maintenance free or sealed.

True SMF batteries are known as VRLA (Valve Regulated Lead-Acid) batteries.

Lead Acid Battery Types

As mentioned earlier 12V batteries have 6 separate cells containing lead plates in an electrolyte (acid) bath, connected together and providing a charge via 2 battery posts at either end of the battery. That is a basic description to give you an understanding of lead acid battery construction. There are variations of these types of batteries, though they are all still classified as lead acid batteries. I will run through some of the most common types.

Wet Cell, Flooded, EFB (Enhanced Flooded Battery)

Basically, your original lead plates in an acid (electrolyte) bath. EFB have improvements over wet cell and flooded battery types to improve cycling and charging in stop/start applications.

Calcium Batteries

Calcium is added to the lead plates to improve strength, charge, and electrolyte loss.

Gel Batteries

The electrolyte is turned into a gel. They have a longer service life than wet cells, are spill proof, very durable and vibration resistant. They are a true sealed maintenance free or VRLA battery.

AGM (Absorbed Glass Mat)

The electrolyte is turned into a paste. They are a popular choice for deep cycle batteries as they are spill proof, maintenance free, fast charging, and work in a range of temperatures. They are a true sealed maintenance free or VRLA battery.

Lithium Battery Types

There are 2 main types of Lithium batteries:


Lithium-ion batteries are often used in electric vehicles and utilise lithium ions that move between the negative and positive electrodes to charge and discharge the battery. The electrolyte will generally be a lithium salt in an organic solution (usually dimethyl carbonate or diethyl carbonate).

Lithium Iron Phosphate (LiFePO4)

These batteries use an iron-phosphate for the cathode and a mixture of metal and a graphitic carbon electrode for the anode. These batteries offer improved discharge and charge efficiency compared to lithium-ion batteries, as well as longer lifespans, with optimal conditions offering up to 10,000 cycles. They’re often used as a deep cycle or auxiliary battery.

Battery Chargers

Once you have identified the battery type and size that needs to be charged, the battery charger selection is the easy part. If you have an existing charger, you may need to upgrade it if it cannot cater to your new battery type. Most new battery types charge better and last longer if the charger can cater to them. They prefer a staged charging approach rather than a simple constant charge. 

Image of a battery charger with booster cables

Most modern battery chargers will detect the battery type (listed above) and charge it correctly based on how much charge is in it. They are simple to hook up and you usually do not need to disconnect the battery and take it out of the vehicle. Charging is best done undercover and out of the weather.

If your charger is older, you need to select the correct battery type and charging current in Amps. Battery chargers have an instruction book and will have recommended settings for battery types and charging Amps. It is worth taking the 5 or 10 minutes to read it rather than damaging your $250 battery.

Common Vehicle Batteries — Lead Acid or Lithium?

Most vehicle batteries apart from EV’s still use some type of lead acid battery. If you have a more modern lead acid battery charger, it will work for all lead acid batteries. The engine start & stop/start batteries are lead acid. It is auxiliary and deep cycle batteries where lithium is becoming popular.

Do not use a lead acid battery charger on a lithium battery unless it has a setting for lithium batteries on it. You will damage your lithium battery if you do not use the correct charger for it. There are battery chargers on the market that specialise in lithium batteries, so best to opt for one of those. 

Head Into Repco for Your Battery Charging Needs

Don’t let the electrical gremlins spoil your next trip or Sunday drive. Stay one step ahead with quality electrical tools and parts from Repco. Not sure how good that old battery is? Bring it in store and we will test it for free. Then you know whether it is worth charging or if it’s best to replace it.

Here at Repco, we can help you out with whatever you need as far as batteries and battery chargers go. With a broad range of batteries and battery chargers, we are sure to have the products you need at a price you can afford. If not, keep an eye out for our specials and sales. Our friendly staff can work with you on your battery charging needs and we also have jumper leads and a range of jump starters to get you out of trouble.

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