Can You Charge A Leisure Battery With A Car Charger?

Is it OK to charge a leisure battery with a car charger?

And the answer is…

Yes. In most cases.

Let’s talk about why and we’ll let you know exactly under what circumstances it’s okay to use a 12V car battery charger to charge your 12V leisure battery.

What’s the difference between a leisure battery and a car battery?

Let’s see what aspects are the same and what aspects are different for leisure and car batteries.

Firstly, what do they have in common?

1. They’re both, in the vast majority of cases, 12V lead-acid batteries.
2. Both leisure batteries and car batteries main categories are:
   • Standard (Flooded/wet)
   • AGM
   • Gel

That means they both have lead plates inside the battery casing, and an electrolyte (a mixture of sulphuric acid and distilled water) in contact with the lead plates.

What differences do car batteries and leisure batteries have?

By far the most important difference is the following:

Car batteries are designed to provide a very large, short burst of power to start the vehicle engine (as well as a stable flow of power for the car electronics systems). Whereas leisure batteries are designed to provide prolonged, slow release of power over a long time.

To satisfy these differing demands, car batteries and leisure batteries have some differences in their internal structure to best meet their respective power demands.

A car battery has many, thin lead plates. The increased surface area allows for more reactions with the electrolyte inside the battery. More reactions means a large boost of power that is powerful enough to start the car.

Leisure batteries, on the other hand, have fewer plates which are thicker. These thicker plates make it easier for the battery to deliver a sustained, steady release of power over time.

Another difference is that in recent years, Lithium leisure batteries have become more popular as they fall in price, while car batteries are still very much dominated by the lead-acid kind.

For the reasons mentioned above, it’s not advised to use a car battery for leisure purposes. They’re not built for a long-term, slow release of power. Their thin plates don’t cope well with being discharged too much (which is what happens often in leisure use).

As a result, sulfation happens much faster and more severely.

What does this mean for charging leisure batteries?

Basically, it means that you can use the exact same charger for leisure batteries as you do for car batteries.

That’s because car and leisure batteries have more in common than they have differences. They both use the same principles to store charge and deliver power.

That is, when fully charged they have an excess of electrons on the negative plates (each cell in a battery has positive and negative lead plates). When they deliver power to something, it’s the transfer of electron the device that provides power to it from the battery.

How do battery chargers work?

Battery chargers of any kind work by sending electrons to the negative lead plates, which then flow to the positive plates.

This results in a difference in potential between the plates (that’s what voltage means), and therefore the battery has now become a source of charge again, which can power things.

The differences between leisure batteries and car batteries mean that you should NOT use a car battery to power leisure vehicles.

But it’s also true to say that:

The similarities between car and leisure batteries mean that you CAN use a car battery CHARGER on leisure batteries.

So will any car battery charger work?

Here’s the important thing.

Leisure batteries tend to have a much higher capacity than car batteries.

A car battery for a medium sized car is only around 40-50Ah, while an average leisure battery is around 100Ah.

Therefore…

You need to make sure the charger provides a high enough amperage for your leisure battery.

Let’s discuss how to do that.

How many charging Amps do I need?

The rule of thumb is that your battery charger should provide charging Amps at least 10% of the battery capacity, in Ah.

So, for example, a 90Ah battery should be charged with a minimum 9A charge. (Since 90Ah * 10% = 9A.)

What will happen if I charge with Amps below 10%?

You may be thinking, ah, it just means it’ll charge slower.

But no, it’s worse than that.

Charging a lead-acid battery with an Amperage below 10% of its capacity means that the charge you’re providing doesn’t have enough oomph to fully charge the battery.

What does that mean?

It means the battery will start to degrade and it’s lifespan will be severely shortened.

That’s because lead-acid batteries don’t cope well with undercharge, and sulfation builds up on the battery plates. Sulfation is the collection of lead sulfate, which effectively smother the battery’s ability to store charge and hence deliver power.

Do I need a special charger for a leisure battery?

Categorically, no. There’s absolutely nothing about a leisure-specific charger that would perform better than a quality car battery charger.

There’s no aspect of charging a lead-acid leisure battery that requires anything different than a lead-acid car battery would.

In fact, that the best lead-acid battery chargers in the world are car battery chargers. The best car battery charger models by CTEK and NOCO have features that are far beyond what other makers can achieve due to their multi-stage charging processes.

So, if you were to try to find a charger specifically for leisure batteries, you would be missing out on the best technology on the market.

What type of charger should I get for a leisure battery?

Ideally, you’ll want to use a smart charger.

A smart charger means that it automatically detects the condition and charging state of the battery, and delivers the right type of charge at the right time.

The best smart chargers, by CTEK and NOCO have as much as 8-phase charging processes. That involves a fast bulk phase, absorption phase and trickling phase, among others. They ensure that the battery is not damaged by receiving too high a charge, and yet still receives the complete 100% charging that it needs to stay healthy.

They also have desulfation modes, such as the famous CTEK Recond Mode, that’s been known to rescue batteries that seemed to be dead due to sulfation. NOCO’s desulfation mode is particularly good as well.

A charger with a quality desulfator mode can lengthen the lifespan of your battery by as much as 2 to 3 times.