A quick guide to trickle chargers

There are many joys to classic car ownership – and also, of course, a few things to be aware of.

For example, classic cars will tend to need more regular maintenance than their modern counterparts – and that is one of the reasons we always recommend some specialist classic car insurance to anyone lucky enough to own a vehicle of a certain age.

Another factor to classic car ownership is that you may well be covering fewer miles in your vintage vehicle than you would be in a modern car.

This is not always the case, of course – some owners treat their classics as regular runarounds. But for many people, a classic car is something that's tucked lovingly away in the garage and taken out for a spin on sunny Sundays, while their modern car performs all the more mundane day-to-day tasks.

And that is, indeed, a lovely way to enjoy a classic. One factor to be aware of, though, with low-mileage cars, is that a lack of regular use can cause damage to the car's battery. Why is this? Well, car batteries need regular use to keep them topped up, and a car that's left unused for a significant length of time – more than a week or two, say – can develop a flat battery, or even a permanently damaged one.

In the case of a car that's getting regular use, the alternator plays the crucial role of maintaining a near-full state of charge – but for a car that's getting less use, and a battery that's been allowed to run down, the alternator won't be much use.

You may have some very valid reasons for only taking your classic out occasionally. Perhaps you don't want to put too much strain on it; perhaps, for much of the year, the worst of the British weather won't do the car any good. Perhaps a stipulation of your classic car cover is that the car only does a limited amount of miles each year.

So, in these instances, how can you keep your car safely garaged for extended periods of time, without running the risk of damaging the battery through underuse?

Step forward two useful little devices – the trickle charger and the battery conditioner.

What is a trickle charger?

A trickle charger is a device that helps an idle car battery to retain enough charge to keep working. It gets its name from the fact that it 'trickles' a low-voltage charge from the mains into the battery, thus averting the risk of overcharging. By doing this, the trickle charger can improve your car battery's long-term health.

More specifically, a trickle charger will top up your car's battery at the same rate as the battery is discharging, allowing it to maintain a constant set of charge. The fact that it uses such a low voltage means that you can leave a trickle charger to do its work for a relatively long time (a little further down, we'll look into just how long these devices can be left on). Some can be left on a car battery indefinitely, in fact – but you should always check the instructions on any charger you buy before using.

What is a battery conditioner?

A battery conditioner does a slightly different job, but can be just as crucial to the welfare of your battery.

Over time, lead-acid batteries in little-used cars can develop deposits of lead sulfate. These deposits can build electrical resistance, and in turn lessen the battery's ability to hold its charge over long, idle periods. That resistance means that the battery is unable to reach full charge – and may even appear to be failing.

The battery conditioner targets these lead sulfate deposits, and thus restores lead-acid batteries to their full capacity. Specifically, the battery conditioner dissolves the sulphur deposits by sending high-frequency pulses through the battery.

From these descriptions you can see that both trickle chargers and battery conditioners can be hugely useful in maintaining the health of car batteries, especially in vehicles that get relatively little road time. Owners of classic cars, 'second' cars and any other vehicles that don't get regular use may find these devices extremely useful.

Should you consider investing in a trickle charger or battery conditioner?

If you have a car that gets relatively little use, the answer is yes. One of these devices will be particularly useful for maintaining the health of a battery in a car that doesn't get a lot of usage.

Weekend classics, vehicles declared SORN, cars left unattended in storage for extended periods – these will all be prime candidates for a battery conditioner or trickle charger. In particular, the latter device can be crucial in keeping your battery healthy and warding off any problems, while the battery conditioner may be required once the battery develops some performance issues.

When should you use these devices?

If there's going to be a prolonged period when you won't be driving your car, you're best off using a trickle charger before this period of inactivity, and before the battery’s capacity goes down. A battery conditioner, meanwhile, is likely to prove useful once your battery is showing signs of holding less charge than before.

Be aware that both devices use mains electricity, so long cables are likely to be involved. If you use on-street parking rather than garaging your car, this may mean running cables across the pavement, which may be an inconvenience or even a hazard for pedestrians.

How to use conditioners and trickle chargers

They may work slightly differently, but the instructions for using these two useful devices are very similar.
First of all, you should ensure that your car is parked somewhere with plenty of air circulation. Also make sure that the engine is off and the key removed from the ignition.

Next, select the appropriate power settings for your battery, using the device’s controls. Typically, a car battery will take a 12-volt charge – but check your owner's manual to be sure.
Before you start charging, use a piece of steel wool to rub away any rust around the battery terminals. This will give a better connection for charging.

Now, you will need to ground the charger, in order to reduce the risk of an electrical surge. You can do this by attaching it to a metal part of the engine (or somewhere on your car's chassis).

Now, attach the charger's red clip to the car battery's positive terminal, and the black clip to the negative terminal. (If you are charging a modern car, you probably won't use the battery's negative terminal, as doing this may bypass the car's battery management sensor. Check your vehicle handbook for clarity here).

Leaving your charger switched off, you can now plug it into the mains socket. You are now ready to switch the charger on. Make sure it's not giving off any sparks or heat – turn it off and re-examine connections if it is – and leave it for charging, for as long as the manufacturer instructions indicate.

Safety precautions

Make sure you follow the instructions on how long the charger can be left working. These devices should not be overworked or allowed to overheat.

The heat produced by the charging process can also, on occasions, produce a harmful gas. As well as being unsafe to breathe, this gas is highly flammable. For this reason, always choose a well-ventilated place to carry out the charging. A dry environment is also essential.

Lastly, check in your vehicle handbook whether the particular battery conditioner or trickle charger is suitable for use with your car battery. You don't want to end up causing damage to your car battery or wider engine components, especially as that damage may not be covered by your vintage car insurance.

In the case of older and classic cars, the handbook may not include this information (these cars will often predate this sort of technology, after all). In this case, it's worth (if you haven't done so already) joining an owners' club for your particular make and model, and asking fellow members if they have found a particular device that's suitable for use with your car.

How long should these devices be left on?

This is a bit of a variable. The reality is that the amount of time you will need to use your trickle charger or battery conditioner will depend on two things: the device's own performance, and the condition of the battery it's being set to work on.

In the case of a trickle charger, you may find it can take up to 48 hours to recharge your car battery to full capacity. This relatively long charge time is due to the fact that the trickle charger is sending in a low power supply – typically one to two amps of power. Some trickle chargers can be left for longer – days or even weeks – but be sure to check with the instructions or manufacturer before you try this.

A battery conditioner, on the other hand, has a different sort of job to do. Breaking down the lead sulfate deposits that have built up in your battery, and then conditioning the battery to receive a full charge, can take anything up to four weeks. It will all depend on how long the battery has been left in a state of low charge – and just how low the voltage has dropped.

Other ways to prolong the life of your car battery

The first tip for prolonging the life of your car battery is to give that battery a regular workout. Every time you start the engine, the alternator will start to recharge the battery. It makes sense, then, to let the alternator do its thing fairly regularly.

The important thing to note here is that, although the alternator supplies charge back to the battery, it actually requires some charge from the battery to get working in the first place. For this reason, a short drive is not particularly helpful as the amount of work the alternator does won't compensate for that power it has taken away on startup.

To get some real benefit, you really need to run the engine for a little while – typically around 20 minutes or so, although this varies between vehicles and batteries. Again, check with the terms of your classics insurance – you may be on a particular limited mileage tariff, which you may need to adjust in order to cover the mileage you need.

Regular use will also help to prevent those lead sulfate crystals from forming, and building up resistance.

If your battery is likely to get cold over an extended period of time – during winter, for example, and/or if the vehicle is stored outside – it's a good idea to keep it as fully charged as possible. The reason for this is that a fully charged battery will be more resistant to freezing than a fully or partly discharged one.

Following on from this, and whatever the conditions in which your classic is kept, it's a good idea to always keep your battery at 75% capacity or above. Again, to explain the science a little here, the majority of car batteries supply a powerful current within a short timeframe – enough to get the car started.

However, they are not designed to go through repeated cycles of emptying and recharging (or 'deep cycling', as it's known). Instead, they remain in much better health if they are kept regularly topped up near the upper end of their charge capacity. Keeping your battery at around 75% or above will ward off those lead sulfate crystals which cause batteries to die.

Specialist cover for your pride and joy

Making sure that its car battery is kept topped up is just one of many ways in which you'll want to look after your classic. Another key step to take is to arrange some specialist classic car insurance, to help you with the various repair and maintenance tasks you may face in keeping your beloved classic in tip-top condition.

Here at Lancaster, we have experience in providing classic motor insurance for a huge range of classics. We can provide a range of benefits including laid-up cover and limited mileage discounts.

Contact us today to arrange some classic car insurance for your treasured vehicle.