► A new battery can cost up to £200 for modern cars
► A trickle charger is less than half that
► A well-maintained battery could last twice as long
Very few things are as frustrating as a car with a failing battery. A hint of glowing lights, a short prayer to the Gods of Volthalla, and a twist of the key that results in a noise more akin to an elephant yawning than a ferocious burst of explosions and movement. In the digital age, even that faintly-optimistic ritual has gone, replaced by ‘computer says no’ as the voltage falls below the still-crucial 12V.
With so much technology on board, your typical 21st century car prevents the classic ‘left the lights on’ moment by switching off radios, lights and other accessories before they drain the battery, but there’s one thing that is guaranteed to wipe the spark out of your car, and that’s a long period of disuse.
But battery chargers are on hand to recharge. Canter through our guide below.
Best trickle chargers: prevent first
Got a tyre inflator in your boot? Got a pair of gloves for checking oil or handling diesel pumps? You’re the kind of person who likes to be prepared – but do you have a trickle charger for your car? There are literally hundreds of unknown-brand ones on Amazon and the like, but there are experts in the field too – trustworthy brands that have been developed for long-term storage of supercars and classics, and these will naturally do a great job of maintaining your cars’ batteries if you have access to a plug.
CTEK battery chargers
CTEK is the leading brand for smart battery chargers and conditioners, and offers a range of solutions from around £70. Accessories allow installation of unobtrusive extension cables and wrapping the charger in a protective rubber shell so it doesn’t bash bodywork. Our picks from CTEK are below.
CTEK CT5 Start/Stop Smart Battery Charger
Designed specifically for use with cars with a start/stop function. The CTEK CT5 Start/Stop charger is recommended to be used once per month to mitigate the extra strain start/stop systems put on car batteries - particularly for owners who mainly undertake short trips.
CTEK CT5 Time To Go Battery Charger
Includes countdown function not seen on other battery chargers. This lets you know how long there is left to reach full charge. Also includes 'Recond' mode for battery reconditioning.
CTEK MXS 5.0 Fully Automatic Battery Charger
Simple to use, reliable, and suitable for both cars and motorbikes. The MXS 5.0 actually delivers its five amp rating when it charges and conditions batteries. IP65 splash and dust-proof.
Ring Automotive car battery chargers
Ring Automotive is well known for consumer and workshop products. Its smart battery charger includes diagnostic tests, seven-stage charging, jump-start boosting and battery conditioning in an easy-to-use package. The informative LCD display gives more detail than the usual red/green/amber status LEDs of most battery chargers and conditioners, too. View the offer on the Ring RSC612 below.
Ring RSC612 12A Smart Battery Charger
Powerful smart battery charger for 12V vehicles up to 5.0 litres. For use with all battery types. Multi stage charging and reconditioning functions.
Best solar chargers: do your bit
If common sense kicked in with lockdown, every car you see parked on the road or driveway would have a little reflective square glinting off the dashboard. Solar chargers are cheap, and easy to use – most will plug into the 12V socket (or cigarette lighter, if you’re old-school) and they’re safe, spark-free and generate electricity for free.
On the other hand, they produce a fairly small amount of electricity, and cars with modern UV-shielded glass will reduce their effectiveness, so you really want to leave them on the roof of the car, in an untinted rear window or if you’re parking on a driveway, mounted somewhere to get the most light. Buy the biggest one you can realistically fit and afford.
For a healthy car, the solar charger will maintain the charge needed for systems like clocks, central locking, computers in standby and alarms. Few will recover an already failing battery, and they don’t provide enough kick to wake the ignition system if the battery is dead.
Eco-Worthy 10W 12V Portable Solar Panel
Eco-Worthy's solar trickle charger is affordable and can be used on most vehicles - from cars to motorhomes to boats. It possesses some decent alligator clips too, but can also be wired via the cigarette lighter if the vehicle allows.
Best traditional chargers: recover an (almost) flat battery
Provided the battery hasn’t been drained to the point of damage, you can recharge it – and boost your car – with a mains-powered charger. This is often the most traditional technology you’ll find, fundamentally unchanged for decades, so there are cheap, robust options.
For the small amount extra it costs to get a more sophisticated charger with boost function, there’s little reason to skimp here. Chances are, if you’ve got a battery flat enough to need charging, you’ll benefit from the jump-start too. View the Ring battery charger blow:
Ring RCB212 12V Battery Charger
Automatic battery charger for 12V vehicles up to 3.0 litres. For use with lead acid and gel batteries.
Or look at the offer on an equally good Sealey product:
Sealey SPI15S 15Amp 12V Intelligent Battery Charger
For use with lead acid batteries. It includes Sealey's Speed Charge technology that monitors and automatically alters the charge output. Also has a float function to keep the battery topped up once charged.
For those with multiple vehicles, you don't have to fret about keep a platoon of battery chargers in order to tend to each vehicle's battery. Indeed, NOCO, one of the industry's heavyweights, has a solution for you:
NOCO Genius 2X2
This is technically a trickle charger, so it reconditions as well as charges. But it can charge a battery that is as low as one volt. You can even charge from zero volts via the unit's manual 'force' mode. The 2X2 has can charge two batteries at once - two amps per bank. But if you need more, NOCO also has the 2X4.
Best jump packs: for when you've left it too long
Traditional jump packs are a little more sophisticated than a car battery in a box – and yes, you can jump a car from another battery still; jumping from another car has become riskier as more sophisticated electronics proliferate. However, another battery is heavy, bulky and a bit of a faff; modern laptop battery technology has lead to the creation of pocketable power packs that can charge your smartphone or jump-start your car.
These are really only suitable for emergency use, but with the advantages of replenishing USB devices and quickly recharging from your car’s 12V socket or USB - taking up little more space than an owner’s manual - they’re also really easy to carry about for emergencies. The downside of the light, portable nature is that the clamps and cables can be quite flimsy – fine for occasional use but unsuited to workshop handling.
Mainstream marques have yet to really adopt this market; navigate the sea of made-up reseller brands and you’ll find decent models for around £60. Our tests of typical examples have found that they will give three or four attempts to start a typical 2.0-litre petrol car before needing to recharge – read the customer reviews to choose the best model. NOCO is one of the best brands in this area - find offers on NOCO car battery chargers here or check out the GBX45 below.
NOCO Boost X GBX45
Delivers 1250 amps. Suitable for use on petrol engines up to 6.0-litres and 4.0-litre diesel. The GBX45 is recharged via USB and can also act as a power bank and features and LED flashlight. Very light at 0.59 kilograms.
If you’re sticking to a workshop or garage environment, booster packs like the Hyundai powerpack are more robust and can be used many times, and often include extra features such as compressors for tyre inflation, inverters or emergency lights. They also have solid clamps and cabling to ensure a long working life. See the offer below.
Hyundai HYJS-950 12v Jump Starter
For vehicles up to 2.5-litre petrol or 2.0-litre diesel. Along with the jumper cables, it has two USB ports and two 12V ports for connecting devices such as phones. It has an LED light above the little digital display and can also act as an air compressor. Note: Currently out of stock. Sign up for restock alert.
Connecting your charger: a guide
As cars have become more sophisticated, they’ve also become more sensitive to fluctuations in voltage. When attaching a charger, you should connect the positive to the positive battery terminal whether using clamps or a quick-connect cable. The earth should be connected to the car bodywork or engine at a suitable point – not the battery itself. This ensures any voltage monitoring circuits are ‘aware’ of the battery status.
Always connect with power off, then switch power on to the charger. On older tech it avoids sparks, on newer tech it allows time for the electronics to optimise the charging programme. You can also avoid poor connections and make it easier to disconnect and drive by using manufacturer’s extension cables and permanent attachments – a very convenient way of keeping infrequently-used cars ready to go.
With lead-acid batteries, still common in production cars (even EVs), don’t leave a conventional charger attached longer than necessary. Trickle chargers, chargers with ‘float’ or conditioners are designed not to provide any more current than the battery requires to maintain the optimum voltage, but older chargers can damage older batteries.
When charging an older battery, you should leave access to it open (bonnet, boot or rear seat if it’s an old Beetle, for example) and ensure the space is ventilated. The hydrogen sulphide gas emitted is flammable (and toxic), and batteries can cause sparks. It doesn’t take a genius to work out how that’s going to end. Though the risk is small, it’s very real in an enclosed space.