CTEK CS Free review: We test a car charger you don't need to plug in to the mains

We all know how important it is to keep our vehicle batteries in good condition. Especially through the winter a weak battery can be a liability and leave us marooned on our driveways, unable to start our cars.

Battery maintenance isn't something we think about a lot, but we should. And then there's dealing with the outcome of poor maintenance - a flat battery.

There are plenty of battery chargers on the market that can help to keep a battery charged up, or restore it to health after it's been depleted, and there are now lots of power packs available to help jump-start a dead battery when needs must.

And there are a few gadgets out there that combine these two functions. I've been testing one by CTEK. It's a new product on the market, and it's a bit of a game changer.

It's called the CS Free, and it's a relatively large car battery charger from a company that has built up an amazing reputation in the industry.

Its products are used by car collectors the world over to keep their batteries maintained. I use one myself, an MXS 5.0, to keep my wife's car's battery in fine fettle when it's not being used and to top up our motorhome batteries.

On the face of it, the CS Free is at least double the size of the MXS 5.0, and apparently more primitive, with no array of LEDs and no other controls beyond an on and off button.

But there's more to the CS Free than meets the eye. A lot more.

Firstly, and most importantly, it's completely wireless. It's larger because it has a built-in battery. And that battery is quite a monster because it's got enough power to start a car with a flat battery. Rather than "jump-start" the car, it gently nurses a battery back to health in minutes, and LEDs on the unit will let you know when there's enough juice to turn the key.

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It will also maintain a battery, just like its MXS 5.0 stablemate, and it can be connected to a solar panel to keep that maintenance cycle up pretty much indefinitely.

What CTEK has created then is one of the first truly off-grid car charging solutions, and the possibilities that creates are almost endless.

Say for example you have a motorhome or camper van, and it's parked up somewhere that has no access to a mains power supply. You could keep the battery healthy with a CS Free attached to a solar panel, for as long as you've got some sunshine. Or you could use a portable power station to prolong the life offered by the CS Free.

Perhaps you've got a classic car or motorbike stashed away in a lock-up somewhere. The CS Free can be hooked up to its dead battery and get it started without you having to bring a jump pack.

Or maybe you own a boat, moored on a towpath in the countryside, and you want to maintain its battery. Like I say, endless possibilities.

The CS Free isn't just a car charger, either. It can act as a power bank, because it has a USB output as well as a USB input. So while it's away with you in your camper van, you can use it to charge up your smartphone.

It charges up either from a 12v USB supply, which is really handy, or more quickly from a mains supply. You can also buy a CTEK solar panel, but this is a pricey option at £199 for a 60w folding panel.

Once the battery's charged, it'll keep its power for up to a year, which is ideal if you plan to use it as an emergency backup solution, for example. It does charge remarkably quickly from a 12v supply, though in less than an hour in some cases.

There really isn't a lot to dislike about the CS Free, it has to be said. The instructions are a bit poor, and it's a shame there's no way of having a quick-connect lead attached to your battery like you can with some of CTEK's other battery maintainers.

It is a bit bulky, but not as heavy as you'd expect, and the cable that connects to the battery is more than long enough.

We should also mention the price. Visit the CTEK website and you'll find it for £179. It's pretty good value for money, but still a fair old expense. I have found one on Amazon though for £148.71. And I do think it's worth it, if you'll get enough use out of it.

Let's be realistic, there are better ways to charge your phones and tablets up, and there are a plethora of cheap jump packs and perfectly competent battery maintainers.

But you'll struggle to find something that combines all of these functions, and the fact it can do it all wirelessly, miles from a power source, is absolutely remarkable.

When I first saw the CS Free being launched, I knew it would be an incredibly useful piece of kit. Now I've tested one, I'm completely enamoured with it. It's another triumphant innovation from CTEK.