Well, here goes a new Car Battery Geek exploration. This time it’s a CTEK CS FREE review.

What is the CS FREE?

Well, it’s a new portable 12V battery charger that can also be used to start your car if it breaks down.

In other words, it’s a combined charger and jump starter (kind of). We say ‘kind of’ because technically it doesn’t jump start your car, it just gives it enough charge to start.

We’ll deep-dive into how it works, whether it’s any good and if so, where’s the best place to get it.


  • Voltage: 12V
  • Battery types: All kinds of lead-acid batteries
  • Dimensions: ‎24.9L x 10.0W x 7.9H cm
  • Weight: 1.4kg

Introducing the CTEK CS FREE Review

The CS FREE is a new development by CTEK and it’s certainly something of a departure from the norm by CTEK. 

For nearly 25 years, CTEK have been producing car battery chargers, and pretty darn good ones. In our eyes, theirs are the best quality chargers on the market.

Now, though, CTEK have produced something different. The CS FREE is still a charger, but it’s a portable one. That is, you can charge your vehicle battery even away from mains power.

This is something that has never existed before, and for one very simple reason:

It wasn’t possible.

It requires a lot of energy to charge a vehicle battery. We’re now used to power banks that we can take anywhere and use to recharge our phones or tablets anytime they run out of juice. But just think about the sheer volume of energy needed to start an engine that powers a vehicle weighing a few tons.

Lithium technology, specifically Lithium Iron Phosphate (LiFePO4), is now developing at an astonishing rate. It’s not just the amount of power Lithium batteries can store, it’s the efficiency and speed with which they can charge.

CTEK have the R&D capacity to take advantage of this burgeoning technology, as well as the best scientific knowledge about Lithium battery charging in the world.

Hence, the CS FREE. 

4 Functions In One

That’s what CTEK say.

  1. Battery charger
  2. Trickle charger
  3. Adaptive Booster
  4. Power bank

Most modern smart battery chargers, including CTEK’s MXS range, already have the ability to act as battery charger, trickle charger and power bank. Those three combined is nothing new.

We’ve reviewed the CTEK MXS 5.0. And here’s our CTEK MXS 10 review.

So, really, it’s the addition of Adaptive Boost that is the key aspect, the advancement in technology.

What we like about this CTEK battery charger

The Simplicity

It’s ridiculously easy to use.

You’ve heard of easy-to-use products before, maybe they have a simple 3- or 4-step process to use it.

How does a 1-step process sound?

STEP 1: Connect the clamps to the battery terminals.


That’s it. The device itself is clever enough to do the rest.

There are no buttons or modes to be selected.

It’ll automatically detect what type of battery you have. Then it’ll detect the current charge level of the battery. Next, it’ll analyse the health of the battery. Finally, it’ll start the charging process. Using the information it has detected, it already knows what you need. It knows how much charge to delivery, at what rate and for how long.

And trust us, these things, rate and amount of charge, are important. Charging a 12V lead-acid battery is not about pumping as much charge as possible, as fast as possible. That’s a fast way to at least damaging your battery, if not being downright dangerous.

The Speed of Charging Your Vehicle Battery

We were shocked by this, and plenty of others are too.

Many people report the CS FREE charger getting their battery to a full charge in an hour to an hour and a half. That’s very fast.

In the case of a breakdown due to battery failure, you’ll have enough power to start your engine after 15 minutes. That’s pretty good.

Speed of Charging the CS Free

Again, this was a shock.

The CS FREE can be fully charged within an hour.

The Build Quality 

The look and feel of the CS FREE and everything included is excellent. The charging unit itself, the plugs, the components, the cables, the connectors, the clamps, every part is the same high quality.

We had been slightly concerned after seeing pictures of the clamps (crocodile clips) that they look a little flimsy. Not at all, though, they’re as tough and well-made as everything else.

That’s something you expect of CTEK. But since CS FREE is a premium product (and a premium price), it’s actually even better than CTEKs other chargers. 

We have no doubts that the this charger will wear extremely well, and last you for a long time.

Durability is something that CTEK are known for, they could all their products to cope with the harshest elements (they were conceived in Swedish winters after all!). This product will be no different.

What didn’t we like about the CS FREE

To be honest we’re a bit flabbergasted about one thing…

No carry case

It ain’t cheap, and as a premium priced, premium quality product, we’d really have wanted a nice case included.

Especially given that the innovative and ground-breaking feature of the CS FREE battery charger is its portability and ability to act as a ‘jump’ starter. Therefore, most people will certainly want to keep it with them in their car, rather than left in their garage.

CTEK have a case available for purchase, but it’s got a hefty price tag.

We’re disappointed with CTEK on that score.

Get Your Expectations In The Right Place

Hopefully, this article has helped you understand what the CS FREE is actually for.

The only people who’ve not had great results with the CTEK CS FREE are those who’ve misunderstood what it’s actually for.

Expectations to have

1) When using with mains power – it’s a high quality battery charger and trickle charger

This will be probably the fastest charging you’ve ever experienced.

And CTEK’s charging process is the best in the world (NOCO is the only one that even comes close, particularly with the NOCO Genius 10 charger.

2) When using portably – Like a power bank, but for your car (start your engine after it’s died). 

If your vehicle battery dies, you can use the CS FREE to charge the battery, then you can start your car again.

In other words, it’ll have the same effect as a jump starter (without actually using a ‘jump’).

Don’t have these expectations

1) Literally like a power bank, but for your car ie. you can charge a dead battery back to full charge again and again.

Power banks can portably charge your devices over and over again, away from mains charge.

If your expectation is for it to literally be like the power bank you have for your phone then you’re going to be disappointed.

With a decent size of phone power bank, if your phone dies your power can may be able to charge it back to 100%, then if the same happens again 2 days later, it can probably charge your phone back to 100% again, without you having charged the power bank.

If you think the same will happen with this CTEK charger, then you’ll be disappointed. Charging a 12V battery from dead to full charge uses up a lot of power, so if you’ve done that once, make sure you recharge the CS FREE.

2) Constant trickle charging for months, away from mains power.

The CS FREE can trickle charge (ie. provide a small amount of charge to keep a battery topped up, preventing it from losing charge). Depending on your battery you may be able to do this for a few days, or with a smaller battery, maybe even a few weeks before you need to recharge.

Don’t expect permanent charging away from mains power. 

All in all, then the CS FREE is…

An excellent and super-fast charger and (permanent) trickle charger if you’re using it when connected to the mains.

A ‘jump’ starter to be used if you break down, or some relatively short-term charging or trickle charging if you’re using it portably

If that’s what you want the CS FREE for, then you’ll be extremely happy with what you get.

Adaptive Boost vs. traditional jump start

At Car Battery Geek, we have plenty of experience with jump starting. That is, the traditional jump starters (boosters) that you attach to the vehicle battery terminals and they give you a huge burst of power to jump start the vehicle.

Check out our review of the No.1 jump starter in the UK, the NOCO GB40.

Therefore, we know that jump starters are always at the mercy of conditions. That is:

  • the condition of the battery
  • how low the battery voltage is
  • the condition of the vehicle components
  • the condition of the battery terminals
  • how good a connection there is between the terminals and the clamps.
  • The most important of all may be the weather. Jump starts are much, much harder to achieve in cold weather (cars batteries lose a huge 35% of their power at 0 degrees Celsius).

The poorer each of these conditions are, the greater the number of Amps will be required to jump start the vehicle.

And then the ability of the jump start to be successful also depends on:

  • how many Amps the jump starter can deliver.
  • Which, in turn, depends on the amount of charge in the jump starter
  • the condition of the jump starter
  • the condition of the clamps
  • and again, the weather.

The cold weather also severely inhibits how many Amps the jump starter can deliver. Even a powerful jump starter can struggle in below zero conditions.

Adaptive Boost, as in the CTEK CS FREE, is different. It doesn’t work by “jumping” your battery ie. putting a large burst of energy through the battery. 

Instead, it works simply by charging your battery back to a level of charge that allows you to start the engine.

It does so within 15 minutes.

If you want an instant jump start, then you’ll need a traditional jump starter. Just be aware, that jump starts are notorious for working in some occasions but not others (for the reasons stated earlier). The more powerful the jump starter, the lower your risk of a failed jump start.


Some people believe that the big surge of current provided by a traditional jump start is harmful to your vehicle electrics.

It’s certainly true that putting too high a voltage across the vehicle battery can harm your electrics, but we at Car Battery Geek, haven’t seen the evidence to suggest that jump starting by modern high-quality jump starters causes damage.

There’s absolutely no doubt that the CS FREE wouldn’t harm the battery or your vehicle electronics, since it’s highly sensitive to the state of the battery, and detects the exact level of charge needed for your specific battery.

Anything else I need to know?

Use as a Power Bank

As we said earlier, one of the 4 functions is as a power bank for your electronic devices. So it’ll recharge smartphones, tablets, laptops etc. whenever needed.

Full Pro Set available (includes carry case)

If you do want the carry case, CTEK offer a discounted package, called the Full Pro Set. That includes the CS FREE, the carry case, a wall mount, charging cable for your in-car cigarette lighter socket, charger for 12V battery.

Stays charged for one year

If you’re keeping it in your car in case you break down, it’ll keep its charge for up to one year.

For all kinds of 12V lead-acid batteries and Lithium batteries

It works with all types of lead-acid batteries. That means Flooded (Wet), AGM, Gel, EFB (AFB), Calcium (Silver-Calcium and Ca-Ca). Calcium batteries need special charging, but CTEK has you covered. And same for AGM charging, which is  also unique.

And also for Lithium (LiFePO4) batteries. CTEK’s Lithium charging technology is equally as good as for lead-acid.

Summing Up The CTEK CS FREE Review

All in all, then, we’re big fans of the CTEK CS FREE.

As long as you have your expectations in the right place, you’ll find it an excellent purchase.

Fastest ever, high-quality charging. If you’ve ever read one of our CTEK charger reviews you’ll know that CTEK’s charging process doesn’t just charge batteries, it has battery reconditioning modes, which heals them. (More on CTEK’s RECON mode) That means they can last 2-3 times longer than they otherwise would).

And the Adaptive Boost technology brings whole new dimension to it – effectively meaning the CS FREE has the functions of a charger and jump starter combined. That’s something special. 

If it’s the one for you…

Here’s the best place to buy it, check it out.

CTEK CS Free charger

Here we must end our CTEK CS FREE Review. 

Keen? Here’s where you can buy it on Amazon.