Frequently asked questions


1. Can I leave the charger connected to the battery for a long time?

Yes. CTEK chargers are designed to fully charge a battery and then automatically switch over to long term maintenance. Before leaving the charger unattended for a long time, ensure that the battery is fully charged, as indicated by the green LED.
 

2. What charger is suitable for my vehicle?

Choose your charger depending on the size of your battery. The more amps the charger can deliver, the faster the battery will be recharged. The website will give ideal battery size range for each charger in their technical specification.
 

3. Can I charge my vehicle through the 12 V (cig) socket? 

Yes, if your socket is still live when the ignition is turned off.  Check the vehicle user manual, contact your vehicle retailer or test it with any other cig-plug device that works with your vehicle. 
 

4. Can I use a smaller or bigger charger than recommended for my battery?

Choose charger depending on the size of your battery. Charging with a smaller charger than recommended will take longer time and will not optimally extend the battery life and performance. If your battery has an Ah rating that exceeds that of the charger limit it could mean that the charger will be unable to charge the battery sufficiently and may even lead to it becoming discharged. Charging with a bigger charger than recommended will not result in a completely charged battery and will not optimally extend the battery life and performance.
 

5. The CTEK manual says: ”Connect the black clamp to the vehicle chassis remote from the fuel pipe and the battery".  In the picture next to this, the black clamp is connected to the battery's negative pole. Which is correct? 

When you use a CTEK charger, you can use both connections.  The charger should be connected according to the vehicle user manual. If there are no other recommendations in the manual, the negative or black connector should be safely connected to the chassis.

The connectors on old “non-smart” chargers can spark if the connectors touch each other, which could be dangerous if this happens near the battery. Keeping the connectors apart, and ensuring the positive connection point is as far away from the negative connection point as possible, will help to minimize any risk. If your vehicle has a BMS you cannot connect to the negative battery pole, the connection must be made to the earth or ground point, if you are in any doubt then connect to the nearest earth or ground point. Eyelets can be permanently connected to the battery as the charger is not usually attached to the eyelet cable when the cable is being connected, so there is no risk. The eyelet connections also give you enough time to check the correct attachment points.

Also, if the battery is disconnected or removed from the vehicle then both connections can be made directly to the battery terminal.
 

6. Can I charge the battery without removing it from the vehicle, or opening the caps?

There is no reason to disconnect or remove the battery from the vehicle – or open the battery caps – while charging. CTEK chargers are spark proof, reverse polarity protected and electronically safe.
 

7. My charger never goes further than the float (first green) level. 

The charger stays in float maintenance mode for 10 days, keeping the battery topped up using the minimum level of current.  After 10 days, the program moves on to the last stage – pulse level – for long term maintenance. 

 

8. My charger gets very warm – is this normal?

Yes, this is normal when the charger is working hard in the bulk charge phase. The heat is generated in certain circumstances, depending on the battery that's being charged.  The charger does not necessarily heat up when it's charging other types of battery.

 

9. My charger will not start charging – is it broken? 

CTEK chargers need some counter voltage to start providing tension/current.  If there's a poor connection between the charger and the battery, charging will not start. If the battery is below 2V, charging will not start.
 

10. Can I charge Lithium batteries with a regular CTEK charger and ordinary batteries with a Lithium charger?

No. Lithium batteries need a different type of charger to lead/acid batteries. We do not recommend using a CTEK charger designed for lead/acid batteries. Charging lead/acid batteries with a Lithium charger will not give the best results and cannot be recommended.