Skip Content


1. Can I charge more than one battery at a time with my 12V CTEK charger?
A. Yes, as long as your 12V batteries are connected in parallel and that your battery bank is within the recommended Ah capacity range of your particular CTEK charger. (example: our MXS 5.0 charger is recommended for maintaining a battery or bank of batteries up to 160Ah in capacity). Be sure that the correct procedure for charging in parallel is followed and that your battery bank is within the recommended Ah capacity range of your particular CTEK charger”.

2. What size solar panels are recommended to use with our D250SA?
A. A 50-300 watt solar panel is recommended with a max output voltage of 23V.

3. Can I safely charge a Lithium battery with any CTEK charger?
A. No. We specifically recommend our Lithium US charger (part number 56-926) to charge and maintain your Lithium battery.

4. Which size cable should I use when installing my D250SA DC to DC charger?
A. Please see page 5 of the D250SA/Smartpass 120 product manual for correct cable and fuse recommendations when installing your DC to DC system.

5. Why is my MUS 7002 charger “clicking” while charging?
A. The relay noise in your MUS 7002 is not unusual and may become more apparent with age or in colder weather. It may also be more noticeable on batteries that are beginning to fail. If it is still providing correct voltage and the indicators show correctly, it is working properly.

6. Why does the power lamp on my charger start to flash after a couple minutes?
A. Either your battery voltage is too low or the connection to your battery is bad. CTEK chargers requires a battery voltage of at least a 2V for the charging process to start. If your battery has more than a 3V charge and the power lamp still flashes after connecting to your battery, please check the in-line fuse in your clamp or eyelet accessory and make sure it is not blown.

7. Why is half-battery lamp flashing rapidly and the full-battery lamp is solid on my MUS 3300 charger?
A. Most likely a bad connection to the battery. Move the clamps or cig plug accessory and make sure there is no loose connection in the quick connector. The charger could also be working in the desulphation phase.

8. How much battery power does Battery Sense use?
A. It uses about 1 mA, equivalent to about 1 Ah per month. The normal rate of discharge from a battery is about 10 mA. discharge from the electronics. We recommend regular use of your CTEK charger on vehicles parked for extended periods.

9. What do the abbreviations GEL, AGM and MF mean?
A. Gel, AGM (Absorbed Glass Mat), MF (Maintenance Free) are abbreviations for different types of lead-acid batteries. CTEK battery chargers are compatible with all types of 12V lead-acid batteries.

10. Why do you have to connect negative to ground and not to the battery?
A. All CTEK chargers observe the directives that apply in the EU. All battery chargers whatever the brand must be approved in line with the same standards. Many more basic chargers can cause the battery to emit a significant amount of oxy-hydrogen gas and also generate a spark when connecting. This represents a major risk of injury and it is therefore stipulated that the first terminal should be connected away from the battery in order to reduce the risk. A CTEK charger is spark free, has a minimal amount of gassing and can therefore be connected directly to the battery. However, we do recommend that you follow specific vehicle manufacturer guidelines when charging the battery. Also the latest vehicles with start stop systems are fitted with a battery management system. The sensor for this system is found on the negative terminal connection at the battery, if the charger is fitted directly to the negative terminal the sensor is unable to detect any charge that the battery receives this will result in system warning lights staying on the next time the vehicle is used.

“Having owned several of another ‘popular’ brand of charger, the CTEK is far and above superior in every possible category. WELL worth the miniscule additional cost. ”