Frequently Asked Questions

Products

1. Which charger should I choose?

   Go to Select Charger and select Application to see recommended chargers.

2. Where can I buy a charger? Can I buy directly from CTEK?

   Go to Where to buy. This is where you can search for a dealer near you.
   The dealer can choose between different distributors, see Distributors. We do not sell directly to consumers or stores.
   

3. Where can I get a copy of the user manual?

   All the manuals can be downloaded from our website

4. What is the difference between Onyx and Multi XS 7000?

   Multi XS 7000 has different charger programs to choose from:
   - 14,4V/Normal. Normal charging
   - 14,7V/Snowflake. Charging of AGM batteries or charging at cold temperatures.
   - Supply. The charger can supply energy to run 12V equipment without a battery i.e. when changing the battery in a vehicle.
   - Recond/Boost. Reconditions stratified batteries.
   Multi XS 7000 has 5 year warranty.
   
   Onyx only provides 14,4V Normal charging, no other charging program.
   Onyx has 3 year warranty.
   
   Both chargers deliver 7A, they charge and maintain most batteries from 14Ah – 225Ah.
   

5. What is the difference between Zafir 90 and Multi XS 3600?

   Zafir 90 has slightly lower performance than Multi XS 3600, which contributes to longer charging time. Zafir 90 has a simpler quick connector and clamps. Apart from this, the functionality is identical. Zafir 90 has a 3 year warranty and Multi XS 3600 has a 5 year warranty.

6. Can I permanently connect the charger in the car?

   Yes, you can permanently mount the charger in the car, but not under the bonnet. We recommend that you mount the charger in the boot or passenger compartment and wire the cables to the battery.

7. I have a 6V battery. Can I charger it with my Multi XS 3600 or do you have any 6V chargers?

   No, we do not recommend charging your 6V battery with the Multi XS 3600.
   To charge a 6V battery with a 12V charger is extremely risky, because the charger will continue charging even though the battery is fully charged.
   XC 800 is CTEK’s 6V charger. It is small but manages batteries between 1.2Ah to 100Ah. Read more: technical info XC800

Charger knowledge

1. Is it possible to charge several batteries of different sizes at the same time?

   Yes, it is possible. The charger interprets it as one battery. Although, make sure that the combined Ah is not larger than our recommendation for your charger and that the cables between the different batteries are strong enough for the energy given. You can get a lot of current from the charged battery to the uncharged battery which can overload the cables; this is regardless of the charger. The best way is to charge each battery first and then connect them all together.
   When several batteries are connected in parallel the positive clamp should be connected to the positive terminal on one side and the negative clamp connected on the negative terminal on the other side of the connected batteries.
   

2. Is it possible to use a CTEK charger on GEL batteries? Is there anything specific that needs to be considered when charging a GEL battery?

   Yes, CTEK chargers can charge GEL batteries. GEL batteries should be charged at 14.4V (Car mode or Normal mode, depending on which charger you have).
   Note, that it is not possible to use the Recond function on a GEL battery! GEL batteries are very sensitive to high currents and will dry out easier than other lead acid batteries.
   

3. I have an AGM battery. Do I charge it in snowflake mode?

   It depends. Optima and Hawker recommend snowflake mode. If there is no indication on the battery, use car mode for batteries over 14Ah or MC mode for batteries under 14Ah.

4. I have noticed that my battery boils a little bit when I charge with 14.4V, especially at the end of the charging. Is this normal or could it damage my battery?

   This is completely normal and necessary for the battery to become fully charged. At the end of the charging cycle, the battery should gas a little, however the battery loses minimal amount of fluid during this period. The battery is not damaged by this.
   Note that there is a difference between gassing at normal charging (”simmer”) and gassing when there is something wrong. If the battery boils heavily during the whole charging times is a sign that there is something wrong with it. It is most likely that one or more cells within the battery are faulty.
   The charger delivers up to 14.4V divided onto 6 cells, i.e. approximately 2.4V/cell at normal charring. If one cell is broken, the charger will deliver 14.4V to only 5 cells, which means that they will get 2.88V/cell and this will cause the battery to boil heavily. If this is the case the battery is broken and needs replacing.
   

5. I have learned that you should always open the battery caps when charging due to/because of the explosive gas. I can’t find anything about this in your manual. Don’t I have to open the battery caps when charging with a CTEK charger?

   No, you don’t have to open them.
   The reason for opening the caps is to give space for gassing, which is hard to avoid with simple chargers. A CTEK charger on the other hand, has a very low ripple voltage and therefore the gassing is eliminated or so low that it doesn’t cause any problems. Hence, you don’t need to open the battery caps.
   

6. Which battery types can I use my CTEK charger on?

   The CTEK charger can charge all the different lead acid batteries (Wet, MF, VRLA, AGM, and GEL).

7. Can I charge Li-Ion batteries with my CTEK charger?

   CTEK’s battery chargers are developed for lead acid batteries only. Charging other types of batteries with a charger developed for lead acid batteries is extremely risky.

8. What does the abbreviations MF, GEL and AGM stand for?

   MF stands for Maintenance free. A maintenance free battery is a sealed battery which you do not have to refill with fluid after use. MF batteries need, like every other battery, maintenance charging to provide the longest service life possible.
   
   In a GEL battery, the sulphuric acid is bound in gel/solid form to decrease the risk of leakage and fluid losses.
   
   AGM stands for Absorbent Glass Mat. In an AGM battery the electrolyte is absorbed in a glass fibre mat. AGM is a perfect starter battery. Because of the enhanced acid density within an AGM battery it needs charging with a higher current.
   

9. Do I have to disconnect the battery from my car when I charge my battery with a CTEK charger?

   No, CTEK’s charger will not harm sensitive electronic equipment and the battery does not need to be disconnected from the vehicle.
   Most vehicle manufactures has a set limit of 16V, to not harm the vehicles electronic equipment. CTEK’s battery chargers do not cross this limit and charges with a very clean and controlled current. The only function close to 16V is Recond/Boost but not over it. If the manufacture gives a warming against high currents and you are uncertain about a specific level, disconnect the battery anyway.
   

10. Can I charge deeply drained batteries with my CTEK charger?

    A battery is considered drained when the voltage is below 10.5V, however, the battery can deliver energy all the way down to 7-8V.
    Because CTEK chargers are spark free and reverse polarity protected the battery charger needs counter voltage from the battery to operate.
    Most models only need a counter voltage of approximately 2V. XC 800 require a counter voltage of 4V and XS 800 requires 6V.
    Note that batteries can become damage if they have been too drained.
    

11. My battery has been frozen. Can I charge it?

    No, the battery has to defrost first. Note that the battery has been completely drained before it froze otherwise it would not have been possible. Make sure the battery does not have any cracks in the casing before charging it.

12. What is the difference between connecting batteries in series and connecting batteries in parallel?

    You connect two or more batteries in parallel if you need a larger battery (higher Ah).
    You connect two or more batteries in series in order to get a larger amount of voltage. If you connect two batteries of 12V each in series, you will end up with a 24V system.
    

13. How do I connect in series/parallel?

    

14. What happens if I use my charger on a larger battery than recommended?

    Using a smaller charger than recommended will give longer charging times. If you are only using the charger for maintenance charging you will get a good result anyway.
    The problem with a smaller charger is, among other things that the charging time at high current becomes extra long and therefore the battery will lose fluid unnecessary. Also, the charger might not fully charge because of the built in overheating protection.
    

15. One supplier recommends the MULTI XS 3600 only up to 75Ah, yet the box says 120Ah. Which is right?

    The MULTI XS 3600 works well up to 120Ah. However, the MULTI XS 7000 or MULTI XS 25000 are better choices above 75Ah with shorter charging times and more features. It is primarily a balance between price and performance.

16. Why does it take less time to charge with a MULTI XS 3600 with just 3.6A compared to my old 11A charger?

    Your old charger starts to charge with a high current that quickly drops. In addition, a lot of energy is wasted from the charger in just heating the battery. A CTEK charger starts charging from a very low voltage with virtually a constant current up until the battery has reached maximum voltage. The charger then continues with a constant voltage until the battery is fully charged.

17. What does ripple mean and how does it affect the battery?

    Current ripple is a measurement of how much alternating current the charger supplies. High current ripple causes high losses which costs money and generates heat in the battery. This heat means that you must charge using a lower current to avoid gassing. Conventional chargers heat the battery up to four times as much as CTEK chargers. Current ripple also has other negative impacts, see Charger Academy - Current Ripple.
    
    Voltage ripple describes the amount of alternating voltage that is mixed with the direct current output. This may cause voltage peaks that could damage sensitive electronics, see Charger Academy - Voltage Ripple.
    

Charger functions

1. The charger switches over to maintenance charging but the battery lacks energy. What is wrong?

   The battery is most likely stratified or at the end of its service life.
   Stratification occurs most of all when the battery has low self discharging and low fluid usage characteristics i.e. Calcium/Calcium batteries (Ca/Ca).
   When these batteries get deeply discharged the low fluid usage becomes a problem. The fluid usage develops when the battery produces gas during charging. Without this gassing there will be no mixing of the acid within the battery and that’s when the battery becomes stratified. In other words you get heavy acid density at the bottom and low density acid at the top. To solve the acid stratification there is a need for higher current to make the acid mix again. With a normal charger this would take too long. CTEK’s larger battery chargers and CTEK Multi XS 7000 have a built in function called “Recond mode” that intentionally causes gassing and with that mixes of the acid. This is done during a limited time period (30min - 4 h depending on the battery need) to avoid excessive water loss. CTEK Multi XS 7000 is the absolute best choice for Calcium/Calcium batteries and other batteries with low fluid usage and when the battery often gets drained.
   

2. I have charged my 75Ah battery with a Multi XS 3600 for several days, but the battery never gets fully charged i.e. the charger does not switch into maintenance charging. What is wrong?

   There can be several different reasons.
   - You have larger energy loads connected to the battery at the same time. The battery gets fully charged, but the energy loads cause the voltage to drop quickly and the charger almost immediately starts charging again. This could be why you do not have time to see it switch over. If this is the case a better choice is Multi XS 7000, when it is fully charged it automatically switches into float maintenance. The charger constantly delivers 13.6V for 10 days which means that larger energy loads can be connected without draining the battery.
   - The battery can be in a bad state and have a high level of self discharge. The charger fully charges the battery but the battery loses its voltage so quickly that you do not have time to see it switch over to green. If this is the case the battery should be changed.
   - It can also be caused there is a broken cell in the battery. It is more difficult for a battery with a broken cell to increase its voltage. The charger will keep charging and trying to get the voltage up. A battery with a broken cell usually gets very hot. If there is a possibility to check the fluid level within the battery you can see if one cell has more fluid left than the others.
   

3. I charge my battery with a Multi XS 3600 for approximately 12h and the charger does not switch into maintenance charging. When I change setting with the mode button or disconnect and connect the charger again, the charger automatically switches to the maintenance mode. Why does this occur?

   When you break the power or change the mode, a new charging cycle begins. At the start of every charging cycle the charger reads the battery voltage. If the voltage is over 12.9V, the charger is considered fully charged and the green light is lit until the voltage drops below 12.9V, then the charger starts charging again.
   This means that the charger was between 12.9V and 14.4V when the charging cycle was cut off, in other words, the battery status was between 90-100 % charged.
   

4. When I connect the charger the orange LED lights for half charged are flashing and the green LED lights for fully charged are permanently lit. What does this mean and what can I do about it?

   There can be two different reasons for the alternating flashing that is described.
   
   One reason can be a bad connection between the charger and the battery. If you move the connections around and make sure there is not loose contact in the quick connector (Comfort Connect) this may solve the problem.
   The other reason could be that your battery is sulphated.
   A sulphated battery cannot accept charge when the lead plates inside the battery are covered with sulphate crystals. The charger is trying, by pulsing electrical currents on the crystals, to”knock” off the crystals and therefore recover the battery. These pulses are what the blinking stands for.
   If you were to measure the voltage within the battery you will most likely find that it is under 10V. Let the charger continue charging for at least 24h. If the charger manages to start the charging curve, the orange LED will light up. If the charger is still flashing after 24h you probably have a worn out battery that needs replacing.
   

5. I am trying to charge my battery with a CTEK Multi XS 3600 but only one LED on the lowest row is lit. What is wrong?

   There could be three different reasons for this:
   1. There is less than 2.2V within the battery. This battery should be considered worn out and be replaced.
   2. Problems with the connections. Make sure that the clamps are connected tightly and that the quick connector (Comfort connect) is properly connected.
   3. The charger is faulty. It is very unusual - less than one in a thousand. Test the charger on another battery. If the error still remains, please contact us.
   

6. I want to connect my CTEK charger, Multi XS 3600 with the help of the “engine heater pole”. The power will be on for 5 min and off for 5 min and then continue on for 5 min etc. How will the CTEK charger manage in this condition?

   Your charger will not have any problems with this, as long as the battery has at least 6V. If the battery has a higher voltage than 6V the charger will remember the setting and resume the charging cycle when the power comes back on.
   Note that the charging time will take twice as long.
   

7. I want to charge my car battery during the winter. The problem is that the power gets cut sometimes. Will your charger start automatically when the power comes back on or do I have to start it manually? Which charger should I choose for this application?

   Multi XS 3600 and Zafir 90 need a 6V counter voltage in the battery to remember the latest setting. As long as the battery is not under 6V the charger will start automatically. CTEK’s other chargers have a built in memory and will remember the setting and start automatically when the power comes back on. To be certain the Multi XS 7000 is the best choice for this situation.

8. Should I use Supply setting for “maintenance charging”?

   No, for maintenance charging the normal charging setting should be used. Supply mode gives a constant voltage on 13.6V. When charging a battery a higher voltage is needed - 14.4V - to become fully charged. Using Supply mode for more than 10 days increases the risk of unwanted fluid loss in the battery. You should use the Supply function when you need a power source to run 12V equipment without a battery, for example when changing the car battery.

9. I have loads connected to the battery and I want to charge the battery at the same time. Should I use the Supply function?

   No, you should use the Normal charging mode.
   Supply is supposed to be used for supplying power without a battery for example when changing a car battery.
   You can use your battery at the same time as you are charging as long as the loads are not bigger than the charge the charger is giving. If the loads are bigger than the charger you should consider a larger charger.
   Note that the larger the loads the longer the charging time.
   

10. In the manual for your charger it is explained that the black cable/clamp (-) should be connected to the chassis in the car, preferably far from the battery. Why? I have always connected the charger straight onto the battery.

    To fulfil the requirements of CE classification the manufacturers are required by law to recommend connection to ground in the manuals. This is regardless of the battery charger or the manufacturer. The reason is that many simpler chargers can make the battery produce a lot of explosive gas. Also, simpler battery chargers are not usually spark free when connecting them. To avoid sparks above the battery where there can be explosive gases it is recommended that connection should be made to the chassis. A CTEK charger is spark free and charges the battery in a controlled matter and therefore almost no explosive gases are produced. Regardless, we have to write the recommendation in order to fulfil the CE requirements.

11. The MULTI XS 25000/MULTI XT 14000 does not have the higher voltage recommended for brands like Optima. Is this a problem?

    We recommend the higher voltage for these batteries. These chargers do not have this setting but can still be used

12. Which setting should I use?

    It depends on the battery type, size and application area.
    The effect of the settings depends on which charger is being used, select charger below.
    Zafir 90, Multi XS 3600, Multi XS 7000, Multi XS 25000, Multi XT 4000, Multi XT 14000
    

13. Can I really just connect the charger and then forget about it?

    Yes, a CTEK charger can be permanently connected on the battery thanks to its intelligent pulse maintenance. The charger is going to fully charge the battery then automatically switches into pulse maintenance. It will turn off the charging and monitor the battery’s voltage. When the battery voltage then drops below 90%, the charger will resume the charge and fully charge the battery again. This function makes sure that you always have a fully charged battery without the risk of harmful over charging.
    Always make sure that the charger has switched into pulse maintenance before leaving the connected charger unattended for long time periods. If the charger has not switched over to pulse maintenance within 3-4 days the charger requires disconnection manually.
    
    Possible reasons why the charger does not switch into pulse maintenance:
    * The battery is too big in comparison to the chargers capacity and there is a potential risk of over charging in the long-term.
    * If you have larger loads connected to the battery at the same time as it charges the battery, the charging time becomes long and even here there is a potential risk of over charging.
    * The battery is sulphated from the start see Charger Academy – sulphation. The charging then take longer because the battery has a higher resistance and it limits the amount to energy the battery can accept.
    * The battery is worn out and needs replacing
    

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