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Part Number: 56-958
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  • Complete Battery Care - Unique and patented system to recover, charge and maintain all lead-acid battery types to maximize performance and extend life.
  • Safe and easy to use - User safety through spark free operation and reverse polarity protection. Vehicle electrical safety through exceptionally clean voltage and current delivery with no surges or spikes. No need to disconnect the battery from the vehicle when charging.
  • Connect and Forget - Simple plug and play operation. Select the program and mode and leave the charger to do the rest.
  • Unique 8 step charging - The patented 8 step program tests battery condition and revives, charges and maintains to ensure maximum battery life and performance. RECOND recovers deep discharged and stratified batteries. FLOAT/PULSE maintenance ensures ideal battery care during periods of inactivity.
  • Charges down to -22°F (-30°C) - Specially developed for use in extreme cold conditions and featuring AC and DC cables adapted for low-temperature use.
  • Extends battery life - The unique features of CTEK chargers combine to maximize performance and extend battery life.


The MUS 4.3 POLAR (Part No. 56-958) has been specially developed to offer excellent all-around charging with special cold weather performance and adapted AC and DC cables to handle severe cold down to -22°F (-30°C). The MUS 4.3 POLAR is an advanced microprocessor controlled battery charger providing unrivaled performance on batteries from 1.2Ah up to 110Ah. Features include the ability to diagnose a battery's condition to establish if it can receive and retain a charge, a patented automatic desulphation program, and a special reconditioning function that will revive and restore deeply discharged and stratified batteries. ‘Snowflake’ mode ensures ideal charging performance even in the most extreme cold conditions. Patented Float/Pulse maintenance makes the MUS 4.3 POLAR ideal for long-term maintenance. The entire process of battery testing, charging, and maintenance is easily followed on the clear LED display.

The MUS 4.3 POLAR is a fully automatic ‘connect and forget’ 12V charger with 8 charging steps and offers selectable 0.8A and 4.3A programs. The RECOND and SNOWFLAKE modes operate individually or together in both 0.8A and 4.3A programs providing great flexibility for the user. Wide charging range on all lead-acid battery types from 1.2Ah up to 110Ah with additional maintenance capability to 160Ah. Splash-proof and dustproof (IP65). The MUS 4.3 POLAR is easy and safe to use, protects vehicle electronics, spark-free, reverse polarity protected, and short circuit proof. The MUS 4.3 POLAR features a 5-year warranty. Alligator clamps and eyelets included.


See a visual demo of the 8-step smarter charging process


Part No.


Input voltage AC

100-120VAC, 50-60Hz

Charge Voltage

14.4 / 15.0 / 15.8 V

Minimum battery voltage required: 2.0V

Charge Current

Max 4.3 A

Type of Charger

8 step, fully automatic charging cycle

Type of Battery

12V lead-acid batteries (Wet, MF, AGM, GEL)

Battery Capacity

1.2-110 Ah, up to 160 Ah for maintenance


5-year warranty