I have the orange cold weather Ctek MUS 4.3 Polar. That I've had for at least 5 years. But at the same time I bot a Noco Genius 1 amp and they both work just fine.
No trouble with the following 2 chargers:
I also have 40 amp Black & Decker microprocessor charger (constant voltage charging & settings for different battery types) that's at least 10 years old:
the 2nd charger is a 25a Power On Board BC25EP that I probably bot at Sam's Club Still use it.
If I buy another charger, I would try this Energizer 9-step: It's a lot of amps for a smart charger for the money.
HOWEVER, lots of complaints for this unit. Still, it's not rocket science, it's just a chipset.
8 amps
9-steps
5 year warranty.
$49 shipped on Amazon:
Energizer ENC8A
9-step Voltage and Current plots (These plots are most descriptive of any spec from all these clowns - so why I'm biased towards buying one of these)
Stage 1 - Diagnosis: Analyze if the battery can accept a charge or not, and then prevent
charging from proceeding on the a defective battery;
Stage2- Desulphation: The charger can rescue most drained batteries with voltages up
to a Min 1.5±0.5V
Stage 3 - Pre-charge: If the battery voltage is less than 12V, charge it at the smaller current,
which will protect the battery better;
Stage 4 - Soft start: Charge the battery to the maximum current gradually and never suddenly.
Stage 5 - CC1/CC2/CC3 (Constant Current): The charger automatically adjusts the current
according to the battery status in constant current, which benefits the battery for a long life;
Stage 6- CV (Constant Voltage): The battery is charged to nearly full, and will top off at 14.6V DC;
Stage 7 - Resting: The charger will cut off with full charged statement, and achieves the
high energy efficiency;
Stage 8-Recond: When it is fully charged and low to 12.8V within 2min, the charger will judge automatically.
Stage 9 - Restoring: The charger monitors a fully charged battery automatically. If the battery falls below 12.8V DC, the charger will restart from stage 3 to stage 6.