Many modern BMWs pull a lot of power from their battery and if driven on mostly short trips or sit for long, will have shortened battery life. This has been especially true for the N63 V8 powered BMWs. A smart battery charger can help extend your BMW’s battery life. BMW used to sell a rebadged BMW “Battery Tender” brand charger but have since changed to a BMW-badged “CTEK” brand smart battery charger which we review here.
Smart battery chargers or battery tenders will charge a battery until full and “tend” the battery. When the battery needs more power, it will cycle on and off keeping it full but not over charging it. This is opposed to they style you see at an auto parts store where they try to rapidly bring the car battery back to life but will keep charging even if the battery is full. Those are not meant to stay on a battery long.
When yet another winter storm hit, our E92 M3 was going to be sitting for going on three weeks as I’ve been driving our i3 in the winter weather. I headed to my local BMW dealer to grab another car charger as my cigarette styled older BMW Battery charger won’t work on new BMWs.
The new CTEK BMW Battery charger has alligator style clips and has four different charging modes. Simply hook the charger’s red and black alligator clips up to your BMW and press the mode button to select either Motor Cycle, Automobile, Cold battery, or recondition battery.
The CTEK charger charging clips are separated from the main charger by a small orange and black connector. CTEK’s alligator red and black clips are detached from the main charger as a safety precaution. Connect the red clip first, then the black and then connect those via the orange and black connector to the main charging unit.
One can either connect the battery charger by directly accessing the BMW’s battery through the trunk or via the engine compartment on the red power terminal and the ground. I’ve done both, but find using the engine compartment easier to get to as opposed to removing parts of the trunk lining to get to the battery. You can even route the charging cables up through the bottom of the windshield and close the engine bay lid and lock the car if needed.
Once connected, select the automobile icon via the mode button and then the CTEK charger will progress through a series of 6 yellow lights. The 7th light is green and means the BMW’s battery is fully charged and that the smart charger has gone into a maintenance phase where it will only charge if the battery’s voltage drops. It took thirteen hours for my M3 to reach the 7th light and will depend on the state of charge of your BMW Battery as to how long it will take. There is an 8th light which will light up if the battery needs a top off but it’s hard to catch seeing it on. Make sure the green power LED light is a solid green and that the line of yellow stage lights have begun lifting up or it’s not connected correctly.
The overall size of this unit is smaller than BMW’s previous version. The CTEK version also has a very convenient black bag to store it when not in use. The overall length is similar to the last generation and it’s just over 13 feet long. My only minor dislikes of the CTEK smart charger is that the main black power cord has a lot of memory and kept rotating the panel of the charger face down.
Modern BMW batteries are expensive to purchase and install as the car has to be programmed when installing a new battery. The BMW CTEK Battery Charger is a simple, inexpensive way to extend your BMW’s battery and save money in the long run. These chargers are a plug it and forget it device when storing your BMW as they will not over charge but maintain the battery at the perfect state of charge.
The CTEK BMW Smart Battery Charger is available from your local BMW dealer parts department for $95 or may be ordered online here P/N 61432358315 and carries a 2-year warranty.
To read our review of the previous generation BMW “Battery Tender” Battery Charger click here.