Hi Gil: I have a 2015 X3 which I leave in my garage in Florida during the summer. I connected a Battery Tender but it doesn’t keep the battery charged. Two years ago I installed a “jelly” battery and it’s alive enough to keep the dashboard alive but not to start the car. What’s the best way to store the car without this recurring problem? Thanks
Hello Jeff, the question is a little more complex than it seems initially. First, by “jelly” do you mean a gel cell or AGM battery? If it is a gel cell, such as the Optima battery, they have a specific charger.
I also have a question, was the battery programmed when it was replaced? It has to be done. The first reason is the vehicle has an intelligent charging system, which means that the alternator will always try to keep the battery at between 60% and 80% charge and at a certain temperature. It does this by varying the alternator charging, it can go anywhere from 5% to 95%. When you program the battery you tell the computer which type of battery you are installing, the amp-hour rating, and that it is a new battery. If this is not done the alternator will overcharge the new battery and it will only last 8 to 10 months usually. The overcharging caused the battery to overheat, which in turn damages it.
If the programming has been done and the issue is still there, you likely have a battery draw causing it to discharge. You can respond with some more details and I can help you find the answer. Thank you.