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| How to install and use BMW Battery Tender | ||
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If you are like me and live where it snows, you probably put your car away for the winter. Or your M3/M4 isnt your daily driver and sits in the garage for long periods of time. It's a good idea to use a battery tender to keep your battery charged up as these cars have very expensive lithium ion battery.
It comes with either the alligator clips (what's used on jumper cables) or the ring terminal connectors which are a more permanent solution. You can connect it to the positive battery lead under the hood and the negative post (as seen in my video).
Tools Needed:
- 3/8" Ratchet and Extension
- T50 Torx bit
Installation instructions:
I had to route the wires reverse since i wanted to route it nice and clean out of the way, I was unable to route the positive end under the windshield washer reservoir because of the fuse, so i had to start from the other side (where the positive post is) and route the quick disconnect and the negative side under the windshield reservoir. You could unscrew it but that takes longer and is more effort. If you dont want to do that you can just use the alligator clips but why would you want to have to put those on and take them off every time you use the battery tender? Use the ring connector option. NOTE: DO NOT connect the alligator clips or the ring terminal quick disconnect ends to the negative terminal post on the battery in the trunk.
You can connect it in the trunk, but you must not connect it to the battery negative terminal. You can get errors with the Intelligent battery sensor that way.
You must connect the negative via the body. The easiest and recommended place to install it is under the hood as seen in photos below
This is fully explained in the manual if you buy the BMW branded charger from a dealer. (what I have linked below)
HOW TO TOGGLE MODES
If you need to toggle between the standard battery and lithium ion battery mode, connect the battery tender to your power supply but DO NOT connect the battery tender to the quick disconnect end that connects to the battery. This way you will be able to toggle between the 2 settings and select Lithium Ion. Once you do that, then you can connect the battery tender to the battery and you're all set!
. I initially had the battery tender connected to the battery and then gave it power. If your battery tender is connected to the battery you will NOT be able to toggle between modes with the select button. I had to read the instructions to figure that out
