Battery Tender Terminal Connections

TK1215

I had read through all that stuff. This is the first vehicle I have had with the BMS and I had zero clue about it. I went and looked at the instructions from The Battery Tender, company and their instructions don’t even mention BMS. They just say hook the red to the positive terminal and the black to the negative terminal. So this is a good lesson learned for everyone. All I know is my battery didn’t even make it two years before I had to replace it. I think if you mix in a week here and there of no driving, constant drain and our wonderful extreme heat here in AZ and there you have it

Modern cars that have upwards of 10+ computer modules do not do well sitting without out some level of battery maintainer device or being driven periodically over 15 or so miles.

Eninty

"BATTERY MANAGEMENT SYSTEM
LIMITATIONS
After battery replacement, or in some cases after charging the battery with an external charger, the battery management system requires eight hours of vehicle sleep time to relearn the battery state of charge. During this time, your vehicle must remain fully locked with the ignition switched off. Note: Prior to relearning the battery state of charge, the battery management system could temporarily disable some electrical systems."

I think this is a significant piece of information. I would say if a battery maintainer is used constantly and attached to the battery when it is at or near 100% state of charge (SOC), the risk of the BMS "disabling some electrical systems" would be rather low because it has no reason to think the battery level of charge can't support full operation of the entire electrical system.

There may be other threads on this, but first I have read this also. On the surface it sounds crazy since most of my batteries are replaced at an auto parts store in their parking lot. Free labor and don't have to return the core, etc.

This makes it sound like you would have to let the car "sleep" for 8 hours before driving. I'm sure it's not that serious and more of a warning. but I imagine most folks will be installing a new battery at a dealer or parts storm then driving home or to work, etc.

Eninty

I keep hearing this, I don't believe it, but where is the data?

We just had this discussion on the F150 powerboost group as well, and this video does an excellent job of explaining the charging with a BMS system on FORD (would apply for Bronco as well). The link is book marked, but the whole video is a good watch.

Xpathf1nderX

We just had this discussion on the F150 powerboost group as well, and this video does an excellent job of explaining the charging with a BMS system on FORD (would apply for Bronco as well). The link is book marked, but the whole video is a good watch.

I've seen that video previously about a year ago when I got into this same discussion on the MachE forum.

My opinion is Ford made a spade on the negative terminal to attach a battery maintainer pigtail to and/or use as a jumper cable clamp connection location. On the positive battery terminal are two unused threaded posts, which IMO are there to connect directly to the positive battery terminal to power auxiliary equipment or connect a battery maintainer positive lead to.

If you look at the negative terminal, the body ground is on the same "side" of the sensor as is the battery post. The ground cable is about 8 inches in length and bolts right to the inner fender just inches from the battery. Connecting the maintainer's negative lead to the body ground bolt or to the spade on the terminal where the BMS sensor is connected makes no electrical difference.

The Bronco owners manual states it takes 8 hours of sleep time to reestablish the battery's state of charge. Putting 12V of charge across the battery's positive and negative terminals will charge the battery. The BMS will eventually establish a new updated battery SOC.