Ford BMS Battery Monitoring System: How it Works and How to Properly Charge Your Battery!

[YOG]

 

[Jonro2009]

That's a good explanation of how the BMS does its job. But as he said, not in so many words, it doesn't really matter because the BMS will relearn and update the SOC. Also, most people know to reset the BMS after a charge or battery replacement anyway. 

[unofix]

Well he did a fair job of presenting the concept of the BMS, but as is all to common he keeps talking about PUSHING current in to the battery. Just to be absolutely clear on the matter, regardless of whether you are dealing with a battery, a headlight, a window motor etc. 'current' can not be pushed in to anything. It is drawn by the device and current is taken from the supply.

The subject of where the battery negative charging lead should be connected seems to have been overly complicated. All that needed to be said was "connect it to a chassis earth point". There is no need to deliberate about if it's an old system, a new system or in fact does not even have a BMS. Just connect the negative to the chassis.

One good point, which perhaps should have been given a bit more emphasis is the fact that, if for any reason the BMS does not get  reset when it should have been, for example a new battery installed, or the old battery recharged off the vehicle. The BMS will recalculate the state of charge of the battery in only a couple of days. The only slight issue will be the 'Days in service' counter won't be reset which if it is a new battery could be confusing to anyone looking for information on the battery age.

[Tizer]

That video confirms the advice that many regular posters on this forum have been saying for a long time.

What the video does not say, and Ford does, is that the BMS should only be reset when a new battery is fitted.

The other interesting thing, and for anyone who thinks Start/Stop is a great thing, is that his truck was drawing 18 Amps with the Ignition on and Engine not running. That is about the same Current draw as my car in the same situation and it all needs to be put back into the battery if you drive for long enough after the Engine starts running again by using extra fuel and creating more emissions.

There is a very unscientific video on YouTube that makes claims about how much S/Stop saves that does not take the above into account.