Battery Charging Voltage

[RSH]

The battery state of charge according to the meter is 42%,, it's borderline marginal. Have you had any battery related issues?

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[kshaw]

You have an AGM Battery .. is that correct?

I believe that it is a standard battery but I have not yet confirmed.

 

[kshaw]

The battery state of charge according to the meter is 42%,, it's borderline marginal. Have you had any battery related issues?

Not yet. I suspect that not using it for over a week will result in some issues like the start-stop function not working.

 

[Dude]

I believe that it is a standard battery but I have not yet confirmed.

I only asked because the voltage in your pic showed 11.94V and also showed 42% SOC. I’ve wondered if battery testers like in your pic just use voltage to look up the SOC (many of the battery testers ask you to input your battery type) .. see this AGM chart. Was curious if you have an AGM battery that’s all.

Also included the chart for the sealed lead acid battery.

 

[kshaw]

I only asked because the voltage in your pic showed 11.94V and also showed 42% SOC. I’ve wondered if battery testers like in your pic just use voltage to look up the SOC (many of the battery testers ask you to input your battery type) .. see this AGM chart. Was curious if you have an AGM battery that’s all.

Also included the chart for the sealed lead acid battery.

I am sure that it is voltage related and your table seems to correspond with my tester readings. I have installed some solar off-grid systems and that is the way that their battery controllers work. They generally use different charging algorithms based on type of battery used, battery level and mine does some variations depending on battery temperature. I noticed that FORScan indicates an AGM battery charging setting and has a 80 percent battery level. That may be the level where it stops doing the start-stop or where it shuts down the accessories when the engine is not running.

 

[Dude]

I am sure that it is voltage related and your table seems to correspond with my tester readings.

I noticed that FORScan indicates an AGM battery charging setting and has a 80 percent battery level. That may be the level where it stops doing the start-stop or where it shuts down the accessories when the engine is not running.

The 80% battery level might also be a point where the battery charge algorithm changes. I’ll take a look at FORScan and see what other battery data is provided.

The relation of battery voltage to SOC for different battery types is well characterized but there are different charts published by different manufacturers (and others) so the 2 posted charts are just one set of many variations.

To me the usability of the charts can be misleading. I think the BMS Algorithm knows more about the battery charge and health then the simplistic charts indicate. It would be nice to have access to telemetry stored by the BMS especially in real time because there are cases where the Bronco Sport will just shut itself down (https://www.broncosportforum.com/forum/threads/2021-ford-bronco-sport-issue-spurs-nhtsa-investigation-battery-failures.10562/).

There is not much info regarding how Ford’s BMS Algorithm operates and I have not seen anything stating the specific battery condition trigger where Auto Start Stop is shut off but my guess is around 40% SOC or lower but I bet it’s much more complicated than that in the BMS Algorithm.

This is Deep Sleep related but is still interesting because it provides some clues to the BMS behavior … Two Ford articles, #1 states 9.5 volts (that seems to be a typo), #2 states charge of 40% or below may enter Deep Sleep mode:

1. Why does my Ford vehicle enter Deep Sleep mode
https://www.ford.com/support/how-tos/fordpass/troubleshooting/why-does-my-ford-vehicle-enter-deep-sleep-mode/

2. Why does my Ford vehicle enter Deep Sleep mode?
https://www.ford.com.au/support/how-tos/fordpass/troubleshooting/why-does-my-ford-vehicle-enter-deep-sleep-mode

 

[kshaw]

I suspect that the Ford BMS is the functional equivalent of the battery controller on a solar system and yes those are really sophisticated. Ford's charging algorithms are likely proprietary which would explain why there is not a lot of technical data.

 

[NMhunter]

The BMS has nothing to do with the voltage you're reading when the vehicle is turned off and the battery is rested. At less than 50%, you've shortened your battery life. If it is reading that low, you either have a bad alternator, a bad BMS, or most likelly, you don't drive on the highway long enough to fully charge your battery.

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