Fiddling with ford’s battery management

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I’ve been noticing a change in the starting note in my f150 lately and started paying more attention to the battery voltages. I’ve got a small digital voltmeter mounted. In other posts I’ve noted the stock behavior:
- 12.4v cruise
- 14.4v deceleration
- 13.5v when lights are on or AC is on the 2 highest fan speeds
- 14.4v after startup for 15-90 seconds
- 14.0v once a month for a few hours

i finally figured out that the battery settings require a newer version of forscan than what I was running. Here are a few notes.

1. i found a post on another forum, written by the engineer who wrote the BCM strategy. He said there is more mpg savings in battery management than in auto start/stop. I’ve seen a decent return on auto start/stop, so that’s pretty impressive.

2. if you know what to look for, it is perceivable when the alternator is commanded to dump 14.4 volts during deceleration. With the voltmeter indicating when it’s happening, you can get a sense for it. It does add a small but perceivable drag to the vehicle, which is rather impressive. Measured, that can be 40amps of current into the battery, which is not small - that’s 3/4 of a horsepower at the pulley, or more with losses.

ford calls for a factory target of holding the battery at 80% state of charge. It chronically runs the battery under-charged while cruising and then blasts it with current whenever you lift off the throttle. the bodycm tracks battery age, calculated state of charge, and considers case size (h6, h7, h8, wet vs agm, and cca).

with forscan, one can change the parameters, such as target state of charge, and then a large drop down list of maybe 20 different batteries in varying size/type/cca combinations. Other forums have mentioned that they don’t see much of a difference, but with the voltmeter mounted, I’ll say that the settings do make a difference. upping the state of charge target increases the time it spends at 14.4 cold start charge before shifting to regular mode (12.4 cruise / 14.4 decel). selecting a battery with greater capacity seems to do similarly.

one can disable the intelligent battery control, which pretty much locks it to 14.1v all day. This also disables auto start/stop. I decided not to do this, because I like the mpg the truck gets. That, and ford will reduce the alternator output during acceleration events. I don’t drive aggressively, but I do like how it feels overall. Realizing the feel of the alternator drag when it hits during deceleration, I decided I kinda agree with their strategy, and don’t really want to change the characteristics of the truck’s throttle feel.

i ending up playing with a few different state of charge targets, and will head to work Monday with 98% set. When I did that this weekend, it spent half an hour at 14.4 volts charging while forscan reported the calculated state of charge slowly ticking up. 98 might be too high…. True state of charge up there can take hours, in which case it may practically defeat the ”intelligent” battery management.

whether or not we agree with intelligent battery management, I was impressed with the amount of design they put into it, and how they integrated it into the feel of the engine response. They clearly did some work here.

-m
 
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I've noticed this behavior on my volt gauge on the Yukon. Seems like they're doing everything they can to eek a little more MPG out of these big vehicles.
 
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So, a little more fuel economy in exchange for wearing the battery out more quickly by under charging. With auto start/stop, it seems like battery will get hammered pretty hard all the time.
 
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So, a little more fuel economy in exchange for wearing the battery out more quickly by under charging. With auto start/stop, it seems like battery will get hammered pretty hard all the time.
Seems that way. I have AutoStopStart disabled on mine, but I still don't like the idea of 80% SOC.
 

CKN

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I've noticed this behavior on my volt gauge on the Yukon. Seems like they're doing everything they can to eek a little more MPG out of these big vehicles.
You would be surprised how many guys on the truck forums notice this to think something is wrong. It is explained in the owner's manual....but who reads those........
 
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I’ve been noticing a change in the starting note in my f150 lately and started paying more attention to the battery voltages. I’ve got a small digital voltmeter mounted. In other posts I’ve noted the stock behavior:
- 12.4v cruise
- 14.4v deceleration
- 13.5v when lights are on or AC is on the 2 highest fan speeds
- 14.4v after startup for 15-90 seconds
- 14.0v once a month for a few hours
You need to try a continuous voltage logger or a storage oscilloscope. What the Ford battery control module is doing is far more complex and varied than your simple description.
 
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For all the complaints on managing the battery SOC around 80%, the first battery in my F150 did 5 3/4 years and 87,000 miles with start stop on my 2016 F150 with the 2.7... Which was not far off from what the batteries in my 3 previous F150's delivered in the same usage without start stop.

I'd also agree with GrumpyCat - there's much more going on - I definitely do not have such discrete voltages though my ambient temps may vary greatly from what the OP is experiencing... Looks like a high of 34 where I will be tomorrow as an example...
 
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I'm happy there's a back door you can use to fiddle with it.

What would happen if you got a little solar panel on your dash that works to top off the battery? 20% of 90 Ah is 18 Ah. This guy claims 5 watts (0.41 amps) which means 44 hours of bright sun are needed to get to your target. And that's before all the inefficiencies.
 

meep

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You need to try a continuous voltage logger or a storage oscilloscope. What the Ford battery control module is doing is far more complex and varied than your simple description.
For all the complaints on managing the battery SOC around 80%, the first battery in my F150 did 5 3/4 years and 87,000 miles with start stop on my 2016 F150 with the 2.7... Which was not far off from what the batteries in my 3 previous F150's delivered in the same usage without start stop.

I'd also agree with GrumpyCat - there's much more going on - I definitely do not have such discrete voltages though my ambient temps may vary greatly from what the OP is experiencing... Looks like a high of 34 where I will be tomorrow as an example...
apologies. I simplified the observations because ive found that brutally long posts tend to be wearisome to the reader. Yes, there is more going on.

@eljefino - I have 50W of PV with a pwm controller mounted to the camper shell. I study, write and lesson prep from the truck often and the PV is useful there. My observations at least with the SOC set at 80, was the PV at 1.2 amps needed about 4-5 hours to reach 14V, every day after getting to work. (I later glued another super-thin panel up there for a total of 100w.

the battery I’m using is older than the truck. It’s a 6.5 year old H8 in the 4.5 year old truck.

m!
 
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What would happen if you got a little solar panel on your dash that works to top off the battery? 20% of 90 Ah is 18 Ah. This guy claims 5 watts (0.41 amps) which means 44 hours of bright sun are needed to get to your target. And that's before all the inefficiencies.
Not sure of a solar panel is a permanent gain or if this would just cause Ford's charging to wait longer/less topping of battery.

Linked panel will not give 0.41A, see further down on the page, short circuit 0.3A and working 0.28A but even this, must depend on direct sunlight. At (probably) a week+ to top off the battery, it seems more useful to combat self-discharge/vehicle drain during extended parking, more than a few days. I suppose you could use a few in parallel or just get a larger panel.
 
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1. i found a post on another forum, written by the engineer who wrote the BCM strategy. He said there is more mpg savings in battery management than in auto start/stop. I’ve seen a decent return on auto start/stop, so that’s pretty impressive.
Too much in your post for me to digest at the moment, but can we get a link to that forum post by the engineer? Thanks!

I do think a little higher SOC would be a worthy trade off, lowering MPG a tiny bit in order to extend battery life.

When I did that this weekend, it spent half an hour at 14.4 volts charging while forscan reported the calculated state of charge slowly ticking up. 98 might be too high…. True state of charge up there can take hours, in which case it may practically defeat the ”intelligent” battery management.

Maybe, or I wonder if once you reach the higher state of charge and keep it there, it doesn't need as long to top it off to that level in the future so you again regain some of the BCM benefits.
 
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Not sure of a solar panel is a permanent gain or if this would just cause Ford's charging to wait longer/less topping of battery.

Linked panel will not give 0.41A, see further down on the page, short circuit 0.3A and working 0.28A but even this, must depend on direct sunlight. At (probably) a week+ to top off the battery, it seems more useful to combat self-discharge/vehicle drain during extended parking, more than a few days. I suppose you could use a few in parallel or just get a larger panel.
Yeah, the physics don't make sense, otherwise Ford would have slapped $25 worth of panels on and kept their 80% target programming. I only expect a panel of that size to maintain all the parasitic loads.
 

meep

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Too much in your post for me to digest at the moment, but can we get a link to that forum post by the engineer? Thanks!
I’ll see if I can find it. He didn’t provide data but more of a testimony of depth of design. It might take me a bit to dig it up; it was somewhere out on the edge of the internet, I think in a ford trucks forum.
 

meep

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@Dave9 here’s the link, https://www.f150forum.com/f118/battery-replacement-469583/index3/

his username is “stormsearch” - starts here “I am the Ford Engineer who writes the Owner Manaul Section, who releases the battery, starter, alternator and BMS sensor and who writes the Workshop Manaul along with FCSD (Ford Customer Service Division).”

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”…Really should do some reading on this site regarding BMS though admittelty have asked the right person. The main purpose for the BMS system goes back before vehicles had start/stop that used a Hall Sensor (also called BMS sensor), not the same module that attaches to the battery negative post. The BMS monitors battery conditions that provides feedback to the BCM charging control strategy. Honda had this special charging control strategy for fuel economy for about 15 years now, way before Ford. One of the BCM charging control strategies is a fuel economy mode. In that mode, the BCM commands the PCM to raise/lower voltage setpoints based on engine efficiency. At low efficiency (idling/high acceleration) the voltage setpoint is lowered to reduce drag on the engine. At high efficiency (coasting or steady state conditions), higher voltage setpoint to allow re-charging the battery. The fuel economy from this system is real, more so than the start/stop system available imo. Fuel economy figures are not publicized and not able to provide this information. This is also why I mentioned previously the BMS operation may actually hurt battery health.

When Ford introduced start/stop systems we needed a more accurate means of determining battery health and developed the sensor which mounts on the battery terminal. It is more accurate and provides temperature information. Ford doesn't want vehicle's engine turning off at stop lights if the battery is unhealthy or unable to restart.”
 
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