15.2v charging seems a bit high while driving

[mcysr]

I've read this whole thread. I have to say, it almost sounds like a LiFePO4 would be a perfect replacement for the stock Ford battery. I'm seeing some LiFePO4 down to right around the $200 USD range. Just need one with internal BMS that shuts off charging in cold weather. And the battery is in the heated area, so it could start charging again after a short time. 100A is probably more than enough. The charging voltages look like they match up.

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[dochawk]

I've read this whole thread. I have to say, it almost sounds like a LiFePO4 would be a perfect replacement for the stock Ford battery.

There's a 20+ page thread on the F150 affiliated forum about adding a LiFePO4 as a backup to the second battery on a PowerBoost. It seems to have been a successful project.

https://www.f150gen14.com/forum/threads/testing-an-aux-batt-solution.17547/

The F-150 and Maverick seem to have similar battery problems. (because they're both motorcraft?)

 

[mcysr]

Thanks! Have to limit charge current. Going to take a deep dive into this.

 

[MakinDoForNow]

Thanks! Have to limit charge current. Going to take a deep dive into this.

The Ford BMS on the negative post should regulate the current to the 12v whether it be 12.8, 14.2, 14.7, or 15.6. on the bus, that is say 1.2 or 2.1 amps or whatever the soc of the 12v requires.
ETA: maybe 15.6 could in a very minor way help desulfate?

 

[Suzukiridr14]

@scotty

Ford will likely not replace your battery unless it doesn't pass their standard battery test. Going by what I've read on these forums, you will have "deep sleep" occurrences well ahead of that time with the stock battery.

Ford likely won't replace it with anything else but a Ford approved battery, which will be another stock FLA battery.

Deep sleep is just mostly a slight annoyance. Nothing more.

Deep sleep roughly explained:

The truck has a bunch of systems active while parked, things like the FordPass connectivity (over the cellular network), WiFi module, keyless entry system (reading the key fob in your pocket), etc. All those systems together require a not insignificant amount of power, which comes from the 12V battery. So the battery drains while you're parked.

When the battery voltage drops to somewhere close to 12V (when the truck is parked) then it will report "deep sleep" on your FordPass app, and then shut down the remote connectivity, as well as things like the interior light when you get into the vehicle, turn off the key fob sensing, things like that.

The truck will still start ok, so there's no real issue.

Shutting down these systems will save quite a bit of power draw, and will make the battery last a lot longer while your truck is parked. There are still some systems active in the vehicle though, but the draw is significantly lower than it was before.

At some point you won't be able to turn on the truck, but by that time the battery is probably well below 11.5V. That could still take weeks.

So "deep sleep" is just a trick up the truck's sleeve to lower the battery draw, so it can sit longer while parked.

Now it turns out, as reported by many others here, that an AGM battery works better in the Maverick Hybrid; it shows more normal 14.6-14.7V charging voltages on average, and will last significantly longer while parked. Mine got to 16 days until it went into deep sleep and that's the only time I have seen it do that.

Before I swapped my battery for an AGM I had deep sleeps happen seemingly randomly, usually after 2-3 days, but sometimes right after parking it (?!). That's when I replaced the battery with a Group 140R AGM.

How the Maverick Hybrid charges the 12V battery:

While driving, the 12V battery gets charged by the DC-DC converter (=the modern day alternator) powered from the high voltage battery (which itself gets charged from the traction motors in the transaxle). The software tries to keep the 12V battery between 60 and 80% state of charge by changing the voltage between 14.4-15.3V (while charging) and 13.0-ish Volts when not charging. I read somewhere that Ford claims that this 60-80% charge philosophy improves battery longevity but I think it is much more likely that it improves EPA fuel economy by a hair, which is probably the real reason.

Interestingly: Driving with my stock FLA battery the system voltage was ALWAYS above 15V, never lower, so it was always trying to charge the battery. With the new AGM battery the system behaves as expected, and will charge at 14.6-14.7V for a while and then sit at 13.0V for long periods (because the 12V battery reached 80% and the system stops charging).



Your question about 80RC:
That stands for Reserve Capacity in minutes, which is a measure on how long the battery will push a given load. The stock battery is I think 65RC, the Group 140R AGM is 80RC, so 25% better.

Bottom line:

If you want the simplest FLA battery swap for an AGM that requires no physical changes and simply drops in: A new H4 / Group 140R AGM is the way to go.

If you want Ford to do this under warranty: they likely won't. At best they'll install another stock FLA battery when your old one is proven toast.

You can also install a much more common (=cost effective) H5 AGM which you can get, as you mentioned, from the Weize brand or various others, but these require bending or cutting the bottom steel locating tab in the truck to make this larger battery fit.

I totally agree with you to replace the original flood battery that came on a hybrid, with a H4 140R AGM battery. I will not chop up my Maverick to install a H5 battery, just because it's larger, and cost less. Why look for problems.

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