Testing an Aux batt solution...

[RyanStroeder]

What I would like to understand, is the wide inconsistencies in our trucks.

Other than never being stranded, I had all the same warnings and shut downs others have experienced. And they did eventually become chronic (daily, or near so).

My truck frequently sits for a week at a time and nearly as frequently, the only interruption from that week, to the next, would be a single, 16 mile round trip.

Still on both OEM batts.

Fan speed 5 had no effect that I could discern.

The only thing that did work, was the BMS reset, immediately after giving a full charge, directly to the engine battery posts.

Poof. All problems gone, never to return.

Why mine but not others?

Hmmmm... it's a head scratcher. Did you install a bluetooth battery voltage monitor? The data would help

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[Davexxxx]

Hmmmm... it's a head scratcher. Did you install a bluetooth battery voltage monitor? The data would help

I did not but would have, had the procedure not been successful.

 

[Davexxxx]

Additionally, I tried several of the other tips. High idle, letting it idle until electric mode before turning it off. Disabling welcome features and turning off climate control.

I don't have to do any of that stuff anymore. Everything I want on, is on and I shut the engine off as soon as I'm done.

The only thing I do, is be aware of the fob location, to not unnecessarily affect the truck.

Thats it. Since last March or so.

 

[RyanStroeder]

Additionally, I tried several of the other tips. High idle, letting it idle until electric mode before turning it off. Disabling welcome features and turning off climate control.

I don't have to do any of that stuff anymore. Everything I want on, is on and I shut the engine off as soon as I'm done.

The only thing I do, is be aware of the fob location, to not unnecessarily affect the truck.

Thats it. Since last March or so.

you are a lucky one indeed!

https://en.wikipedia.org/wiki/The_Last_Unicorn_(film)

just joking

 

[Davexxxx]

you are a lucky one indeed!

https://en.wikipedia.org/wiki/The_Last_Unicorn_(film)

Which is unusual, since I'd more often, more closely resemble a Murphy's Law type.

 

[Shane150]

What I would like to understand, is the wide inconsistencies in our trucks.

Other than never being stranded, I had all the same warnings and shut downs others have experienced. And they did eventually become chronic (daily, or near so).

My truck frequently sits for a week at a time and nearly as frequently, the only interruption from that week, to the next, would be a single, 16 mile round trip.

Still on both OEM batts.

Fan speed 5 had no effect that I could discern.

The only thing that did work, was the BMS reset, immediately after giving a full charge, directly to the engine battery posts.

Poof. All problems gone, never to return.

Why mine but not others?

I have the battery monitor and still on both OEM batteries so I will try this and see if it makes a difference. Thanks!

 

[Jmitchelltfo]

What could potentially go wrong if I use a LFP in colder climate? Where I am, it is not cold for extended period of time but there are nights that it will drop below -4F.

I'm not sure about the LFP options that @Snakebitten and @HammaMan are running but the X2 that I bought has a BMS with safety feature that will not allow it to accept a charge until it warms up to 33ºF. I had several mornings that were below 0 and the battery would always begin charging with about 25-30 minutes of driving. Even on 4-5 short trips where the LFP wasn't recharged it still showed over 80% on the monitor that X2 includes. I think I could safely assume that I will be able to get the battery warmed up before it becomes depleted, unless I plan a trip way up north.

I'm not saying that the X2 is a perfect solution for my climate, but it has worked great for the coldest part of my year...... so far. The original battery in my 2021 should not be woking this well when it shows 1400+ days in service, but with the help of my parallel LFP setup I think it might hang on for a while longer.

 

[Tank]

I don’t know if you run a battery monitor, but it’s been super informative since I installed mine a couple weeks ago.

This would be one of the biggest differences between a decently sized LFP battery vs the AGM.
Mine has a resting voltage of 13.25 and even on the rare occasion that the starter gets utilized the main battery will never get close to 12 volts. Keep in mind that my main battery has never been replaced……so I’d say that is pretty good.

Yessir..I monitor everything...for almost 2 years...my Main battery and Aux battery stay between 15.1v and 13.4 v now..

My main battery is still the orginal stock one too..

 

[Jmitchelltfo]

Yessir..I monitor everything...for almost 2 years...my Main battery and Aux battery stay between 15.1v and 13.4 v now..

My main battery is still the orginal stock one too..

Yes, I run a MX+ also, and can see voltages while driving. I was referring to resting voltage and the "sag" when the starter is used.

If you run a Bluetooth monitor on your batteries, you might notice some differences. I'm not saying that your AGM isn't a good option, but it probably won't have as high of a resting voltage and you might notice a bit more of a dip when the starter is used. Just food for thought if your Oreilly's battery ever bites the dust too.........I'm not sure about their warranty but Walmart only had 90 days listed for their powersports version of the same battery, that's why I went with a 10 year warranty on the X2.

 

[HammaMan]

I'm not sure about the LFP options that @Snakebitten and @HammaMan are running but the X2 that I bought has a BMS with safety feature that will not allow it to accept a charge until it warms up to 33ºF. I had several mornings that were below 0 and the battery would always begin charging with about 25-30 minutes of driving. Even on 4-5 short trips where the LFP wasn't recharged it still showed over 80% on the monitor that X2 includes. I think I could safely assume that I will be able to get the battery warmed up before it becomes depleted, unless I plan a trip way up north.

Thanks for confirming the X2's behavior. None of their literature lists its functionality. The BMS in the cell I have does not have low temp protection built in. I'm fully aware of this. LFP can be charged at lower temps and it does affect its lifespan by a factor of about 10:1. The impact is variable dependent. Below freezing isn't an actual magic hard limit, It varies +/-8c or so, depth of discharge, rate of charge, and total charge taken.

For context a daily driven LFP batt will have a lifespan of 15 years before its capacity becomes 80% of that when it left the factory (and even that number is based off it being discharged/charged 80% of its capacity, which doesn't happen here). If a few dozen below freezing top offs drop it to 10 years I'm still more than happy with that. I'm about 2 years into having one in the truck and it's already paid for itself. Honestly I expect this batt to last the life of the truck.

 

[Tank]

Jmitchelltfo...My starter is rarely used...
I always drive the last 2 miles to my house in Sport mode, so everything is charged for the next day...
...so my truck always starts its journey thr next day in electric for the first 1/2 mile or so... so it uses the generator to start the engine, not the starter..

And if the Aux battery ever died on me, in an emergency I'll just disconnect it and let the main battery start the engine..

When I turn my truck on in the morning, the OBD Mx+ is showing resting volts(because the engine isn't on) and it's always above 13.1v

 

[HammaMan]

And if the Aux battery ever died on me, in an emergency I'll just disconnect it and let the main battery start the engine..

The aux batt is a transient buffer (think capacitor) for the DC/DC converter when it opens the battery isolator while performing rolling engine start up -- it's there to keep the voltage constant. For 21-23 trucks this is done via the BISG belt starter. On 24+ the bendix flywheel starter is used to start the truck while in-motion. When parked the traction motor fires up the ICE, the 12v batts/starters are not used.

Due to the hybrid rolling starts opening the battery isolator, I believe this to be behind the standard operating voltage of ~12.9v the truck generates when it's not trying to charge the batteries. This is the resting voltage of an AGM.

 

[Tank]

The aux batt is a transient buffer (think capacitor) for the DC/DC converter when it opens the battery isolator while performing rolling engine start up -- it's there to keep the voltage constant. For 21-23 trucks this is done via the BISG belt starter. On 24+ the bendix flywheel starter is used to start the truck while in-motion. When parked the traction motor fires up the ICE, the 12v batts/starters are not used.

Due to the hybrid rolling starts opening the battery isolator, I believe this to be behind the standard operating voltage of ~12.9v the truck generates when it's not trying to charge the batteries. This is the resting voltage of an AGM.

True, but if you disconnect the aux battery... the truck will still run and operate normally

 

[HammaMan]

Haven't tried rolling starts w/out the aux installed. Seems ford still doesn't outright trust the DC/DC on its own yet. I mean, maybe an extreme failure mode if isolator somehow sticks open and the DC/DC quits it's got at least the aux to park it? I'm not complaining about being able to add 30ah usable reserve capacity with 15 minutes of work.

 

[RyanStroeder]

The aux batt is a transient buffer (think capacitor) for the DC/DC converter when it opens the battery isolator while performing rolling engine start up -- it's there to keep the voltage constant. For 21-23 trucks this is done via the BISG belt starter. On 24+ the bendix flywheel starter is used to start the truck while in-motion. When parked the traction motor fires up the ICE, the 12v batts/starters are not used.

Due to the hybrid rolling starts opening the battery isolator, I believe this to be behind the standard operating voltage of ~12.9v the truck generates when it's not trying to charge the batteries. This is the resting voltage of an AGM.

Thanks for the additional details @HammaMan, do you have any knowledge of why they switched on the 24+? Issues with the belt starter? or?

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