Powerboost 12v battery charging tip

[Snakebitten]

Thanks for your explanation of how the PB system works. Is there a detailed technical discussion of the electrical system anywhere? It seems to be a real black box.

Looking through the electrical diagrams in the PB Modifiers Guide there appears to be a belt driven starter/generator located on the engine. So is there another source of electricity in the PB other than the hybrid battery?

Honestly, with the combination of the Factory Service Manual and monitoring the LV & HV pids that I do, along with the invaluable sharing of some smart people on this forum, I have a fairly good idea of WHAT is actually going on.
Why or How? Not so much. ?

There's a LOT of information that eventually explains what is happening in these PIDs. (the bottom half 8 sensors.

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[HammaMan]

Managed to knock some of it out earlier than I expected.

I can't explain why but my results have a more normal result re charging and blower but only measuring volts at this time.

Truck was undisturbed for ~18 hrs. Last driven, several days ago.

6:15 a.m. Popped the hood.
Engine batt = 12.12V per digital multimeter.
Key off, fob out of truck = 12.64
6:34 a.m.

By voltage alone your 12v system was already at a low SOC. My 12v bus battery at-rest voltage is ~13.3v which results in a 100% SOC for the under hood AGM. Things get muddy around the 70% SOC level for the under hood batt. Keep in mind that despite the rating of the battery, at 50% it's dead and a factory truck under perfect conditions should reach 80%, leaving at best a 30% usable capacity. By the time the truck goes back to sleep I'd expect the battery to be around 12.6 at best. I documented current consumption of wakeup scenarios of the truck in another thread. Just 5 wake ups can cause up to 7ah to be drained from the 12v system and at that point the systems enter low power mode.

More than one occasion pre-LFP with the truck running I found the 12v bus to have 12.8v on it. I've been doing a lot of tinkering and it's amazing just how fast low power mode can occur when the LFP is off of the 12v bus. With the LFP in place I'm in control of its BMS so I'm more concerned about having the truck supply 12v supply when the key is on. I found the conditions and shared them so that anyone who may have weird issues will know how to for-sure enable 12v generation. Due to the LFP keeping the 12v AGM floating at 100%, the generation voltage on my 12v bus peaks around 13.7v, but w/ the HVAC blower on setting 5, I can insure that every time I use the truck, it's actually got the 12v generation on.

Anyone with a separate battery voltage monitor like what snake has installed can witness this behavior. Knowing this conditions is just another point to put the owner in full control of their property.

Oh, @Snakebitten the aux batt does have a current transformer on it so the truck is monitoring it. Just not sure what it's good for. Ford used to use the CTs for under hood before switching to the shunt.

 

[turbopilot]

More than one occasion pre-LFP with the truck running I found the 12v bus to have 12.8v on it. I've been doing a lot of tinkering and it's amazing just how fast low power mode can occur when the LFP is off of the 12v bus. With the LFP in place I'm in control of its BMS so I'm more concerned about having the truck supply 12v supply when the key is on.

Joining this thread late. What is "LFP"?

 

[HammaMan]

Joining this thread late. What is "LFP"?

A battery chemistry. I have one in place of my aux batt.

https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery

 

[turbopilot]

Ford's BMS logic is poo.

It sure is. Here is what it looks like with blower on "Auto" and blower manually set at 6.

 

[HammaMan]

It sure is. Here is what it looks like with blower on "Auto" and blower manually set at 6.

Interesting that even with your 12v SOC showing 100% it's still upping your voltage to 14.1. Notice how it was consuming your battery vs charging it? This is why regular charging still produces marginal results because the truck will use the batt when you drive it.

 

[turbopilot]

Interesting that even with your 12v SOC showing 100% it's still upping your voltage to 14.1.

Saw that. May not be good news but given the choice I prefer to see the voltage in a normal float range. Did not get a picture but as things heated up the voltage did fall down to 13.8 so there may be some temperature compensation in the system.

I wonder if Ford is pumping up the voltage with high fan settings to get more are blowing through the system. Probably a big difference in air flow between 12.3 volts and 14.0 volts.

 

[HammaMan]

Saw that. May not be good news but given the choice I prefer to see the voltage in a normal float range. Did not get a picture but as things heated up the voltage did fall down to 13.8 so there may be some temperature compensation in the system.

I wonder if Ford is pumping up the voltage with high fan settings to get more are blowing through the system. Probably a big difference in air flow between 12.3 volts and 14.0 volts.

The argument they make is that it's prolonged battery life. Personally I don't care if I get longer battery life if it's not meeting the requirements. Sure the AGM isn't a traditional lead acid, but I've always gotten 5 years + out of my FLAs with 14.4v coming from alternators. If battery life is shortened ~20% but performs as it should, it's a small price to pay.

 

[imnuts]

Best guess, this is probably a carry over from traditional ICE trucks with auto start/stop. In the few vehicles I've driven with auto start/stop, over a certain HVAC fan speed the engine doesn't shut off. Requiring battery charging at a certain fan speed seems like an easy way to keep the engine running.

 

[Snakebitten]

I have never seen or heard of the 12V battery being at 100% SOC on a Powerboost. That's amazing.

If mine was even at 90%, I'd have no complaint seeing it being drawn on, even if it makes no sense to do so.

 

[Davexxxx]

I have never seen or heard of the 12V battery being at 100% SOC on a Powerboost. That's amazing.

If mine was even at 90%, I'd have no complaint seeing it being drawn on, even if it makes no sense to do so.

This gives me some questions.

If the batt is disconnected and hooked to a smart charger, if it hadn't already been damaged by the FORD SOC regimen, or aged out, you could get it to 100%. It wouldn't stay there but what would the harm / hassle be? I know this resets some things but what? How big a hassle and is there risk. I also know the BMS will be blind to this but will catch the next day, right?

Same scenario for the batt under the seat? I plan to at least take the cover off and put eyes on it this weekend, take some measurements and readings etc.

Also, am I right that you monitor of the 12v is the 2 batts combined, or is it just the engine batt?

 

[turbopilot]

This gives me some questions.

If the batt is disconnected and hooked to a smart charger, if it hadn't already been damaged by the FORD SOC regimen, or aged out, you could get it to 100%. It wouldn't stay there but what would the harm / hassle be? I know this resets some things but what? How big a hassle and is there risk. I also know the BMS will be blind to this but will catch the next day, right?

Same scenario for the batt under the seat? I plan to at least take the cover off and put eyes on it this weekend, take some measurements and readings etc.

Also, am I right that you monitor of the 12v is the 2 batts combined, or is it just the engine batt?

It is not very impressive. Note the negative lead has a Hall effect transducer to measure amps flowing.

 

[HammaMan]

It is not very impressive. Note the negative lead has a Hall effect transducer to measure amps flowing.

As of yet I haven't found what if anything that thing does. I refer to it as a current transformer. The BMS only cares about the one under the hood. I have some small loads attached to the ground of the rear battery, but they're routed through that CT so the truck can see them -- it doesn't care. I've even pulled 100 amps through that thing and again, no response from the truck.

 

[turbopilot]

As of yet I haven't found what if anything that thing does. I refer to it as a current transformer. The BMS only cares about the one under the hood. I have some small loads attached to the ground of the rear battery, but they're routed through that CT so the truck can see them -- it doesn't care. I've even pulled 100 amps through that thing and again, no response from the truck.

Looks like that. It is isolated by a diode from the main 12 volt battery, so it can get charged but not supply 12 volt power. But where is it supplying 12 volts. Whatever it feeds it only is good for 7 ah.

 

[HammaMan]

Looks like that. It is isolated by a diode from the main 12 volt battery, so it can get charged but not supply 12 volt power. But where is it supplying 12 volts. Whatever it feeds it only is good for 7 ah.

From my testing the only time that isolator opens is on flywheel starter engagement.

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