How does the hybrid battery interface with the 12v system?

[Snakebitten]

Did this guy get it wrong? He seems to suggest that the Powerboost does have an alternator, same as the 3.5L Ecoboost. https://www.cargenerator.com/blogs/...j-a-m-cargenerator-ford-powerboost-comparison

He definitely used the term "alternator", but according to Ford the Powerboost doesn't have one. And there's a reason, of course. It doesn't need one. Heck, it barely needs the traditional bendix style starter since most situations for starting the ICE does not even use it.

It's a fascinating arrangement of electrification in so many ways.

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[JBinFla]

Did this guy get it wrong? He seems to suggest that the Powerboost does have an alternator, same as the 3.5L Ecoboost. https://www.cargenerator.com/blogs/...j-a-m-cargenerator-ford-powerboost-comparison

The only reference to alternator I found on that page is the reference to using that car generator (what he is selling) and your cars alternator to generate electricity. He wasn't referring to the powerboost alternator he was referring to comparing the powerboost to the car generator on any other car. I did read something on his site of interest; it was a picture diagram of the electrical system. It shows the starter and oil pump are connected by belts nothing about an alternator. It also states the 12v battery is for starting and the converter provides the low voltage power to the rest of the vehicle which is in line with the 12v battery being for "surge demand" type scenarios as mentioned in the manual we were reading (they don't use the term surge but it seems best way to describe it). I would post the picture here but I'm on my phone and not sure how to do that. It appears to be a Ford produced document so I tend to trust it.

Anyway I'm comfortable in what I believe I know now as it relates to what I'm doing. Stereo works fine connected to main 12v battery in the engine bay (I specifically told them to avoid the smaller one conveniently right there under the back seat). And there are no dimming and such from the amp. This amp is digital though and from what I understand these newer digital amps are loads more efficient than the old one. I'm surprised at how small it is and it's a high end Kenwood amp. It's been 20-years since I messed with car stereos so I'm (re)learning as I go.

 

[JEB]

He definitely used the term "alternator", but according to Ford the Powerboost doesn't have one. And there's a reason, of course. It doesn't need one. Heck, it barely needs the traditional bendix style starter since most situations for starting the ICE does not even use it.

It's a fascinating arrangement of electrification in so many ways.

I’d probably put more stock in Ford publications as well. SO, no alternator.

But where I’m still losing the thread is the pathway between the hybrid battery system and the truck’s traditional 12v accessory system. The Ford schematics show the link between the battery bank and the DC/AC inverter. That’s the Pro Power part of it. That’s simple. That’s just a big Goal Zero. Then there is a direct pathway between the hybrid battery and the 35Kw electric motor boosting power and torque to the transmission. Get that too. DC/DC link to the electric motor that appears to be bi-directional. The electric motor is both a boost to the transmission to provide extra power and a generator to recharge the hybrid battery bank depending on which way the power flow is most needed. That’s the hybrid drivetrain in a nutshell. But where’s the pathway from the hybrid battery bank to the 12v accessory system? I can’t find it anywhere. That strikes me as the key pathway to identifying how integrated the hybrid battery is with the truck’s conventional electrical system. I suppose that that pathway could be the electric motor which recharges both systems—the 12v and the hybrid. But that’s not the kind of direct link between the hybrid battery and the 12v side I thought we were talking about.

 

[JBinFla]

The manual states there is a DC/DC inverter. I believe the electric motor would run on the "native" battery voltage (approx 450v) and not need an inverter. The DC/DC inverter is for stepping the high-voltage battery down to 12v. I'm going from the limited info we've all talked about but to me it makes sense. I would welcome someone with the Ford repair manual who can actually dive deeper into any separation there may be. To me the 12v system has three sources of power, starting battery in engine compartment, small booster battery under back seat, and the DC/DC inverter. Seems to me they would all be connected to a common "bus" but that part I don't know. How else would it be able to use batteries for "surge" demand if not? That would be some more complicated electronics that we haven't even talked about yet and to my non-electrical engineer self would seem to be superfluous.

I don't really want to fuss with any of the high voltage parts, I paid for an extended warranty and don't want to void it but I am curious. And I also want to know what I need to stay away from. It also helps to diagnose problems to have an understanding of how this stuff ties in to each other.

 

[JEB]

The manual states there is a DC/DC inverter. I believe the electric motor would run on the "native" battery voltage (approx 450v) and not need an inverter. The DC/DC inverter is for stepping the high-voltage battery down to 12v. I'm going from the limited info we've all talked about but to me it makes sense. I would welcome someone with the Ford repair manual who can actually dive deeper into any separation there may be. To me the 12v system has three sources of power, starting battery in engine compartment, small booster battery under back seat, and the DC/DC inverter. Seems to me they would all be connected to a common "bus" but that part I don't know. How else would it be able to use batteries for "surge" demand if not? That would be some more complicated electronics that we haven't even talked about yet and to my non-electrical engineer self would seem to be superfluous.

I don't really want to fuss with any of the high voltage parts, I paid for an extended warranty and don't want to void it but I am curious. And I also want to know what I need to stay away from. It also helps to diagnose problems to have an understanding of how this stuff ties in to each other.

Well, we still have a problem then. Part of it might be sloppy terminology in the manual. There is no such thing as a DC/DC inverter. You can INvert DC to AC. You can CONvert AC to DC. You can’t do either DC to DC. What the manual might be talking about is the equivalent of a step down transformer where high voltage DC is stepped down to lower voltage DC but that’s not inversion. And it still leaves the problem of the pathway. I still don’t see anywhere where there is a link via a transformer between the hybrid battery and the 12V system. And that is what you asked about in the title of your thread. Taking what you asked at face value, I don’t see the connection between the two DC systems. On the contrary, if you could defeat the deep sleep protocols, I’m pretty certain that if you turned on the headlights, stereo, head unit, etc., you’d run the starting battery and the aux battery dead and the hybrid battery wouldn’t do a thing to stop it. That’s all I’m getting at, taking your thread title at face value.

 

[beavo451]

This is interesting, but I’m not sure the 12v starter and aux are isolated. They might be, but here’s the wrinkle. When the Sync system was having lock up issues, one of the suggestions made was to disconnect the starter battery to cut all accessory power and allow the Sync system to reset. That procedure doesn’t work on the Powerboost because there is still retained power from another battery system, even when starter battery is out of the loop. Can that retained power can come from the DC/DC converter and the hybrid battery if the key is off? I’m not sure it can. If not, that leaves only the aux battery to provide retained power directly when the starter can’t handle it—in this example because it is disconnected.

To clarify, the batteries are isolated in that one won’t charge the other(that would be bad).

I can’t come up with a good theory as to why there needs to be an auxiliary 12v battery. The only thing I can come up with is that the aux 12v battery provides all accessory power when key off to avoid killing the under hood battery.

I’m pretty positive that the high voltage battery and the DC converter are inactive when key off.

 

[beavo451]

Well, we still have a problem then. Part of it might be sloppy terminology in the manual. There is no such thing as a DC/DC inverter. You can INvert DC to AC. You can CONvert AC to DC. You can’t do either DC to DC. What the manual might be talking about is the equivalent of a step down transformer where high voltage DC is stepped down to lower voltage DC but that’s not inversion. And it still leaves the problem of the pathway. I still don’t see anywhere where there is a link via a transformer between the hybrid battery and the 12V system. And that is what you asked about in the title of your thread. Taking what you asked at face value, I don’t see the connection between the two DC systems. On the contrary, if you could defeat the deep sleep protocols, I’m pretty certain that if you turned on the headlights, stereo, head unit, etc., you’d run the starting battery and the aux battery dead and the hybrid battery wouldn’t do a thing to stop it. That’s all I’m getting at, taking your thread title at face value.

The DC converter goes only from the high voltage system to the 12v system. It does not go the other way around. Well it could, but it makes zero sense and would require huge cables. There is no reason why you would want to charge the high voltage system with the low voltage system even if it did have an alternator.

A transformer only works with AC.

The electric motor itself is probably an AC motor since Ford has stated that the inverter is integral to the drivetrain. It’s also easier and cheaper to recover energy when regen braking with the electric motor.

Therefore, in operation, the high voltage system runs everything electrical via the DC/DC converter. It is the simplest way to run everything as opposed to basically maintaining two separate DC systems and depending on lead acid batteries for the start/stop operation.

Plus, using the high voltage battery also gives you that long idle time with the engine off. And it allows for the propower without having to run the combustion engine continuously.

 

[JEB]

Therefore, in operation, the high voltage system runs everything electrical via the DC/DC converter. It is the simplest way to run everything as opposed to basically maintaining two separate DC systems and depending on lead acid batteries for the start/stop operation.

I found the entirety of your discussion very thoughtful. But this was the key statement I derived from it and where I am still struggling. I agree this would be the simple set way to run everything but not necessarily the simplest way to install it from the factory. Looking through the schematics, I don’t see that level of integration between the two systems. This hybrid system seems to be more of a bolt-on/hybrid assist from what I can see than a full integration. That’s why I keep asking about the pathway between the hybrid batteries and the 12v accessory system and why an aux battery would even be needed if the hybrid battery was actually supplying 12v to “everything electrical.” The aux as a supplement for transient loads when the starter is taxed—makes sense. But this use undercuts the notion that the hybrid is fully integrated.

As for the long idle times, I’m not sure that is evidence of full integration either. When the motor is started, it can simultaneously charge both batteries banks. And during operation in Pro Power mode the generator functions like a Goal Zero “generator” that lacks an ICE providing AC power only via an inverter until recharged. The starter battery installed at the factory is very much like a marine battery with CCA ability and deep cycle properties. At 85Ah, just over 92Ah if the aux ties in, you can run the accessories for quite a while without having to crank the motor to provide a charge. So, they can still function independently for quite a while without having to presume the only way you get long operation between engine starts is via the hybrid batteries. The need to function independently is also why some people with these trucks are finding the 12v starter batteries inadequate and are upgrading them not for the additional cranking amps but for the additional amp hours.

 

[JBinFla]

I don't believe the engine charges the 12v system directly (via alternator). It charges only the high voltage system, which in turn charges the 12v system. I'm not entiry sure where this inverter lives and how exactly it is wired. If you have the Ford repair manual schematic wiring diagrams (and can share) that may be very helpful but all I have are those generalized overview marketing type images that leave out all the nuts and bolts.

 

[JEB]

I don't believe the engine charges the 12v system directly (via alternator). It charges only the high voltage system, which in turn charges the 12v system. I'm not entiry sure where this inverter lives and how exactly it is wired. If you have the Ford repair manual schematic wiring diagrams (and can share) that may be very helpful but all I have are those generalized overview marketing type images that leave out all the nuts and bolts.

True. No alternator. But there has to be some way for the motor to provide a charge because as was noted above it would be risky to use the hybrid batteries to recharge the starter directly.

As for the inverter, that I’m pretty sure it is just a bolt-on directly above the hybrid batteries. It converts DC to AC on two 30A circuits that are otherwise separate from the truck’s electrical system.

Unfortunately, I have the shop manual but there is a separate wiring manual that I don’t have.

Correction to my earlier post: the H7/94R battery installed at the factory is a dual purpose battery very similar to a marine battery but its Ah is closer to 80, not 85. Still overkill if the hybrid batteries were providing 12v accessory power in my opinion.

 

[JEB]

I’ll provide one additional thought and then I’ll bow out of what has been a highly entertaining debate.

There was something about this “DC/DC Converter” mentioned in the modders’ manual that was eating away at me until I finally realized that I’ve seen something like this in another automotive application—camping, specifically towing a travel trailer. If this device is what I think it is, then it confirms (or at least strongly suggests) that the hybrid system and the truck’s 12v electrical system are indeed separate because it is nothing more than a battery charger.

Those of us who tow travel trailers have frequently faced the problem of the 12v house batteries draining when traveling from place to place. The biggest draw is the refrigerator. Although there is a 12v pin on the 7-way plug that provides a charge to the 12v batteries, it is little more than a trickle that does not fully offset the draw from the fridge.

To get around this problem, we install in the tow vehicle a device called, you guessed it, a “DC/DC Converter.” What it does is provide a direct link between the truck’s alternator and the batteries on the travel trailer, providing much more amperage than the 7-way and can actually keep the 12v batteries fully charged despite the presence of 12v loads. Does the DC/DC Converter provide supplemental power to the trailer’s 12v system? Nope. You still need the 12v house batteries— they are providing all the power. The only difference is that the house batteries can remain close to fully charged. But the electrical system cannot handle any additional load. There is no direct tie in between the truck’s electrical generation and the trailer’s electrical system via the DC/DC converter. If you start out with dead trailer batteries, nothing works even if you connect the converter until the 12v batteries have time to recharge.

I think the DC/DC converter in the Powerboost is no different. It takes high voltage DC current and steps it down to low voltage DC current to recharge the 12v battery but it provides no direct power to the truck’s 12v system. It’s just a battery charger. That’s why the hybrid can’t handle any more 12v accessory load than any other F150. It just might be able to handle those loads for a longer period of time because the starter battery has a built-in recharging source.

So, getting back to the OP’s original question. If the lights would dim when the subwoofer kicked in, it would still dim whether you had a hybrid system or not.

 

[beavo451]

I found the entirety of your discussion very thoughtful. But this was the key statement I derived from it and where I am still struggling. I agree this would be the simple set way to run everything but not necessarily the simplest way to install it from the factory. Looking through the schematics, I don’t see that level of integration between the two systems. This hybrid system seems to be more of a bolt-on/hybrid assist from what I can see than a full integration. That’s why I keep asking about the pathway between the hybrid batteries and the 12v accessory system and why an aux battery would even be needed if the hybrid battery was actually supplying 12v to “everything electrical.” The aux as a supplement for transient loads when the starter is taxed—makes sense. But this use undercuts the notion that the hybrid is fully integrated.

As for the long idle times, I’m not sure that is evidence of full integration either. When the motor is started, it can simultaneously charge both batteries banks. And during operation in Pro Power mode the generator functions like a Goal Zero “generator” that lacks an ICE providing AC power only via an inverter until recharged. The starter battery installed at the factory is very much like a marine battery with CCA ability and deep cycle properties. At 85Ah, just over 92Ah if the aux ties in, you can run the accessories for quite a while without having to crank the motor to provide a charge. So, they can still function independently for quite a while without having to presume the only way you get long operation between engine starts is via the hybrid batteries. The need to function independently is also why some people with these trucks are finding the 12v starter batteries inadequate and are upgrading them not for the additional cranking amps but for the additional amp hours.

I believe the simplest answer is the best answer. You wouldn't want to use lead acid batteries, even marine/deep cycle batteries, when you are powering electronics that are going to deep-cycle a battery. There's a rechargeable lithium battery available which handles charge and discharge cycles way better.

If there is 92Ah of lead acid battery available, that's just over 1kwh (1.1kwh) of run time available. You do not want to regularly discharge lead acid batteries past 50% so in reality you have about 500Wh of lead acid battery power.

I know when I idle my truck, it will high idle for 1-2 minutes and give me about 20 minutes of battery only idle. That kind of duty cycle would absolutely murder lead acid batteries.

 

[Oxford_Powerboost]

This is all rather out of my realm, but I do believe in the idea that the simplest answer is probably the most likely - that the DC/DC step down converter, inverter, whatever the appropriate name is, is simply there to bring high voltage down to 12V to charge the 12V batteries. Then all of the vehicle’s 12V components are run from these batteries. Maybe there are two to provide that surge protection or high load protection in the case that the DC/DC converter cannot supply enough power to keep them fully topped up. (I’m a computer person, and I’m thinking about the phenomenon where some laptops use the battery as a big capacitor when plugged in because the charge brick may only deliver 75 watts, but with a CPU and GPU at full load, they may consume 90 watts of power, the battery handles the extra demand and will slowly discharge as the system is taxed at full load. Once load drops under 75 watts, the power brick will deliver excess power to the battery for charging).

Teslas, which are fully electric, have a similar system. Most of their accessories run on a 12V system because they’re A) safer to work on and B) more standardized - lower cost to not have to create proprietary accessories designed around the high voltage system. You can actually end up with a “dead” Tesla that won’t “start” because the 12V battery is unable to energize the relay to engage the high voltage battery and step down converter that charges the 12V. So in a Tesla, the high voltage battery has a similar system where it steps down voltage to charge the 12V, and the 12V runs all the 12V accessories.

 

[beavo451]

This is all rather out of my realm, but I do believe in the idea that the simplest answer is probably the most likely - that the DC/DC step down converter, inverter, whatever the appropriate name is, is simply there to bring high voltage down to 12V to charge the 12V batteries. Then all of the vehicle’s 12V components are run from these batteries. Maybe there are two to provide that surge protection or high load protection in the case that the DC/DC converter cannot supply enough power to keep them fully topped up. (I’m a computer person, and I’m thinking about the phenomenon where some laptops use the battery as a big capacitor when plugged in because the charge brick may only deliver 75 watts, but with a CPU and GPU at full load, they may consume 90 watts of power, the battery handles the extra demand and will slowly discharge as the system is taxed at full load. Once load drops under 75 watts, the power brick will deliver excess power to the battery for charging).

Teslas, which are fully electric, have a similar system. Most of their accessories run on a 12V system because they’re A) safer to work on and B) more standardized - lower cost to not have to create proprietary accessories designed around the high voltage system. You can actually end up with a “dead” Tesla that won’t “start” because the 12V battery is unable to energize the relay to engage the high voltage battery and step down converter that charges the 12V. So in a Tesla, the high voltage battery has a similar system where it steps down voltage to charge the 12V, and the 12V runs all the 12V accessories.

Can you give a good theory why there is an auxiliary 12v lead acid battery?

 

[Oxford_Powerboost]

Can you give a good theory why there is an auxiliary 12v lead acid battery?

My assumption (and that’s just what it is, an assumption) is that it’s just for surge extra capacity. Trucks tend to have more items to run than say a Tesla does (trailer lights, trailer brakes, charging trailer batteries, accessory lights, accessory equipment, etc.). I would guess ford felt the step down converter needed a good bit of help on the high load situations and added the auxiliary battery.

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