Powertrain Malfunction / Reduced Power

[elizarrj]

I took my truck to O'Reily Auto Parts to do a battery load test since, the dealer is booked until Feb 4. O'Reily did the test and they said the battery looked good, but the charge level was very low. I did charge the battery to full right before I went to O'Reily and drove perhaps 6 miles at most. Is it normal to have a low SOC and not driving very far? I guess it still could be a bad battery or perhaps like what DudeRino said " a bad high voltage battery module " or something? I am very curious what Ford finds out.

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[TaxmanHog]

I took my truck to O'Reily Auto Parts to do a battery load test since, the dealer is booked until Feb 4. O'Reily did the test and they said the battery looked good, but the charge level was very low. I did charge the battery to full right before I went to O'Reily and drove perhaps 6 miles at most. Is it normal to have a low SOC and not driving very far? I guess it still could be a bad battery or perhaps like what DudeRino said " a bad high voltage battery module " or something? I am very curious what Ford finds out.

It is unusual for the SOC of the 12v to drop so quickly in 6 miles, I suspect something is wrong with the DC/DC converter, have you put a volt meter on the battery terminals while the truck is in run mode?

IIRC you'll see high 13 to 14 volt value if the battery is being charged by a healthy system, if it is, then maybe the 12v battery itself is the problem!

 

[El Duderino]

Edit: I agree with TaxMan above. Confirm your DC/DC converter is supplying charging voltage to the 12v battery. For reference, it's converts high voltage battery DC voltage from 300+ volts to ~13.5 volts to charge the battery. Dealer can do this also.

But the 6 mile drive should not have lowered the state of charge much at all from a full charge. The Ford BMS can lower the state of charge if it thinks the battery is supposed to be lower SOC due to age and it's algorithm. I would due to a BMS reset on your battery. And also make sure your BMS sensor on the negative battery terminal is the updated part. The 2022 and 2023 Lightnings had a BMS issue and there was an updated part # created and released. There is forum info and others that know more about this than me. A quick search might be worth it.

 

[elizarrj]

Edit: I agree with TaxMan above. Confirm your DC/DC converter is supplying charging voltage to the 12v battery. For reference, it's converts high voltage battery DC voltage from 300+ volts to ~13.5 volts to charge the battery. Dealer can do this also.

But the 6 mile drive should not have lowered the state of charge much at all from a full charge. The Ford BMS can lower the state of charge if it thinks the battery is supposed to be lower SOC due to age and it's algorithm. I would due to a BMS reset on your battery. And also make sure your BMS sensor on the negative battery terminal is the updated part. The 2022 and 2023 Lightnings had a BMS issue and there was an updated part # created and released. There is forum info and others that know more about this than me. A quick search might be worth it.

The battery is toast. I needed batteries for my Volt meter tool. I went to the store and got the batteries and then got home. I put the batteries in my Volt tool. I Started the truck and it immediately Power Train Malfunction except this time I could not shut down the truck. I had to pull the battery cables from the 12V to get everything shut off. I called the dealer and they are going to look at my truck tomorrow. I will either get road side assistance to tow it there or I will try to drive it there. The battery was almost completely dead. I am charging it now. Their EV mechanic said to charge it.
I do have a question. I know the 12V battery is used to start the car. Do you think the truck can stay running and go 12 miles if I don't turn the truck off? Or is it safer just to get it towed?

 

[chriserx]

The battery is toast. I needed batteries for my Volt meter tool. I went to the store and got the batteries and then got home. I put the batteries in my Volt tool. I Started the truck and it immediately Power Train Malfunction except this time I could not shut down the truck. I had to pull the battery cables from the 12V to get everything shut off. I called the dealer and they are going to look at my truck tomorrow. I will either get road side assistance to tow it there or I will try to drive it there. The battery was almost completely dead. I am charging it now. Their EV mechanic said to charge it.
I do have a question. I know the 12V battery is used to start the car. Do you think the truck can stay running and go 12 miles if I don't turn the truck off? Or is it safer just to get it towed?

Am I reading that right? You had to remove the 12v just to shut off the truck? Is that a known thing cuz if that happened that sounds more like a bad 12v DCDC. Kinda like cutting the alternator belt on an ICE with a bad battery.

 

[elizarrj]

Am I reading that right? You had to remove the 12v just to shut off the truck? Is that a known thing cuz if that happened that sounds more like a bad 12v DCDC. Kinda like cutting the alternator belt on an ICE with a bad battery.

I absolutely could not turn off the truck. The truck was making a weird noise underneath by the big battery. I was on the phone with the mechanic while this was happening and said it was the 12V being extremely low and I should start charging and then after some charge I could turn the truck off. I really didn't like the sound I was hearing so I opted to disconnect the battery and it stopped immediately. I then connected the battery and started charging. I was going to drive it in the morning to the dealer, but i'm worried the truck will die completely while driving if the SOC hits 0. I'm thinking of just letting Ford Roadside just tow it to the dealer. I'm still under warranty so the tow will be covered. It is just more convenient for me to drive it in myself as I have a meeting tomorrow a block away. One of my co-worker will then take me home. Would you risk driving it?

 

[chl]

Hope when you are charging it you have the negative connected downstream of the BMS, either to the jump post or truck frame ground or to the post on the BMS sensor away from the battery blue circles not red X's:

 

[elizarrj]

Hope when you are charging it you have the negative connected downstream of the BMS, either to the jump post or truck frame ground or to the post on the BMS sensor away from the battery blue circles not red X's:

I'm charging the way Ford Recommends. I took the 8 or so plastic screws. Like this image:

I already have 4 missing plastic screws, so it was pretty easy for me to do this, otherwise I would have done it like you showed.

 

[Zprime29]

@Ford Motor Company This is why we need to see SOC for the 12v battery! This is a safety issue, no one wants to get stuck in the middle of the highway with a dead 12v. At a minimum there should be a warning indicating low charge on the 12v and to pull over. But honestly, both the warning and a meter for SOC would be best. It's incredibly misleading for a power train malfunction warning to show up for a bad converter.

 

[chl]

It is unusual for the SOC of the 12v to drop so quickly in 6 miles, I suspect something is wrong with the DC/DC converter, have you put a volt meter on the battery terminals while the truck is in run mode?

IIRC you'll see high 13 to 14 volt value if the battery is being charged by a healthy system, if it is, then maybe the 12v battery itself is the problem!

The apparent sudden drop:

That can happen, it depends on the health of the battery, and how the SOC of the 12v battery is being measured. A load test will reveal the health is bad when the SOC if measured with just the terminal voltage will say it's ok.

If you have a really bad battery, a charger might charge it as far as it can and call it full, but in reality it is not - it is charged as far as it can go which may be not much. The terminal voltage may seem like the battery is close to fully charged, but put it under a load and it will fail, that's why they do load testing.

Hence the report that "the battery looked good but the charge level is very low."

So the DC-DC converter may be fine but it cannot put energy into a battery that won't accept it because the plates have been sulfated from deep discharges, like what the Lightning BMS puts it through.

Disconnecting the negative post of the battery to turn off the truck, which I am assuming he did, probably disconnects the DC-DC converter as well from ground, otherwise the truck would not shut off.

The weird noise he heard may have been the battery cooling system running - not much else on the truck that makes noise that I am aware of.

I'd bet on a bad 12v battery and an OK DC-DC converter. But anything is possible.

Once started, the truck could stay running on just the DC-DC converter, assuming there is not short anywhere in the 12v system.

EDIT: the load might be too much for it without the help of a healthy battery and thus the shutdown.

On an ICE car, if the alternator works, the car will run with a bad/weak battery once started - the voltage may vary a lot with the alternator speed if the battery is bad, which is not great for your vehicle electronics - one sign of a bad battery, or bad voltage regulator, in an ICE vehicle, if it starts at all, could be fluctuating voltages on gauges etc.

But on the Lightning, the DC-DC converter should be able to run the truck after it starts without that voltage fluctuation issue, assuming the DC-DC converter voltage is well regulated (which it should be) and can supply adequate current.

Of course the techs should check the 12v battery BMS system as well as the DC-DC converter.

I agree with the post that Ford ought to make this 12v battery problem go away.

But I can tell you from experience with my 2012 Nissan Leaf, that other EV makers have the same 12v battery issues, due to the load on it when the vehicle is "off."

When I left my Leaf sitting for several weeks after the Dec 2011 delivery, I came back to a 'dead' 12v battery - jump started it and it worked fine. But since then it has been on a battery maintainer, 14 years later still the 12v battery is still doing fine.

My 2023 Lightning 12v battery is also on a battery maintainer, so far so good.

 

[elizarrj]

The apparent sudden drop:

That can happen, it depends on the health of the battery, and how the SOC of the 12v battery is being measured. A load test will reveal the health is bad when the SOC if measured with just the terminal voltage will say it's ok.

If you have a really bad battery, a charger might charge it as far as it can and call it full, but in reality it is not - it is charged as far as it can go which may be not much. The terminal voltage may seem like the battery is close to fully charged, but put it under a load and it will fail, that's why they do load testing.

Hence the report that "the battery looked good but the charge level is very low."

So the DC-DC converter may be fine but it cannot put energy into a battery that won't accept it because the plates have been sulfated from deep discharges, like what the Lightning BMS puts it through.

Disconnecting the negative post of the battery to turn off the truck, which I am assuming he did, probably disconnects the DC-DC converter as well from ground, otherwise the truck would not shut off.

The weird noise he heard may have been the battery cooling system running - not much else on the truck that makes noise that I am aware of.

I'd bet on a bad 12v battery and an OK DC-DC converter. But anything is possible.

Once started, the truck could stay running on just the DC-DC converter, assuming there is not short anywhere in the 12v system.

EDIT: the load might be too much for it without the help of a healthy battery and thus the shutdown.

On an ICE car, if the alternator works, the car will run with a bad/weak battery once started - the voltage may vary a lot with the alternator speed if the battery is bad, which is not great for your vehicle electronics - one sign of a bad battery, or bad voltage regulator, in an ICE vehicle, if it starts at all, could be fluctuating voltages on gauges etc.

But on the Lightning, the DC-DC converter should be able to run the truck after it starts without that voltage fluctuation issue, assuming the DC-DC converter voltage is well regulated (which it should be) and can supply adequate current.

Of course the techs should check the 12v battery BMS system as well as the DC-DC converter.

I agree with the post that Ford ought to make this 12v battery problem go away.

But I can tell you from experience with my 2012 Nissan Leaf, that other EV makers have the same 12v battery issues, due to the load on it when the vehicle is "off."

When I left my Leaf sitting for several weeks after the Dec 2011 delivery, I came back to a 'dead' 12v battery - jump started it and it worked fine. But since then it has been on a battery maintainer, 14 years later still the 12v battery is still doing fine.

My 2023 Lightning 12v battery is also on a battery maintainer, so far so good.

Thanks for this information. The truck is at the dealer and I talked to their EV tech, and he said virtually the same thing as you. It is most likely the battery, but they are going to give the whole truck a once over. I should have the truck back on Monday.

 

[B177y]

Thanks for this information. The truck is at the dealer and I talked to their EV tech, and he said virtually the same thing as you. It is most likely the battery, but they are going to give the whole truck a once over. I should have the truck back on Monday.

Your profile says that you're in Boise. Has it been cold? If so, that will quickly render a borderline 12 volt in "normal" temperatures into a useless brick.

 

[elizarrj]

Your profile says that you're in Boise. Has it been cold? If so, that will quickly render a borderline 12 volt in "normal" temperatures into a useless brick.

So far it has not been really cold. It is coming. I do keep the truck in the garage and precondition before I leave for work. But I suspect your right, the cooler temperatures probably did it in.

 

[chl]

Thanks for this information. The truck is at the dealer and I talked to their EV tech, and he said virtually the same thing as you. It is most likely the battery, but they are going to give the whole truck a once over. I should have the truck back on Monday.

Glad to hear it!
I see a battery maintainer in your future!

It is such a shame that a high tech complicated computerized machine like the Lightning will completely fail because the geniuses who designed it overlooked keeping the 12v battery topped off to 100% all the time using that massive energy stored in the HVB!

Sort of like the war of the worlds story - a microbe defeated the Martians when all our weapons failed!

Or the arrow hitting Achilles in the heel where his mom had held him when she dipped him into the bath that made him otherwise invincible...

Always something, eh?

 

[chriserx]

The apparent sudden drop:

That can happen, it depends on the health of the battery, and how the SOC of the 12v battery is being measured. A load test will reveal the health is bad when the SOC if measured with just the terminal voltage will say it's ok.

If you have a really bad battery, a charger might charge it as far as it can and call it full, but in reality it is not - it is charged as far as it can go which may be not much. The terminal voltage may seem like the battery is close to fully charged, but put it under a load and it will fail, that's why they do load testing.

Hence the report that "the battery looked good but the charge level is very low."

So the DC-DC converter may be fine but it cannot put energy into a battery that won't accept it because the plates have been sulfated from deep discharges, like what the Lightning BMS puts it through.

Disconnecting the negative post of the battery to turn off the truck, which I am assuming he did, probably disconnects the DC-DC converter as well from ground, otherwise the truck would not shut off.

The weird noise he heard may have been the battery cooling system running - not much else on the truck that makes noise that I am aware of.

I'd bet on a bad 12v battery and an OK DC-DC converter. But anything is possible.

Once started, the truck could stay running on just the DC-DC converter, assuming there is not short anywhere in the 12v system.

EDIT: the load might be too much for it without the help of a healthy battery and thus the shutdown.

On an ICE car, if the alternator works, the car will run with a bad/weak battery once started - the voltage may vary a lot with the alternator speed if the battery is bad, which is not great for your vehicle electronics - one sign of a bad battery, or bad voltage regulator, in an ICE vehicle, if it starts at all, could be fluctuating voltages on gauges etc.

But on the Lightning, the DC-DC converter should be able to run the truck after it starts without that voltage fluctuation issue, assuming the DC-DC converter voltage is well regulated (which it should be) and can supply adequate current.

Of course the techs should check the 12v battery BMS system as well as the DC-DC converter.

I agree with the post that Ford ought to make this 12v battery problem go away.

But I can tell you from experience with my 2012 Nissan Leaf, that other EV makers have the same 12v battery issues, due to the load on it when the vehicle is "off."

When I left my Leaf sitting for several weeks after the Dec 2011 delivery, I came back to a 'dead' 12v battery - jump started it and it worked fine. But since then it has been on a battery maintainer, 14 years later still the 12v battery is still doing fine.

My 2023 Lightning 12v battery is also on a battery maintainer, so far so good.

Agreed with everything except grounding, I'd think the system remain grounded even without the battery. As far as the edit about the DCDC not able to handle spikes, it may be true, but I don't think its very likely since there really isn't that much 12v draw in the truck without accessories and it's not very spiky. What I do think is more probable is that the 12v BMS and/or DCDC converter detects no battery and halts but even that would make me ask more questions like why?

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