12V battery replacement poll

[Lytning]

On an associated 12 volt battery topic ... I am curious what others have seen regarding the charging current to their 12 volt battery. Using the Car Scanner app on CarPlay, I recorded 43 amps. On another short trip, which I did not record, I seem to remember 72 amps. Has anyone else recorded or observed their charging 12 volt charging amps?

Sponsored

 

[mr.Magoo]

On an associated 12 volt battery topic ... I am curious what others have seen regarding the charging current to their 12 volt battery. Using the Car Scanner app on CarPlay, I recorded 43 amps. On another short trip, which I did not record, I seem to remember 72 amps. Has anyone else recorded or observed their charging 12 volt charging amps?

https://www.f150lightningforum.com/forum/threads/12v-battery-replacement-poll.32774/post-606879

 

[chl]

https://www.f150lightningforum.com/forum/threads/12v-battery-replacement-poll.32774/post-606879

I find those relatively high charging current numbers rather alarming and wonder if they are accurate?

High charging currents reduce the lifespan of batteries significantly.
Lower charge currents extend the life span of batteries.

The Lightning 12v battery is a 35Ah AGM battery.

Generally a max charging current of 20% to 25% of the Ah capacity is a rule of thumb for lead-acid batteries in general.

For AGM batteries 30% of Ah capacity is often specified as the max current. That would be 10.5A for a 35Ah battery.

But sometime 40% of Ah capacity is specified as a safe max, which would be 14A max.

Because it is an AGM, it goes through a series of charge stages, bulk, absorption and float, from high to low current.
---
Bulk is a constant, high current stage which quickly bring the voltage up until it reaches approximately 14.4V or so, the absorption voltage.

During the absorption stage the charger holds the voltage at the absorption voltage as the current decreases until it reaches a particular level depending on the battery capacity.

During float, the voltage is reduced to a constant voltage of around 13.5V or so to keep the battery at 100% but not overcharge it.
---
According to the Ford documentation about the Lightning charging system, the DC-DC converter will provide 300Wh of energy when the battery reaches 40%, that is, needing 21Ah to be full at 35Ah.

That indicates a charger voltage of 14V from the DC-DC converter:
300Wh/14V=21Ah

Using the 14A rule of thumb for an AGM battery max current, it would take 1.5 hours to fully charge (bulk stage) from 40% to 100%: 21Ah/14A=1.5h That is reasonable and typical.

If those high current numbers being reported are accurate, it could be one reason why the Lightning AGM batteries fail regularly in under 3 years time.

So I wonder...

 

[Lytning]

I find those relatively high charging current numbers rather alarming and wonder if they are accurate?

If those high current numbers being reported are accurate, it could be one reason why the Lightning AGM batteries fail regularly in under 3 years time.

So I wonder...

I believe the 43 amps is correct. However, after reading your comments, I realize that I assumed that all of that current was charging the 12 volt battery. I have attached a photo of the Car Scanner data display, which shows the 43 amps was DC-DC Low Voltage. It is certain that a portion of that current was being used by other 12 volt devices, and not all being used to charge the battery. From "random" observations of 12 volt battery SOC while driving, it does seem that the 12 volt battery charges more quickly than I would expect.

 

[NW Ontario Ford Lightning]

I really like the idea of a 12v DC charging point at the HV-plug area like Chi shows.
I would like a nice neat bulkhead style fitting for the truck side - and then a convenient plug adapter to fit the bulkhead fitting end.
Mayby a KWAY type fitting? something that looks like it belongs inside the HV-plug cover?

 

[mr.Magoo]

I find those relatively high charging current numbers rather alarming and wonder if they are accurate?

I'm afraid they are....

I'm using the battery current PID for those graphs.

0x22402B

BAT_CURRENT

For a second I thought I might have screwed up my configuration (although it has registered negative currents in the past) so I made a test this morning to verify.
10mV on the clamp meter is 1A, so, 30mV on the multimeter is 3A on the clamp meter, picture was taken at 7.56am Also added the DC/DC charger PID for reference. (it only logs every 5 min, so not as granular)

 

[TaxmanHog]

Continuing the tangential topic of cool/cold weather pre-conditioning.

Since yesterday into this morning, temps were not as cold lows in the 40's with rain rolling in from the S/W, this mornings conditioning routine while on the plug used less than half the energy as yesterday, possibly some residual carry over heat in the pack and just not as cold.

Process started at 0712, ready to drive at 0755, unplugged at 0800, using 4.32 kWh of energy.

 

[The Weatherman]

I am going to have to change my poll vote. From: Replace on Fail -to- Other

I have ordered an OHMMU Lion spec for the Lightning.

The truck is showing early signs of LVB degradation. It is slipping into Save Battery mode too frequently for my taste now.

It is a very early 22MY dealer first delivery Mannequin (BD 3/31/22) which makes the 12V battery likely 4yrs old or older.

The OHMMU is a little pricey, but they are having a ‘BlackFriday’ sale going on now.

Looking forward to its arrival probably sometime after Thanksgiving.

 

[Lytning]

I am going to have to change my poll vote. From: Replace on Fail -to- Other

I have ordered an OHMMU Lion spec for the Lightning.

The truck is showing early signs of LVB degradation. It is slipping into Save Battery mode too frequently for my taste now.

It is a very early 22MY dealer first delivery Mannequin (BD 3/31/22) which makes the 12V battery likely 4yrs old or older.

The OHMMU is a little pricey, but they are having a ‘BlackFriday’ sale going on now.

Looking forward to its arrival probably sometime after Thanksgiving.

Don't let it hit you in the head when you pick it up.
It is unbelievably light for a battery.

 

[chl]

I'm afraid they are....

I'm using the battery current PID for those graphs.

0x22402B

BAT_CURRENT

For a second I thought I might have screwed up my configuration (although it has registered negative currents in the past) so I made a test this morning to verify.
10mA on the clamp meter is 1A, so, 30mA is 3A, picture was taken at 7.56am
Also added the DC/DC charger PID for reference. (it only logs every 5 min, so not as granular)

Not following you.
Your meter in the picture is on mV (millivolts) not amps.
10mA is 0.010Amps, so how are you getting your current number?

I was thinking about it last night and wonder if maybe everything is off by a factor of 10 which makes sense to me - 30A charging current is really 3A, eh?

That would be more in line with a reasonable charging current.

The 70A in the linked numbers is maybe 7A then?

No way you'd ever put 70A charging current or even 30A on a 12 volt AGM battery, eh? It would fry it pretty quick!

The only other thing I thought is maybe thee are other things drawing current and that is showing up on what ever line is being measured?

You know, if it doesn't make common sense, usually the numbers must to be wrong.

 

[chl]

I really like the idea of a 12v DC charging point at the HV-plug area like Chi shows.
I would like a nice neat bulkhead style fitting for the truck side - and then a convenient plug adapter to fit the bulkhead fitting end.
Mayby a KWAY type fitting? something that looks like it belongs inside the HV-plug cover?

Yes they make that sort of thing - I just had the SAE cord handy so went with that.
I earlier had put a cigarette lighter type charge port inside the frunk, but decided I did not want to have to leave the frunk open to trickle charge.

Some other folks have put a port under the HV charge port cover - I could not find that CTEK outlet - if I ever do, I might change my set up.

PS: it's CHL, "L" not "i" but I am full of CHI energy so it's all good, lol.

 

[mr.Magoo]

Not following you.
Your meter in the picture is on mV (millivolts) not amps.
10mA is 0.010Amps, so how are you getting your current number?

You know, if it doesn't make common sense, usually the numbers must to be wrong.

You're overthinking it... (although I just noticed a unit typo in my original post)

The black thingey hooked up to the multimeter is a current transducer which outputs 10mV / 1 A
https://www.velleman.eu/products/view/ac-dc-current-transducer-appa-32-appa32/?id=374622&lang=en

(and yes, I did zero it before I took the measurement)


If you look at the graph below for example, the chaging current tapers off pretty quickly, after 15min you're down from 52A to 7A, in the same timeframe the SoC have gone from 56% to 79% which is about 8-10Ah, which devided by 0.25 (15min) equates to an average of 30Ah during those 15min, which tracks pretty well with what you're seeing.

Hypothetically, lets say I was off by a factor of 10 and the max I've ever seen (100A) is 10A and the norm which is around 20A or less (see my 90day chart, which would only be 2A then), well, in that case we're talking about 2-3 hours to charge from 40% SoC (when the automatic charging kicks in) and we all know it doesn't take that long... (I attached one of those events as well for s-ts and giggles, as you can see, it takes about 45min to go from 35% to 94% SoC, max charge current that time was 80A)

 

[Pioneer74]

Some other folks have put a port under the HV charge port cover - I could not find that CTEK outlet - if I ever do, I might change my set up.

https://a.co/d/dpkCqDi

 

[chl]

You're overthinking it... (although I just noticed a unit typo in my original post)

The black thingey hooked up to the multimeter is a current transducer which outputs 10mV / 1 A
https://www.velleman.eu/products/view/ac-dc-current-transducer-appa-32-appa32/?id=374622&lang=en

(and yes, I did zero it before I took the measurement)


If you look at the graph below for example, the chaging current tapers off pretty quickly, after 15min you're down from 52A to 7A, in the same timeframe the SoC have gone from 56% to 79% which is about 8-10Ah, which devided by 0.25 (15min) equates to an average of 30Ah during those 15min, which tracks pretty well with what you're seeing.

Hypothetically, lets say I was off by a factor of 10 and the max I've ever seen (100A) is 10A and the norm which is around 20A or less (see my 90day chart, which would only be 2A then), well, in that case we're talking about 2-3 hours to charge from 40% SoC (when the automatic charging kicks in) and we all know it doesn't take that long... (I attached one of those events as well for s-ts and giggles, as you can see, it takes about 45min to go from 35% to 94% SoC, max charge current that time was 80A)

Oh that's the conversion of the ammeter, I see.

Going down to so low an SOC is another negative for the battery lifespan, assuming the current really goes to 52A.

56% of 35Ah = 21Ah and 79% of 35Ah = 27.65Ah so
56% to 79% in 15 min is: 27.65Ah - 21Ah = 6.65Ah in 15minutes, or
6.65Ah / .25h = 26.6A not 52A

Charging an AGM battery with the DC-DC converter's 300W at 26.5A would mean a voltage of 11.32Volts, but AGMs are typically charged at 14V to 15V during the initial bulk stage.

The Ford spec is that the DC-DC converter uses up to 300W for the AGM battery charging from what I read anyway.

Assuming the 300W and the usual 14V-15V, so assume 14.5V would be a max of 20A during the initial bulk stage.

The rule of thumb for a 35Ah AGM would be at the most 30% of the Ah so 10.5A max current.

I really have a hard time accepting the numbers your seeing, because I assume the Ford engineers would not subject a 35Ah AGM battery to such high currents. But if they did, then it is no wonder these batteries are failing so often.

I had thought the failures were more likely due to letting the batteries get too deeply discharged, not because of over-current charging.

And if the Lightning really charges them at such high currents, then why do we so often have OTA failures due to LOW SOC?

IF the Ford Lightning battery gets deeply discharged which 40% would be, then I would expect the Lightning BMS to start with a low current when recovering them. An SOC of 50% or below is a deeply discharged AGM and is not recommended for AGM batteries to begin with.

A deeply discharged AGM should start with a low current at around 10% of its Ah rating. So for this 35Ah battery, about 3.5A.

The changes to the BMS software has elimintated some of the low SOC OTA problems, but please don't tell me it will lead to overcurrent charging problems!

Not over-thinking it, just using industry standard AGM charging specifications which leads me to question those numbers.

They just don't compute with proper engineering.

 

[chl]

According the the Ford wsm for 25 ym, " Depending on the vehicle and environmental conditions, the DCDC is capable of outputting as many as 260 amps to the 12-volt battery. "

I think it means it is available for the 12v systems (outlets etc. for after market items is limited to continuous 55A) and maybe for the other on-board things like AC etc., not for charging the battery - that number has always been 300W, which at 14-15 volts would be at most 20A.

The dc-dc converter "powers all the standard 12-volt vehicle accessories, such as lights, the audio system, wipers, seat adjusters, window motors, locks, and computers. The 12-volt battery also acts as a temporary backup if the converter's output is exceeded..."

Do you see any 4/0 copper wire going to the 12 battery charger? That's the size needed for 260Amps!

And imagine how fast 260A charger would fill up a 35Ah battery?

35Ah / 260A = 8 minutes!

Yea, I think that's a misleading typo.

Sponsored