Testing an Aux batt solution...

[Jmitchelltfo]

I was having low battery for awhile I believe and then got the 12 volt warning in the app which led me to take action.

I had previously replaced the original battery shortly after purchasing my '23 powerboats with an H7 battery. It is probably 2-2.5 years old.

After the warning I replaced the Aux battery with the larger Aux battery discussed in this thread. I charged it fully as I did for the main 12 volt battery under the hood. (I pulled the main AGM battery and charged it outside the truck. I reinstalled everything and reset the battery monitoring system)

I decided to go with the lithium battery as well. I purchased a 12V 30 Ah battery from DC house with low temp protection.
https://www.dchousepower.com/produc...e-lifepo4-lithium-low-temp-protection-battery

I charged the lithium battery with a 12v charger I purchased from DC house.
https://www.dchousepower.com/products/12v-10a-ac-to-dc-lifepo4-portable-battery-charger

I hooked the lithium battery in parallel with the AUX battery under the passenger seat.

My voltage went up to 13.2 as seen with other people in this thread.

I drove for the next few days making short trips of roughly 10-20 minutes several times a day. I used Fan 5 setting.

After about 3-4 days my voltage dropped down to 12.8 volts.

I pulled the lithium battery and charged it again last night and reinstalled it. Voltage went from 12.8 to 13.1-13.2.

Would this suggest that the main 12V battery under my hood is at end of life and not maintaining charge? I did not go through the trouble of balancing the lithium battery but I don't know if that is necessary. Appreciate any suggestions before I start throwing more money at the problem.

Are you running an MX+ to monitor temps and voltages?

I check the screen every morning to make sure the DC/DC charger (Powerboost version of an alternator) is working.

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[Snakebitten]

It's possible that 12.8V represents a less than robust H7 AGM. But 12.8 is still a nice safe resting voltage for your Powerboost.

Still, the previous post is pointing out that you might want to confirm your Fanspeed-5 is triggering the expected 13.9-14.1 charging voltage.

 

[JMoney17$]

@Jmitchelltfo I have an MX+ but I was not running the data fields you are showing.

I just downloaded the @Snakebitten files for the MX+ so I will give it a try tomorrow and see what they are showing.

I monitored the voltage today and it dropped from 13.2 to 13.1.

Thanks for the suggestions! I will report back what I find out.

 

[JMoney17$]

@Jmitchelltfo I can't seem to find those dashboard monitors in the MX system? Do you know where they are?

I tried downloading snakebitten's dashboards but they don't seem to be working correctly for me using an iPhone.

 

[Jmitchelltfo]

@Jmitchelltfo I can't seem to find those dashboard monitors in the MX system? Do you know where they are?

I tried downloading snakebitten's dashboards but they don't seem to be working correctly for me using an iPhone.

To have access to all the available PID's I had to go through the OEM specific option on the MX+ menu.

It would be nearly impossible for me to explain it, since I only did it one time, but you might be able to find a video or tutorial on the OBDlink website.

Once you have access to all the PID's you can search using keywords for the gauge/sensor you want to monitor.

 

[JMoney17$]

To have access to all the available PID's I had to go through the OEM specific option on the MX+ menu.

It would be nearly impossible for me to explain it, since I only did it one time, but you might be able to find a video or tutorial on the OBDlink website.

Once you have access to all the PID's you can search using keywords for the gauge/sensor you want to monitor.

I found them I think. Thanks!

 

[Snakebitten]

@Jmitchelltfo I have an MX+ but I was not running the data fields you are showing.

I just downloaded the @Snakebitten files for the MX+ so I will give it a try tomorrow and see what they are showing.

I monitored the voltage today and it dropped from 13.2 to 13.1.

Thanks for the suggestions! I will report back what I find out.

13.2 seems low for DC/DC converter low voltage side if you have fanspeed on 5 and the Ford PID for SOC is less than say.... 95+?

 

[Jmitchelltfo]

13.2 seems low for DC/DC converter low voltage side if you have fanspeed on 5 and the Ford PID for SOC is less than say.... 95+?

Totally agree.

13.8 volts is the lowest I’ve seen my battery drop to since I’ve added my lithium battery. It is normally at 14.4v or higher though.
I also keep the fan speed on 5 or higher, all the time.

 

[JMoney17$]

This is the Data I was able to pull tonight. Again I fully charged the main 12v battery and installed/charged a larger AUX battery about 2 weeks ago. I fully charged the lithium battery Sunday and reinstalled it. I have previously set forscan to maintain a charge of 100%.

I don't know why my battery current shows as 0 (must be a setup error on my part). But that being said, I have to believe my main battery is not healthy and must be draining down the lithium and Aux battery and that is why my state of charge is 91%. Open to other thoughts. I think my main 12v battery may still be under warranty.

 

[M.R.F.O.R.D.]

Is it just me but the fan speed doesn't do anything on a 2024 PB? My voltage doesn't change. Using OBDlink to monitor

 

[Jmitchelltfo]

This is the Data I was able to pull tonight. Again I fully charged the main 12v battery and installed/charged a larger AUX battery about 2 weeks ago. I fully charged the lithium battery Sunday and reinstalled it. I have previously set forscan to maintain a charge of 100%.

I don't know why my battery current shows as 0 (must be a setup error on my part). But that being said, I have to believe my main battery is not healthy and must be draining down the lithium and Aux battery and that is why my state of charge is 91%. Open to other thoughts. I think my main 12v battery may still be under warranty.

0.0 amps shown for the battery current just means that there isn't a load or current being pulled from your 12v system. If you use your power steering or any other high draw 12v accessories, you will see that number increase.

 

[Jmitchelltfo]

Is it just me but the fan speed doesn't do anything on a 2024 PB? My voltage doesn't change. Using OBDlink to monitor

My 2021 did that after an OTA update, for a week or so.

Other than that limited amount of time, fan speed 5 has increased my DC/DC charge voltage ever since I started monitoring with the MX+.

 

[Porpoise Hork]

13.2 seems low for DC/DC converter low voltage side if you have fanspeed on 5 and the Ford PID for SOC is less than say.... 95+?

I'll have to keep an eye on mine since replacing the primary aux battery but for a while now it would drop down to 13.2-13.6v even with the fan speed on 5 and/or the lights on. Both of which should cause it to raise up to around 14.2v. Regardless if the SOC reporting 100% or not. Its gotten to the point that it'll alternate between 13.2 and 14.2 every 2-3 key cycles and the SOC might be at 100% or will randomly drop to 90% overnight despite my having just driven it for 60+ minutes the day before with it reporting 14.2v the entire time.

Since replacing the aging aux agm battery and resetting the BMS again which took it two days to decide what the actual SOC is and finally report 100% again, it seems to be resolved but I have not driven it enough to confirm. If it keeps acting up I'm seriously considering replacing the BMS negative terminal sensor since it's surprisingly cheap at under $20 and had a couple revisions along the way. Apparently older variants would sometimes under-report the actual SOC and cause various low 12v warnings, modules to be forced into deep sleep, unexpected HV battery drain when parked. All symptoms mine has exhibited. The current revised part did not start getting used until late 21 builds but it appears that 22-23's could also have earlier revisions installed.

Latest revision of the BMS sensor.
ML3Z-10C679-B

 

[Jmitchelltfo]

I'll have to keep an eye on mine since replacing the primary aux battery but for a while now it would drop down to 13.2-13.6v even with the fan speed on 5 and/or the lights on. Both of which should cause it to raise up to around 14.2v. Regardless if the SOC reporting 100% or not. Its gotten to the point that it'll alternate between 13.2 and 14.2 every 2-3 key cycles and the SOC might be at 100% or will randomly drop to 90% overnight despite my having just driven it for 60+ minutes the day before with it reporting 14.2v the entire time.

Since replacing the aging aux agm battery and resetting the BMS again which took it two days to decide what the actual SOC is and finally report 100% again, it seems to be resolved but I have not driven it enough to confirm. If it keeps acting up I might consider replacing the BMS negative terminal sensor since it's surprisingly cheap at under $20 and had a couple revisions along the way.

ML3Z-10C679-B

Are you talking about the battery voltage or the DC/DC charge voltage? I'd recommend watching the DC/DC voltage if you haven't been looking at that on a regular basis.

 

[JMoney17$]

I think I am just going to replace my main 12V battery.

I have been monitoring the voltage with the truck at rest parked. With the lithium battery it goes from 13.2V down to 12.7 volts over the course of 3 days. These graphs demonstrate 2 cycles of using the lithium battery with rapid draw down.

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