Testing an Aux batt solution...

[Porpoise Hork]

I checked the BMS part number on mine and it's ML3T-10C652-BA (engineering number) manufacture date 11-12-2021 and links to either NL3T-10C652-AC or NL3T-10C652-AD. These modules were found to have issues with inaccurate state-of-charge readings, leading to them being superseded by the improved ML3Z-10C679-B part number. (Edited)

This can also cause blocking of OTA updates, and incorrectly disabling modules due to incorrect SOC readings. It has been superseded by ML3Z-10C679-B, so I went ahead and ordered the updated version.

This makes me wonder how many others on here having issues are due to older/faulty BMS sensors.

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.

The PID I am monitoring is listed as the "Control Module Voltage". Which should be the real-time charging voltage from the DC/DC converter. At least according to the documentation from CarTest app and what the Vgate iCar Pro dongle can see.

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[RcFlyer330]

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

Okay here is what I have noticed on my '22. The fan speed 5 never worked for me until i replaced the main battery. You need to look at charging voltage, current, and battery SOC in obdlink. If the voltage is around 14v low SOC fan speed 5 does nothing. If when you are driving the voltage drops to the 12v range ~80% SOC and 0 charging amps then fan speed 5 will jump the voltage to 14v and charging current will come up.

Before I replaced my battery my charging voltage was always between 13.5 and 14v with some charging amps between 1 and 60 (60 amps was a very low battery). fan speed 5 did nothing during this time no extra charging amps no higher voltage. With the new battery I have noticed when the vehicle thinks its fully charged the voltage will drop to around 12.7v and 0 amps. When it does this fan speed 5 will put the voltage back to 14v with somewhere between 1 and 15 amps charging the battery.

Here is what I would do. Put your vehicle on a charger (dont use the higest amps use 5 amps or less) at least over night. This will get the battery fully charged. When you start the truck turn the fan off the SOC should be 80% or above, voltage around 14v, and some amount of current. After a few minutes (5 to 10 minutes) voltage should drop current should drop and the vehicle will now not be charging turn the fan to speed 5 see if voltage and current come up.

A little Side note that I have noticed with chargers you need the voltage to be 14v or greater for longest amount of time for the vehicle to register the soc accurately. If you put 20 amps to the battery in 15 minutes the soc will only go up by maybe 10% but the charger will say its fully charged and drop the voltage.

 

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

Okay here is what I have noticed on my '22. The fan speed 5 never worked for me until i replaced the main battery. You need to look at charging voltage, current, and battery SOC in obdlink. If the voltage is around 14v low SOC fan speed 5 does nothing. If when you are driving the voltage drops to the 12v range ~80% SOC and 0 charging amps then fan speed 5 will jump the voltage to 14v and charging current will come up.

Before I replaced my battery my charging voltage was always between 13.5 and 14v with some charging amps between 1 and 60 (60 amps was a very low battery). fan speed 5 did nothing during this time no extra charging amps no higher voltage. With the new battery I have noticed when the vehicle thinks its fully charged the voltage will drop to around 12.7v and 0 amps. When it does this fan speed 5 will put the voltage back to 14v with somewhere between 1 and 15 amps charging the battery.

Here is what I would do. Put your vehicle on a charger (dont use the higest amps use 5 amps or less) at least over night. This will get the battery fully charged. When you start the truck turn the fan off the SOC should be 80% or above, voltage around 14v, and some amount of current. After a few minutes (5 to 10 minutes) voltage should drop current should drop and the vehicle will now not be charging turn the fan to speed 5 see if voltage and current come up.

A little Side note that I have noticed with chargers you need the voltage to be 14v or greater for longest amount of time for the vehicle to register the soc accurately. If you put 20 amps to the battery in 15 minutes the soc will only go up by maybe 10% but the charger will say its fully charged and drop the voltage.

I can confirm that's how it works. I just tired it out. Charged the truck last night. Played with the fan speed and I can see the voltage go higher. Thanks again.

 

[kd-]

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.

I'm in a similar boat I think. I did try a BMS reset for kicks, and have a long trip this weekend, but if that doesn't resolve it I'm thinking of replacing the under-hood battery.

I went to AutoZone and had them test the battery for another data point, and they said it was fine - full rated CCA.

From what I can tell having the LFP sit at 12.5V isn't the _worst_ thing, but it's definitely a low SOC.

 

[JMoney17$]

I'm in a similar boat I think. I did try a BMS reset for kicks, and have a long trip this weekend, but if that doesn't resolve it I'm thinking of replacing the under-hood battery.

I went to AutoZone and had them test the battery for another data point, and they said it was fine - full rated CCA.

From what I can tell having the LFP sit at 12.5V isn't the _worst_ thing, but it's definitely a low SOC.

So I went and replaced every battery and made sure everything was fully charged. I reset the BMS. Voltage initially popped up to 13.2V at rest but has continually trended down. I did about a 4 hour drive this weekend and it does not appear to have changed the downward trajectory. I usually do four - 10-20 minute drives a day. My results definitely don't mirror what other people report here.

 

[Jmitchelltfo]

So I went and replaced every battery and made sure everything was fully charged. I reset the BMS. Voltage initially popped up to 13.2V at rest but has continually trended down. I did about a 4 hour drive this weekend and it does not appear to have changed the downward trajectory. I usually do four - 10-20 minute drives a day. My results definitely don't mirror what other people report here.

Looks like you possibly have a small amount of parasitic drain. It never recovered from the drop that happened on the 20th.

Dash cam or any other devices installed?

 

[JMoney17$]

Looks like you possibly have a small amount of parasitic drain. It never recovered from the drop that happened on the 20th.

Dash cam or any other devices installed?

I have the battery monitor and the OBD MX+ hooked up. That is it. There shouldn't be any other devices.

 

[Jmitchelltfo]

I have an update on my aux battery setup.

A couple weeks ago I noticed that my resting voltage dropped a bit on my pickup. I started watching individually between the bluetooth app on my OEM H7 and the LFP aux. Instead of a resting voltage of 13.2v, the aux battery was showing 12.8v. I kept an eye on it for a couple days, and last week the aux just bit the dust. I pulled it out to try and charge it on a dedicated LFP 5 amp charger. No change after 3-4 days on any of my chargers.

I replaced it with a 30 ah LFP that I've had for about five years. My pickup is back to a 13.3v resting voltage. While I wait on Batteries Plus to get me a replacement. They think the BMS went bad, and are currently not selling the 20ah version that I bought. There is supposedly a 35 ah version being released soon that should fit in the same spot as what I've got now.

https://ampedoutdoors.com/products/30ah-lithium-battery-lifepo4-tall

After thinking about all the long days of my pickup running for 10-12 hours during road trips, I wonder if the BMS on the X2 just didn't like being charged continuously.
I am considering an isolation switch or some other device to disconnect the LFP from the OEM aux battery on longer drives. Then I can hit the switch before I lock my pickup to reconnect the two batteries.

 

[kd-]

I have the battery monitor and the OBD MX+ hooked up. That is it. There shouldn't be any other devices.

How's your voltage these days @JMoney17$ ? I pulled my LFP out and fully charged it, huzzah - 13v resting after gulping down 30Ah (say ~10% charging losses, so maybe it was sitting at 10% SOC?). Unfortunately, it was short-lived and I'm back to the mid-12V range - no real change since 10/3, despite those spikes well into 14V.

I decided to do some debugging with FORScan - one finding so far is that in "Battery Refresh" mode the Fan Speed 5 trick doesn't seem to do anything - current is constant.

V_BATT_BCM    14.20 V    Battery Voltage
BATMOD    14.30 V    Battery Module Voltage
BAT_CURRENT    2.00 A    Vehicle Battery - Current
BAT_CURR_2    2.47 A    Vehicle Battery Current 2
BAT_CUR_PRD    -106.44 A    Battery Current - Predicted
BAT_ST_CHRG    88.00 %    Vehicle Battery - State of Charge
BAT_CHRG_MODE    Battery refresh     Battery Charge Mode
ConvLoCurre    23.00 A    DC/DC Converter Low Voltage (LV) current
BATTERY_AGE    18      Vehicle Battery - Days in Service
ConvHiCurre    1.30 A    DC/DC Converter High Voltage (HV) Current - Measured
BATCURBECM    1.46 A    Hybrid Battery Current
BAT_PACK_VOLT    274.75 V    Hybrid Battery Pack Voltage
BATT_CHAR [SOC]    45.53 %    Battery Pack State of Charge (SOC)
LoVoltSet    14.40 V    DC/DC Low Voltage Setpoint

"Days in Service" was reset because I tried a BMS reset.

The theory in my head the past few weeks has been that despite available voltage, there's not available current for the LFP to get charged. I'm not sure it would have been in "battery refresh" mode the entire time?

edit: After letting the truck run for a couple hours and work the battery SoC up to ~90% I did see the DC/DC setpoint drop and Fan 5 brought it back up. Highest resting voltage I got at that point was 12.8-12.9v

 

[tsigwing]

Here is mine after sitting for 20 hours or so. Did run errands yesterday and had the fan on 5. Was at 100% when I got home.

 

[JMoney17$]

How's your voltage these days @JMoney17$ ? I pulled my LFP out and fully charged it, huzzah - 13v resting after gulping down 30Ah (say ~10% charging losses, so maybe it was sitting at 10% SOC?). Unfortunately, it was short-lived and I'm back to the mid-12V range - no real change since 10/3, despite those spikes well into 14V.

I decided to do some debugging with FORScan - one finding so far is that in "Battery Refresh" mode the Fan Speed 5 trick doesn't seem to do anything - current is constant.

V_BATT_BCM    14.20 V    Battery Voltage
BATMOD    14.30 V    Battery Module Voltage
BAT_CURRENT    2.00 A    Vehicle Battery - Current
BAT_CURR_2    2.47 A    Vehicle Battery Current 2
BAT_CUR_PRD    -106.44 A    Battery Current - Predicted
BAT_ST_CHRG    88.00 %    Vehicle Battery - State of Charge
BAT_CHRG_MODE    Battery refresh     Battery Charge Mode
ConvLoCurre    23.00 A    DC/DC Converter Low Voltage (LV) current
BATTERY_AGE    18      Vehicle Battery - Days in Service
ConvHiCurre    1.30 A    DC/DC Converter High Voltage (HV) Current - Measured
BATCURBECM    1.46 A    Hybrid Battery Current
BAT_PACK_VOLT    274.75 V    Hybrid Battery Pack Voltage
BATT_CHAR [SOC]    45.53 %    Battery Pack State of Charge (SOC)
LoVoltSet    14.40 V    DC/DC Low Voltage Setpoint

"Days in Service" was reset because I tried a BMS reset.

The theory in my head the past few weeks has been that despite available voltage, there's not available current for the LFP to get charged. I'm not sure it would have been in "battery refresh" mode the entire time?

edit: After letting the truck run for a couple hours and work the battery SoC up to ~90% I did see the DC/DC setpoint drop and Fan 5 brought it back up. Highest resting voltage I got at that point was 12.8-12.9v

My voltage just steadily trends down every day. The LFP battery provides a brief rise in resting voltage but it drops back down over a week. I am wondering if I have some other parasitic drain. I have a usb voltage monitor for the battery and the mega ohm device to turn off the EV sounds but nothing else hooked up besides that.

 

[kd-]

My voltage just steadily trends down every day. The LFP battery provides a brief rise in resting voltage but it drops back down over a week. I am wondering if I have some other parasitic drain. I have a usb voltage monitor for the battery and the mega ohm device to turn off the EV sounds but nothing else hooked up besides that.

One common thread between us is the DC House battery - I wonder if the BMS is just behaving differently with this brand and it's not good for this application? Anyone else have _success_ with a DC House battery?

"Cheap" experiment would be to tear the thing apart and try another BMS. Or another brand and see if something else works. Or, slightly riskier perhaps, disconnect the BMS and experiment?

 

[kd-]

disconnect the BMS and experiment?

I couldn't resist trying this and I believe I've proved it's the LFP BMS that DC HOUSE put in the case. The amps are there from the DC/DC converter, but the battery isn't pulling them. Bypassed it for testing (checked that all cell voltages were balanced at the same time) and...

That last spike is ~5 minutes of fan speed 5 parked AFTER the BMS was bypassed, all the ones before that were the as-previously-installed setup. This small window was enough to get resting voltage >13V and stabilize overnight in the high 12.8V range.

I did a bunch of research last night and running without an LFP without a BMS isn't the most unsafe thing, but I'd prefer the extra protection + balancing action - so I spent a little extra and went with a quality one, JK-BD4A8S4P from JBKMS which is all over the DIY Solar Forum. Seems configurable, so if the initial setup has the same problem I'm hoping I can work around it. Not sure it's going to fit in the existing case but worst case I'm going to 3D print a replacement.

@JMoney17$ if you're still in the return period of the DC HOUSE that might be the easiest path. Otherwise you can join me on this BMS replacement journey!

 

[kd-]

...and I accidentally punctured a cell and almost started a fire so I guess I'm going a different direction now. Be careful with lithium cells folks!

6 of 8 cells survived so I might still use that BMS and have a 15Ah (4s1p) battery instead of a 30Ah.

 

[JMoney17$]

...and I accidentally punctured a cell and almost started a fire so I guess I'm going a different direction now. Be careful with lithium cells folks!

6 of 8 cells survived so I might still use that BMS and have a 15Ah (4s1p) battery instead of a 30Ah.

I am going to try an eco-worthy battery first and see how that works out.

When I look at the voltage monitor attached to my main AGM battery it says 100% charge.

The vehicle battery state of charge in the OBD MX tool is 86%. Additionally when I put in the new battery and reset the BMS system it never changed the age of my battery in the OBD MX program.

I unhooked the LifePO4 battery and hooked up my battery charger which stated system was at 95%.

Some things I need to figure out.

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