LVB battery & BMS saga

[Jseis]

My LTE’s BMS started exhibiting some odd behavior 12-2023 that impacted sound system, proximity alarm tone (cold frog), interior lighting, volume control, and a whole gamut of error messages including “accidental unplug”, “low battery-drive car”, “electrical system drain”, etc.

The most daunting was the 4% SOC of the LVB so about two months ago after some single digit low battery SOC notices in the morning, I contacted the dealer, they asked me to send a pic of the BMS, and I got the recall the same week. Took 6 weeks on the BMS shipping to the dealer and I had it replaced 9 days ago. Took that nine days for the BMS to “stabilize”? with the charging system and so now it operates normally or similar I think. I bribe just under 90 miles a day so that kept the LVB charged.

Now.. in the prior months, the lowest SOC charges I saw were 4% and 6%. Fortunately it always started and I ran the truck at work for up to 2+ hours to charge the LVB back up. At least the Veepeak said I was charging up. Honestly I’m unsure what was really going on as what was the true SOC? 9 days after the new BMS, things are looking up. I have a circulating fan that’s auto stop-start. Never heard it before. Maybe an OTA will sidle up. I’ve one since late June 2023 purchase.

4% SOC was low. Saw 6% one eve and I was the last to leave work. But no issues. Did a couple flash headlights/pump the brakes “resets” but not sure if that helped.

Hovers in the low 90’s SOC now so next? OTAs!!!

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[TaxmanHog]

Honestly I’m unsure what was really going on as what was the true SOC? 9 days after the new BMS, things are looking up.

Great, hopefully it continues to perform well, surprised those very low SOC's didn't damage the battery health.

 

[Jseis]

I was surprised it went so low, then it would charge back to 90% in my hour drive home. That daily cycle can’t be good for a battery. Typically it would go 90% to 40% in 4 hours of just sitting, then nearly charge to 100% in one hour of evening driving. The next morning same thing, start low, then charge to 80-90% by the time I get to work, sit for 8-9 hours, discharge, then recharge back to 90%.

 

[potato]

14.4 volts is not 4% on a 12 volt lead acid battery. I thought the whole point of the CSP was that BMS module not correctly reporting the state of charge of the low voltage battery.

 

[ctuan13]

14.4 volts is not 4% on a 12 volt lead acid battery. I thought the whole point of the CSP was that BMS module not correctly reporting the state of charge of the low voltage battery.

That's true, but I'm guessing the truck is probably running. If it is, the DC to DC converter is on and you're seeing the charge voltage, not the resting voltage. The capacity is likely calculated with a combination of voltage tracking and a built in shunt.

 

[RickLightning]

Every time you check the 12v battery level, you are draining it like 5% or more.

 

[Maxx]

I thought HVB is suppose to top it off long before it hits 4%.

 

[RickLightning]

I thought HVB is suppose to top it off long before it hits 4%.

WHEN it works right.

Mach-E owners have had dead 12v batteries because it didn't work right.

I was gone for 22 days with the Lightning, and put the Mach-E on a Battery Tender.

When the truck is used irregularly, it's on a Battery Tender also.

 

[Jseis]

Here’s what the current charge looks like. A fundamental difference from two weeks ago. I can disconnect the Veepeak OBD sensor in like 5 seconds so that draw is like non-existent.

I figure the LTE would eventually go dead. It now appears to draw down to 80%, charge up to 90-100. I’ve seen 100% in the morning after being connected to the ChargePoint charger all night (schedule is 1 am to 7 am) and I’ve also seen the LTE charge from 90% to 100% on my hour evening drive home. That being said, it appears to be stabilizing in the 80%-90% SOC range. I’ll probably leave it unconnected to the CP charger for 2-3 days to see what happens.

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