12V Battery replacement with H4

[jthiesse13]

I'm planning on replacing my 3 year old 12v battery in My Lightning. Can I simply disconnect it like in an ICE vehicle or are there special steps to take since the Lightning is electric? TIA

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[chl]

How did you add a battery maintainer? Just plug it in to the frunk outlets? And run the maintainer into the battery compartment?

I did what I saw some others had done an put a small hole in the plastic near the charge port door hinge and ran a wire to the battery compartment, Easy to reach in when the frunk is open to route the SAE charge wire - I had a spare with a built in fuse I used.

I bought a NOCO Genius1 - it has a proprietary charge plug on it so had to also get the adapter for the SAE standard ($15 groan), and I got a 15ft SAE extension cord so I could put it in my garage next to my FCSP EVSE and run the wire next to the CCS1 cable to my driveway.

Here are some pics:

The port door closes fine with the SAE cord there.

I had used a plastic bag and some twist ties to cover the CCS1 and the SAE wire connection when we had a snow and ice storm - kept them dry very well.

Inside my garage I can plug the NOCO in out of the weather.

See this thread for other ideas on ways to use a maintainer with the Lightning:

https://www.f150lightningforum.com/forum/threads/charging-12v-battery.16979/

 

[Shawnson]

That is awesome, thanks.

I did what I saw some others had done an put a small hole in the plastic near the charge port door hinge and ran a wire to the battery compartment, Easy to reach in when the frunk is open to route the SAE charge wire - I had a spare with a built in fuse I used.

I bought a NOCO Genius1 - it has a proprietary charge plug on it so had to also get the adapter for the SAE standard ($15 groan), and I got a 15ft SAE extension cord so I could put it in my garage next to my FCSP EVSE and run the wire next to the CCS1 cable to my driveway.

Here are some pics:

The port door closes fine with the SAE cord there.

I had used a plastic bag and some twist ties to cover the CCS1 and the SAE wire connection when we had a snow and ice storm - kept them dry very well.

Inside my garage I can plug the NOCO in out of the weather.

See this thread for other ideas on ways to use a maintainer with the Lightning:

https://www.f150lightningforum.com/forum/threads/charging-12v-battery.16979/

 

[chl]

I'm planning on replacing my 3 year old 12v battery in My Lightning. Can I simply disconnect it like in an ICE vehicle or are there special steps to take since the Lightning is electric? TIA

One thing you have to do is reset the BMS when you put in the new battery:

LVB BMS reset

Make sure 12v battery is fully charged (drive an hour, or after an hour actively charging the HVB)
Start Accessory mode
flash high beams 5 times
step on brake pedal 3 times
red battery icon on dash should flash 3 times

If the dealer changes the 12v battery, they should do this, but they don't always. If they plan on keeping it overnight, there is a good chance they will - Just ask when you pick it up.

---
turn on accessory,
flash the high beams 5x and
press the brake 3x,
battery light then flashes.

 

[RLXXI]

I'm planning on replacing my 3 year old 12v battery in My Lightning. Can I simply disconnect it like in an ICE vehicle or are there special steps to take since the Lightning is electric? TIA

Yes, as a matter of fact, in the owners manual it tells you to disconnect it for long periods of storage. Nothing special, 10mm wrench and disconnect the negative terminal.

 

[jwrezz]

so the battery can slide under the rear seat.

I'm confused by "so the battery can slide under the rear seat". My battery is behind the plastic in the back of the frunk.

 

[Adventureboy]

I'm confused by "so the battery can slide under the rear seat". My battery is behind the plastic in the back of the frunk.

Rear seat in the battery tray. It's the bar at the back of the battery tray where the base of the battery slides under to hold it securely.

 

[jwrezz]

Rear seat in the battery tray. It's the bar at the back of the battery tray where the base of the battery slides under to hold it securely.

I feel so silly!

 

[jthiesse13]

Yes, as a matter of fact, in the owners manual it tells you to disconnect it for long periods of storage. Nothing special, 10mm wrench and disconnect the negative terminal.

Great, thanks!

 

[RLXXI]

Great, thanks!

Welcome.

 

[CoolViper777]

If it is measuring SOC, versus only voltage, then it would measure voltage, current and probably also temperature as a correction factor.

BMS system generslly should not care about the battery capacity. Its only job is to get it to a full state of charge.

Maybe the Lightning BMS also adds some sort of charge time limit algorithm which says "a 35Ah battery at X SOC should be done charging in Y time at Z temperature". Using lookup tables to fill in X, Y, & Z.

I suspect not, but the only way is to try.

Maybe the real solution is to put a 12V solar trickle charger on your dash when not driving.

I don’t have any hard evidence but I don’t believe the BMS is only concerned with voltage. I believe it is a ”fuel gauge” type of BMS and is monitoring the current in and out of the battery. If it only cared about the voltage it would just connect to the positive lead and would not need to be in series with the current path. That is why it is important to always connect a charger downstream of the BMS. A voltage only BMS would not care where you connected.

Thinking about it some more it still probably doesn’t matter but the SOC number will probably be wrong. The BMS is calibrated to a full 35 Ah battery so if for example you have drawn 3.5 Ah from the H3 it will show 90%. If you have an H4 your actual SOC after drawing 3.5 Ah will be 93%. You will always read lower than your actual SOC which should actually help keep it charged.

 

[Adventureboy]

BMS system generslly should not care about the battery capacity. Its only job is to get it to a full state of charge.

Maybe the Lightning BMS also adds some sort of charge time limit algorithm which says "a 35Ah battery at X SOC should be done charging in Y time at Z temperature". Using lookup tables to fill in X, Y, & Z.

The BMS has a few more tasks than just getting to a full state of charge:

• Track SOC - to do this, it needs battery capacity and the coulombs in/out. That is the purpose of the little black module on the negative terminal
• Use the SOC to determine when it needs to activate the DC-DC charger to top up the 12v. Voltage doesn't work for this since the voltage at the posts can vary a fair bit when loads are applied, which happens when you walk by the truck and it lights everything up.
• Track the SOC, charge cycles and/or time so it can put the truck into deep sleep if necessary.
• Track the capacity as the battery ages and accurately calculate SOC so it can do the things above.

It also tracks SOH in some fashion (rudimentary at least), which is based on capacity, whether measured or calculated. This is why the truck can tell you if your battery is nearing the end of its useful life (which it didn't do in the early years). It is also the reason you need to reset the BMS when you drop a new battery in it.

Incidentally, Marine and Solar BMS systems have been doing this for decades for Flooded, AGM and now LFP.

There is no BMS-imposed time limit for charging. The voltage at the posts goes to 15v when charging the HVB, and when the truck is ON and stays there until the HVB is done charging or you shut off the truck.

 

[mr.Magoo]

The voltage at the posts goes to 15v when charging the HVB, and when the truck is ON and stays there until the HVB is done charging or you shut off the truck.

Assuming your LVB SoC isn't 100%, yes, but it doesn't stay at 15V no matter what.

 

[Adventureboy]

Assuming your LVB SoC isn't 100%, yes, but it doesn't stay at 15V no matter what.

I'm interested in what you've seen on this front.
I've tracked it for 2 years, and the only scenario where I've seen it drop from 15v at the posts with the DC-DC charger active is in Accessory mode, where it only goes to around 14.x.

 

[Xtremestang]

I see you have a BT (Ancel?) battery monitor. I've had my Ancel BM200 for almost 3 weeks and it still gives extremely incorrect SOC readings compared with my OBD reader. Anyone else have that monitor behavior? Is mine malfunctioning or does it take a very long time to equilibrate?

Same here big difference from Ancel 200 compared to car scanner. Removed and returned to Amazon.

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