How do the dual OBCs work?

[chl]

Would it not be 50A since it's limited to 48A ? Screen shows it charges @ 10.5/240v=11,520W

Sorry not following what you are saying...

What screen are you referring to?

And what is the 10.5? Hours?

11.520kW / 240V = 48A

123kWh/11.52kW=10.67 hours

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[chl]

When my truck is charging, the instrument cluster screen tells me at what rate it's charging at, in my case 10.5kW/240v=43.75A

Oh, ok.

Yes, my truck never gets above about the same current, but that is due to losses in the system from service panel to battery, software control, etc.

So the numbers before, 48A, 240V, 11.3kW etc are all nominal design spec ideal numbers, in reality there are always losses due to resistances from wire and other components producing heat energy losses.

And of course the software is in control - so while one of the 'chargers' might be capable of 50A or more, the software will limit it so there is a safety margin.

The EVSE will tell the truck I can charge at a max 80A, but the SR truck like mine will only draw it's nominal max of 48A before losses of up to about 10% as reported by several posts depending, and the state of charge of the battery at the start - the current will be varied through the charging session and slowed if you go above 90% for example.

So it is all fuzzy and averaged over time depending on the sampling rate, precision of the measuring devices, and so forth. Tolerances in parts, torque on connectors, wire sizes, ambient temperatures, and so forth.

Such is engineering, always some fudge factoring going on when reality set in. So designs allow for some tolerances up to a point.

 

[ZSC100]

@ZSC100

They are different.. Different firmware and different part numbers..

GFM2 = Second charger
Part Number - NL3Z10B689E
Strategy - NL38-10D681-AL

SOBDM = Front Charger
Part Number - LK9Z10B689M
Strategy = NL38-14F476-AM

Darn it Jesse, you are the master of legit Ford quantitative software/hardware research. I've never actually looked at part #'s in PTS or physically sat both chargers off the truck side by side, but as far as I can tell they are identical. It would make sense for them to be identical too, right, why would Ford dick with 2 parts when they are identical in function. Separate production firmware I can see, b/c that can be done post install on the assembly via automation.

Seems like I remember now that the back charger is the same as the MachE or something. Maybe it has to do with mounting of the Off Board Charge Control Module which is mounted on top of the SOBDMA where in the bed there is nothing up there, it's right on top of the back motor.

Martin and I have talked about trying EverDrive out on a MachE. I suspect it would work with no modification as all the Ford BEV's share the same CAN Message structure and PID database. Next time I visit martin I will confirm a few things regarding the differences here.

 

[vvgogh]

current will be varied through the charging session and slowed if you go above 90% for example.

Something is wrong with your battery if AC charging is slowing down above 90% - that's a symptom of a faulty battery module and the truck being extra conservative to protect itself. 80A AC charging (16.x kW) shouldn't slow down until 98 or 99% (as reported on instrument cluster) with healthy battery modules.

 

[chl]

Something is wrong with your battery if AC charging is slowing down above 90% - that's a symptom of a faulty battery module and the truck being extra conservative to protect itself. 80A AC charging (16.x kW) shouldn't slow down until 98 or 99% (as reported on instrument cluster) with healthy battery modules.

I meant above 80% - that is the way the BMS controls the charge curve.

With AC charging it is not as dramatic as with DC fast charging but it is still slowing down over 80% with AC charging.

It is a built in battery protection mechanism.

You may also note that depending on the ambient temperature and the temperature of the battery, the start to finish charge rate will also be different at the beginning of the charge cycle to precondition the battery, heating or cooling it for optimum charging.

That is a charge cycle with preconditioning involves warming or cooling the battery before charging to optimize the charging speed and extend battery life.

So my only point is really the BMS will control the current during the charge cycle start to finish and the resulting current may vary during the charge cycle.

So initially - condition the battery
Then charge at a constant high current level for some time the CC (constant current) stage.
Then taper as the SOC approaches 80-90%.
Then maintain a steady voltage as the current reduces the CV (constant voltage stage) - there can be a 10% to 20%. current reduction.

It also depend on the SOC when you start charging - if it is high, the current will be lower than if the SOC is low when you start the charging.

The BMS factors all this into the charge based on its programming to conform to an ideal charge curve under the circumstances.

So, it is normal, not a sign the battery has issues.

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