How do the dual OBCs work?

[SmoothJ]

How do the dual OBCs work on the truck? Are they load balanced so they share the incoming load (even low amps), or one needs to get at capacity before the other one kicks on?

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[TaxmanHog]

Interesting questions that @Ford Motor Company {Brian} might help with.

I appreciate the nerdy details too.

 

[RickLightning]

I believe they split the incoming AC charge in 1/2.

 

[Ford Motor Company]

Interesting questions that @Ford Motor Company {Brian} might help with.

I appreciate the nerdy details too.

Chasing a 100% accurate answer, but the documentation on the charger system suggests the second charger is only used when input current is above 48A.

 

[RickLightning]

Chasing a 100% accurate answer, but the documentation on the charger system suggests the second charger is only used when input current is above 48A.

And then it is split 50/50?

 

[vvgogh]

If a single on-board charger is 48A, why are we limited to 80A with dual on-board chargers? Are the two AC/DC converters not identical?

 

[fhteagle]

80A with dual on-board chargers

My guess is because 80A is the highest contemplated by the J1772 specification.

 

[vvgogh]

My guess is because 80A is the highest contemplated by the J1772 specification.

Then the question becomes why doesn't Ford use dual 40A chargers? Wouldn't that have been cheaper?

 

[SpaceEVDriver]

Then the question becomes why doesn't Ford use dual 40A chargers? Wouldn't that have been cheaper?

Probably not if they wanted to offer 48A for the vehicles without dual OBC. It’s almost certainly cheaper to design for, bulk purchase one type of OBC instead of two different kinds, and simplify the logistics of tracking which (40A or 48A) charger is installed.

 

[bmwhitetx]

In reading the Workshop Manual on AC Charging System Operation, every vehicle has a SOBDM which is the considered the primary Battery Charger Control Module (primary BCCM). Some vehicles (e.g. 22-23 ER's) have a secondary BCCM known as as the GFM2.

Then in another section, the manual makes this statement:
Some vehicles are equipped with a secondary On-board Battery Charger Control Module (BCCM), also known as the GFM2 ... that facilitates and provides additional charging capacity for the high voltage battery when an high output level 2 EVSE is utilized. The primary On-board Battery Charger Control Module (BCCM), also known as the SOBDM communicates and controls operations of the GFM2 via dedicated communication circuits.

So sounds like the second charger only kicks in when using high output level. Doesn't say if that level is 32, 40, 48 amps though.

 

[Maquis]

And then it is split 50/50?

If I had to guess, I’d say that the secondary charger is smaller, so no. The secondary charger could be as small as 32A.

 

[tls]

If a single on-board charger is 48A, why are we limited to 80A with dual on-board chargers? Are the two AC/DC converters not identical?

Because the J1772 standard maxes out at 80A (100% pilot duty cycle). There is no standard way for a charger and EVSE to indicate that either side is capable of handling more current.

There are a lot of other practical reasons for this limit. 96A charging would require a 125A breaker at the panel, not commonly available for plug-on residential panel types; J1772 connectors and cables max out at 80A rating; the wiring from charge port to onboard chargers is likely sized for 80A; etc.

Also, wire sizes start to get very large and inconvenient when drawing this much power from a single-phase circuit. It's not a coincidence that there's a medium duty charging standard (seldom seen in the field) for vehicles like light transit buses, medium duty trucks, etc. and it is 3-phase, though I believe with a single-phase mode. It uses totally different connectors and I don't know what protocol it uses for signaling.

25kW DC chargers do exist. It might seem like they're inherently less efficient due to an extra AC-DC conversion but since you get to skip the one onboard the vehicle, that's actually not so. However, there's a ton of extra complexity involved and unless you already have 480V service where you charge...not worth it.

 

[Jesse-Infotainment]

The SOBDM handles primary AC from the EVSE.. The GFM2 kicks in when commanded by the SOBDM (BAttery CHarger)

The GFM2 is the secondary charger. It is under the bed in the rear.. THe main Charger (SOBDM) is in the frunk.

They are not Identical.

Here is the operation from the workshop manual


Overview

The high voltage battery charging system is responsible for charging the high voltage battery while the vehicle is not operating. The high voltage battery charging system consists of Off-Board AC (120V or 240V) or DC fast charge Electric Vehicle Supply Equipment (EVSE), On-Board Secondary On-Board Diagnostic Control Module A (SOBDM) (also known as the BCCM (Battery Charger Control Module), OBCC , and Charge Status Indicator (CSI). Some vehicles are equipped with an additional On-board charger known as the GFM2 .

AC Charging

The SOBDM , also known as the On-board Battery Charger Control Module (BCCM) is a liquid-cooled component that charges the high voltage battery. High voltage battery charging occurs when the vehicle is not operating and plugged into an AC (120V or 240V) Electric Vehicle Supply Equipment (EVSE). During 120V charging the EVSE cordset is rated up to 12 amps or 30 amps for 240V charging depending on the household receptacle being used. It is recommended to use a dedicated electrical outlet to ensure adequate current supply for charging. A 240V ( AC Level 2) household charging station or commercial charging station can also be utilized rated up to 80 amps. The primary function of the Secondary On-Board Diagnostic Control Module A (SOBDM) is to coordinate charging operations and convert AC from the EVSE to DC . The Secondary On-Board Diagnostic Control Module A (SOBDM) controls the Charge Status Indicator (CSI) LED light segments via LIN and the charge cord lock actuator. The Secondary On-Board Diagnostic Control Module A (SOBDM) incorporates an integrated module that communicates with other modules over the HS- CAN . Depending on government regulations the charge port lock actuator locks the charger plug during AC charging.

Some vehicles are equipped with a secondary On-board Battery Charger Control Module (BCCM), also known as the GFM2 is a liquid-cooled component that facilitates and provides additional charging capacity for the high voltage battery when an high output level 2 EVSE is utilized. The primary On-board Battery Charger Control Module (BCCM), also known as the SOBDM communicates and controls operations of the GFM2 via dedicated communication circuits.

 

[kstype]

Just wanted to say - this was a great thread to read through - thanks for the excellent dialogue!

 

[ZSC100]

How do the dual OBCs work on the truck? Are they load balanced so they share the incoming load (even low amps), or one needs to get at capacity before the other one kicks on?

The two chargers share the load equally past a minimal charge rate that is like 4kW. @Martin Rebuilds knows more about this. But I'm curious why you care or what you're working on to want to know.

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