48 Volt Battery?

[z06ontrack]

All right; I've searched and searched and can't find a definitive answer. The EPC is a 48 volt unit, is there a 48 volt lithium battery somewhere in the B9 RS5? Or is the generator 48 volt with an inverter for the 12 volt systems and battery?

[Smac770]

If you mean electrically powered compressor (because it's normally Electronic Power Control in Audi-verse), then there is no such thing on any B9 2.9T. It's on the 2.9T in the NAR C8 S6/S7. And it's on the B9.5 RoW market S4/S5 3.0 TDI, the only B9 MHEV implementation of a 48v subsystem (also used in the RoW C8 S6/S7). All other B9 MHEV are 12v subsystems.

[Burrcold]

If you mean electrically powered compressor (because it's normally Electronic Power Control in Audi-verse), then there is no such thing on any B9 2.9T. It's on the C8 2.9T in the S6/S7. And it's on the B9.5 RoW market RS4/RS5 3.0 BiTDI, the only B9 MHEV implementation with a 48v subsystem. All other B9 MHEV are 12v subsystems.

You mean RoW B9.5 S4/S5.

[Smac770]

Yep, yep, RoW RS is same as NAR US, 2.9T petrol engine.
Looks like it's just a single turbo config as well, not the bi-turbo from prior gen.

[z06ontrack]

The RS5 and the S6 / S7 engines have the exact same output so, obviously the they are the same engine, which means, the RS5 does have a supercharger supplemental unit just like the S6 / S&.

[JohnEnglish]

The RS5 and the S6 / S7 engines have the exact same output so, obviously the they are the same engine, which means, the RS5 does have a supercharger supplemental unit just like the S6 / S&.

They have the same output but they're not the same engines. Only the S6 and S7 have the electrically powered compressor. The RS4 and RS5 do not. The electrically powered compressor does not add any horsepower or torque. It (almost) eliminates the turbo lag by spinning up (almost) instantly and providing air pressure until the turbos can come up to speed.

Have a look at this link from the official Audi Media site: https://media.audiusa.com/en-us/releases/397. You'll see that the EPC is for the S6 and S7 only.

Brought to the U.S. market for the first time in the Audi S6 and S7, the EPC system comes paired to the 2.9-liter, twin-turbocharged TFSI® V6 engine. It consists of an electric motor with a small turbine that helps quickly build turbo boost pressure, sharpening throttle response and reducing any noticeable turbo “lag.”

[z06ontrack]

Thanks, it's just weird that it wouldn't be on an Rs but, is on the S

[Smac770]

B9 started off, RoW and NAR, with 3.0T single twin-scroll turbo gas engine for B9 S and 2.9T bi-turbo gas engine for B9 RS. These are not MHEV implementations.

Then D5 and C8 come out, with a 48V MHEV subsystem for V6 and V8 engines. For the C8 S models, a 48V EPC was included, for the 3.0 single variable-geometry turbo diesel engine for RoW and for the 2.9 bi-turbo gas engine for NAR. Why not the pure ICE 2.9T already in the B9? The C8 had to live up to the outgoing 4.0T V8, and the heavier vehicle was not going to be snappy with a pure ICE turbo engine alone.

Why did Audi backport the developed 48V EPC 3.0 TDI to the B9 S for RoW? No clue. It provided alignment with the fuel option used for the C8 S models, diesel in RoW, gas in NAR. But did this really matter? Apparently so.

Why did Audi not backport the 48V EPC 2.9T to the B9 RS? They didn't to. Would have added weight and cost, and the B9 RS already crushed the prior gen performance.

[z06ontrack]

Thanks Smac770 for clearing that up; see why I was confused

[c99]

EPC is something different:

EPC is short for Electric Power Control and it's one of the dashboard warning lights. If the light is on, that means that there's a problem with the throttle system or sensors.