Quote:
Originally Posted by RZNT4R
You misunderstand.
The alternator is still a 3 phase alternator. It's a lot more powerful than the 2016, but it's still a 3 phase alternator.
The difference between the 2016 and 2017 is in the way the alternator is controlled, the 2016 alternator has a big 12V charging post and a connector with 3 wires: A turn on circuit, a charge lamp control circuit and a control circuit from the PCM for a square wave input, the duty cycle of which controls charging voltage. The 2017 alternator has just 2 wires going to it: A big 12V charge lead and a single control wire. It gets it's 12V and Ground internally and the single control wire is a LIN bus interface, it's not driven by a square wave from the PCM, but rather it regulates itself internally and receives charging requests as network packets and can output diagnostics to the PCM over that same wire.
A 2017 alternator in a 2016 car would not work. The connector for the control wires doesn't fit in the socket, and even if it did, the 2016 PCM would be sending a square wave instead of network communication.
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Technically, I didn't misunderstand.
I know that the charging circuits have had a redesign and since I only have my '15 FR-S to look at under the hood, not being able to compare it with the newer design, I was speculating if it is at all possible for the newer alternator (or even an aftermarket replacement alternator that may look identical on the outside to the OEM alternator, just not have the same internal electronics, i.e. made in China) to be installed in place of the older OEM alternator, and could that be the source of the problem.
But it looks like you've answered that question. If the OP isn't getting a CEL or has any DTC's in the ECM then yes, it's probably the correct matching alternator for his model year.
We still need to find out if his charging system is still stock or not. Maybe at some point his alternator was replaced with a lower quality aftermarket unit that simply didn't have the tighter OEM tolerances.
I've read a lot here about other members tracking their cars but this is the first time I've read about multiple brand new batteries leaking in one car.
There could still be a current sensor intermittently going bad under extreme heat environments such as during track use that may be causing the problem, or again an intermittently faulty alternator internal component that breaks down under high heat.
A constant voltage monitor and data logging during track use would reveal an intermittent overcharging situation.