worf928

You are backwards.

"It" - the car - cannot tell the difference. That's why the PIWIS laptop is required: to tell the car that you have replaced the battery with a new and/or different-Amp-Hour one.

the_buch

worf928

I *suspect* but do not know that 'it' keeps track of battery usage over the life of the battery and uses some built-in 'knowledge' of expected battery degradation over time and usage. Thus, even an identical replacement, would need to be coded so that 'it' knows that the battery is new and thus 'reset' the statistics.

All this, under the assumption that all of this effort is to ensure that the stop/start system works as-designed.

Personally, stop/start OFF is default for our entire fleet. So, I don't GAF about stop/start.

Only those folks that make regular use of stop/stop *may* need to worry about keeping the battery statistics current in the ECUs.

Again, all of this is *speculation.* If PAG would open-source all of the code we could paw through it and determine exactly what's what.

worf928

Tom's link confirms my speculation.

Although, I think the warnings about damaging "your car’s fragile electrical system" is ... rather ... over-stated.

Perhaps alternators and AGM batteries are a different beast than in the 'old' days of the infant '00s. But, alternators have been 'over-charging' lead-acid batteries for almost a century and alternator and electrical system lifetime hasn't been an issue. Thus, I will remain skeptical of 'damaging' my Porsches' fragile electrical systems by not PIWISing the battery.