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The workshop manual states the following in connection with the battery change:

If the battery is replaced, both numbers (serial number and part number)must be entered in the gateway control unit under:

Gateway/Maintenance, repairs/Change battery

 

Can anybody  tell me what this means? Do you have to code something into the electronics of the vehicle when you change the battery?

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This is one of those.. "can't actually do this" sort of things. I read this same message, and after installing a new AGM battery (identical to the old one) called two different Porsche dealer service departments to ask about having it done. They both said "What?" "We don't do that.."  So I visited an independent with several different high-end code tools. The tools thought they could do it - but they couldn't. Wouldn't write to the ECU.  My DuraMetric doesn't even offer the option, so I bought an ICarScan tools that does - it offers to do it and then tells you it can't do it.

 

So I put a voltmeter up on the dash PCM multi-display as one of the lines in it. Found the system was happily charging away at around 13.2-13.5V no matter what (idle, higher engine speeds, more items on - it stayed the same..)  Somehow I then pressed the "sport" button and spotted the charge voltage immediately jumped 1V higher (14.2-14.5V). Switched off "Sport" and it dropped back down. Tried manually selecting gears to get the same engine RPM/speed - the voltage didn't change. Went into "sport" mode - voltage went up, manually selected a higher gear to drop RPM - voltage remained up.

 

So - figured out what the deal was - Porsche was maximizing MPG in "normal" mode. That's where the MPG rating is taken - not in sport mode. So by limiting the charge voltage and current, that minimizes the load on the engine, which ups MPG. In sport mode no one gives a darn about MPG - so they let it charge in a "normal" manner.

 

Given that - there is no reason to program the ECU to the new battery. The charge circuitry is more interested in MPG than maximum battery life. MPG costs Porsche $$ (gas-guzzler tax) - which costs sales.  The bean counters basically are setting your charging parameters.

 

Short version: Fugeddaboutit.

 

HTH,

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All this system is trying to do is to record the battery install information for later retrieval during diagnostics.  It does not do anything, it just keeps the information with the vehicle as the owner typically is often vague about such minutia when asked. 

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All this system is trying to do is to record the battery install information for later retrieval during diagnostics.  It does not do anything, it just keeps the information with the vehicle as the owner typically is often vague about such minutia when asked. 

JFP - I think the concern comes from the BMW family tree - where charge parameters were actually changed over the life of a battery to optimize the charge characteristics to match the battery age/use. Some early battery failures on BMWs have been blamed on the failure to reset the charging parameters when changing batteries.

 

As far as I can find - the charge voltages that Porsche uses are fine for any AGM battery that might be used... so no need to change the parameters.

Edited by deilenberger

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We have never seen any change in how the vehicle operates, regardless of what data is, or isn't entered into the system, so the conclusion is that it does not seem to matter, making it a data store more than anything else.

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