Replace battery?

[lloydsound83]

Ok great, will contact precision Porsche.

The cold start has been cleared up with the battery change - it would seem

Apologies for putting you in a difficult position regarding the business, nor was I encouraging on here

 

[Zingari]

Interesting about rate of charge on the dash. My 2015 GT4 shows around 14.6v as its charging rate even when I've taken it off a trickle charger hours before.

I thought it might be a sign the battery is on its way out but from what I've read the +14v charge rate is normal? Battery was checked by OPC last year as part of the interim service and they said all was good. :dont know:

 

[Luddite]

Zingers, I am quoting from a website. "AGM batteries are designed to require 14.6 -14.8V when performing a full charge from a state of discharge, whereas a standard lead acid batteries need 13.8-14.4v." end of quote

Using my logic, failed or otherwise, even if you just unplugged the charger you either opened a door or lifted the frunk to do so.. in which case lights may have illuminated, that being the case, it seems you have already started to discharge the battery on many Modern cars... Touching the door handle may cause the fuel pump relay to pull in and run the fuel pump to prime the system ready for start up, and no doubt other aspects of the control systems may awaken, the dash may illuminate too, and all this before you turn the key to fire it up...?

When you fire it up, the starter motor is perhaps the largest single load on the battery and by the time the alternator is on line it will likely see the battery not as one that has just come of a CTEK and fully charged, but as a battery that has just done a job of work and needs replenished, in which case given the above quote 14.6v would seem to be perfectly normal charging voltage..? Had the car been sitting without the benefit of a conditioner/charger attached, then I suspect 14.8 volts might be the voltage reading until the alternator had replenished the battery to a fully charged state, as monitored and determined by the voltage regulator....?

As an aside... Apparently again from the aforementioned quote.... Best not to fit an AGM battery to the "B" as an upgrade, given it`s charging system will be regulated to operate at a lower.. fully charged.. voltage cut off point thus the AGM battery will never reach a fully charged state... :?:

 

[Steve997]

Just put a new like for like replacement AGM battery on my car.

Battery is fully charged at 12.6 volts when resting but when driving the cars charger indicates 15.2 volts. Seems a touch high imo but within the hi and low scales on the cars display which suggests it's within limits.

For info the battery was coded to the car using icarsoft Porsche specific scanner and correct codes entered. 80ah AGM.

Are other people getting 15+ volts in charging ?

 

[Luddite]

I claim zero expertise, but it seems to beg the question as to what or who determined fully charged as being 12.6 volts for an AGM battery..?

Added to the above that you seem to be charging at 15.2 volts may seem to suggest there could be issues :?:

 

[deMort]

For battery AGM info please look here ..


http://911uk.com/viewtopic.php?p=1631372#1631372

 

[Zingari]

Zingers, I am quoting from a website. "AGM batteries are designed to require 14.6 -14.8V when performing a full charge from a state of discharge, whereas a standard lead acid batteries need 13.8-14.4v." end of quote

Ludds, well done. Thought I'd read it somewhere that the higher figures were normal :thumb:

 

[Steve997]

Thank for the reply Equally Im not any form of expert, but from what I gather from Internet searching, 12.6 volts seems the widely accepted standard for a fully charged, at rest battery in good health.

I have just purchased a new AGM battery from Halfords and coded it to the car. I will keep an eye on charging volts but as I say it appears within the scale displayed in the car, its just me and my OCD feeling its high, so I was asking if others have similar experience.

Maybe the volts will drop. I will keep an eye on it :thumb:

 

[Luddite]

Zingers, I am reluctant to pass on info without personal experience as there is so much fake news on the web, but as those readings matched that which you posted, also that DeMort had educated us in the past to the extent that just touching the door handle powers up the fuel pump into a prime mode and may bring other circuits to life, that along with my base level electrical logic suggested your charge rate might match expectations. Glad it hopefully reduced your concern.

Steve, no argument from me re your internet findings, just that mine differ.. :dont know:

Now that DeMort has posted PORSCHE based info, I take that as gospel. Of course it is best to remember that the on board kit can alter in spec with the passage of time thus model year or in some cases VIN number may make a difference in maintenance data required to service appropriately.. :?:

I suspect your non O.E. battery will be fine, though I would be keeping a weather eye on voltages for a while till I became comfortable that there were no issues arising.

Me..? After many years of minimising costs on parts for all the vehicles I ever ran other than Porsches on which I ever stuck to O.E. parts given the quality difference in the days of air cooled.
These days I am not as impressed by Porsche engineering as I was back then, though having typed that, such is the complexity of the on board systems that even in the case of a battery I prefer to stick with O.E. to avoid complications. Also as my 991 is under the extended warranty scheme, I prefer to avoid giving Porsche an out should I be in the unfortunate situation of having to make a claim.

One other thing Steve that might be worth considering relative to the 12.6 volts at REST... Generally in times past, to measuring battery voltage as one means of attempting to determine it`s condition, the measurements would be made with the battery disconnected from the vehicle, and not having been on charge for at least 30 mins, thus avoiding the chance of some circuit or other drawing power, and that if recently taken off charge, the battery voltage would have had time to settle somewhat and thus avoid creating a false determination of condition when using voltage as a measure.. :?:

I am well out of touch, and modern vehicles seem to ever have the possibility of some device being in circuit drawing current, and given the difference in voltage may only be in tenths of a volt when attempting to make determinations of condition, it seems a simple matter to get it wrong.. :?:

All that typed I think it is perhaps simpler if not a prerequisite to go with specific vehicle data if available. :?: