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So I hadn't driven the car for couple of weeks after swapping the battery and it was not on the tender. I enabled the voltage gauge as soon as I got in the car, 13.1v, about an hour of driving later without any stops, 14.8v.
Someone please tell me whether (1) this is a normal voltage and (2) whether I should consider using the tender again if I won't be driving for few days...
Still waiting bro get booked with the local Indy for a brake fluid flush and to find out if he can register the battery.
So I hadn't driven the car for couple of weeks after swapping the battery and it was not on the tender. I enabled the voltage gauge as soon as I got in the car, 13.1v, about an hour of driving later without any stops, 14.8v.
I take it the 13.1V was the instant after you started the car? That would be OK for a number of seconds at which point it increases to somewhere in the 14s. But the 14.8V is perfectly normal while cruising down the road at the temperatures you were probably at (50-65F).
By the way, my 2015 991 with the original Banner battery does not need a battery maintainer all summer long and there are times the car is parked for 2 or 3 weeks at a time. It starts without any issue.
This is my 991 just after I came to a stop with the engine idling...
I take it the 13.1V was the instant after you started the car? That would be OK for a number of seconds at which point it increases to somewhere in the 14s. But the 14.8V is perfectly normal while cruising down the road at the temperatures you were probably at (50-65F).
By the way, my 2015 991 with the original Banner battery does not need a battery maintainer all summer long and there are times the car is parked for 2 or 3 weeks at a time. It starts without any issue.
This is my 991 just after I came to a stop with the engine idling...
Yes instant after I started the car it read 13.1. Glad to know it's normal as well as the 14.8v during cruising. Nice GTS cluster color btw!!
So I hadn't driven the car for couple of weeks after swapping the battery and it was not on the tender. I enabled the voltage gauge as soon as I got in the car, 13.1v, about an hour of driving later without any stops, 14.8v.
Someone please tell me whether (1) this is a normal voltage and (2) whether I should consider using the tender again if I won't be driving for few days...
Still waiting bro get booked with the local Indy for a brake fluid flush and to find out if he can register the battery.
Couple comments -
1. Check the voltage b4 you start out of you want to see the charge state of the battery. 12.8 volts is good.
2. If you leave it for several weeks without a tender very often, your battery won't live as long. Sulfation will be accelerated. Think 'prevention', not just about charging a discharged battery.
My 911's battery is still going strong at nearly 6 years. I always put a CTEK on it if I'm not going to drive it for more than 3 days. I don't like battery replacements every few years.
So I hadn't driven the car for couple of weeks after swapping the battery and it was not on the tender. I enabled the voltage gauge as soon as I got in the car, 13.1v, about an hour of driving later without any stops, 14.8v.
Someone please tell me whether (1) this is a normal voltage and (2) whether I should consider using the tender again if I won't be driving for few days...
Still waiting bro get booked with the local Indy for a brake fluid flush and to find out if he can register the battery.
Well...I'm in a long term hotel situation here where I live since our house isn't ready (construction delays in Florida, imagine that). Anyway, I keep the car in a storage garage. There's no outlet I can plug my NOCO Genius 1A tender in.
I left it last Saturday for a week. Got in yesterday to drive around, and noticed the startup voltage on the car MFD readout was 11.7V. Charging voltage quickly rose to around 14.6V. Apparently according to what I see on-line for 12V batteries that puts me at about 25% "state of charge".
Battery is original, Banner, 80Ah, manufacture week 14 of 2017, per the stamp on the negative terminal.
I've not had any issues starting, but on our trip up to Werks Reunion Amelia Island I had an electrical oddity. Starting the car after lunch on the way back, the PCM just blacked out, which was odd. I stopped and started the car and it hasn't happened since.
Forward plan is to swap it out in July in our new place. I got the battery for my 981S at Batteries Plus for $2xx, so I'll likely go that route. Only decision is what to do with the BMS reset; have my dealer code it, get an iCarsoft V2.0 and DIY, or ignore it like I did on my Cayman.
Well...I'm in a long term hotel situation here where I live since our house isn't ready (construction delays in Florida, imagine that). Anyway, I keep the car in a storage garage. There's no outlet I can plug my NOCO Genius 1A tender in.
I left it last Saturday for a week. Got in yesterday to drive around, and noticed the startup voltage on the car MFD readout was 11.7V. Charging voltage quickly rose to around 14.6V. Apparently according to what I see on-line for 12V batteries that puts me at about 25% "state of charge".
Battery is original, Banner, 80Ah, manufacture week 14 of 2017, per the stamp on the negative terminal.
I've not had any issues starting, but on our trip up to Werks Reunion Amelia Island I had an electrical oddity. Starting the car after lunch on the way back, the PCM just blacked out, which was odd. I stopped and started the car and it hasn't happened since.
Forward plan is to swap it out in July in our new place. I got the battery for my 981S at Batteries Plus for $2xx, so I'll likely go that route. Only decision is what to do with the BMS reset; have my dealer code it, get an iCarsoft V2.0 and DIY, or ignore it like I did on my Cayman.
Reset only an issue if CCA of new battery is different than CCA of old battery. Dealer charge to code is $200+. Before I would do that, I would buy a Foxwell or iCarSoft for $120-150 and do myself and still have the OBD scanner afterwards.
Reset only an issue if CCA of new battery is different than CCA of old battery. Dealer charge to code is $200+. Before I would do that, I would buy a Foxwell or iCarSoft for $120-150 and do myself and still have the OBD scanner afterwards.
I'm planning to get one of these, a Group 49 92Ah Duracell:
Battery currently in the car is an 80Ah Banner OEM. Would you code the BMS based on changing the battery Ah capacity in this case, or not? (In this case, I would DIY it myself with an iCarsoft v2.0, not at the dealer).
Paid $219.99 online with store pickup. They took off another $22.00 with a promotional code, and there is some kind of mail in rebate going on as well. Battery was a Duracell AGM 92 Ah SLI49 Group 49, purchased at my local Batteries+Bulbs here in Venice FL.
Install is straightforward, as most here know. I had done this on my 981S, and I'd say the process is identical.
Unsnap the cover and remove the emergency air pump, undo the two T20 Torx screws that hold the air pump housing. Remove 13mm bolt holding in the battery adjustment plate, then take off both 13 mm nuts holding the battery strap.
I pondered some way to keep the car powered during the swap, but in the end I just did it pretty fast. I'd say it was disconnected no more than 45 seconds between removing the negative/positive terminal nuts (10 mm) from the old and sliding them onto the new. I carefully reinstalled the hardware, then spent some time tie wrapping my NOCO Genius 1A charging pigtail for the charger. As far as I can tell, there was no loss of memory or function during the swap, at all. One note: this 92 Ah battery is a little wider than the 80 Ah, so I just moved the retaining/adjustment plate one hole to the right on the tray.
Tip: To ensure that the firewall-side 13mm retaining nut does not get dropped and lost in the bowels of the frunk, use a teeny piece of black Gorilla tape (or similar) and "stick" the nut onto the 13mm socket and 4" extension. That way, the nut will be less likely to fall out of the socket. Maneuver the nut/socket/extension off the ratchet gently and slowly into place on the stud, then carefully thread the nut on. Once the nut is on, withdraw the socket and extension, connect it to the ratchet and tighten normally.
Car starts and runs fine. Previously (with the Banner OEM 80 Ah, 04/17 production date) the car would be at about 11.6V on initial startup, then charge around 14.7V. After installing the new AGM, the car is at 12.3V at startup and is charging at 14.3V. I have an unrelated service visit to my local dealer next week so I will have them reset the BMS (I know, I know, I could buy a BMS reset tool, but I already have an Autel that resets the OCI, and I really don't want to buy another just to reset the BMS) as long as it isn't too dear. I doubt it will change the charging profile, it's just my inner OCD to do this.
Good DIY for less than $200.
Last edited by Rich_Jenkins; 08-06-2021 at 02:46 PM.
Replaced mine today in 30 mins following your instructions, thank you. I did notice the battery bracket did not fit snugly across the top of the battery do may go back in and shim it with firm rubber to avoid it bouncing around. Batteries Plus was great - ordered online and got 10% off, then went by the store to pick it up and drop off the core. Everything works as it should and volts reading 14.2.
Replaced mine today following above instructions. Went with the Duracell AGM from Batteries Plus. ~$220 plus tax.
Old battery was out of the car for about 90 minutes while I picked up the new battery and ran some errands. I didn’t bother with the CTek or any interim power source and all my settings were fine when I got hooked back up to the new battery. The time on the clock was wrong but it reset itself once I started the car. I have no plans to have the new battery “programmed” by the dealer.
Installed a new 70 ah new Duracell AGM battery today, same size as the OEM. I did not use a trickle charger. There are 2 torx 30 screws and 3 13mm nuts. It’s not too bad. Everything works, no issues.
Just curious - why did you install a new battery with a lower ah rating than OEM when it appears that everyone else is going for an increase in ah with their replacement battery?
Just curious - why did you install a new battery with a lower ah rating than OEM when it appears that everyone else is going for an increase in ah with their replacement battery?
DaveGee
I installed the exact same spec/size battery as the original battery (2012 made) that came from factory. I know some install the 90/95 ah battery. The way I look at it this eliminate any worry about coding since spec is the same. I have a 991.1. What size is your battery from factory?
05-28-2021, 04:56 PM
