JimEb

My battery is 8 years old original. I tested it and it came up with “replace” which isn’t surprising.

Plan to swap it out with an Interstate AGM from a local store. No prob, my question is to reset or not to reset.

I have an icarsoft PORv2.0 that claims it can do it, but sounds like it requests parameters (part number, serial) that only come on OEM batteries. Can you just ‘fudge’ some numbers there as long as the type and amps are correct? Does it really alter the charging profile to get longer life out of the battery? Or should I just change the battery and not overthink it?

jimmiejam

I changed my eight year old OEM battery about a year and a half ago. I did not reset and have not had any issues. I'm sure that you can input a "rouge" battery number and get it to reset.

DaveGee

Same here. Changed mine myself last year and didn’t bother with the reset. No issues.

DaveGee

asellus

Replace it with a like size and you won't need to futz with the BMS at all.

You can do it on your POR with an aftermarket battery. This was discussed in a recent (last year maybe?) thread, and if memory serves you can just put all zeroes or something silly.

koala

https://rennlist.com/forums/991/1041...ement-diy.html

TL;DR - some people insist you need to go through the programming steps, others think it's a waste of time. I personally think it's a waste of time.

spiderv6

If you google this you will come up with a 50/50 opinion.

I changed mine, didn’t do anything else and have not had a problem.

MingusDew

Interstate makes good batteries. I replaced my factory battery when I bought my car a couple of months ago, and at the time the MTZ model was on back order so I ended up going with the MTX-94R/H7 which was the same size/spec as the factory battery. Interstate doesn’t actually list a battery for our cars, but any H6, H7 or H8 should fit as long as the posts are in the correct location and the other stats (cold cranking, amps, etc.) are all similar. No problem swapping mine out, didn’t bother to hook up a charger to cigarette outlet like some do, just move quickly and hook up the new one without delay. It seemed that only some dealerships say the computer needs to be reset, some say it’s not needed, and most independents from what I’ve read say it’s just an excuse for dealers to charge more $. I didn’t bother to reset the ecu, and so far no issues.

barncobob

gave my indy 300 and he dealt with it

tmarino

Same here, just swapped out batteries and never an issue. Installed a new Interstate battery and drove away. Didn't worry about being unplugged as it was without a battery for at least 15 minutes with no problem. That was 2 years ago.

straka

I read that the reason for programing a new battery is as the battery ages the charging rate, based on the date of the new battery install, will increase with battery age. Without the programing refresh the new battery will have a shorter life as the car won't recognize the new battery and it will receive the previous higher old battery charge rate. Not from my experience, just information I read.

Valvefloat991

Precisely. If you don't reset, you won't see a problem for the first few years, but your battery probably won't last as long. Of course, given what a reset might cost at the Porsche dealer, you might still come out ahead financially.

JW911

Generally speaking, it is a waste of time and money. Your dealer will charge about as much for a reset as a new battery costs. But if you already own the reset tool like the OP does, then sure you should do it.

JimEb

Update - done and I way overthought this.

Replaced with an Interstate 49/H8 AGM. Didn't necessarily want a battery that big, but that was the only AGM they had in stock. It fit, used the last hole in the battery tray to clamp it down. Assume this must the the largest battery this car will accommodate.

Disconnected the battery tender. Removed the air pump and housing, battery clamp and strap. Battery was loose now. Quickly like a racing pitstop, I undid the terminals, pulled out the battery, dropped the new one in the tray and connected the terminals. Then reinstalled the clamps and everything. Car was unpowered for only about 20 seconds and did not lose a thing. Clock was all good, windows, no warning messages, etc. I connected my PORv2.0 scan tool and went to Service / BMS. It asked for 'capacity', entered 95 ...assume it was asking for the Ah. Entered AGM from the type drop down menu. When it asked for the serial/part numbers it said they were 11 digit and 15 digit numbers. If you didn't enter the correct number of digits it would say "Invalid", or something like that. I just entered in 1234567890.... on each of those prompts and it took it. Clicking 'next' after entering all the info it asked for it just got the end and it returned to the beginning screen. I assume it wrote the data to the car but it didn't give any indication that it did anything. Scanned the car to see if any codes got thrown and nothing. Went for a test drive and everything was normal.

What made me nervous with this is I've had cars do all sorts of stupid stuff when changing batteries. My Honda minivan's radio and GPS didn't work for a bit as I didn't have the radio code to enter. When I went through all my vehicle settings I was inexplicably locked out of some. This is the settings like how long you want the lights to stay on after power down, unlock one door or all, etc. It would just say "Unable" when attempting to change them. I gave up and rechecked a month or so later and I had full access again. Weird.

Class5Kayaker

I did the Carplay install this weekend. Had the negative post of my battery disconnected for like 4 hours, didn't lose any settings other than having to re-program the windows which happens every time you disconnect the battery no matter how short the time period is.