Gen 2 Replacement Battery

[Badinternet]

Forgive what is undoubtedly a duplicate thread but with as many battery posts as there are when I search, it became too time consuming to find the ones about a Gen 2.

My car locked itself after a short drive yesterday and wouldnt let me unlock with fob. Had to unlock through trunk and the emergency latch on the door.

I thought the key fob was the problem and read that if unrecognized the car wont start. So I replaced fob battery and still nothing. Used multimeter to check battery and fuses and all are <12V. I tried charging the vehicle for probably close to 30mins and the reading went from 11.9 to 11.93.

So a new battery seems like it could fix the problem but then I’ll still be dealing with the car locking me out/not recognizing the fob (i tried the manual fob reset with DB2 connection and it didnt work, could just be user error and not properly grounding the 4th pin with paperclip, tho).

But that aside. I think I need a new battery regardless. Recommendations abound. Amazon and Autozone say Group Size 78 and 34, respectively, will fit. Reidperformance website for the Antigravity batteries say Group 47.

What is the absolute best performance battery to buy so I can stop dealing with this problem (had to jump my had probably 6 times in last 12months) and also which group size fits??

Thank you for any help.
D

 

[Steve-Indy]

My preference for our Vipers (5) where the battery resides behind the left rear wheel, I have moved to Interstate groups MTZ series. These are AGM batteries and outlast the flooded lead acid batteries by a factor of 2-3 times...and, they carry a 4 year fully refundable warranty after which time, there is a prorating formula.

While heavy and expensive, these batteries have valve in my opinion by decreasing the frequency of going through the battery change procedure on these models.

 

[Badinternet]

Thanks, Steve. I just ordered this Odyssey AGM 3478, how does that compare to what you recommended?

 

[Badinternet]

Nevermind, Steve. Just looked them up and they seem very similar. Glad i made a good, albeit expensive, choice.

 

[Badinternet]

If anyone has any ideas wth its locking me out though that is going to be the next issue to solve.

 

[Steve-Indy]

Odyssey is a great battery in my opinion. I did not list it because I have not tried tobinstall a group 78 in a Gen I or II where it could be a tight fit.

I do have the Odyssey Group 34 in 3 other Vipers and they are all still going strong at over 14 and 16 years later.

By the way, when you install it, carefully check the cable connectors to be sure that the fine wires in the cable are not "corroding away" where they enter the actual connector. Follow the ground cable to the frame to be sure that connection is clean and tight.

You MAY solve your door lock issues with a new battery. As you may have read, be suspicious of broken wires in the harness to both doors where they often break...causing multiple issues with door locks, windows.

 

[Badinternet]

Well, to update: the multimeter showed the battery was running at 11.9, and so were the fuses, which meant it could still be both a bad battery and the security system locking me out. The keyfob tester showed the fob was working fine, so at least it ruled out a faulty fob, although the OBD2 method to reset the security system and allow me to use the fob was still not working. I ordered a new battery, the Odyssey AGM 3478, which was supposed to arrive yesterday but didn't. The weather was going bad, and it was starting to sleet and ice, so I needed to move the car. I purchased a regular battery, took out the old one, did a hard reset by pumping the breaks after removing the battery, and waited ~30 minutes for the computer to completely reset, which would reset the security system. Installed a new battery, reset the key fob, and the car turned over, and the fob started working again.

Now, I just have to replace this battery when the AGM arrives and get a new spare tire because after getting home, I realized that the spare tire is flat.

/I have a love-hate relationship with this vehicle, but I think she hates me more.

 

[TEALLIFE]

Well, to update: the multimeter showed the battery was running at 11.9, and so were the fuses, which meant it could still be both a bad battery and the security system locking me out. The keyfob tester showed the fob was working fine, so at least it ruled out a faulty fob, although the OBD2 method to reset the security system and allow me to use the fob was still not working. I ordered a new battery, the Odyssey AGM 3478, which was supposed to arrive yesterday but didn't. The weather was going bad, and it was starting to sleet and ice, so I needed to move the car. I purchased a regular battery, took out the old one, did a hard reset by pumping the breaks after removing the battery, and waited ~30 minutes for the computer to completely reset, which would reset the security system. Installed a new battery, reset the key fob, and the car turned over, and the fob started working again.

Now, I just have to replace this battery when the AGM arrives and get a new spare tire because after getting home, I realized that the spare tire is flat.

/I have a love-hate relationship with this vehicle, but I think she hates me more.

for what it's worth, I swapped my spare out for a full size stock front (as I have aftermarket wheels). As I didnt want to get stranded 3 hours from home ever again and not able to drive that far on a donut.