Need Help: 488GTB Battery Issue

Need help - 488 battery issue: sitrep: 2017 488 GTB. Battery was showing signs of failure (like less than 48 hours without being on trickle charge resulted in slow crank and the usual christmas tree full of alerts when it started). So..got the recommended replacement battery (Odyssey 48H6) and went through the pain of replacement. But...car is completely dead now! I've attached the trickly charger to the new batter via clamps but something else seems amiss. Would appreciate any help or insights from you guys. Particularly bummed as I was supposed to be at a car show with it tomorrow. Thanks in advance

 

Thanks for the reply. I triple checked the connections & followed a really good YouTube video for the replacement process. I don’t see anything about a reset process in my owners manual - do you have a link or any more info about that?

 

Never mind. Found it online but doesn’t apply as key fob didn’t do anything - car is completely dead. I’m starting to wonder if the new battery I bought is dead - it has dust all over it as if it was sitting on a shelf a long time

 

thanks guys. got the multimeter coming today. I trickle charged the old battery overnight and it reached full charge but took a LONG time to get there, so I'm still thinking it's weak. Oddly, I'm hoping like hell that the new one is actually dead; otherwise I've got something else serious going on :-(
Re-checked all connections again and there's nothing out of place (it's really not that complicated to swap the battery after you've done it once!

 

Update: problem resolved and she's back to life! Thanks to all that tried to help. In the spirit of contributing back in case anyone else encounters this: the problem was rooted to the prior owner swapping out the battery and loosening a nut that didn't need to be, and then not tightening it completely. There is a cable assembly attached to the top of the negative battery post that effectively extends the connection point for the entire vehicle to a location about 12 inches lower and in front of the battery, with a quick release latch connector. As part of the battery replacement process, I removed the entire extension assembly (which was easy) and never touched that nut. Multimeter showed great voltage measuring top post positive and negative, but when I checked the lower connection post (where the quick release latch attaches), the voltage varied from zero to about 2.5 volts. Initially thought the extension assembly wiring was faulty (ugh!) but then my hand hit that circled nut and it moved from a gentle touch - it was finger loose! Tightened it up, rechecked voltage at the lower contact point and it was perfect. Attached the quick release latch, and she came to life! Thank God. Having removed and re-attached all the connections three times, I'm now a self-declared expert on this so if anyone needs help replacing the battery on your 488, just tag me here. Thanks again guys!
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