'17 23 LSV - Battery/Alternator Question

[2THEL8K]

I've done a bit of searching on the forum and may just be missing some obvious threads, but looking for some battery advice.

This past weekend, we appeared to lose our alternator (Raptor 410 on a '17 23 LSV).  I say appeared because the dealer did not officially troubleshoot yet, they just ordered a new alternator based on the symptoms (lost screens/stereo while driving.  When we stopped to power cycle the batteries, they came back dead initially.  Was able to jump once, but service warning alarm came on, screens very dim or not displaying anything at all, shifting didn't work (stuck in neutral).  Was able to re-start and shift after floating for 30 mins with another jump, but was in limp mode driving...ultimately requiring a tow into the marina when it died again).  The dealer will troubleshoot when the new alternator comes in, but are confident this is the issue.  By the way, the alternator availability is another issue.  I was told 14 days for a replacement, which seems absurdly long.  I really like my dealer, they said they have to quote longer lead times as there are some challenges with the Indmar warranty process since Malibu insourced engines.  I'm not sure if this is the case or not, but this is what I was told.  I reached out to Malibu customer service, they told me "sorry for your trouble, contact Indmar customer service".

Regarding the batteries, the boat came with Deka dual purpose batteries.  Is there any concern that the batteries were damaged being drained so low?  Trying to decide if it's worth taking a chance that the batteries are still ok, or if I should just purchase new batteries to be safe (essentially 3 years old).  I was going to ask the dealer if they have any way to test the batteries when I take it back in for repair.  Not sure if testers are available to give a true read on the battery health.

While I'm at it, any recommendations for good replacement battery (brand) if it's recommended they be changed?

Have loved the boat over the past few seasons and still do.  It's been relatively trouble free. While I understand that mechanical things break, only disappointment so far is handling of the alternator replacement with such a long time for a part that should be readily available.

Thank you for any guidance. 

[Sride]

They are probably AGM. Have to be honest, in a world now with the complexity and expense of these systems I am changing them. That being said, my 2011 has only required 1 battery change in ~ 10 years. I use Interstate batteries and a tender when the boat is in storage.  

Edited May 17, 2020 by Sride

[cbftbl87]

Fully charge first, then take the batteries to a battery/auto parts shop to get load tested.  I doubt the batteries were damaged since they didn't sit there dead for a long period of time, plus deep cycle batteries are designed to be drained down then recharged without getting damaged.  My bet is they are okay.

[MLA]

Heck, if they reach a full charge, theres your answer. Deep and repeated cycles result in the battery not returning to the previous state of charge. Most failed load tests are a result of load testing an under charged battery. If my volt meter says the battery is fully charged, 99 of a 100 times, the battery is good. 

[2THEL8K]

Cool, appreciate the replies from everyone