Brand new cranking battery at 4.7 volts

[fire92]

Just bought a 12 volt cranking battery after my other one died. I connected it and used it to trim the motor then it sat for a few days, now when I go to check it today I have no power to the boat. My multimeter when everything was still connected registered 4.8 volts, once I disconnected everything I got 7.8-8 volts. From what I understand the battery is now permanently damaged whereas if it was just dead I should still have around 10.6 volts. Any help would be appreciated as I'm worried there is something draining power to a critical level as opposed to just buying a bad battery which is unlikely. Main power switch was off and everything was connected as I have had it for years previously. Thank you!

 

[alldodge]

still connected registered 4.8 volts, once I disconnected everything I got 7.8-8 volts.

Something is draining the Bat. Bilge pump maybe, not running but pulling power

 

[QBhoy]

Hi. My first place to look, would be to things that are directly hard wired to the battery, or that have a constant feed uninterrupted.
So things like the automatic bilge pump. Is the float jammed up and activating the pump ? Perhaps you are talking water in and genuinely triggering the pump ?
What about the stereo system? Is it taking power 24/7 ? Have you recently upgraded to a new stereo with Bluetooth? They can occasionally want to constantly search for a phone to connect to, causing a draw. Another common cause might be a short somewhere. Most famously might be a trim switch or relay issue and causing a constant or occasional activation of the trim motor. Likewise for a failing ignition switch or relay? Some food

 

[airshot]

Sounds like you have a drain alright, but...I have bought new batteries that were bad right off !!! I always check a new battery with a digital vm and it must read 12.6 or above or I dont bring it home !! We pay good money for these so if they dont like me checking before buying...to bad!! You should be able to get the battery
replaced with no issue, however...you need to find your issues before they cause you a bigger problem!!