House battery over charging!

[Gootman8]

Hey tige fam, I've been searching this forum for hours now and i cant seem to find anything on this subject!! just bought 2012 tige z1, boat had not been used in about 18 months so had a service done and a few things replaced, one being the alternator. My question is, the house battery is coming up on the TT screen with 18.6volts, even with the engine off it comes up with 18.6volts. This only came to my attention when my wetsounds amp syn6 which runs the in boat speakers and sub kept cutting out then back on, it is flashing the code for, ( high voltage protection) at the start I thought it may be the amp that is cooked, but when I realised the screen is saying the house battery is putting out 18.6volts then that has me thinking that maybe the amp isn't cooked and it is actually just doing its job properly, the boat ran all day without a single problem other than the speakers cutting in and out.
I'm just wondering what could be the problem here? This forum has been fantastic since purchasing this boat, I changed the TT screen just 3 weeks ago with all the information i found here so im hoping i might have a little luck woth this issue, cheers

[Gootman8]

[chpthril]

This will help narrow things down a little for you. That boat's charging system does not have the ability to overcharge the house and not the main. If the house is indeed seeing 18+, which should be verified by a handheld volt meter, then I suspect the rest of the boat is seeing the same voltage. Best advice, return to the shop that installed the alternator.

[Gootman8]

Thanks for the reply mate, I also forgot to mention, that picture I posted was before the boat had the new alternator installed, so it was actually putting out 18.6v prior to the new alternator, the boat had a trickle charger attached to it regularly over the 18+ months off the water, could that have caused the house battery to over charge and potentially ruin the battery? I'll definitely be taking it back, I'd be testing everything myself but my boat is kept 2 hours away from where I live, again mate thanks for your reply.

[chpthril]

Regardless of who does the testing, someone needs to get in there and verify the voltage coming right out of the alternator as step one. Since the MFD reads about the same with the old and new alt. This could be a firmware glitch in the screen or a failing main charging system cable.

[Gootman8]

Cheers mate

[Grebva3]

I have had this issue for a while and yet to find a solution or find out where the system reads the house voltage.

[Gootman8]

Update! I went and checked absolutely everything, everything is working as it should but for some reason the screen is saying the house battery is 18.6v when it is 100% not, good result really.