Battery Wiring Issue - SYS 0.0V

[Nick Hughes]

Just getting to my boat for the season and was reinstalling both my batteries. In the fall I always tie my house wires together but this year something is wrong. Boat starts, stereo is fine, but getting a voltage comm error and the SYS is showing 0.0v. House is showing 12.x. I tested both with a multimeter and both at 12.x.

Can’t figure out what I did wrong. I have the positive from the switch coming from start switch to start battery. 3 negatives from within the boat to start batt negative. labeled little TCR black to start. Then 1 more black that connects the 2 batts. Everything else to house. Took some pics to hopefully gain some @HELP with the issue. Already burned a night out, hoping some smart guys like @Mainah will chime in quick. Thanks!

 

[Bruce]

Do you have two batteries or three?

However you resolve this I would put terminals on the bare wires connecting to one of your positives. Or even better add a fuse box and fuse those connections whatever they are.

 

[Nick Hughes]

Two batteries. Yeah, I agree on terminals. I got a mess right now and no stores near the lake with that stuff. Ordering on Amazon now!

 

[Bruce]

Two batteries. Yeah, I agree on terminals. I got a mess right now and no stores near the lake with that stuff. Ordering on Amazon now!

So you have two batteries total and you use both as house batteries?

I do something similar with my house load switched by a low voltage disconnect. https://jetboaters.net/threads/my-unusual-alternate-dual-battery-setup.5632/

I have all my house loads beyond the fused factory house circuit connected through one of these https://amzn.to/46FvrGn

 

[Nick Hughes]

Because of your question, I reread my original and updated, it was a little confusing.

 

[Bruce]

So you have three batteries.

Where are the two engine positives and negatives connected?

Is ground connected across all three batteries?

 

[FSH 210 Sport]

All the grounds should be connected.

Both engine grounds should be on the start battery, then a jumper from the start battery ground to the house batterie(s) ground which are also tied together, dvsr ground tied to start battery, accessory or house loads ground landed on house battery. While I need to do this too, all of the negatives should be landed on a common bus, with only one main ground wire attached to each battery, and accessory / house grounds attached to the ground bus.

Both positives from the engine should be landed on the start battery.

Accessory / house loads positive landed on the house battery.