Has anybody installed a shunt?

[jms02050]

Hi - It's time for new batteries and I'm looking to install a monitor to see my daily amp draw while on the hook, especially that of the old Norcold. Was going to have someone do what should be a DIY job but getting a marine electrician to return a call let alone commit is impossible where I am.

Anyhow, searched the forum and didn't see that anyone had taken this on when searching for "shunt". I've put together a little scratch diagram of my layout (which I could post) which i think is standard from the factory on a 28. Best approach appears to be installing a bus bar to pick up the ground from the bank(s) and then go to the shunt.

Has anyone done this? I'm confused by the ground jumper between the start and house banks as well as having separate grounds from each bank - 1 which I think (without fully chasing it with a voltmeter) goes the to DC panel and 1 which I think goes to the neutral bus bar in head behind the vanity mirror.

Any and all info is appreciated. Only 8 weekends til launch!

[rcwhite]

These aren't hard to install. You do need to consider the maximum rated amperage
and what you want to monitor though.

For example, a shunt rated for 500 amps should not be used in the starting circuit. There
are plenty of circumstances where you could see a starter draw more than that.

Installing the shunt between the ground bus and the house load (but not the common to the
engine battery) will allow you to monitor the voltage & draw but you will not see the input amperage from the Alternator. It will see any other charger or solar panel as long as the ground for this is after the shunt.
This is generally a reasonable compromise installation and doesn't require the shunt support the full starter + heater load.

If you would like to post or PM your diagram and thoughts I would be happy to review.

[Pitou]

I looked into battery monitors, amperage use monitors and digital volt meters and setlled on the simpler solution of a DVM's / digital volt monitors for their ease of use and simplistic understanding. With a simple glance to a DVM for each bank you'll know exactly where you are as far as battery capacity. Do a search for DVM and you'll find a number of posts to this regard. Also read the article by RobS linked to the Seaboard Marine website through the DVM posts to get a more thorough explanation.

Here's a picture for an easy understanding of battery state of charge in relation to voltage:

Battery-State-of-Charge-Spreadsheet.jpg

[Pitou]

I realized that I hadn't answered your question and I have not installed a shunt for your application and have only installed one for my battery charger.

Marine How To has a helpful article to your question. I had looked at the Marine How To articles for battery monitoring a couple of years back and decided to go with DVM's because monitors at that time needed constant calibration to be accurate.

Technoligies seem to have changed and the new Balmar Smartgauge and the Balmar SG200 might be worth a look.

Here's a link to an article at Marine How To that has links within for the Balmar products and how to wire them including the shunts. I hope this helps and will be curious as to which direction you head.

https://marinehowto.com/installing-a-battery-monitor/

[jms02050]

Hi, thank you both. I've seen the DVM threads, Rob's article and I'm a frequent visitor to Marine How To (PBase's site). All good stuff. The DVM is certainly enticing. What's led me down this path is that aside from the 2 or 3 week long stays on the boat we spend most weekends from May - Sept on a mooring for 3-4 days. So, I was thinking with the big pilothouse roof, why not go solar to keep the fridge going and put some juice back in the house bank? I enjoy living out of coolers to a point - but it gets dicey for perishables and especially meats. The first question for solar is what is your daily amp draw? This always leads back to the fridge. If the forecast holds I might be back on the boat tomorrow to chase down the rest of the system and finish up my diagram...

[jms02050]

Wanted to follow up with a secondary question... has anyone installed a bus bar to clean up the battery connections? Between the house and start bank I’ve got 7 ground wires - pretty sure that’s how she left the factory. Not much real estate on the bulkhead in front of the banks due to the charger being mounted there...

[Norseman]

Installed a shunt on a previous boat: Part of a Xantrex Battery Monitor system. Also installed the battery temp sensors hooked up to a Xantrex charger, with a solar booster MPPT and 2 Siemens 75 watt panels. A bit of work running cables and taking boat apart to do a clean install.
Labor of love..
Besides that, easy installation of the shunt.

[MerryKate]

Jim - it may not be very clear in this picture, but here is the ground bus bar I installed on my motor box 28 TE on the forward bulkhead just under the helm seat. Vastly improved the cabling and robustness of the battery bank installation. A short span of 00 cable made up from battery negative terminal (common to house and start batteries) to the bar.

[jms02050]

Hi there. Thx for the pic. I was finally able to do something similar by mounting the bus under the charger. I’ll post a pic of the finished product once I’ve wrapped things up. So much better in terms of cleaning up the grounds. Had 4 on the house and 3 on the start bank when I started this journey. Found a location for the shunt, now looking for a spot for the battery monitor. I’ve got room on the helm panel but not sure how it will do “outside” in the pilothouse versus in the cabin....