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Adding a battery monitor???

Posted: Fri Dec 16, 2016 12:25 pm
by deising
Hi, all.

We bought hull 91 just a few months before leaving on the Great Loop and due to prioritization of projects, my hope to install a battery monitor got postponed. I installed a Victron on our former sailboat and loved having good info about the Ah's in and out, state of charge, charging current from the solar panels, etc. of the house bank. I now want to add one to our PDQ 34.

It is imperative to mount the current-sensing shunt on the 12V battery negative so that ALL loads go through the shunt. Under the lower helm seat is a post that ties together the main battery neg cable to a 2/0 cable running to the neg buss in the console, as well as 2 large (4/0) cables. One is for the inverter. I don't know what the extra one is for. Any ideas?

In any event, the logical location for the shunt is in the small space behind the house battery switch and it appears I can just make it fit. Another possibility is where the neg cable passes under the removable access panel for the aft fuel tank. There "should" never be any sparking, and diesel fuel is not that volatile, but installing it so close to the fuel tank is not my preference.

So, has anyone installed a battery monitor? If so, where did you put the shunt?

Re: Adding a battery monitor???

Posted: Fri Dec 16, 2016 1:21 pm
by AMCarter3
I can't answer your battery 4/0 cable question, but I can suggest a location for the shunt. There is a large open space behind the entry door steps (right in front of the house battery locker)... 4 screws hold the steps in place. Our battery monitor is tied into a shunt located in that area.

Re: Adding a battery monitor???

Posted: Sun Dec 18, 2016 9:52 am
by James Power
Follow the extra 4/0 cable from the negative post under the helm seat and it should lead to the inverter as a chassis ground.
James

Re: Adding a battery monitor???

Posted: Tue Dec 20, 2016 8:37 am
by Gusto
I installed a Blue Sea Systems monitor. I mounted the shunt on the bulkhead just forward of the batteries and connected the shunt to the battery with a short battery cable so I didn't have to cut any cables. The monitor works great. I can easily manage the house bank between 50% and 85% at anchor. The boat is in St Petersburg. You are welcome to check out the installation anytime.

Re: Adding a battery monitor???

Posted: Tue Dec 20, 2016 10:30 am
by AMCarter3
Sounds like Gusto installed the same Blue Sea analog battery monitor that we did on our boat. It is so much easier to track all of the batteries with this monitor vs. the ones that track amp hours only. It instantly shows the state of the two engine start batteries and our 4 AGM house batteries as a percentage of power left. The model we installed is the M2 DC SoC Monitor (SoC stands for State of Charge) <https://www.bluesea.com/products/1830/M2_DC_SoC_Monitor>

(FYI -- We replaced the 4 golf cart house batteries with much larger capacity AGM's and installed one 180 amp high capacity alternator this past summer to hit our goal of up to 3 days of anchor time without starting the engines).

Re: Adding a battery monitor???

Posted: Wed Dec 28, 2016 1:43 pm
by deising
Wow, guys! I am really sorry for not responding sooner. I have no idea what happened but I never saw an email telling me I had replies to my post.

That is great info and much appreciated. I'll report when I am done.

Re: Adding a battery monitor???

Posted: Wed May 17, 2017 7:20 am
by deising
I see that I failed to report the completion of my battery monitor installation. I will say after several months of use that I do NOT feel I made the best choice. I wound up using a KID MPPT controller for the new solar panel installation and it serves a dual purpose as a battery monitor when you install a shunt and a data wire.

Anyway, the suggestion to install the shunt behind the removable steps was super and there was plenty of room to work. I ordered a 2 foot length of 4/0 cable and therefore did not have to cut an existing cable and try to crimp terminals. It serves the function of measuring Ah in and out, but I suspect the Blue Sea system is far better as a battery monitor.