I would like to monitor two battery banks on our boat. We have kind of an odd setup - each engine room has a large battery bank (32v). The bank in the engine room starts that engine; additionally, the bank on one side serves as the house battery bank. I would like to monitor these two banks as accurately as possible while still allowing for the occasional high cranking amps required to start the 12v71 engines.
Current gear includes a Cerbo GX (currently only interfaced with fuel senders, as I needed a way to view fuel status from helm) and a Smart IP battery charger for a separate 24v system. These two devices don’t currently talk to each other, although I would like them to. I would also like the new battery monitor(s) to integrate with the Cerbo GX. End goal is a screen on the boat that allows me to view all this info (fuel levels, 24v battery status, 32v bank 1 status, 32v bank 2 status), and the ability to remotely monitor the same info. Bonus points if the system can alert me when there’s a battery issue.
Current issues:
The Smart IP battery charger can only be monitored when I’m physically on the boat using bluetooth; I’d like it to be available via the Victron Connect app so I can check status remotely.
I’m not sure which battery monitor/shunt I need
High-amp cranking (1000+ CCA)
Ability to integrate with Cerbo GX (wirelessly would be great, but I can run a long cable if needed with some extra effort)
Can I monitor both 32v banks with a single unit, or do I need separate units? Pros/cons
Most Victron equipment has to connect to a Cerbo GX through a wired connection. I can’t think of any of my Victron equipment that communicates with the Cerbo GX via Bluetooth. Sensors can be wireless or wired.
How are the two battery banks related? In other words, are they completely isolated?
A single SmartShunt can monitor two batteries (battery banks). It cannot monitor three. While my RV with a 48 volt house battery has a separate 12 volt battery (for starting the generator), I don’t monitor it (but it’s on my list of things to do) so I don’t have any experience with what you want to do. The schematic in the 2nd link below has an example of monitoring a second battery. The first link is to the datasheet. Note that there are multiple versions of the SmartShunt, all the way up to 1000 amps and there is also an IP65 version.
In the past, I believe that there was a 1-to-1 relationship between a shunt and a Cerbo GX. That’s changed as Victron has allowed shunt’s to take on different properties within a system. A second shunt can be configured as a DC Meter in VictronConnect, but I don’t think that is going to solve your design. Hopefully someone that has implemented more than one shunt in a system will chime in here.
I think you could use a Victron Battery Monitor on each battery bank, then connect to the Cerbo with VE Direct cables. You can get shunts up to 6000 amps. On our motorhome the starter batteries are connected through a BMS to the Cerbo. The starter batteries are shown in VRM.
I don’t have any choice but to take cranking amps through shunt; each battery bank serves as the starting bank for its respective engine. I’m not sure I would’ve done it that way, but Hatteras thought that was the right solution back in the day.
Given unlimited time and budget (mostly budget, lol) I’d re-wire the whole boat and update everything…but that’s not really an option at this point. I just need to figure out how to monitor and make due with what I have.
Then you need >1000A capable shunts, with VE direct cabling as a start. Have a look at your engine specification, this should include a “locked rotor” current for the starter motor. This is the magnitude of the initial starter current drawn as the pinion first hits the flywheel (Actually the bendix gear reaching the end of its travel).
yes, If you want to also monitor the allways on loads and bilge pumps etc, then their negatives also need to go the the “old Switch” side of the shunt, so an additional negative bus may be a good idea.
Thanks. Everything on the boat currently goes to the “old switch” side, so that shouldn’t be hard. I just need to locate and relocate the starter negative to the new bus bar, I think.
