sanity check on power infrastructure for all-electric boat build

[0xkruzr]

Hi all,

Trying to figure out whether or not I have a handle on all the nuances of the bits I need for the all-electric pontoon boat I'm putting together. I have two 48V Hangkai 2200W motors driven by four 24V 100Ah batteries (46A peak power draw, not 40 as it says in the diagram), the batteries are two pairs of different brands but I get the impression that doesn't matter that much. My plan is to put those pairs in parallel and then have both motors tap off the same bus bars coming off the batteries (rather than something unnecessarily[?] complicated like one motor off one pair and one motor off the other), then have a step-down for 12V things like lights, stereo, possibly a fridge, etc. Also looking to keep things charged with some panels on the roof - not sure how many or of what voltage yet but I'm pretty sure I can fit at least six up there.

Things I don't know yet:

• Do you normally just connect all the panels in parallel up to a charge controller like this one? https://www.amazon.com/SmartSolar-MPPT-100-Charge-Controller/dp/B073ZJ43L1/
• Why some charge controllers have six contacts (panels, batteries, load) and some only have four (panels, batteries)
• What brand/type of equipment is most friendly to "outside interaction," i.e. are Victron or Renogy or ??? most robust with respect to having usable APIs etc.
• Is it possible to charge the batteries "en banc" with a single 48V power source instead of having to do something annoying like charge each one separately at 24V?
• If I want a fair amount of intelligence about power going in and out of my system, do I need something like this https://www.amazon.com/Victron-Energy-BPP900450100-Cerbo-GX/dp/B0851KGF57/ (apparently has had a history of issues with 48V power despite it being officially supported?) with this https://www.amazon.com/Victron-GX-Touch-50-BPP900455050/dp/B0844GR5LR/ or are there better/more "open source" options?

Incredibly professional diagram of all this found below. TIA.

 

[Rocketman]

the Victron mppt charger you picked is not a 48v - you probably want the Victron smartsolar mppt 150/35 or 150/45. It will depend on how much solar you put on the roof - if less than 2000w go with the 150/35. The voltage needs to be 5v above the 48v battery- so you will probably want to hook the up panels in a 3s2p arraignment.

You will also need a battery monitor. - either a Smartshunt or BMV712. The bmv712 may be helpful to have as a display or extra display.

Make sure those batteries (their bms’s) can be wired in series. (Some can not).

The Cerbo and touch should be fine at 48v. You will need some cables to connect the mppt and shunt to the Cerbo.

Batteries- if you buy any more - look for 48v batteries. Also make sure the 24v batteries are completely full before hooking them up in series.

You will probably have to disassemble the pack and recharge each 24v battery to balance them out occasionally. If you can check the cell voltages by Bluetooth you will know when you need to do it. if you don’t have bluetooth for your batteries- you may want four accurate voltage displays- one for each battery- that way you can see the voltage imbalances Easily.

You may also want a 48v lithium charger so you can recharge faster than the sun. You will need the 24v lithium charger occasionally to rebalance the batteries.

Will you ever be in temps below 32F? If you charge Lithium’s below 32F you will ruin them. If they might be connected in the boat - get the optional temp sensor for the Smartshunt/BMV712- then you can set the Cerbo with DVCC and set the mppt to not charge below __(user setable)__F (mine is 40F).

Good Luck with your project.

 

[Rocketman]

To answer some of your other questions:

The load terminals on some mppt’s are for some small loads - you would not use them.

The solar panels need to be 5v above the battery voltage to start. Because your battery is 48v you will need at least 2 panels in series- if you have 6panels you will probably want 3 in series and 2 strings in parallel.

What kind out “outside interactions” do you want to do? By connecting the Cerbo up it will display lots of info. If WiFi is available you can look at the Cerbo data anywhere on the internet through VRM (Victron Remote Management) app or webpage. The Cerbo has other things that can be attached - temp sensor - for the fridge, GPS. Also through NodeRed there is LOTS more that can be done - but I don’t know much about that. This is one area that Victron shines!

Yes after fully charging the 24v battery- put them in series for a 48v battery and test them as a 48v until you need to rebalance them.

48v can be deadly- especially around water. Make sure all connections are safe from touch. Also , you need to add fuses for the wire.

You may want to consider the Victron PowerIn and add fuses (lookup how on YouTube). That gives a good distribution point with four fuses 2 for motors, one for mppt, one for 48v-12v step down. A main power switch on the positive and the shunt on the negative then they go to the batteries.

You need a breaker or switch between the panels and the mppt - so you can “turn the sun off”.

Redo your “professional drawings” ?, after you research a bit more and add then needed items.

Good Luck

 

[0xkruzr]

Thanks for the detailed reply! Small question: does the Cerbo + display do the same job as the BMV712?

 

[Rocketman]

No the Cerbo +touch does not do the same job as the BMV712.

The Smartshunt and BMV712 are the battery monitor shunts. Their job is to count the power in and out of the battery. They both will report the data to the Cerbo (over VE.connect cable and they will report info via Bluetooth to your phone over VictronConnect app.
The 712 has a basic display that can also show you the data. It also has a relay for other purposes- which could be helpful -think big red warning light at____%battery (verify that is possible- I am just thinking out loud). The other difference is the VE cable connects to the display and the Bluetooth is on the display.

The Cerbo’s job is to bring all the data into one place and manage it. It can also start generators, using WiFi send the data to the cloud (VRM), manage charging, transmit battery voltage, current and temperature to charging devices (DVCC-set it up) and more add GPS to the VRM data, etc.

The Touch is the display for the Cerbo.

 

[0xkruzr]

Batteries- if you buy any more - look for 48v batteries. Also make sure the 24v batteries are completely full before hooking them up in series.

main reason I didn't go with 48V batteries is IIRC they were way more expensive per Ah than the pair of 24s.

 

[FloaterBoater]

I'm trying to plan a 48v marine system as well (for AC leisure loads, not propulsion). One thing to consider is how you're powering your 12v loads. In my case it's 24v loads. I'm planning to use a DC-DC charger to step down from 48 -> 24v and then connect this to a smaller 24v battery bank to power the loads. This way I don't need to worry about overloading the voltage converter, and if something goes wrong I still have power here. Some accessory loads can be safety critical, like a bilge pump, nav lights, etc, so you want to make sure they're always able to be run.