Stuck at first-time 2000W solar setup on boat

[Don B. Cilly]

The SCC is the Solar Charge Controller :·)
If it were my boat, I would just use the thickest wire that fits comfortably, have the panels in parallel, and not worry about voltage drops too much. Or at all. 40V open circuit, to charge 12V batteries, on two separate SCCs, I mean, you are not going to lose a significant amount of current even if you use loudspeaker wires :·)

 

[Horsefly]

Didn't notice this thread earlier, so I'm sorry for coming in late. I also apologize if I am covering ground that has already been discussed (although, I did try and read through the thread).

I recently helped someone upgrade his house electrical system on his 40' sailboat. I put in 2 4S 280Ah packs (Eve) each with one 4S 150A JBD BMS. Then the two came together through one Victron Smart Shunt. The JBD BMS's do a good job of protecting the 2 batteries, but they give no single view of the SoC (State of Charge) of the house battery. If I understand correctly, you (@horstenegger ) will have 14 parallel batteries, each managed by a JBD BMS. That's pretty hard to figure out what your SoC is for the overall battery. With the Smart Shunt, you are getting the the current in/out at any time as well as the SoC of the overall bank.

I don't know that I understand what you dislike about the Cerbo GX. If you are getting Victron Smart MPPTs, a Victron Multiplus, an a Victron Smart Shunt, the Cerbo GX integrates all that info in one place and gives you local Bluetooth and VRM access to exactly what is going on. I'm a retired Electrical Engineer and love playing around with Raspberry Pi (and Arduino, and ESP32s, etc.) but this just seems like a no-brainer for the Cerbo GX plus a GX touch display.

 

[horstenegger]

The SCC is the Solar Charge Controller :·)
If it were my boat, I would just use the thickest wire that fits comfortably, have the panels in parallel, and not worry about voltage drops too much. Or at all. 40V open circuit, to charge 12V batteries, on two separate SCCs, I mean, you are not going to lose a significant amount of current even if you use loudspeaker wires :·)

Ah, so SCC = MPPT. Gotcha.
Again - with 2000W total solar power (even if realistically not true 2000W) I am indeed not too worried about small voltage drops. It's wire bulkiness that I'm worried about. I guess I'll just need to find a way to figure out how much space I will have for the wires before deciding on final configuration, which will always remain a bit of a hit or miss when the moment of truth comes, but hey ¯\_(ツ)_/¯

I recently helped someone upgrade his house electrical system on his 40' sailboat. I put in 2 4S 280Ah packs (Eve) each with one 4S 150A JBD BMS.

Thanks for your input! I also have the Overkill / JDB BMS, so that's a good start.

Then the two came together through one Victron Smart Shunt. The JBD BMS's do a good job of protecting the 2 batteries, but they give no single view of the SoC (State of Charge) of the house battery. If I understand correctly, you (@horstenegger ) will have 14 parallel batteries, each managed by a JBD BMS. That's pretty hard to figure out what your SoC is for the overall battery. With the Smart Shunt, you are getting the the current in/out at any time as well as the SoC of the overall bank.

That explains why RocketMan recommended this. Thanks. What about using more MasterShunts (or other, perhaps less costly shunts) to also provide the BMS with more accurate readings though?

I don't know that I understand what you dislike about the Cerbo GX.

Cost. I have a couple of RPi's laying around. Plus, I kind of already intend to use other systems to monitor the battery bank (BRNKL and/or Orca, both of which I already have installed as well).

If you are getting Victron Smart MPPTs, a Victron Multiplus, an a Victron Smart Shunt, the Cerbo GX integrates all that info in one place and gives you local Bluetooth and VRM access to exactly what is going on. I'm a retired Electrical Engineer and love playing around with Raspberry Pi (and Arduino, and ESP32s, etc.) but this just seems like a no-brainer for the Cerbo GX plus a GX touch display.

Of course what you say makes nothing but sense. I somehow just prefer more hybrid / less proprietary setups in general. Going all Victron sort of feels like being slurped into the Apple ecosystem. But perhaps sometimes I should put my principles aside.

 

[Don B. Cilly]

It's wire bulkiness that I'm worried about.

Well, stop worrying about it. :·)
Use whatever wire will fit, it'll be all right, we're not talking about hundreds of amps.
-

 

[horstenegger]

Well, stop worrying about it. :·)
Use whatever wire will fit, it'll be all right, we're not talking about hundreds of amps.
-

Alrighty then ?

 

[Horsefly]

What about using more MasterShunts (or other, perhaps less costly shunts) to also provide the BMS with more accurate readings though?

I don't know anything about MasterShunt, but when I go to the web page what I see first is stuff that costs almost double what the Victron Smart Shunt costs. Anyway, your question doesn't make any sense to me. The shunt (*ANY* shunt) doesn't provide the BMS with any information. The BMS (or at least the JBD BMS) gets all its information from the battery cells.

The JBD BMS's also don't normally provide any info except to your phone. There is an open source package to interface the JBD to VenusOS, but it replaces the Bluetooth interface, and VenusOS would not know what to do with 14 BMS inputs.

Of course what you say makes nothing but sense. I somehow just prefer more hybrid / less proprietary setups in general. Going all Victron sort of feels like being slurped into the Apple ecosystem. But perhaps sometimes I should put my principles aside.

I am certainly not an Apple fan (my daughters think I'm an Apple hater), but this is way different. Victron has done something great with all their boxes able to talk to one central status / configuration device (either Cerbo GX or a Raspberry Pi running VenusOS). You really lose quite a bit by trying to avoid that based on principle.

 

[Don B. Cilly]

Just thought... if the "problem" are the holes in the bimini tubes... you can "parallel" wires.
Make more holes - at a small distance so you don't compromise the tube structurally...
-

 

[horstenegger]

I don't know anything about MasterShunt, but when I go to the web page what I see first is stuff that costs almost double what the Victron Smart Shunt costs. Anyway, your question doesn't make any sense to me. The shunt (*ANY* shunt) doesn't provide the BMS with any information. The BMS (or at least the JBD BMS) gets all its information from the battery cells.

I can't find it right now but in a different thread I read that the BMS readings are often not very precise (something about 'based on coulombs') and that placing a shunt between it provides more accurate measurements. But perhaps I read / remember it wrong. This project is so overwhelming that my recollections are a bit all over the place sometimes.

The JBD BMS's also don't normally provide any info except to your phone. There is an open source package to interface the JBD to VenusOS, but it replaces the Bluetooth interface, and VenusOS would not know what to do with 14 BMS inputs.

Our BRNKL can read out all 14 BMS inputs, so there is a way. However, I do agree with the concept that that's not a very efficient way to monitor the entire bank but rather for troubleshooting individual batteries / cells/

I am certainly not an Apple fan (my daughters think I'm an Apple hater), but this is way different. Victron has done something great with all their boxes able to talk to one central statis / configuration device (either Cerbo GX or a Raspberry Pi running VenusOS). You really lose quite a bit by trying to avoid that based on principle.

I am an Apple victim which is exactly why I've made a vow to myself that I will no more succumb to single brand ecosystems and have myself extorted into premium pricing for every single component of the eco system while it's definitely not even close to necessary. But you're right, screw it, let's go all Victron ?

Just thought... if the "problem" are the holes in the bimini tubes... you can "parallel" wires.
Make more holes - at a small distance so you don't compromise the tube structurally...

The problem is that the point where the tube meets the hull, the maximum size of that hole is limited, regardless whether single hole or multiple smaller holes.

 

[Horsefly]

I can't find it right now but in a different thread I read that the BMS readings are often not very precise (something about 'based on coulombs') and that placing a shunt between it provides more accurate measurements. But perhaps I read / remember it wrong. This project is so overwhelming that my recollections are a bit all over the place sometimes.

So the mismatch may be how you are interpreting what you saw. Most any BMS including the JBD will give you an SoC estimate, but it is more rough than what you will get form a good smart shunt. If you want a good SoC estimate, it is better to get it from a shunt-based device (battery monitor or smart shunt). But that is different than thinking the BMS will benefit from the shunt. It doesn't.

In your case it is even more benefit to have a single shunt-based SoC device: You've got 14 batteries, and 14 BMSs. So if you use the BMS SoC, you have to look at 14 of them and figure out what the overall means.

 

[horstenegger]

Thanks for the clarification @Horsefly, makes sense. I really wonder why my marine electrician was so adamant about any type of shunt being totally redundant because I already use BMS ?‍ (before anyone asks: he had to leave to Grenada for another project before he could finish our install, otherwise I would of course asked him all these questions instead of here)

Anyway, so, I'm sold. 1 BMS per batter + MasterShunt for SoC measurement it is, embedded in an all-Victron setup.
Now, how do I determine whether I need the 500, 1000 or 2000 MasterShunt for my 1400Ah house bank?

 

[Horsefly]

Anyway, so, I'm sold. 1 BMS per batter + MasterShunt for SoC measurement it is, embedded in an all-Victron setup.

Not to be pedantic, but if you are doing an all-Victron setup, you want the Victron SmartShunt, not the MasterShunt.

Now, how do I determine whether I need the 500, 1000 or 2000 MasterShunt for my 1400Ah house bank?

That's purely based on the maximum current you will have going into / out of the battery bank and through the shunt at any one time. I suspect very few DIY installations will be over 500A, but boats tend to have some pretty massive loads, like bow thrusters, windlass, and winches.

 

[horstenegger]

Not to be pedantic, but if you are doing an all-Victron setup, you want the Victron SmartShunt, not the MasterShunt.

Lol, yeah sorry, had some wines. MasterShunt SmartShunt, obviously.

That's purely based on the maximum current you will have going into / out of the battery bank and through the shunt at any one time. I suspect very few DIY installations will be over 500A, but boats tend to have some pretty massive loads, like bow thrusters, windlass, and winches.

Yup. So better go with the 1000A I presume, just to be safe?

 

[Horsefly]

Lol, yeah sorry, had some wines. MasterShunt SmartShunt, obviously.


Yup. So better go with the 1000A I presume, just to be safe?

First of all, are you actually putting all those on the house battery? My buddy (and others I've seen post here) put the bow thrusters and windlass (and maybe winches) on a separate battery bank, usually AGM since it can pump out big current without the fear of a BMS cutting out.

Second, what things may be on all at ounce, and what current? Over 500A seems unlikely, but it is up to you. Like you said, you can just to be safe go 1000A, but it is probably not needed.

 

[horstenegger]

First of all, are you actually putting all those on the house battery? My buddy (and others I've seen post here) put the bow thrusters and windlass (and maybe winches) on a separate battery bank, usually AGM since it can pump out big current without the fear of a BMS cutting out.

Yes, and there's a wonderful solution for this when powering devices like these to LFP batteries: Softstart. It's also a commonly used solution for boats with A/C for instance (which we don't have btw).

Second, what things may be on all at ounce, and what current? Over 500A seems unlikely, but it is up to you. Like you said, you can just to be safe go 1000A, but it is probably not needed.

Not sure. At this point I indeed highly doubt that we'll exceed 500A (probably the highest pulse draw for now will be the winch and/or windlass, which will be approx. 100~200A), but I can imagine we might do in the future (for example . So can it hurt to install a 1000A SmartShunt even if your draw remains well below 500A? Apart from potentially over paying for an overspec'd SmartShunt of course ?

On other note: regarding splitting up the house bank from one group of 14 batteries to 2 banks of 7 batteries - do I understand correctly that the benefit of that would be that it's easier to troubleshoot which battery (bank) has issues in case a decrease in performance is detected (assuming we have one SmartShunt on each group of 7 batteries)? Or is there another benefit as well?
And if so, would it make more sense to order 8 more cells so we can build 4 groups of 4 batteries with 4 SmartShunts?

 

[Rocketman]

I am assuming you have good spaces to fit four batteries in your boat.
Yes a 4p4s4p battery would be awesome. You would only have one Smartshunt for your whole system. (You could buy four more - one for each battery- but I am not sure if it would help much).
Also, you could go with a 3p4s4p battery and not use 8 cells right now,

For each individual battery have a class T fuse right at the battery. You will need exactly the same length of battery cables to connect to the bus bar. If you choose the Victron Power-in - look for a YouTube that shows how to add Mega fuses to it. The Mega fuse will not be that useful as a fuse the class T will be batteries primarily fuse - but if you need to take a battery out of service- you can pull the 2 fuses so the positive wire is completely dead.

Because each bms will have a 100a limit (or is it 120a?)… the system max will be 400 amps - although most people derate them a bit - 300 amps is still enough to max out a 12/3000 Multiplus. Your solar to recharge will probably be the overall limiting factor.

If you make four batteries- get the 500a Smartshunt- the bms’s on those batteries can’t deliver over 500a.

About BMS’s. I have heard many boaters go with Orion or Rec-bms because then they can have one big battery with the amps only limited by the cells. For that reason I used Batrium BMS for a single battery 2p4s w/272a cells - so a 500a battery. These are more expensive bms’s and they have Can-bus access to the Cerbo - so the bms controls charging and discharging. I like the Batrium - others won’t recommend it for a critical situations - calling it too hobby - but it works for me. (But RV’s aren’t as critical as boats).

You probably need as least four batteries to get the amps needed - eight would be even more difficult to keep them all in synchronized.

This may be a case of what fits best in the space.

 

[horstenegger]

I am assuming you have good spaces to fit four batteries in your boat.

Yup! Like I said - I could fit twice as many cells in the compartment that they're in now.

Yes a 4p4s4p battery would be awesome. You would only have one Smartshunt for your whole system. (You could buy four more - one for each battery- but I am not sure if it would help much).
Also, you could go with a 3p4s4p battery and not use 8 cells right now,

Naaah, I think I'll just order 8 more cells and go for 4p4s4p ? Although it may take a while before they arrive, so a temporary setup would be desirable at least, since we're going into the water on March 15th.

For each individual battery have a class T fuse right at the battery. You will need exactly the same length of battery cables to connect to the bus bar. If you choose the Victron Power-in - look for a YouTube that shows how to add Mega fuses to it. The Mega fuse will not be that useful as a fuse the class T will be batteries primarily fuse - but if you need to take a battery out of service- you can pull the 2 fuses so the positive wire is completely dead.

Because each bms will have a 100a limit (or is it 120a?)

150A even!

the system max will be 400 amps - although most people derate them a bit - 300 amps is still enough to max out a 12/3000 Multiplus. Your solar to recharge will probably be the overall limiting factor.

If you make four batteries- get the 500a Smartshunt- the bms’s on those batteries can’t deliver over 500a.

You mean four battery groups of 4 batteries, i.e. 16 batteries in total? Because at the moment I already have 14 batteries ?

About BMS’s. I have heard many boaters go with Orion or Rec-bms because then they can have one big battery with the amps only limited by the cells. For that reason I used Batrium BMS for a single battery 2p4s w/272a cells - so a 500a battery. These are more expensive bms’s and they have Can-bus access to the Cerbo - so the bms controls charging and discharging. I like the Batrium - others won’t recommend it for a critical situations - calling it too hobby - but it works for me. (But RV’s aren’t as critical as boats).

I refrained from REC BMS due to Will's not so great review of them. My choice of going for the Overkill / JBD BMS has the same origin (Will). I already have 14 of them, so I don't really feel like replacing them...

You probably need as least four batteries to get the amps needed - eight would be even more difficult to keep them all in synchronized.

Again - you mean 4 batteries per group (of which I would have 4 as well if I order 8 more cells), right?

 

[Rocketman]

Yes - when I was saying 4 batteries, I was meaning 4 battery groups.

It took me much longer than I thought to make my battery- hope is goes nice and quickly for you.

 

[Horsefly]

Yes, and there's a wonderful solution for this when powering devices like these to LFP batteries: Softstart. It's also a commonly used solution for boats with A/C for instance (which we don't have btw).

I'm not aware of softstart units that work on 12VDC, and I'm not aware of the loads we are talking about (bow thruster, windlass, and winches) working with 230VAC (or 240VAC over across the pond). I am new to all this boat thing, so I really don't know though. Anway, I think that solution will probably not fit.

 

[horstenegger]

You're right, they don't. The windlass and winch (we don't have bow thrusters or any other high power DC equipment) most definitely won't draw more than 100~150 amps, will never run for longer than a minute or so, and are very unlikely to be used simultaneously. So, assuming that a winch or windlass would be active at the same moment that my admiral turns on her hairdryer for instance, that's where the softitart could come in handy.

Anyway, for now I've decided to keep things simple and go with parallel connected panels and have therefore ordered the following:

1. Victron Multiplus II 12/3000/120-32 230V
2. 1X Victron 150/100 MPPT VE.Can MC4
3. 1X Victron 150/60 MPPT VE.Can MC4
4. Victron SmartShunt 1000A
5. Victron Cerbo GX (just the controller, not the touch screen)
6. I already have a master fuse and switch.
7. Missing anything? (apart from wiring of course)

@Rocketman - Sorry for my ignorance, but I'm still missing what exactly the benefit is of splitting up the 14-battery bank into 2 banks of 7 batteries. Is it because otherwise I'll have one bundle of too many amps? Is that too dangerous? Even if every battery is fused with a Class T fuse? Or is there a different reason behind this recommendation?

 

[Rocketman]

I think your later posts of 4 batteries groups is better with your choice of BMS’s. It will be easier to keep four batteries in sync and four will provide all the needed amps.