Diagram Check - before I burn down our boat ;)

[ericjanvanputten]

Hi everyone,

My first topic starter here and it's a Diagram Check request, so shoot at it/me

The wiring diagram can be seen, and zoomed into, here: https://lucid.app/lucidchart/293e52...onId=inv_6c856dcc-2da2-4f01-a8cd-446b4f2c2ddb

The project:
Renew & modernize the main electricity and batteries on our french 1992 boat...
The goal is to be able to live on it at some moment in the future, and it's the wife and I.

The question:
Do I overlook something major here that will pose a risk to comfort, or health.
I do try to do this pretty close to as best ISO (so boathowto was awesome) as possible.

Main components and ideas behind them:

• 4x EVE 280AH Lifepo4 12 volt banks (4 cells each)
• 4x BMS JBD-SP04S020 at 120amps each for combined max of 480amps
• Active balancers, not really needed but they can serve a purpose, and I will put an on/off button on these
• cables will be double isolated 70 degrees celsius, NON-tinned, but crimped everywhere

From the main battery busbar (40x10mm copper bar):

• double class t 225amp to protect the wires (also double)
• Contactor (big ass relay EV200) as last resort that can be killed by the BMV-712
  This contactor can handle 500amps cont.
• Contactor also has a manual button on it so I can kill it manually

Than we have a Load & Charge busbar:

• the chargers will be connected to this
  • MPPT 1 to start, optional to 4 MPPTs
  • a DC to DC to the engine(s)
  • initially also the wall charger (Mastervolt 12/70-3 that support lithium)
    This will later become part of the inverter if we switch to a victron multiplus 12/3000
• to the Load busbar I have put a main power switch

Than we have the load busbar:

• On the busbar several fuses, incl 2x class T 225amp's to the inverter (first a 2kva, later the multiplus 12/3000, so its prepped for that)
• The life line, the backbone that basically goes to where the current center of electra is. This one is fused at 175amp. This so I dont have to fuse every cable to the J boxes (Junction boxes) from where it goes into small fuses to all the devices.
• and several other things

What is not in here (that i'm aware off):

• that balance sheet on how much power & generation I might need.
• the 220v AC
• the solar panels that will be added
• bilgepumps go via the junction boxes, and yes I know that you can consider them directly on the main batteries, but I'm fine with having this behind a J. box.

what am I overlooking?

thank you!

edits:
26-11-2021: incorporated several feedback points from this forum into the image.

 

[jwelter99]

Fuses/breakers for each battery? If one battery/BMS has an issue you don't want them all ties together without any fuses.

MRBF fuses would work, but 4 breakers might be better as you can also use them as an isolation switch.

 

[ericjanvanputten]

Fuses/breakers for each battery? If one battery/BMS has an issue you don't want them all ties together without any fuses.

MRBF fuses would work, but 4 breakers might be better as you can also use them as an isolation switch.

MRBF fuses or circuit breakers could be a good idea, I will add it to the todo list
Thanks @jwelter99 !

 

[DJSmiley]

- I personally would skip the contactor. It's like $150 or so and the BMSses should do the same job. Also, it draws 0.13A as hold current. Although that's not much by any means, it's, imho, still approx 3.5Ah/24 hour useless energy.
Also, those contactors dont like the inrush current of a inverter, if you frequently use it, it will burn the contacts and killing it. (as some here already experienced). But for emergency-use only you can take the risk, since it's not supposed to release daily.

- Instead of 4 seperate banks, you might go for 2 banks using a 2P4S setup with a 200A BMS. Slightly cheaper, saves a little on wiring, easier (the 200A has busbars instead of soldered wires). The 200A is also available in a heated version, which has support for external heaters to allow charging below 0c once warmed. And you only have 2 BMSses to monitor/configure

- do NOT use those crap DC automatic breakers, they are junk, unless they are a genuin BlueSea or so.

- For the wall charger, especially if it's temporary untill you have a multiplus, look into Meanwell. The Meanwell PB-1000-12 is a 60A charger for approx 400 euro, the RPB-1000-12 is a 100A charger for about 500 euro. I would opt for the RPB-1000 since you have 4 sets, so 100A charging is approx 25A/bank... still takes 12 hour to full charge from empty to full.
It only has a noisy fan which will run at full blast once on temperature... but it's a whole lot smaller than the Mastervolt, cheaper and more amps.

Any specific reason not to opt for a 24V system? Assuming your biggest load is going to be the inverter that will give you half the amps, thus much easier to handle (and less issue with high currents / connections)
For 12V equipment you can use a step-down converter, generally 30A or so will be sufficient

 

[Rocketman]

I use the Eve200 contactor, the inrush can be a problem, what I did is I added a Rec-Bms pre-charge.

 

[ericjanvanputten]

I use the Eve200 contactor, the inrush can be a problem, what I did is I added a Rec-Bms pre-charge.

Thanks @Rocketman, I'm not that deep into that part yet, but for say 30 euro's I can easily add that. Do you know if that works stand-alone?

 

[ericjanvanputten]

- I personally would skip the contactor. It's like $150 or so and the BMSses should do the same job. Also, it draws 0.13A as hold current. Although that's not much by any means, it's, imho, still approx 3.5Ah/24 hour useless energy.
Also, those contactors dont like the inrush current of a inverter, if you frequently use it, it will burn the contacts and killing it. (as some here already experienced). But for emergency-use only you can take the risk, since it's not supposed to release daily.

- Instead of 4 seperate banks, you might go for 2 banks using a 2P4S setup with a 200A BMS. Slightly cheaper, saves a little on wiring, easier (the 200A has busbars instead of soldered wires). The 200A is also available in a heated version, which has support for external heaters to allow charging below 0c once warmed. And you only have 2 BMSses to monitor/configure

- do NOT use those crap DC automatic breakers, they are junk, unless they are a genuin BlueSea or so.

- For the wall charger, especially if it's temporary untill you have a multiplus, look into Meanwell. The Meanwell PB-1000-12 is a 60A charger for approx 400 euro, the RPB-1000-12 is a 100A charger for about 500 euro. I would opt for the RPB-1000 since you have 4 sets, so 100A charging is approx 25A/bank... still takes 12 hour to full charge from empty to full.
It only has a noisy fan which will run at full blast once on temperature... but it's a whole lot smaller than the Mastervolt, cheaper and more amps.

Any specific reason not to opt for a 24V system? Assuming your biggest load is going to be the inverter that will give you half the amps, thus much easier to handle (and less issue with high currents / connections)
For 12V equipment you can use a step-down converter, generally 30A or so will be sufficient

Great, complete, answer and feedback @DJSmiley - thank you!

• Contactor - It's a last line of resort kinda thing and probably will cause more issues than it will help so I might consider removing it, but for a 250,- euro* having an additional (next to the BMSs) last line of protection is kinda nice
  *If I need to add a pre-charge as well
  
  And just in case I will probably prep a wire/something to bypass this completely if it's getting annoying
  
  
• 4 -> 2 banks - I had considered that as one of the options (also considered 1 bank, but wanted redundancy). I eventually went with the idea of 4 banks so I could use the JBD-SP040S020 BMS which seems to be good (also the overkill model basically)
  
  
• wallcharger - looks like a cool model, but I currently already have the Mastervolt 12/70-3 so that would be my temporary version.
  
  
• 12 / 24 volt - Never really even considered it, but I have several heavy users on 12 volt like 2 winches & 1 windlass. And it feels a bit overcomplicating it with another device. The counter version is just to use (way) thicker wire.
  Overall the 12 volt base is very probably more expensive (thicker wires, more MPPTs needed, more expensive inverter, etc) but it does feel more fool proof*
  *which I might be undoing already with the contactor part, the double cables, the appr. 600 fuses

It's the beautify and downfall of electrical stuff, there are so many ways of approaching it.

I would like again to thank you for the thorough answer!

 

[Bud Martin]

I would put small in-line fuse on the small positive wire feeding the shunt monitor electronics.

 

[ericjanvanputten]

I would put small in-line fuse on the small positive wire feeding the shunt monitor electronics.

Sounds cheap and smart - good point!

 

[DJSmiley]

Makes sense to use the Mastervolt if you already have that one
Just make sure you can configure it, many vendors require additional cables for configuring (eg Masterbus-USB for some Mastervolt devices, SBP-001 for Meanwell or MK3-USB for Victron)

As for the BMS: The 120A JBD is indeed identical to the Overkill one.
The 200A versions are their bigger brother, and just recently (somewhere in may) released. But basicly they all are identical. The 200A has 1 small benefit over the 120A version: It has 150mA balance current (compared to 50mA for the 120A versions). And it's cheaper to get 1 (or 2) 200A ones than 2 (or 4) 120A versions. Also, i like the external busbar above the short wires (Default the wires are short - Overkill provides longer leads, or you have to solder yourself). But the Overkill price + shipping + taxes doesn't make it an interesting option for EU imho. I usually order them from lithiumbatterypcb and receive them in 2-3 weeks on average (to NL). Disavantage is they don't offer customizing as Overkill does (Eg the longer wires)

 

[ericjanvanputten]

Based on feedback from @Rocketman and additional input from another subpost in this forum, I have adjusted that:
- added a Rec BMS pre-charge
- the BMV-712 will with its relay talk to the pre-charge
- the pre-charge will switch the contactor & do its pre-charge thingy

Good or bad adjustment?

 

[jwelter99]

View attachment 73945

Based on feedback from @Rocketman and additional input from another subpost in this forum, I have adjusted that:
- added a Rec BMS pre-charge
- the BMV-712 will with its relay talk to the pre-charge
- the pre-charge will switch the contactor & do its pre-charge thingy

Good or bad adjustment?

Ask yourself what is the BMV-712 role to play in the overall system and is it the best device for that role?

You maybe surprised as I suspect it is just a capacity meter and therefore the entire contactor is pointless; as any battery faults will be handled by the BMS in the batteries before the bus; or the fuses I pointed out to add between battery and bus. Not sure the BMV could ever see a situation that would require it to open the circuit, or close the circuit.

 

[Rocketman]

You have some pretty heavy draws on your system. Will the bms’s you have choose be able to power those loads?

Usually the contactor is being driven by the bms - not as an extra step above it.

Also make sure you understand the Victron assistants programming - to verify it will operate as you expect it to.

I think if you keep the contactor you need to keep some kind of pre-charge - a precharge is cheaper than a replacement contactor.

Good luck!

 

[ericjanvanputten]

@jwelter99 - I will add the battery fuses, great input!
The idea of the contactor is a last line of defense kinda thing, so if voltage drops or gets to high, it kills everything. Last defense to protect the batteries, something the JBD BMS's should do as well. So maybe it is overkill to do the contactor thing.

@Rocketman - 4x 120amp JBD BMS's adding up to 480amp. Which we will almost never see (I hope), but we can if needed
The BMS can't drive the contactor (that I know), so that is why the Victron just on voltage is a nice last resort thing.

But I'm heavily starting to doubt the contactor thanks to input from you guys on this forum, and why:

• creating extra points of failures (pre-charge & contactor)
• extra costs

that might not weigh up to the benefits, certainly not if the BMS's will take care of business.

 

[jwelter99]

@jwelter99 - I will add the battery fuses, great input!
The idea of the contactor is a last line of defense kinda thing, so if voltage drops or gets to high, it kills everything. Last defense to protect the batteries, something the JBD BMS's should do as well. So maybe it is overkill to do the contactor thing.

@Rocketman - 4x 120amp JBD BMS's adding up to 480amp. Which we will almost never see (I hope), but we can if needed
The BMS can't drive the contactor (that I know), so that is why the Victron just on voltage is a nice last resort thing.

But I'm heavily starting to doubt the contactor thanks to input from you guys on this forum, and why:

• creating extra points of failures (pre-charge & contactor)
• extra costs

that might not weigh up to the benefits, certainly not if the BMS's will take care of business.

Consider a contactor a "wear" item. They are only good for so many cycles when under load. You can extend this life with pre-charges and such but it is still a mechanical device in the middle of your system that can fail so if not required why is it there?

I would trust the BMS to manage the batteries. The only nice to have would be an emergency cutoff for the entire system - you could move the battery cutoff you have in the drawing to where the contactor is; and then off the bus on that protected side all your other stuff.

 

[ericjanvanputten]

Consider a contactor a "wear" item. They are only good for so many cycles when under load. You can extend this life with pre-charges and such but it is still a mechanical device in the middle of your system that can fail so if not required why is it there?

I would trust the BMS to manage the batteries. The only nice to have would be an emergency cutoff for the entire system - you could move the battery cutoff you have in the drawing to where the contactor is; and then off the bus on that protected side all your other stuff.

Well the idea is that the contactor is the emergency cutoff, and doesnt do that many cycles (if a cycle is open/close, the idea is that its almost always closed (letting current through)).

But by the sound of it it continuous to feel that it adds more risk than that it is suppose to reduce