HELP! - Newbie to BMS. installation on a boat. 8S 4P/8P 800AH 24Vdc

[Guy Odell]

I hope someone can guide me here. At present there are no solar panels involved. The supply is either shore power or generator into parallel Old generation Victron Pheonix Multiplus 3000/24/70 inverter chargers configured in parallel. This would be used to charge the house battery bank.

I have 64 x 3.2V 100AH cells. I need to configure them to deliver 24Vdc. I believe that the best configuration will be to mount the cells in a set of 8 in series for bank 1 and repeat up to bank 8 or alternatively configure with Bank 1 being 16 cells to make each bank 24v at 200AH by series and parallel connection to make 4 banks of 24v 200AH. The end of the day an output of 24Vdc 800AH.

Ok next comes the bit i am stuck on. Battery management side. I think the electrodacus system would be a good solution but I do not understand how i should connect the electrodacus units to the 4 or 8 bank of 24v batteries.  How many do I need? Is the Electrodacus able to deal with the array i am configuring? Should i buy one and will it do everything or do i need more?

Can anyone help or advise the solution on employing the right type of BMS system. Is the Electrodacus solution the correct way to go. If so how should i configure or set it up.

Regards

Guy

[Paul Barrette]

If you have four 24v banks you will need 4 BMS's

If you have eight 24v banks, you will need 8 BMS's

You need to have 1 BMS per bank so that it can balance the cells in the bank it is connected to... BMS's cannot balance cells between different banks.

Another option you can look into is to create one single 24v bank with all 64 cells.... 8 cells in parallel and 8 in series.

[Guy Odell]

Dear Paul,

Thank you for coming back so fast. I note your suggestion about building one 64 cell bank. If i do that is there any fault tolerance if one cell goes down. Would the whole thing shut down then?

Sorry not an expert in this. learning fast

[Guy Odell]

While I am thinking about this. what electrodacus units should i buy for the 64 cell version you mentioned or the 4 x bms version. I see there are a few variants.

[Paul Barrette]

If you loose an entire cell.. the BMS will definitely shut everything down since it will not detect the minimum voltage you require to have in a cell and yes in the case of a single battery... you will lose all power.

For the BMS model., it depend if you wan the current to pass through the BMS or not. The SBMS40 can support a load of 48A and the SBMS120...144A but you can remotely control external devices. The SBMS0 can only remotely control devices and no current passes through it... see the documentation

The SBMS0 is a very popular choice.

[Dacian Todea]

Guy,

The only correct version to make a single 24V battery from your 64 cells is to have groups of 8 parallel cells (parallel means all positive terminal from all 8 cells connected together same for negative) and this groups will be in no way diffrent from a single 800Ah cell then 8 of this groups will be connected in series for 24V

You only need a single SBMS0 to manage and control the battery.

Bellow is a similar installation just those are 300Ah cells and groups of 3 in parallel so this is a 24V 900Ah battery pack controlled by a single SBMS and then he has 3 parallel 3000VA Victron inverters also controlled by the SBMS.

[Dacian Todea]

Guy,

You need to post on the forum and con not use replay button in email.

You mentioned that there will be no solar panels thus you do not need the DSSR20 or DEXT16 only the SBMS0 and eventually the WiFi/USB addon.

As you see in the photo I posted above cells are connected with copper bus bars so there are no cables between cells.

Here is a 4s4p battery as another example your will just be 8s8p so quite a bit larger but can be connected in same way

[Guy Odell]

Dacian

Regarding fault tolerance. I need to have some protection so that the array will keep running if one cell in the array fails. Will the sbsm0 be able to handle that and keep the rest of the cells operating although 100ah down.  Is this a challenge that would require a change in the array design. which i have just measured up and does fit in the original space onboard.

Rgds

Guy

[Dacian Todea]

Guy,

It is extremely unlikely for any cell to fail but say one of the cells has high self discharge due to some internal dendrite short then the group of 8 cells contain that self discharging cell will drop in voltage while not charging and it that becomes significant you can just identify the cell with the problem and remove from the circuit and as a result you capacity will be reduced to 700Ah

My own battery is made of 80 cell 8s10p and is already 4 years old with almost like new condition even with heavy usage every day powering my house.

[Dave McCampbell]

Guy.  I also have a LiFePO4 lithium house bank on a cruising boat.  I tried two parallel batteries using 8 272ahr DIY cells configuration early on.  It is a nightmare to wire all the relays and other things you will need to properly protect and monitor even my two sets of 4 cells, 540ahrs.  And then there is the significant additional expense for multiple BMSs and other components.  Dacian can explain this to you in much more detail if needed.  We are now configured 4 sets of 2 parallel cells in series or 4S2P.  Only one BMS and much easier system wiring.  For monitoring 32 individual cells, there are many small inexpensive monitors available that can let you see each cell if you want that level of detail.  Some can be displayed on a computer/cell phone/etc via blue tooth/wifi.  We are using a very detailed display with Node Red to our remote computer via wifi to monitor our daily cell status.  If anything happens to even one cell we will be able to see it immediately.  There will be much more on this on Oberon's Beginners' Guide and elsewhere soon.  We think the Electrodacus system is the the best reasonably priced way to safely handle a lithium system  on a boat.

[Guy Odell]

Dear David & Dacian.

Thank you for reaching out. Yes i need the detail. if I understand Dacian correctly, he is proposing an 8S8P configuration for my 800AH 24Vdc system. 

Also the only one BMS to monitor all the cells entire battery bank. this is using his SBMS0 which i don't fully understand how it works yet. 

Assuming my understanding is correct I now need a list of equipment that i need to purchase to complete the system. 

Dacian if you can help on this i would appreciate. I am sure it is not just the SMBMS0 + wifi :) .

Currently we have the following already installed in the existing system

2 x Victron Pheonix Multiplus 24/3000/70 inverter chargers. Old but reliable type.

1 x Shore supply wth dual input isolation transformer

1 x HFL Ranger 1 230Vac, 104A, 24kVA 19.2kW generator

1 x 24v Balmar high capacity Alternator and Balmar management regulator

So this all comes into the inverter charger system and connects to the battery bank with two humungous wires to the existing lead acid 1250AH 24V house system. 10 x 72kg batteries. Heavy to say the least.

At present all i know is how to connect the batteries together and that i can use the electroducas sbms0 and wifi pack to manage it. But i need the gaps to be filled in. I feel i am missing out on some critical understandings

Do you have a link for Oberon's guide?

Thanks again for reaching out. any help and guidance is greatly appreciated. i have just a couple of weeks to sort all this out.

[Dacian Todea]

Guy and David,

What you need to understand is that parallel cells are in absolutely no way different from a single higher capacity cell.  All parallel cells have no choice but to have the exact same voltage so all cells are monitored as they do act as a single cell (exactly like a large single cell and in no way different).

To make things even more clear here is a cutout of a small Winston LiFePO4 cell and a look inside. Notice as it looks like two parallel cells connected on each side of the terminal but you can also count each plate as a different cell and then you can say this is actually made of 30 or so parallel cells. And this is probably a 100Ah cell or maybe 160Ah cell but Winston sells 400 or even 1000Ah cells. Point is that parallel cells are in no way different from a single larger capacity cell.

[Guy Odell]

Hi Dacian,

Ok i have got it. Finally. It makes a lot of logical sense and also dispels a lot of the panic that seems to be put out. So now I need to order stuff from you is there any way you can advise about what i need to do to put the SMS0 system into my existing system. with the wifi module. I am looking for the victron manual because i am not sure how the sbms0 will relate with the victron units ir they have to at all. Still confused about this bit too since again reading through the forums i see so much confusing info.

Can i also thank you for your guidance so far.

Br

Guy

[Dacian Todea]

Guy,

This is the document that describes how Victron Multiplus will need to be setup to be controlled by an external BMS including the SBMS0 that is compatible with that https://www.victronenergy.com/upload/documents/Manual-Connecting-other-lithium-battery-systems-to-Multis-and-Quattros-EN.pdf

All settings as shown in that example except for last two where you will select Disable charger.

[Guy Odell]

Ok thanks Dacian, the reading resumes heh heh. My system is the old system so fingers crossed. I keep reading about shunts being needed. Where do i use those?

All the best

Guy

[Dacian Todea]

Guy,

Shunts are nothing more than a power resistor. The SBMS0 will measure the voltage drop across the shunts and be able to calculate the current based on that.

See SBMS0 manual for where the shunts need to be installed and see this tread for discussions about current shunts https://groups.google.com/g/electrodacus/c/ReL-z6vGFdw/m/vsmKm0grAQAJ

[Oberon Robinson]

Guy, here is a link to the Beginner's Guide: https://groups.google.com/g/electrodacus/c/T7F0HvW-kfA/m/To-vuq-HBgAJ

Latest version is 0.5, I am working on an update that will include control of Victron components and have a section on mobile considerations.

[Guy Odell]

Awesome, Oberon, thank you. I have just read through the victron document that Dacian sent through for me. Trouble is that my victron system is the old Phoenix multiplus inverter charger and it only works with the older version of software controller. Victon said their solution to the firmware upgrade was to buy two new charger/inverters!!!!  Now that is tech support heh heh....

Anyway the journey is progressing so thank you again for the link will dive in now.

All the best
Still looking for the answers.

Guy

[Dave McCampbell]

Guy.  Earlier you said that you only have a couple of weeks to put this all together.  Is that really true?  What are your future cruising plans, and why have you decided to install lithium batteries at this time?  Most cruisers in the tropics for good reason primarily use solar for daily charging.  Is there a reason you are not doing that?  Are you sure you want to take this on now with only a couple of weeks to do it?  There are other good boat battery solutions that would be much quicker to install with the equipment you have.  This is especially true if you are planning coastal cruising for the next few years. 

Lithium is a very complicated undertaking that takes considerable time and effort to get right.  There is much conflicting information available on lithium batteries that you need to sort out for your installation before you start building your own system.  Some solutions are better than others, and it will take you time to find those.  It has taken me almost a year to feel fairly comfortable with the terminology and rational for how things should be done for a reliable and safe installation.  I am very familiar with lead acid battery technology, but am still reading and learning new things every day about lithium.   

If you have settled on a lithium system and the SBMS0 for your BMS, I recommend you start by looking at a few of the UTube videos on Electrodacus.  Just Google UTube/Electrodacus SBMS0.  Those will give you a quick one day overview, but certainly won't cover all you need to know.  Then you should thoroughly read Dacian's SBMS0 and DSSR20 manuals a couple of times.  Then study Oberon's Beginners' Guide and the references at the end.  Once you have done that you should be familiar enough with how the equipment goes together to get started making an equipment list and placing orders.  There will still be some things you don't fully understand, and equipment decisions to make, so that is the time to ask questions on this forum. 

I will be doing a guide for our website on how I did our installation on our catamaran soon.  But it won't cover all the options, and I am not using Victron equipment.  You could also find additional suggestions as to how others have done their installations by looking at some of the wiring schematics and other information posted on this forum.  If you want to do this right, and that is very important on a cruising boat, there are no shortcuts.  I found the learning curve to be very steep and time consuming, but also very worthwhile for us full time cruising.  Dave

[Guy Odell]

Hi David, Oberon, Dacian,

Ok the acquisition of things progressing for my SY Miss Elle LiFePO4 project.  I need your advice and guidance again.  I have a, What must i buy, What spec and how to question regarding the protection of the house battery bank charging alternator. 

The alternator is a 130A 24V Balmar unit controlled by an older generation Balmar 624 regulator. 

I have contacted Balmar regarding the way to program the regulator for charging the LiFeP04 800AH bank and they have provided an idiot sheet in this regard. thank you Balmar. 

I understand that the ignition line from the ignition key (load) to the regulator must have a relay in line that is normally closed to turn off charging control when the SBSM0 senses that the batteries are full. This relay control has to be connected to the sbsm0.

 

What I do not know is what sort of current rating the relay should be to break the connection in the regulator ignition line and how i should connect this to the sbsm0 via the relay and exactly what type/model of relay i need to buy and should I to take power from the house bank to power a relay hence again what type or model relay i need to buy. I am concerned about ordering the incorrect item since it typically takes a couple of weeks to get anything here.

Thanks for your patience and help in advance.

Guy

[Guy Odell]

ok guys i also have another question in relation to how to connect my legacy (coz its old) Phoenix Multiplus inverter charger 3000/24/70 to the SBMS0 so that it can do its magic.

Attached is the front panel image of a similar multiplus to mine. Also an image of the connectors that are referred to as H in the victron diagram. The final image showing the location of connection H and a description of its operation.

So reading about connection H it is a three connector link that depending on how the terminals are linked controls what the system does. Now this is an old multiplus so i do not have the aux 1 and aux 2 assistant facility the firm ware it too old and cannot be updated. So now i need to know how i can connect my soon to arrive SBSM0 to my multiplus so that it can control the multiplus.  I need the inverter to be running while the charger is either on or off. I am worried about the overcharging of the cells. Earlier I posted a query about the Alternator that i know you guys will be able to advise on but bolstered with confidence i am also asking for a solution to this. 

I need to have power via the battery bank and inverter regardless of whether the unit is charging via generator, shore power or main engine alternator but at the same time i don't want to overcharge anything or for that matter allow the batteries to get to minimum charge level. Given this how can i connect my pair of multipluses to my SBSM0 so that it can do its magic

BR

Guy

[Dacian Todea]

Guy,

Is this alternator specific just for charging the LiFePO4 battery ? Or is there some starter Lead Acid that is also charge from this alternator?

You will need to check that charging will stop completely when the ignition signal is removed (0V) and then you will also need to measure how much current passes through the ignition wire if you can not get this info from Balmar then you will know what sort of ideally SSR you can connect there and that will need to be normal open SSR.

Not sure if that inverter you have has the Assistant so it may not be usable as inverter/charger with the LiFePO4. It can be used as an inverter only or as a charger only bot not both.

[Guy Odell]

Hi Dacian,

The alternator is dedicated supply into the old victron phoenix multipluses and then into the battery bank.  There is a separate alternator for the starting circuit of the engine.

Balmar have come back to me on that question. The ignition line is simply a signal line to the regulator

"It is just a signal to the processor, about 10 to 15 milliamp. A relay that can handle 10 to 18 volts at 1 amp would be more than adequate for the job."

So on that basis what do you suggest as a solution.

Ref inverter need to find a solution to that that does not break the bank. ouch

BR

Guy

[Dacian Todea]

Guy

You do not need a relay if it is just 10 to 15mA as that can be handled directly from one of the SBMS0 EXT IOx or you can use any external optoisolator. A relay even a small one will be to wasteful.

[Guy Odell]

Ok great. I will test the current directly before hand before hooking it up to the SMBS0. I figure it should be arriving soon??

I need a solution for the inverter chargers though. Any magical ideas???

[Dacian Todea]

You will connect ignition to a 1KOhm 1W resistor then the other side of the resistor to EXT IOx+ and then the EXT IOx- will be connected to Balmar ignition connector.

The EXT IOx will be protected by the 1KOhm resistor even if current is much higher than what they mentioned 10 to 15mA

[Guy Odell]

ok got it will order a resistor now

[Guy Odell]

Hi Dacian,

Just to let you know that the SBSMO arrived today. Thank you. But, still waiting for cells to arrive.

All the best

Guy

[Dacian Todea]

Guy,

Glad to hear. It seems shipping times may start to improve.

[Guy Odell]

Hi Dacian,

Long time no speak. Still waiting for the batteries to arrive.  Quick question. for the battery sense cabling from the SBSM0 to the batteries. The ribbon cable is way too short for me.  If i solder some solid cat7 cable to the existing ends can i extend the cables about 3 metres to get to the batteries? When they arrive!

Best regards

Guy

[Dacian Todea]

Guy,

Why are the batteries so far from the SBMS0 ?
All other connections like current shunts and remote ON/OFF will need to be close to both batteries and SBMS0 so is best if the SBMS0 is within 1.8m or less that is why I ofer the max ribbon cable of 1.8m

If you really need to extend to 3m then is possible but you will need to make the ribbon cable much shorter say 20cm and then continue with thicker cables. Not sure if that solid CAT 7 is 22AWG or it is less as there are many versions.

If is 22 AWG then you can go up to 5m total if is 24AWG max will be 3m that is with the ribbon cable cut to just 20cm

[Guy Odell]

Hi Dacian,

Answer to query one. Not sure if you recall but my installation is on a 70ft steel sailing yacht. The batteries are below deck and in a secured bulkhead area the electrical control panel for the vessel is above it but the route is via two bulkheads. So I have no way of being able to see the SBMSO and configure and control the unit without having to lift up floor panels if installed within and down below. I can install the shunt etc down with the batteries though although the actual ships main DC Junction box is about 5 metres away which actually would be the best place for installing the shunt and breaker and the battery protect. Also i have to run the ignition line loop to the sbms0 which is at the main electrical control panel.

I don't know if this is a valid idea but in terms of interfacing protocol. Most yachts and boats use a communication protocol NMEA2000. This basically deals with all the nav sensors and plotters and radar comms etc. But also it has the capacity to monitor batteries etc and i was wondering if you would consider exploring incorporating NMEA2000.

Ok so  ribbon shortened to 20cm soldered joints with heat shrink etc.

The Cat7 is actually 24AWG. So i have a 3m max total. 

Best Regards 

Guy

[Barry Timm]

Would it not be best in this situation to keep the SBMS and shunts etc at the batteries, and have a remote meter for your battery SOC/PV/Loads etc? In my experience, living full time in our RV, I only glance at the SBMS display once or twice a day to see the battery SOC% and Charge status. I have literally not needed to touch anything on the SBMS0 system since installation, and it works perfectly with no "handholding" required, provided you have the loads and charging functions setup correctly. I think a remote meter might be best for you to just keep an eye on the status.

[Dave McCampbell]

Hi Guy.  Good to hear you are making progress.  I agree with Barry.  There are many options for remote monitoring at your nav station or on your computer/pad/phone.  See my post to you above of 9 April.  We like the Wifi option with Node Red, but also use the Electrodacus link.   These can be monitored worldwide which is a big help when we are off the boat.  I believe the NMEA 2000 is mainly a boating protocol, so not much use for RV and OffGrid applications.  Dave