Critique my LiFePo4 Plan!

[nebster]

Originally Posted by s/v Jedi

I have so many plans, like for smart breakerpanels etc. that my mind is blown a couple of times a day as I realize more possibilities opening up

Okay, keep us up to date with your implementation(s)!

[Oceanride007]

Regarding the Zeva product mentioned above. Had some correspondence.


Quote

"We don’t have many great options for 12V (4-cell) packs - most of our products are designed for higher voltage! If simple under-and over-voltage protection is sufficient, the 8-cell battery monitors can be used with 4 cells. The module is used to switch larger power relays for managing loads and charging sources, to isolate the battery when protection is needed.

The more advanced but more expensive option would be one 12-cell BMS module (can work with 4 cells) connected to an EVMS as the master controller, and optionalls an EVMS Monitor for viewing data/doing setup and a CAN current sensor for state of charge calculation etc. The economics aren’t great for 4-cell packs but can be justifiable with large packs, if the other functionality offered by the EVMS is useful. Further information about both options is up on the website.


If you need to use multiple packs of smaller cells, in most cases it’s best to connect cells in parallel so they can be treated like single larger cells (as far as the BMS etc is concerned). Multiple packs in parallel require multiple BMS modules, which does work fine but gets more expensive. Example picture attached showing the difference between parallel cells vs parallel strings to help clarify (only an example - it’s fewer cells than your application). Note that both the 8-cell monitors and the 12-cell BMS modules only work with a single string of cells in series, i.e you can’t use one module to manage two 4-cell packs in parallel, because in the middle there’s a big negative voltage where it swaps to the other pack"



Zero Emission Vehicles Australia
http://www.zeva.com.au

[Oceanride007]

Regarding ^^^^.
If using parallel Cells and only one BMS would think BMS may not be able to detect a low or high cell.

[nebster]

Originally Posted by Oceanride007

Regarding the Zeva product mentioned above. Had some correspondence.

Yeah, while I like Zeva stuff for larger batteries, there are tons of inexpensive 4s BMSes available. It's the*larger BMSes that are harder to source affordably.

[witzgall]

I have installed and am evaluating the ZEVA for my LTO battery system. I originally selected them as the offerings that could work with my setup were limited, and theis seemed to be w ell thought out and reasonably priced system.

My experience thus far with the company has been positive. I originally bought the version2 evms and cell modules. Before I installed (Months had passed) the EVMS v3 was introduced. I was very interested in the change that allowed balancing throughout the voltage range. I sent them back to EVMS, and he upgraded my modules, monitor and swapped out the v3 evms for a very reasonable fee. They have been good with email support from Aus to USA.

My config is 5, 10-cell Lithium Titanate modules. So I have 5 12-cell modules. The monitor shows all 50 cells.

Right now with the boat on the hard, I only have the EVMS wired up to stop charging of my Victron 24/300 through a relay, which works fine. Since they sat and were not balanced for two years, I am currently using the dynamic balancing to slowly bring the cells back to the same voltage. It is working, but slowly - I expected that and actually prefer it. I have a battery module that may be bad (low cell), so once they are all brought to the same voltage I can test.

Chris

[oneeyedjackass]

Originally Posted by Mabruteam

Simple, charge your lithium bank with the inverter and solar panels, feed your house, install a secondary charger to charge your Lithium house, and your Two Engine and windlass AGM , the one on the pictures will do both, then install an isolator one alternator 3 banks, this way it will charge you 3 banks, the house lithium will not be charged all the way up to 87% but will not damage them, the secondary charger will bring them at 100% on shore powers, or with your solar lithium controller

This is interesting but I'm having a hard time understanding. Do you have a diagram you could post up?

[Qismat]

Okay, I'm back with an updated plan.

-I've removed the relays i chose, and am looking for recommendations for the LVC and HVC relays

- I've upgraded to an REC BMS with Victron compatability. I'm looking into adding the Venus GX to the system - I'm not sure how much benefit it would provide me seeing that the I/C is a Xantrex and wont connect.

-I've changed the start battery setup.

-I've added fuses - Ignore the ANL fuses, i just used them as I had the images.

What I'm wondering is:

-With the REC BMS - How many Disconnects can I control?
-Can I use a Venus GX to control the MPPT controller?
-Can I use an output on the BMV 712 to control a relay for the whole system or am I better off using the REC?
-Do i need a sterling Aternator protection device? I think I do as the charge bus can be cut off from the batteries by the relay and/or the main bus battery switch. It seems theres nowhere to go for a load dump. Please confirm?


Thanks,

[mbartosch]

B2B Charger input should go on house load bus.
A proper answer to the question regarding alternator protection as a proper answer has been posted several times on this thread, so I won’t repeat that.
NOI, but some of your questions indicate that you still have some basics to learn. There is nothing wrong with that, and, really, no offense intended. But are you really confident in designing and implementing your own electric system which has the capability to burn your boat down if done incorrectly?

[Steve_C]

It would appear that the inverter has a direct path back to the bank with no contactor or way for the system to disconnect it.

I am becoming uncomfortable giving advice on this because it's a very complex system and you are missing a lot of basic things.

Also, spending time creating a clear and easy to read wiring plan is a lot easier than actually building the system. If you are having difficulty with the first, maybe you need to not undertake the second without involving someone with more electrical experience.

I don't mean to sound harsh, but there are a LOT of details that could be dangerous with a system like this.

Please make sure that you have someone with training and experience helping you.

[Qismat]

Originally Posted by mbartosch

B2B Charger input should go on house load bus.
A proper answer to the question regarding alternator protection as a proper answer has been posted several times on this thread, so I won’t repeat that.
NOI, but some of your questions indicate that you still have some basics to learn. There is nothing wrong with that, and, really, no offense intended. But are you really confident in designing and implementing your own electric system which has the capability to burn your boat down if done incorrectly?

No offense taken. That's why I'm here to ask questions and learn well before starting this project. My aim is to have everything planned out so that I can build upon that plan.

I've done loads of 12v wiring including rewiring an entire custom car, and this is my first large project on a boat electrical system. Hence all The questions as an intent to learn.

Regarding the apd - it looks like the answer is yes, but that's why I'm asking. I'd rather ask twice and be confident in my results than to do my own research down a rabbit hole and end up with the wrong result.

My goal of this thread was to have you all rip this apart and tell me what I'm doing wrong.

To calm your nerves, I will not be even starting this until I'm entirely confident in the plan.

[Qismat]

Originally Posted by Steve_C

It would appear that the inverter has a direct path back to the bank with no contactor or way for the system to disconnect it.

I am becoming uncomfortable giving advice on this because it's a very complex system and you are missing a lot of basic things.

Also, spending time creating a clear and easy to read wiring plan is a lot easier than actually building the system. If you are having difficulty with the first, maybe you need to not undertake the second without involving someone with more electrical experience.

I don't mean to sound harsh, but there are a LOT of details that could be dangerous with a system like this.

Please make sure that you have someone with training and experience helping you.

I'm not an engineer, or a software developer, or even a computer expert. I don't have the software to create a ridiculous looking plan like some of you do online. I have drawn everything out on paper as it should be but I'm not going to scan paper onto the computer.

Regarding the inverter - there is an on/off switch in line from the batteries to the inverter. The inverter/charger also contains a system control panel with an on/off switch that can be shut down.

One of my questions was should I have a disconnect in between that shuts down from the rec bms?

[mdenize]

Originally Posted by Qismat

I'm not an engineer, or a software developer, or even a computer expert. I don't have the software to create a ridiculous looking plan like some of you do online. I have drawn everything out on paper as it should be but I'm not going to scan paper onto the computer.

Regarding the inverter - there is an on/off switch in line from the batteries to the inverter. The inverter/charger also contains a system control panel with an on/off switch that can be shut down.

One of my questions was should I have a disconnect in between that shuts down from the rec bms?

Yeah I hear you...I am some of those things and I refuse to pay for endless software that does not do as well as a pen and paper (except being able to virtually move things around) but in reality I think you use less paper without the computer and the paper circuit diagram is alot less complicated.

The answer to your question is really how much the BMS draws and how long you leave the system sitting idle. Some BMS systems draw alot more than the natural loss of charge of the cells so it is better to just turn the BMS off rather than have it deplete the battery it is trying to protect,

Of course if the solar will replace all of that energy it is better to leave it on so it can do its job of protecting the battery. Mine has quite an inrush current too so a switch is better than the spark created when you connect it up. (but of course you wont have any fuel vapour on the boat will you...

[Steve_C]

Originally Posted by Qismat

I'm not an engineer, or a software developer, or even a computer expert. I don't have the software to create a ridiculous looking plan like some of you do online. I have drawn everything out on paper as it should be but I'm not going to scan paper onto the computer.

Regarding the inverter - there is an on/off switch in line from the batteries to the inverter. The inverter/charger also contains a system control panel with an on/off switch that can be shut down.

One of my questions was should I have a disconnect in between that shuts down from the rec bms?

Nothing at all wrong with a hand-drawn schematic. A lot of mine are drawn on paper first and then I use Paint or PowerPoint to make a nicer version. You are clearly using something similar to create what you posted. I would rather see a picture of a CLEAR hand-drawn version than a confusing digital one.

Even a hand-drawn version on paper needs to be clear and easy to read. While it makes total sense to you, the way you show some things is not clear . You need to assume anyone you are asking advice from is looking at this for the first time and has no clue about your assumptions. For instance in some spots you show a symbol of a device, but in others you simply show a line intersecting another line with some text. Is this a spot where a HVC will go? I have to assume so. I just believe you might get more input if you went to a little more trouble with your plan. To date you have not gotten a lot of feedback from many others.

You definitely need some form of automated disconnect between the inverter and the Bank, At least I would consider it mandatory. Ideally the inverter (or any other source) would be controlled (By the BMS or perhaps the Victron) before voltage could get too high, but I would ALWAYS want the system to be able to be able to disconnect just in case the normal control was not stopping the input.

I'm glad you have done a lot of wiring in the past, but this is a much more ambitious project and when you start working with really large loads its a much more potentially dangerous undertaking. At the very least you could damage or ruin a lot of very expensive stuff, and of course it could be a lot worse than that. From the way you bolt bus bars together, to how you treat dissimilar metals, to the types of fuses you use and what device controls what it can very confusing for anyone. Lots of opportunities for un-foreseen issues.

Keep up the questions and please consider all of this just constructive feedback.

[mbartosch]

Originally Posted by Qismat

Regarding the apd - it looks like the answer is yes, but that's why I'm asking.

There were at least four answers to this question on this thread, including the two possible technical solutions:

post3065875

post3067344

post3067725

post3067783 (list item 5)