I asked then If I can put in parallel Liontron 40Ah with Liontron 80Ah, below their answer:
So, about my Victron SuperPack LiFePo4 to be put in parallel with my future LiTime 230Ah (200A BMS) I am afraid I'll have troubles.
Hooking dissimilar batteries together _can_ be done, but is seldom the best idea. They will have different internal resistances so will charge and discharge at different rates. Starting at 100% on both as the smaller discharges it will start pulling current from the larger one then eventually you will bottom both out. But that constant pulling and pushing of energy will have a certain percentage of waste.
Far better to get two or more identical batteries and parallel them.
Mixing different BMS that have different current limits really becomes an issue which is what Liontron was trying to say.
Why do I need smartshunt? Why I cannot let the BMS to cutoff when battery is almost empty? My inverter also has such feature.
A smart shunt you can calibrate it - i.e when you are at 100% you set it to 100% and it tracks from there on out because it has every joule of energy going through it. The inverter only indicates what happened through the inverter. It will be in the ballpark, but needs to be checked more frequently. And if you have ANY separate input or output energy that happens direct to/from the batteries the inverter can't keep track of that.
In your design the SCC and inverter are separate units - so you won't be close to accurate at any point. The shunt goes right next to the negative terminal of the battery, from there a bus bar to hook everything else to.
About wire to MMPT protection, this would be the case of short circuit inside the battery? or inside the inverter?
Why do I need circuit breaker and not another 50A fuse?
In case my appliances consumption will be 200A, how do I know I won't blow the 50A fuse if this fuse will be connected on my 300A fuse? Here the busbar would play its role as it would separate the current flow?
3700w is a very large inverter for 12v. If you haven't already got it might want to swap everything out to 24v. Assuming you do already have that
3700w/12.8a = 289amps
289amps * 1.25 = 361amps (wire sized for this)
289amps * 1.20 = 346amps - this is your fuse size before the inverter positive.
Here 361amps would be windy nation welding wire sized at 4/0 good to 440amps - There it will depend on what the common sizes, strand count, and sheath temperature rating.
Unless you parallel at least 3 batteries with 200amp BMS each it is very likely that they will trip into potection mode randomly if you hit the inverter hard. For your surge rating you need 4 batteries in parallel with 200a BMS.
On each battery you need a fuse.
Not a breaker, but a fuse. Fuses act 10x quicker than breakers. You can also do a breaker in addition, but that is not required. And if you are thinking the BMS will shut things off that may be true, but it also may become a dead short if the MOSFETs inside it fail. Don't leave it to chance and fuse it. In your location you can look for Mersen brand gG series fuses and holders, BS88, or you can get the class T style from the states. You want a fuse labeled as 'semicondutor' or power fuse because that implies a very fast acting time vs current curve.
NOTE - fuses are there to keep your wires from getting red hot in a short situation and causing a fire. They might also protect your gear, but that isn't their purpose. And if they are properly sized you will never blow them. When buying get a spare and it will be ready just in case.
EACH battery gets its own fuse - this should be rated for 120% of the output from the BMS - the wire should be sized for 125% of the output of the BMS.
The LiTime 12v230ah battery comes with a 200amp BMS - so a 240amp fuse - or 250amp if that is the nearest available size - you can go up but not down. If you do go up you upsize the wire as well. It would take Windy nation 2awg for 205 amps which is close so I would go to 1/0 for 285amps. There as before you will need to figure out the local sizing.
This fuse goes right off the battery post and connects to the positive bus bar. Off that positive bus bar you add another fuse of the same size to the inverter. IF these battery wires are longer than about a foot you may need another fuse where they connect to the bus bar. This is in case there is a short midway on the wire.
Here is a sample that is similar to what you are doing - not the only way to do it by far, but gives an idea. It uses MRBF fuses on the batteries and class T to the inverter. Inverter is 3000w.
I will replace the battery once it's empty with my next ones, Liontron 80Ah, Victron 100Ah (prefilled before going to my off-grid location)
Having a large inverter but consumption like 300-400W (except when I use the vacuum cleaner which will mean +2600W surge and +1000W continuous use) will that require still 340A plan? I will use 300A class T fuse for short circuit failures on battery or inverter, that's my current plan.
See above for fuse and wire calculations - you are a bit off
My inverter idle consumption is 0.6-0.9A, I monitored that via mobile application connected to the battery, it was advertised with 0.4A consumption though
If your inverter has an Eco mode - it will turn on and off periodically checking for load and that is what they meassure. If it doesn't have that they just mistated the usage.
assuming a circuit breaker is better economical option than using a fuse, which one would fit my 150/45 MMPT Smartsolar Victron?
View attachment 233118
Leave this style breaker to the automotive market where it was designed for. It is a thermal breaker and will give you false trips if it is mounted where it is above 25C air temp. The other thing is they get hot and waste a lot of heat that way. And if you trip them with current going through them it won't take long before the internal contacts are fried and they become a fire hazard. For breakers you want ones that are DC rated and magnetic trip. Midnite solar, Carling, etc produce them - you will have to figure out what is available to you there.
See above for fuse and wire size discussion.
Poke through my answer thread linked below - there are things you may not have thought about.
