Getting Started

Intro to Batrium

Your battery project is unique, so your BMS should be too. Our system is modular and configurable, allowing it to adapt to your chemistry and pack configuration to meet your needs exactly.

When you choose Batrium you choose a system that is:

• Backed by over 10 years of BMS experience
• Compatible with any Lithium-based or Sodium-based chemistry
• Integrated with leading inverter/charger brands
• Leading the industry for ability to configure and customise
• Backed by an Australian support team that knows our products inside-out

What makes up a Batrium System?

A note on legacy products

We've been around for a while, and we're always learning and releasing new hardware and software. While we don't recommend using these products for new systems, we keep them in stock and software-supported as replacements for our valued customers long after newer, better replacements are released:

• LongMons
• BlockMons
• LeafMons
• Older WatchMons

What should you buy?

Pack Configuration

The first step is to to determine your pack configuration. At the end of the day, it is your decision and we can only provide suggestions. You will need to consider:

1. The battery voltage range of your inverter
   • For LV (48V) inverters, this is typically served by:
     • 16S LFP (most common)
     • 14S NMC
     • 22S LTO
   • For HV (150V+) we usually see:
     • 48S LFP/NMC and above
     • 96S NIB due to the large voltage range
   • You can use up to 250S, or 20 K9s per system, whichever comes first. Need more? See Multi-system
2. Your current/power/energy requirements
   • You will need to parallel cells to ensure your inverter can reach its capacity without overloading the cells past their C-rating.
   • You will need to ensure your pack is sized for your needs. If you are off-grid, this will usually meed 3 days of power, if you are on-grid/hybrid, you can get away with less
3. Parallel cells or multi-string?
   • We refer to parallel cells as nP, where n represents the number of cells in parallel.
     • For example, a pack consisting of groups of 2 cells in parallel, then those groups connected in series would be 16S2P.
     • Since the cell voltages are tied to each other, this could be monitored by 1 K9
   • We refer to multiple independent strings of cells as Multi-string.
     • For example, a system with 3 banks of 16S connected to one inverter/charger would be referred to as 2M-16S-1P
     • This would require 3 K9s, as the individual cell voltages are no longer tied, and must be balanced independently.
     • We cannot currently shut off one bank at a time, so no extra redundancy is gained. Watch this space for developments on this :)
   • As you can see, you can simplify your system greatly by paralleling up cells first, then putting those groups in series
   • This will depend on your physical/mechanical constraints as well, i.e. how are your shelves/enclosures arranged?

Planning K9 Wiring

K9s are quite flexible, any K9 can measure between 3-16 cells in series but you should avoid split banks. For example, suppose:

• Your bank is split into two groups of 8 cells, each on their own shelf, with a cable in between
  
• Even if this cable is very large (0AWG), there will be a small resistance across it.
  
• According to Ohm's law, V=IR, under high inverter currents (e.g. 120A), you will see a voltage difference across the wire, which appears as one cell being high, one low.

For more information, see K9 Wiring

Shunt sizing

We offer shunts in 4 sizes, for any type of project:

• 500A
• 1000A
• 2000A
• 6000A
  They are rated for 80% current all day, and 100% for short periods. In other words, our 500A shunt can withstand 400A forever, but 500A for short periods (800A for the 1000A model, etc.).

You should refer to your inverter/charger datasheet, as well as consider your generators (solar, petrol, wind, grid etc.) and loads (house, EV motor, etc) to find the maximum power they can draw/push from/to the battery, considering efficiency. Some datasheets also quote a maximum DC load for the battery connection, which you can use. You should also allow a safety margin on top.

• For example a typical 5kW LV house inverter might be 80% efficient, so it would have to draw $5000÷0.8=6250\text{ W}$ of power from the battery to reach this output.
• From there, you can divide by the lowest cell voltage you expect to see under load. For a 14S Li-Ion system this might be $3.5\text{ V}\times 14\text{S}=49\text{ V}$.
• Using these, we can calculate our maximum current as $6250÷3.5\approx 127\text{ A}$
• Since 127A is less than 400A, we can safely pick the 500A shunt variant

WatchMonCORE

Every system needs a WatchMonCORE to watch over the system, communicate with the inverter, and act as a bridge to your local network and our BMI platform. It is our latest and greatest, and currently our only supervisor option, so there is not much to decide, however you will need to check whether your inverter can communicate with it. You will need to:

1. Check that your inverter supports communication over CANBUS. We currently do not support CAN-FD or Modbus, but we are working on a product to add this to our capabilities.
2. Check our existing profile list to see if your inverter/charger is already compatible. If it is, good news! There's nothing more you need to do.
3. If your inverter is not on the list, check whether one of our battery emulators is on the list of compatible batteries for your inverter/charger. We can currently emulate:
   • Pylontech LV and HV batteries
   • BYD HVS/HVM batteries
   • LG RESU HV batteries
4. If you can't use the above options, you will need to contact your inverter manufacturer to request a protocol document to pass along to our software engineers. Without this, we are unable to implement support for new inverters.

To Expand or Not To Expand?

That is the question. Our WatchMonCORE has one relay output available to drive external equipment. This is usually taken up by a circuit breaker shunt trip, so if you need extra equipment such as:

• Contactors
• Manual switches to control battery logic
• Heating pads
• Cell cooling fans
• Liquid cooling loops
• Electronics cabinet fans
  You will need to purchase an Expansion Board to sit beside your WatchMon on a DIN rail.

We are currently offering them for free with any WatchMonCORE purchase (use code EXPANSION), so we recommend you add one to your order just in case.

Other Equipment

Safety

You will need to consider the safety of your pack, and plan accordingly. While we can recommend approaches, the final decision is yours.

We recommend, at the minimum:

1. Fuses on the balancing wires close to the cells, especially on systems that will see vibration or movement (e.g. EV projects)
2. A circuit breaker on the main battery connection to your charger inverter with a short circuit rating (Isc) of at least 10kA (potentially more for larger systems), and a shunt trip installed (small coil that can force the CB to trip when driven with 12V/24V/48V) and wired to our BMS.

We sell Fuse Kits for the balancing wires, and MCCBs with suitable ratings can often be found online at sites like eBay, or if a local industral operation is shutting down.

See our Wiring Best Practices guide for more recommendations

Summary

To keep it simple, almost all systems will need:

• 1x WatchMonCORE
• A number of CellMate K9s depending on your cell configuration
• 1x ShuntMon
• 1x Expansion board (recommended)
• A number of fuse kits (same as K9)
  We've provided three examples of the most common types we see:

Example: 16S Low Voltage System:

• This customer has chosen to keep their battery system simple by putting their 32 LFP cells in parallel groups of 2, then in series to reach 16S.
• They have large Victron charger/inverter capable of 15kW of output. The calculations give ~366A of discharge amps at full power. Once you add a safety margin, it becomes clear that a 1000A shunt will be much more comfortable than a 500A shunt.

Following our above instructions, we determine we will need:

• 1x WatchMonCORE
• 1x CellMate K9
• 1x ShuntMon 1000A
• 1x Expansion board
• 1x Fuse Kit

Example: Multi-String Low Voltage System

• This customer has chosen to add capacity by adding 2 additional banks of LFP cells at 16S. This means they have more individual cells to monitor (they are no longer tightly coupled and can unbalance), so they will need 3 K9s for their 3 banks.
• Their inverter is on the smaller side at 5kW, so the maximum current comes out at 127A. This means a 500A shunt will be enough.

Following our above instructions, we determine we will need:

• 1x WatchMonCORE
• 3x CellMate K9
• 1x ShuntMon 500A
• 1x Expansion Board
• 3x Fuse Kit

Example: 96S High Voltage System

 

• This customer needs a BMS to monitor their HV battery pack. They have 96 NMC cells, which is under the limit of 250, and can be monitored by 6 K9s, operating at 16S each.
• Since this is a HV system, even though they have a large 30kW inverter, they are only expecting 111A, so a 500A shunt will be fine
• Just to check, their maximum system voltage will be $4.2\text{ V}\times 96=403\text{ V}$, which is under the ShuntMon's 650V maximum, so it will work well.

Following our above instructions, we determine we will need

• 1x WatchMonCORE
• 6x CellMate K9
• 1x ShuntMon 500A
• 1x Expansion Board
• 6x Fuse Kit

Legal Stuff

Batrium BMS products are produced to be safe and robust, and perform as described. However, since we have no control over the integration of our products into a battery system, we can assume no responsibility for the final safety or functionality of the completed installation.

It is up to the end-user to determine the suitability of the products for the purpose and the end-user assumes all risks associated. Products should only be installed by suitably qualified and experienced persons. Incorrect installation can be hazardous.

The product should always be used safely and lawfully according to any local requirements. Using the product other than what it is intended for, especially if that compromises its core functions, including modification of components, is considered improper use and will void any warranty.

Where to from here?

If you still have questions, visit our Wiki, and if that doesn't have your answers, you can email us to get answers to non-standard questions.

Once all your questions are answered, head to our Store to take your battery project to the next level!