¶ CellMate-K9
The CellMate-K9 is suitable for a shared wiring harness that can be used in conjunction with the WatchMon supervisor.
¶ Overview
- 3s to 16s enabling monitoring of 3s - 12V systems all the way to 16s 48V systems
- Two or more CellMate-K9 can be daisy-chained to create a higher-voltage battery
- Multi-string is possible using multiple CellMate-K9 (e.g. one per CellMate-K9 per 12V, 24V or 48V bank)
- Many CellMate-K9 can be daisy-chained to grow your system
- Requires the WatchMonCORE supervisor
- Separating cell monitoring from the supervisor for a more robust solution
- Able to have a Fan mounted to enhance balancing
- Pluggable connectors for easy wiring
- Enable second-life use of existing balancing connectors in OEM packs like Tesla, Nissan Leaf, Chevy Volt, etc. that use "shared" wires between each cell in series (recommended to attach 3A fuse inline as close to the battery as possible to protect cabling)
- Cell monitoring from 0.50V to 5.50v with 0.001v resolution
- Configurable to suit LiFePO4, Lithium-Ion or custom chemistry
- Auto-Level (balancing) function at 500mA with activity LED on each cell
- Capable of 6 Ah/day balancing adjustment for each cell
- User-configurable presets and controls
- 4 external temperature sensors
- LEDs showing operating status and communication
- The CellMate-K9 optoisolation chip is 2500V* (*However, we do not recommend going much higher than what we have tested of 400V nominal as there are many other considerations.)
¶ What's Inside the Box
- 1 x CellMate-K9
- 1 x Din-rail holder
- 4 x Temperature sensors
- 1 x 5 pin 15cm connection cable
Optional Extras:
- 16 series TestMon to suit CellMate-K9
- Set of 18 inline 3A fuses
¶ Dimensions
- Length 107 mm x Width 86 mm
¶ Balancing Power
Cellmate-K9 is fabricated with 4 Ohm resistors to suit LiFePO4, Lithium-Ion or custom chemistry. This results in an Auto-Level (balancing) function of approximately 500mA achieving more than 6 Ah/day balancing adjustment for each cell.
The system operates in a four-cycle sequence of 5-second intervals. This allows for approximately 50% duty cycle between adjected cells in series to not impact cell voltage sensing or exceed wiring or fuse ratings.
When balancing is required, the four stages are as follows ODDS, EVENS, resting, then sensing and repeat. Ensure that the balancing wires are dedicated to this function and do not share any circuit with other devices.
If you run other devices that need their own circuit, take time to consider the power of other equipment, like supervisors which should have their own cabling.
Be careful not to have shared wiring with adjacent CellMate-K9 from higher voltage series as these will impact each other.
¶ Mounting a Fan
CellMate-K9 has been designed to allow a 60mm Fan to be mounted to enhance balancing performance if the customer desires.
*Note that fans and standoffs are not supplied when ordering.
- M3 screws to mount Hex standoffs to the CellMate-K9
- Standoffs should be 30mm in order to clear the heat sink.
- Fan hole centres are 60mm apart.
- Fan power can be triggered by the logic of the WatchMon CORE
- Adopt any of the Relay/SSR to switch the fan power ON.
- Fan selection and voltage is you decision (i.e. 12, 24, 48, 5V etc).
- The fan's speed only needs a light breeze (small airflow), not a gale (high breeze). Do not run a high volume airflow fan it will not help, will be noisy, shorter lifespan and waste power. The smaller the better. With just a light breeze the temperature will drop from 60ºC to less than 10ºC above ambient when running.
- Always consider where the heated airflow is sent as capable of more than 20W combined. If within an enclosed box containing the battery cells this heat may be desirable or not, either way, consider where the air vents.
- Fan power if 5V must not be powered from the onboard 5V DC-DC of the WatchMon CORE
- Except for the initial commissioning (combining cells), the balancing should not be operating for an extended period of time except if cells have no defects.
¶ Cable Specification
Cable joins the CellMate-K9 to WatchMonCORE and/or CellMate-K9 to additional CellMate-K9s in a daisy chain with a terminator on the last CellMate-K9 in the daisy chain.
See image:
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¶ Purchase the CellMate-K9
¶ Communication Network for Single CellMate-K9
¶ Communication Network for Multiple CellMate-K9
Note: Each cable can be 1.5m, capable of up to 20 CellMate-K9 monitoring modules for a CMU network. However, will require external 5v power beyond 6 units.
Contact us for more details if you consider this application.
Adopt twin twisted pair cable with sufficient core to ensure no voltage drop 22-26AWG tinned and multi-strand. The cell can be in series, parallel or multi-string as each cell monitoring module is fully isolated from the CMU port. Relocate the loop back to the end of the network.
Maximum length of cable to connect two or more CellMate-K9 together? We have tested to 10m total length combining all sections, beyond this is experimental and we cannot advise further.
¶ If you want to use a different cable, other than the one we provide:
It is OK to use the CAT5 network pair (This has 4 twisted pairs. Make sure to use multi-strand patch lead not the in-wall solid core variant.) *Shielding is generally not required.
For extra 5V power to the supervisor, with a supply above 30Vdc (i.e. 48V battery pack voltage), we highly recommend always connecting to an isolated DC-DC (ideally 24Vdc). This power can be injected into the CMU port pin for 5V and GND for the CellMate-K9, and ensure that the CMU ground pin to the supervisor is connected for the communication to work.
Consider the following booster power to run the system:
- Isolated DIN Rail Mount DC/DC Converter, Railway, 4:1, 15 W, 1 Output, 5 V, 3 A
- Input Voltage DC Min 18V Input Voltage DC Max 75V
*This should be enough as the CellMate-K9 consumes 40mW (5V 6-8mA each).
¶ Wiring from the Battery - Fused at Cell NOT BMS
Note: Ensure fusing within 15cm of the cell terminal or closer if possible. Ensure the wiring gauge is appropriate and avoid using over-rated cables. Consider putting it into a protective cover when combining multiple cables.
We typically recommend hooking up your typical 22-26 AWG hook-up cable to an in-line 3A fuse (preferably ceramic sand-filled) to extinguish the DC arc.
Read more: Battery Cabling and Wiring Best Practices
¶ Cell Terminals on CellMate-K9 for 16 Cells in Series
¶ Cell Terminals on CellMate-K9 for 14 Cells in Series
¶ Cell Terminals on CellMate-K9 for 12 Cells in Series
¶ Cell Terminals on CellMate-K9 for 8 Cells in Series
¶ Cell Terminals on CellMate-K9 for 7 Cells in Series
¶ Cell Terminals on CellMate-K9 for 3 Cells in Series
¶ Wiring Diagram for Multiple CellMate-K9
Remember: When wiring multiple CellMate-K9s, you need to treat each as an independent pack so that both the positive and negative of each module go direct to the cells. They cannot have a shared wire from one module to the next, nor drop the negative and only run one of the two.
Each needs to match your cells as they are built for example if in groups of 8 or something else. Ideally, each should be approximately the same voltage, with roughly the same number of cells in series, and not just have the last monitor a couple of cells.
