You can connect to the 123\SmartBMS with your phone or tablet. Download the 123\SmartBMS app, which is available in the Google Play store and Apple App Store.
First connection #
Go to the App store for Apple devices and search for “123SmartBMS”. Install the 123SmartBMS App on your Apple device. For Android devices go to the Play store and search for “123SmartBMS”. Install the App on your Android device. Enable Bluetooth on your device.
Start the App, You will see the dashboard. Tap on Settings in the right bottom corner to open the settings section.
Tap on the discovered 123\SmartBMS device to make a connection. The App will ask for a password. This password is stored in the BMS to prevent anybody with a phone/tablet from accessing your BMS. The default password is “1234”. After the connection has been made it’s time to configure the system.
To disconnect, tap again on the BMS ID with the checkmark next to it.
Dashboard #
The dashboard displays most important battery information. When a second current sensor is connected and the loads and chargers are separated, the dashboard will display extra information for charging/solar/MPPT and discharging/loads.

Battery #
In the middle of the dashboard is the battery. Next to it is important information about the battery:
-SoC (%). The amount of remaining energy.
-Current going in or out of the battery (A). When the battery is being charged, this value is positive. When current is flowing out of the battery, the value should be negative. If this is reversed, then the direction of the power cable through the current sensor is probably reversed.
-Remaining energy in the battery (kWh)
-Power (W). A positive value means the battery is being charged, a negative value means the battery is supplying energy to the loads.
-Voltage (V). The voltage of the complete bank, which is a sum of all cell voltages in series.
If the BMS is newly mounted on the battery, the SoC may not show the correct value. There is a red exclamation mark next to the SoC percentage. Charge the battery pack until all cell voltages are above V-balance and the charging power is <= 5% of pack capacity. The SoC will then be synced to 100%. The red exclamation mark will disappear. This SoC syncing happens every time the battery pack is fully charged.
Charging #
When a second current sensor is connected, “current sensor 1” is seen as the current sensor mounted on the power cable, where all charging sources like MPPT, AC charging etc are connected to. The solar panel with sun icon displays this information.
Displayed parameters are:
-Charging current (A) – this value should be a positive value when charging
-Charging power (W)
-Charged/produced energy today (kWh) – this value can be reset at Settings->Clear energy counters
-Charged/produced energy total (kWh) – this value can be reset at Settings->Clear energy counters
Discharging #
When a second current sensor is connected, “current sensor 2” is seen as the current sensor mounted on the power cable, where all discharging sources like inverter, motors etc are connected to. The light bulb icon displays this information.
Displayed parameters are:
-Load current (A) – this value should be a positive value when discharging
-Load power (W)
-Consumed energy today (kWh) – this value can be reset at Settings->Clear energy counters
-Consumed energy total (kWh) – this value can be reset at Settings->Clear energy counters
Relay status #
The status of the charge and discharge signal relay on the BMS are displayed as icons. Between solar panel and battery icon is the Charge signal relay. Between battery icon and light bulb icon is the Load signal relay.
When the two dots in the icon are connected with a wire, the relay is closed. This means that the relay is turned on and current can flow.
When the two dots in the icon are not connected with a wire between them, the relay is open. This means that the relay is turned off and thus, current cannot flow.
Be aware that this is the status of the signal relays. It is up to the installer to connect anything to the potential free contacts of these signal relays, for example an energy efficient power relay to control the high currents from inverter and/or charger.
Cells #
The cells overview is quite straightforward. On top, the active errors are displayed.
E: error. If no other error is lighting up, there probably is a communication error between the cell boards
Vh: one or more cell voltages are over Vmax. Vmax can be set in the app at Settings
Vl: one or more cell voltages are under Vmin. Vmin can be set in the app at Settings
Th: one or more cell temperatures are over Vmax. Vmax can be set in the app at Settings
Tl: one or more cell temperatures are under Tmin (charge or discharge). Tmin can be set in the app at Settings
Next are all individual cell voltages and temperatures. When the cell voltage is green, the cell voltage is between Vmin and Vbalance.
When the cell voltage is orange, the cell voltage is above Vbalance. This means that the cell is balancing.
When the cell voltage is red, this means that the cell is either under Vmin or over Vmax.
When a cell temperature is green, it means that the temperature is between Tmin and Tmax.
When a cell temperature is red, it means that the temperature is below Tmin or over Tmax.
Please be aware the measured cell pole temperature during balancing can be higher than before, because balancing produces heat. After balancing is finished, the temperature will go back to the old value.
Log #
SoC History #
The SoC history contains a SoC graph of the last 7 days.
Errors #
All errors are logged into the error history. The most recent errors are displayed here. Information includes which cell (if applicable), which value and the timestamp when the error occured.
Settings #
Devices #
All found 123\SmartBMS systems near the phone/tablet are displayed in a list. Tap on a device to connect. A checkmark next to the device displays that you are connected to that device.
Tip: when you have multiple 123\SmartBMS installations, add a sticker/note on each 123\SmartBMS system and write down the unique system ID. This simplifies the identification of a system.
System configuration #
Solar peak power: Set the maximum power of your incoming energy source, for example solar panels. If the system contains 10 solar panels of 250 Watt each, the total power of 2.50 kW has to be configured.
Inverter peak power: Set the maximum power of the consumers, for example an inverter. When your inverter can supply 5 kilowatt, 5.00 kW has to be configured.
Battery capacity: The battery capacity can of course be set to the total capacity of the battery. We advise however to take only 90% of the rated capacity, to create a “spare energy region” and compensate for cell aging and temperature effects.
Example: If you use four 200 Ah cells à 4 x 200 x 3.2 = 2560 Wh. In this case we advise to use a value of 2560 x 0.9 = 2304 Wh -> set the value to 2.3kWh.
Current sensor: Please set the current sensor type you are using. The standard current sensors supplied in the set are “dual range 500A – 20A”. If you loop the cable 2x through the current sensor, select “dual range 250A – 10A”. For 4x loop, select “dual range 125A –5A”.
Critical mode:
Changes the algorithm when the charge and load signal relay switches on/off.
In normal mode, charging is stopped when the pack is full (all cell voltages >Vbalance) and turned on when the SoC is below “charge restart SoC %”.
In critical mode, charging is allowed as long as all cells are below Vmax and within configured Tmin and Tmax. Discharging is allowed as long as all cells are above Vmin and within Tmin and Tmax.
In Critical Mode, the BMS will only switch charging and/or loads off when there is a critical error. See the algorithm section for more information on when loads and/or charging is allowed.
Critical Mode is recommended for combined chargers/inverters with only one + cable to the battery pack because otherwise when the pack is fully charged, the combined charger/inverter is switched off and thus discharging is also not possible.See Appendix section C for more info.
Change PIN: It is recommended to change the password of the BMS to prevent intruders can sabotage the system. Tab the “change PIN” line and follow the instructions.
Clear energy counters: Totals of incoming and outgoing energy will be stored into the BMS. If you like to set these total counters to zero, tab the “Clear energy counters” line and follow the instructions.
Relay override #
Keep charge relay off: When activated, the charge signal relay will be forced to stay off. This can be handy if you want to test a connected power relay or if you are going to store your pack away for a longer time. This will prevent chargers from slowly draining the battery pack because of leakage currents.
Keep discharge relay off: When activated, the discharge/load signal relay will be forced to stay off. This can be handy if you want to test a connected power relay or if you are going to store your pack away for a longer time. This will prevent inverters from slowly draining the battery pack because of leakage currents.
Battery parameters #
V min: If one of the cells gets below this minimum cell voltage threshold the “Vl“ warning indicator on the battery details screen is switched on. The “allow to discharge” relay to control external devices will be switched off.
V max: If one of the cells gets above this maximum cell voltage threshold the “Vh“ warning indicator on the battery details screen is switched on. The “allow to charge” relay to control external devices will be switched off.
V balance: This is the balancing voltage where you want all the cells to end up. Above this voltage the cell modules start to dissipate 1 ampere to balance the cells. This setting can be changed with the option switches on the Begin Board.
T min charge: If one of the cells gets below this minimum cell temperature threshold the “Tl“ warning indicator on the battery details screen is switched on. The charge signal relay, to control external devices, will be switched off.
T min discharge: If one of the cells gets below this minimum cell temperature threshold the “Tl“ warning indicator on the battery details screen is switched on. The discharge/load signal relay, to control external devices, will be switched off.
T max: If one of the cells gets above this maximum cell temperature threshold the “Th“ warning indicator on the battery details screen is switched on. Both relays to control external devices be switched off.
Charge restart: The charge relay switches ON again if the capacity is below the programmable “Charge restart” and the BMS is in “Normal mode”. This is to prevent toggling relays.
Discharge restart: The load relay will be switched on again if the capacity is above the programmable “Discharge restart” and the BMS is in “Normal mode”.
Firmware version #
Displays the installed firmware version on the BMS (only for gen3 and newer). When connected to internet, the latest available firmware version will also display. If a newer version is available, the update button becomes active.
Note: during a firmware update, the charge and load signal relay will turn off, out of safety.
App settings #
Prevent auto-lock: Enabling this function prevent the device goes into sleep mode.
Show simulator: If you don’t have an 123\SmartBMS but you like to discover the App, you can run a simulator.
Support #
You can contact the app developer and give your feedback. The App version will be showed here.