In short
- Android needs location and nearby-devices permissions for the JK app to even see the BMS.
- Only one phone can be connected at a time; a forgotten tablet in the house blocks everyone else.
- Metal cabinets and battery steel cut the range to a few metres.
JK boards use Bluetooth Low Energy. It is designed to save power, not to reach far, and it accepts one connection at a time. Most problems come from those two facts.
The list stays empty
On Android, the app needs the location permission and, on recent versions, the nearby devices permission, with location switched on in the phone. Without them, the scan returns nothing even when the BMS is a metre away. On iPhone, check that Bluetooth access is allowed for the app in the settings.
Someone else is connected
A JK BMS talks to one phone at a time. A tablet left in the workshop with the app open, or a second phone in a pocket, keeps the link and hides the BMS from everyone else. Close the app on other devices, or switch their Bluetooth off for a minute.
Range and metal
Inside a steel rack or a metal cabinet, the range can drop to a few metres or less. Open the door, stand in front of the battery and try again. If it works only with the door open, the signal is the issue, not the BMS.
The connection drops after a few seconds
Often an old app version or a phone that aggressively saves battery. Update the app, disable battery optimisation for it, and remove the BMS from the phone’s paired devices before scanning again. JK boards do not need classic pairing in the phone settings.
The password
The app may ask for a password to change settings. The default is usually given in the JK documentation, and installers often change it. Reading values does not change anything, but writing settings does, so keep that password where you will find it.
When Bluetooth is not enough
Bluetooth is fine for a quick check standing in front of the pack. To see the cells from the house, or from another country, JK BMS Monitor reads the BMS through its RS485 port and shows everything on its screen, on your Wi-Fi, in Home Assistant and in the free Cloud. The Bluetooth app keeps working alongside.
Common questions
Can I use the JK app and JK BMS Monitor at the same time?
Yes. The box uses the RS485 port, not Bluetooth, so the app still connects as before.
Does JK BMS Monitor need the BMS password?
No. It only reads values and never writes a setting, so no password is needed.
My BMS has no RS485 connector. Can I still use the box?
Some JK boards need the RS485 adapter or use a different connector. Tell us your exact board when you order and we confirm before shipping.
