After reading this comprehensive post on battery monitoring
, I finally broke down and got two monitors, one for each 12v battery. (Note that 2021 and later models have only one battery.)
Here’s the BM6 monitor I bought. You can see it here on Amazon
. It's deceivingly small...you can fit two in the palm of your hand.
Download the required app by using the QR code on the monitor or looking for it where you get your apps.
Hooking it up and setting up the app were simple, and the (Android) phone read the battery monitors automatically, without going through the normal Bluetooth pairing process. In fact, even when the monitors are connected to the phone, you cannot see the monitors on the phone’s list of Bluetooth-connected devices.
Connecting the monitors to the phone requires that you enter the monitors' serial number in the app. Take a photo of this number so you have it handy, since once the monitor is installed, you may not be able to see the number easily. I’d recommend hooking up one monitor and make sure everything is working before hooking up the second monitor and battery. To add the second monitor for the Aux battery, I just entered the monitor’s serial number and it, too, began reading instantly.
Here’s what the app’s home screen looks like. It gives the battery's SOC as well as the voltage and temperature, and can monitor four batteries. When it's charging, the app will say "Charging" where it says "Battery OK".
And here’s a sample app-generated graph showing both batteries’ voltage. You can also display SOC or temperature, and it will also export the data using Excel.
The export feature allows you to export the data from either 12v battery, but the Excel spreadsheet it creates is awkward. The interface exports tabs within the cells, so they don’t work for charting. You’ll have to do some manipulating to get rid of the tabs and leave a number in the cell before creating a chart. You’ll also need to reformat the dates if you’re going to use Excel. In the end, I found it easier to just use the charts that the app creates.
The Android app is a real battery hog for your phone, and it won’t let the phone sleep while you have it displayed. Shut it down when you’re not using it…the data will catch up next time you start the app within range of the car. The monitors will store 32 days of data that the app will collect next time it's connected.
The app is intrusive, and wants permission for all kinds of access to the phone…some of which you may not want. My advice would be to grant everything it asks for until you have the app and monitors running to your satisfaction, and then change the access later if you want to.
FYI, the BM6 app will NOT connect to the monitors without the phone's location enabled, even if you’re not using any location-required features.
Now that it’s installed, it works great… but I’ve got some issues with the readings I’m getting. I’ll put them in another post