Many of us have known for a long time that it’s necessary to keep watch on the charge status of our 12V batteries. COVID-19 has made this very real for many unsuspecting sitting at home drivers. There are a lot of ways to do this like multi-meters, etc. Some are easier to use than others and you still have to remember to do it. Some of us have multiple vehicles to keep up with. It can get to be a pain real fast. This is where Bluetooth monitoring devices make your life a lot easier. I have to give @Salamander_King credit for mentioning BT devices to monitor 12V batteries in recent threads. There are several hardware devices and there are also several free and paid apps that work with them. I like tools that make my life easier and I have no affiliation with any of these products. This is a very simple overview and does not cover everything. The hardware . . . . 1. I have a CTEK MXS 5.0 battery charger so I looked at their CTX Battery Sense BT battery monitor. The physical device looked very good until I saw the price $50 – 60 US, each. Ouch. It has more capability than the others, but even if I had brand loyalty, the recent reviews on their app are pretty harsh. I kept looking. 2. Next I looked at the device that @Salamander_King was using, the Quicklynks Battery Monitor II (BM2). It's small, well made, and priced between $17-$28 US. It stores data internally for 35 days and power consumption is very low @ 1.0 mA and works in temperatures -40F to 185F (-40C to 85C) The BM2 is the device I chose to go with and am very pleased. I ordered three and installed on each of my vehicles in less than 15 minutes. Here's the Prime's install. The software . . . . I have 3 vehicles which complicates my monitoring need but I think fits many of your garages as well. There are several free and paid apps but only two that I can find support “simultaneous” viewing of multiple battery info. I use and evaluated these apps with a Samsung Galaxy S20 Plus 5G. The apps I evaluated are: CTX Battery Sense BT battery monitor—OEM, only works with the CTEK device which I ruled out above due to $$ price and bad reviews on the app store. Battery Monitor BM2—free on playstore, displays only one battery at a time but can switch between multiple vehicles in the settings. NO data export. Works with Quicklynks Battery Monitor II (BM2) hardware device. I ruled this app out "for me" due to no data export but works OK otherwise. JMP BattMon II— free on playstore, displays one battery at a time but it can switch between multiple vehicles in the settings. It CAN export data. Works with Quicklynks Battery Monitor II (BM2) hardware device Battery Monitor BM3--$9.99 on playstore. Can simultaneously display 4 different batteries and it CAN export the data. Works with Quicklynks Battery Monitor II (BM2) hardware device. Also, you can give FRIENDLY names to each battery instead of a long alphanumeric number. My Choice . . . . My "personal" choice is the $9.99 BM3 because of the 4 battery interface. I just open the app with BT on and it gives me the present battery conditions of all three vehicles on one screen. No muss, no fuss. I also have and use the JMP BattMon II. Use it if you don’t want to pay for an app or if you only monitor one battery. Note, it's possible to use both of these apps with the same BM2 monitors since the data is on the monitor. Each exports data slightly differently. App Screen shots . . . . BM3 main screen Details page below. Tap a time on the screen and you get a voltage detail of each battery. JMP Battmon II main screen below. Note unfriendly MAC address style name, not changeable. JMP Battmon II screen to pick a different battery to display. It works, but is a pain. See below I hope this helps.
PS, I used my multi-meter (Craftsman 82139) to compare the Quicklynks Battery Monitor II (BM2) voltage with the meter and it was dead on for all three vehicles. The device is BT Ver 4.0 and my phone is BT Ver 5.0. It has a very decent range (depending on the number of walls) of about 30' and more in places.
Thank you for a great summary. Must have taken a long time to write up... Yeah, BM3 app looks nice if you have to monitor more than one battery. But I wonder what the utility of displaying "Battery Total Voltage". lol There is another BlueTooth Battery Monitor in market sold by Ancel. I don't have any experience with it, but at $40 price tag, it falls in between BMII and CTEX. I am happy with BMII for now, so if someone buys the unit, I would like to hear about it. http://www.amazon.com/ANCEL-BM300-Bluetooth-Automotive-Motorcycles/dp/B07WCW49YM/ref=sr_1_26?dchild=1&keywords=battery+monitor&qid=1589488963&sr=8-26
Only because the forum dumped me off as I clicked post and I had to recreate it. I wondered about that total as well. I didn't see the Ancel. Good catch.
Came to this from the vampire current draw thread! So how much current does this draw? Also, would be great if someone built it in the form factor that plugs into the OBD2 connector like several of the OBD2 readers do. I believe the 12V there is unswitched since so-called memory savers plug into it but I could be wrong.
1mA draw max, but it is not on all the time, only when you connect to the Bluetooth app, I believe. Most Bluetooth OBD2 readers can connect to the app only when the car is ON. I am not sure if there is any Bluetooth OBD2 battery monitor. I know there are many battery voltage meters that can be read from the 12v cigarette socket, but I am not aware of any Bluetooth-enabled one.
The Quicklynks Battery Monitor II (BM2) is a cool device. I am interested to know more about the JMP and BM3 app export features. For example, do the apps only export up to a 24 hour period? For $9.99 can the BM3 app export multiple days, week(s), and/or a month? Would it be possible to show a few samples of the export? Thank you.
For the JMP app, it can export all the data that is stored in the phone indefinitely as long as you periodically synch the app with the unit within 30 days period. The unit, I think, stores up to 30 days of data then it gets purged in a rolling base as new data gets stored. The caveat is that the data can be downloaded only 1 day (24 hours period) at a time. So if you have multiple days to download, the display must be changed and data exported on that screen. I never purchased the BM3 app, but I think the system is the same. You can only download 1 day at a time, but I am not sure. The export function is just sending the xls file to whatever email address you input. It will show 3 columns, Name of device, Time, Voltage, in the 2-minute interval from 0:01:00 am for 24 hours. A partial spreadsheet screenshot is shown below.