BM2 Bluetooth Battery Monitor 12V Car Battery Tester for Lead Acid, Auto Battery Load Tester with Cranking Charging Test, LowVolt Alarm for Car/RV/Motorcycle/Truck/Boat/Solar Power System

I got this to use on a secondary car that is left parked for potentially long periods of time. I have a solar powered battery maintainer hooked up to it but I also wanted to easily check on its state of charge just in case. The BM2 fills that purpose perfectly. Installation is simple. You just clip its wires to the respective battery terminals and secure the unit somewhere safe (I just zip tied it to the top mounting bracket of the battery). After installing the app, it detected the monitoring unit and started reporting the voltage automatically. You can set alerts and also offers start and charge tests. It does use Bluetooth, so range is limited (especially considering it has a metal hood covering it normally). YMMV. Worst case, you may have to walk close to the car to get a reading. But at least you don't have to pop the hood or mess with the battery. It does keep a history which it updates to your app next time it connects, so you won't lose data points. All in all, it does exactly what I need.

Bought this here instead of Aliexpress bc its a similar price. Very simple to install and works immediately. Download the Battery Monitor BM2 app from the app store. You have to be in bluetooth range to get a reading. You can get a current reading, or charts that track voltage over time, and you can set notifications to let you know when the voltage drops to certain levels.

This is a great little device, it helps me keep up with my batteries. And that's very important in a off grid system. Does what it's serpose to do. Good app that goes with.

Got this for a hybrid so the cranking feature isn't used. But the car is used infrequently and there are some occasional electric loads as the car does diagnostics and other stuff in the background, so monitoring it is helpful to see when it needs a booster charge. It works exactly as advertised, and I'm surprised that I can be anywhere in the house and still pair with the car for a reading.

I’m impressed with this easy-to-use battery monitor. Just connect it to your battery, download and install the app, pair with Bluetooth and you’re ready to go! As long as you’re near your vehicle (or whatever you’re monitoring) it will auto connect and download the saved data when the app is launched. It will store up to 30 days of measurements. Since the data is transferred to your device, it’s designed to be used with only one phone or tablet otherwise the data will be scattered across devices. It captures the battery voltage once a minute allowing you to view charge and discharge profiles. I’m using one in my car and one on my 12v solar system.

PHEV use case - Excellent product; easy to install; great value; limitations discussed I decided to get a battery monitor after my 2019 Kia Niro PHEV gave me a mysterious battery alert, but neither the built-in diagnostics nor anything I could read through a scanner (TopScan https://www.amazon.com/dp/B0C3QQYQ1B ) revealed anything. The active tests supported by the car itself through the TopScan wouldn't allow me to do any useful tests with the battery. So, battery monitor time. At least with a battery monitor I'd be able to get some degree of long-term diagnostic data, so I hunted around, and this one came up top after all my research, even though I would have been happy to pay way more had I found a better-seeming option. A few notes on the pics: In my case (Kia Niro PHEV), the low-voltage battery is stored behind the right rear wheel, and is accessed through a hatch in the trunk. The positive terminal for the battery is covered by a plastic cover, which can be removed by popping it off its hinge pin. It's necessary to cut a small chunk out of this cover to be able to mount the positive terminal of the monitor and still be able to close the cover to protect the battery's positive terminal. Once I got it out, I found that the cover was actually considerably more solid than I expected. I ended up using an oscillating tool to trim out a slot, and I cleaned it up with a rat-tail file. Lots of other tools would work, e.g. a coping saw. There wasn't really a good place to mount the monitor next to the battery, so I resorted to a couple of zip ties. Another option would have been double-sided tape, i suppose. Given these encomia, I should point out that the utility of a monitor like this is likely to be limited specifically with a PHEV. In particular (at least with my car), there's no good way to do a cold crank test that completely isolates the low-voltage (auxiliary) battery from the high voltage battery. This is not the fault of this product, of course, it's just a fact of life with PHEVs unless the manufacturer provides active test features to support such isolation. You'd think that it'd be an obvious feature for the manufacturer to provide, but even the official manual doesn't provide any real method to do a crank test, short of pulling the battery and putting it on a load cell of some sort. The average car owner isn't going to be able to do this, of course, so as far as I can tell all you can really do is try to monitor the gradual degradation of the charge state of the auxiliary battery, and just get a new one when things look bad enough. The cost of swapping the battery is bound to be less than the cost of getting any professional to try and perform any diagnosis on it - at least where I live. Bottom line - great product, and great value.

Been using this for a year to monitor the 12V drain on my 2024 Ford Maverick Hybrid (seems to be a common issue with these trucks .... random discharging of the 12V battery. This monitor works well and draws almost no power itself. Only gripe is in the app when you look it historical voltage levels (up to 30 days old), the app does not allow you to zoom in to see a smaller window of time. that would be a HUGE inprovement. that said, the device works as advertised.

I’ve been using this item for about 3 months off and on with my deep cycle RV battery which is brand new. I noticed every time I checked it from week to week it was reading 60-70% charge in its resting state. When I put it on the charger it would only charge a few minutes and then stop reading Full on charger. So using a multimeter and a battery charger tester on the same deep cycle battery, they both read 12.7 volts which is a full charge in resting state. And this battery monitor reads at 70% charge in compaction to my other to methods of testing. So I’ve determined this Quicklynks unit I’m using is very inaccurate on the charge level. I would not recommend. Had me thinking my brand new battery was bad and would not fully charge. Cheaper and simple is not always better nor reliable.