BM2 Battery Monitor Review

The BM2 is an interesting little device. We first tested it a looong time ago.

At that time, we couldn’t quite see how useful it was (we are by definition battery snobs, and our thinking was: it’s just a voltmeter!), but we’ve kept an eye on it over the years, and seen it grow in popularity. Why, we wondered.

Well, now we get it. So, we’ve gone back and checked it out again, and here’s where you’ll see our thoughts on it.

So, here is our BM2 Battery Monitor Review.

See it on Amazon here. And here are the basic facts and figures.

BM2 12V Battery Monitor

  • Voltage: 12V
  • Dimensions: 5.5 L x 3.5 W x 1.5 H cm
  • Weight: 80g
  • Average current drain: 1mA

What did we take into account in our BM2 Battery Monitor review?

We rated it in these categories:

  • Accuracy of voltage testing
  • App quality and ease of use
  • Usefulness of the data obtained
  • Casing and component quality
bm2 battery monitor

Rating the BM2 Bluetooth Battery Monitor

Let’s begin our deep dive and check out the positive and negative aspects we identified about the BM2.

BM2 12V Battery Monitor

Plus points and who needs this 12V battery monitor:

Super useful for tracking battery voltage over time
This is something that we didn’t think was all that useful at first. But after giving it a go over the space of several weeks, as well as getting feedback from distributors and other car people that have used it, we get it. And the BM2 shows this data in a very useful, easy to interpret and analyse format.

Accurate voltage readings
The voltage readings were broadly accurate. We compared with the voltage readings given by a high quality (and expensive) car battery tester.

Build quality is good enough
A little unit with plastic outer casing and decent enough wires and connectors, so it is what it is. And yet it seems to be lasting well, people are getting years of good use out of this monitor.

It won’t drain your battery
A heck of a crucial issue this. There’s not much point in getting a monitor to track your battery health is that same device is worsening its health and state of charge. At an average 1mA, the BM2 bluetooth battery monitor’s drain (what is current drain?) is pretty much negligible.

Negative points and why it may not suit your needs:

It doesn’t measure battery health
Your voltage readings are not, at least at the level of an individual voltage reading viewed in isolation, a measure of the health of the battery. That can only be obtained by a battery tester that measures CCA (Cold Cranking Amps). Voltage, rather, is a reading for the amount of charge the battery has at that particular moment. However, this is where the BM2’s voltage graph comes in handy. Checking the trend of the voltage over time does give an indication of the battery health. If the voltage is consistently low, dropping over time, and isn’t holding charge well, you’ll know that the battery isn’t in the best of health and can take appropriate action.

No wifi connection possible
How useful would it be to have an App you could connect with from anywhere and see a live update on your battery health? Pretty darn great, we say. But no dice in this case, you’ll have to make do with Bluetooth, when you’re near your car.

Where can you get it?

Here’s where to get it on Amazon.

BM2 Battery Monitor Review Summary

That, then, was our BM2 Battery Monitor Review.

As you saw, it’s a very useful piece of kit. We get it now. The voltage graph over time is much more useful than we originally thought. It’s a clever way to track how your battery is doing (FYI, here’s how to know if your battery needs to be replaced).

Other crucial aspects: the App works well, even if it’s not beautifully designed! It also only draws a very small amount of current.

It was no.2 in our Best Car Battery Monitor With Bluetooth article.

By the way, here’s where you can see BM2’s price and specifications on Amazon.

Good luck, then, with your decision on whether this is the right 12V battery monitor for you.