Back in the 1980s and 90s, there was a war among the world’s largest battery manufacturers. With consumer electronics taking off, battery makers were furiously competing to power everything from portable cassette players to transistor radios. It was an ‘all hands on deck’ sort of thing. The war led to some rather unique innovations, including the on-board battery tester.

Duracell and Energizer both introduced on-board testers on the same day in 1995. One thing led to another and, before long, the two companies were involved in a patent suit along with Eastman Kodak Company and a team of small-time inventors led by James Burroughs and Alan O’Kain.

Burroughs and O’Kain eventually prevailed, but producing the batteries was no longer worthwhile by the time the legal dust settle. A technology that promised to sell more Duracell and Energizer batteries went by the wayside.

How It Worked

An on-board battery tester is pretty straightforward. It utilizes a piece of foil and a heat sensitive paint. When you charge an alkaline battery for the first time, the paint changes color. It changes back as the battery is discharged. However, you wouldn’t want the meter operational at all times as it would drain the battery.

To overcome this problem, battery manufacturers installed a small switch. When on, a small amount of electricity would flow into the meter and generate heat. The heat would change the color of the paint, making it apparent how much electrical charge remained.

The idea works because discharging an alkaline battery results in something known as off gassing. A chemical reaction inside the case produces hydrogen gas and heat. The greater the remaining charge, the more heat generated during discharge. That is really all there is to it.

Building Better Batteries

So, why did the on-board battery tester not last? It didn’t result in a better battery. Having an on-board tester did not make batteries last any longer. It didn’t reduce their self-discharge rate or improve shelf life. In the end, on-board testers were more of a novelty than anything else. Manufacturers didn’t want a mere novelty; they wanted to build better batteries.

Those better batteries were born with the lithium-ion revolution. Lithium-ion batteries are rechargeable. They offer comparable performance to alkaline batteries, making them better than NiCad and NiMH batteries for some uses. Best of all, they are more cost-effective over the long term.

For example, a typical Pale Blue Earth USB smart battery can be charged up to a thousand times. Even though Pale Blue Earth batteries cost 4 to 5 times as much at the cash register, they pay for themselves within half-a-dozen recharge cycles. The remaining 990+ charge cycles do not cost users a penny.

Other Ways to Test Battery Level

Lithium-ion batteries are better batteries because they are rechargeable. That’s it in a nutshell. If you’re still an alkaline user, don’t lament the loss of the on-board tester. There are other ways to test battery level. For example, have you heard about dropping a battery on a hard surface and seeing if it bounces?

The bounce test really does work. The more a battery bounces, the less charge it has remaining. There is some debate as to why this is, but it boils down to density. Also note that the bounce test is not highly scientific. It cannot tell you how many hours of charge you have left.

You can purchase a tester if you are a heavy alkaline user. But if you are going to go that route, you might just as well put the money into rechargeable lithium-ion batteries. They are better batteries even without an on-board tester.