BMZ, the largest manufacturer of ebike batteries in Europe, has introduced a new format for the cells used in batteries. Along with other technological improvements, this should lead to a battery life of 12 years instead of the current 3-4.

Ebike batteries have made tremendous progress since a few years ago. Having gotten rid of the old lead-acid batteries, lithium batteries continue to be improved. As we know, the quality of the production process is important to ensure good battery life, along with proper maintenance. However, even the best batteries see performance decrease after 3-4 years.

BMZ is not a famous company. But it is the largest European battery manufacturer, not just for ebike. BMZ has seen its revenue increase a lot, thanks to the boom of ebikes. That’s why they have decided to invest in research and development in the industry, presenting the results of these investments to the recent Eurobike.

Everything revolves around a new format of the cells that make up the batteries. If we opened an electric bicycle battery (an operation we would not recommend as potentially dangerous) we would find ourselves in front of a series of cylinders, somewhat simliar (but bigger) to the classic AA batteries we all know. These cylinders are battery cells, interconnected and operated by a control unit. Probably 99% of electric bike batteries are made up of 18650 size cells, 18mm in diameter, with a length of 65mm.

The novelty presented by BMZ does not seem particularly important at first sight. BMZ has simply chosen to begin producing 21700-size cells: 21mm diameter, 70mm length. This simple enlargement of the format is matched by some productive improvements, not better specified by BMZ, which are allowed by the new format.

The result of all this are batteries that, compared to the normal batteries used so far, present the following characteristics:

• With equal volume, they have an increased capacity of 60% (and therefore need to be reloaded less often)
• Always at the same volume, they weigh less
• They produce less heat during charging (and therefore internal materials are less stressed)
• They have better performance in terms of amps supplied to the engine
• All of this, of course, according to BMZ (here the press release, in German): we will see if the promises will be maintained. The trade name of this set of technologies is 3Tron.

It’s above all the greater capacity, and the lesser heat while charging, to be of interest. This in turn means that the batteries will have to be charged less often; on the other hand, when they are recharged, they will be stressed less. The recharging phase is particularly stressful for internal battery components, and it is primarily responsible for performance decay. That’s why according to BMZ these new 3Tron batteries, thanks to less frequent and less stressful recharges, will be able to maintain their performance for up to 12 years: if that were true, it would be a revolutionary thing for electric bikes.

Take for example a standard 500Wh battery, as can be found in the latest electric bikes. An increase in capacity of 60% means having a 800Wh battery of equal volume, with the possibility of increasing the mileage by far.

Now, virtually every month comes news about some big, theoretical step made in battery technology. However, this is almost always news from research laboratories, with mass production remaining very distant. Here, however, the news was announced by the largest battery factory in Europe, with a production plant of 55 thousand square meters. Even if BMZ exaggerated in presenting the improvements made by the new 3Tron format, and instead of a lifetime of 12 years, we would assume a lifespan for its 5-6 years battery life, it would still be a huge step forward compared to the current 3-4 years.

But we must notice a contradiction in the background. The longer life span in BMT’s 3Tron batteries translates, as it is easy to guess, into a smaller amount of sold batteries in the long term: instead of replacing batteries every 3 years, customers will eventually replace them every 6 or even 12, years. BMZ will definitely make his calculations, thinking that better batteries will increase the spread of electric bikes and thus increase sales; moreover, it is likely that BMZ batteries mey be sold at a higher price.

BMZ supplies batteries directly to manufacturers of ebike systems. It is likely that the various Bosch, Shimano, Yamaha, Brose, Bafang and others are already studying the possibility of using this new 3Tron battery. Will they already be in the ebikes of the 2018 season? We’ll see.