smart electric drive - 90% capacity after 2,000 cycles

That my smart still has 90% capacity remaining is already known. But I still have been interested in the conditions under which it got them. The battery management system (BMS) is responsible for the battery and it may be that it begins to be extra careful with the battery, thus limiting performance and / or longevity.


The full experience report as well as a detailed cost and repair list can be found here: 200,000km with the smart electric drive



Under which conditions does it have the 90%?


90% remaining capacity - does the BMS use tricks for that?


A number alone is not enough for me. So I still have got 90% of the original 17.6kWh available, that's clear. The question that still bothered me: Has the BMS already given up buffers to keep the usable capacity high?

Usually, battery cells are not operated in their full voltage window. But if you let it grow a bit larger with age, the usable capacity stays the same for a longer time. But that would be only a short-term solution, in the long run, the battery wear would increases even faster. To see what my battery does I measured a new one smart ED3 battery to compare it with mine. The result was clear, my 2,000 cycles old battery has not shifted the upper (4.2V) and lower end voltage (3.2V). So it defines 100% and 0% at the same point as 2013 when my smart rolled off the line. This means I can assume that the battery should continue to lose its capacity linear. In this case the 80% will be reached at about 400.000km.


90% remaining capacity - 100% driving pleasure?


To find out if the BMS is extra careful with the old battery, I put it on a test bench. I was interested in whether the smart still delivers the peak power of 55kW. As a comparison, I also test a 30,000km old smart ED3. The result was that my smart even had slightly more power than the 30.000km smart ED3.

This is absolutely within tolerance, cars never have exactly the same performance. +/- 5 PS are perfectly normal. Accordingly, it is also clear that even a 2,000-cycle old smart is still as much fun as on the first day.


Conclusion


The BMS does not trick, the battery is actually as good as it seems. So as already in the detailed report after 200.000km written, it will most likely outlive the mechanics of the smart. Awesome!



smart electric drive on dynamometer


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