Leaf capacity loss: reading the battery bars honestly

The short version

The bars down the side of the Leaf's gauge are a coarse summary of pack health, not a measurement you should buy or sell a car on. A proper state-of-health read costs a fraction of a wrong decision.

Why the early Leaf ages differently

Most modern EVs actively cool the pack. The 2011 to 2017 Leaf does not: it is air-cooled by whatever the weather provides. In a mild coastal climate that is survivable, which is why Bay Area cars often look better than their mileage suggests, and why the same car with a history in a hot inland valley usually does not.

What the bars actually mean

• Twelve bars is not one hundred percent. The top bar covers a wide band, so a car can lose real capacity without dropping one.
• The first bar goes around fifteen percent loss. After that they fall faster, which is why a car seems to decline suddenly.
• Bars do not tell you about balance. A pack can hold charge and still have cells drifting apart, and only a proper read shows that.

How we read one properly

We pull the pack's own state-of-health and the per-cell voltages over a short drive, which gives a percentage and a spread rather than a bar count. On a used car that is the difference between paying for the range you think you are getting and paying for someone else's hot summers.

A note on why this one has no count

The articles on this site normally carry a repair-order count from our own records. Leaf work is not a large part of what comes through these bays, so there is no figure here worth quoting, and we would rather say that than dress up a handful of jobs as a dataset. These are field notes: what we know from the cars we have seen and from the EV Partners network.

Reading a state-of-health number properly

The figure that matters is state of health as a percentage of original capacity, read from the pack itself rather than inferred from the dash. Alongside it we look at the spread between cells, because a pack averaging seventy-eight percent with tight cells behaves very differently from one averaging seventy-eight percent with two cells dragging.

On a used car we do this before purchase wherever we can, because it is the single number that determines whether the car does what you need. Real-world range is roughly the original range multiplied by that percentage, minus what the weather takes.

Which years to be careful about

• 2011 to 2012. Earliest chemistry, no thermal management, often the most degraded. Judge strictly on measured capacity.
• 2013 to 2015. Revised chemistry that holds up better, and the sweet spot for value if the car has lived somewhere mild.
• 2016 to 2017. The 30 kWh pack, which had its own early degradation issues and a software update that changed how capacity was reported.

What actually causes the loss

Heat and time, mostly, with fast charging as an accelerant. A pack held at high state of charge in a hot car park loses capacity faster than one cycled gently in a mild climate. This is why a Bay Area Leaf frequently measures better than its mileage and age suggest, and why one that has spent summers inland often does not.

Living with a degraded pack

A Leaf at seventy percent is still a perfectly good car for a short commute, and plenty of people run them exactly that way with their eyes open. The mistake is buying one expecting the original range. If you know the number before you buy, the car is honest; if you find out afterwards, it feels like a failure.

What we can and cannot do

We can measure the pack accurately, tell you what it will realistically do, and advise on whether a replacement makes economic sense on your particular car. We do not rebuild Leaf packs in house. Where a replacement is the right answer we will say so and point you at the options rather than pretending otherwise.

What to ask a seller

• Where has the car lived? A coastal Leaf and an inland one of the same year are different cars.
• How was it charged? Daily fast charging in heat is the worst combination for these packs.
• Has it had a battery replacement or warranty work? Some early cars did, and it changes the maths entirely.

None of those replace a measurement, but they tell you whether the measurement is likely to be good news before you spend time on a viewing.

Counts on this page are repair orders at our shop, synced from Shop-Ware. This is general information about a pattern we see. Your car is its own case, and we'd rather look at it than guess.