Battery degradation: what actually happens, and what it means in Georgia

Updated July 2026

What degradation means

Battery health is measured by how much energy the pack holds today against when it was new. A 60 kWh battery that now holds 54 is at 90 percent.

In practice that means range falls proportionally and nothing else. The car does not break down, does not lose power and does not stop without warning. It simply covers fewer kilometres on a full charge than it once did.

The important part is that degradation is not linear. The first year shows the steepest drop, roughly 3 to 5 percent, after which the curve flattens to one or two percent a year. People who panic after year one are usually just unfamiliar with the shape of that curve.

Two different kinds of wear

A battery ages for two independent reasons and they add up.

Calendar ageing depends only on time. The pack ages while the car sits in a garage. Two things speed it up: high temperature and a high state of charge. A full battery on a hot day ages far faster than a half full one somewhere cool.

Cycle ageing depends on distance, that is, on how many times you have emptied and refilled the pack.

For most drivers in Georgia the first matters more than the second. Annual mileage here is typically low and summer temperatures are high. Your battery is ageing more from the calendar than from being driven.

Why Georgia is a particular case

General advice on degradation is written for European and American conditions. Two differences matter here.

Heat and battery cooling

Most modern EVs cool the pack with liquid. For such a car a Tbilisi or Rustavi summer is not a problem.

The problem is models where the pack is only air cooled. The best known example is the first and second generation Nissan Leaf, one of the most common EVs in Georgia. Parked in the sun in August, such a car sits at high temperature all day with no way to cool the pack. That is why Leafs that have lived in hot climates degrade markedly faster than the same car driven in northern Europe.

None of that means you should not buy one. It means checking the pack before you buy, and taking shade seriously afterwards.

The share of fast charging

In the West most EV owners charge at home and use fast chargers on trips. In Tbilisi it is the other way round: a large share of drivers live in flats, have no home charger, and take almost all their energy from public DC.

Taken alone, one fast charge harms nothing. But when it is the only method for years, especially on an uncooled pack in summer, the effect accumulates. If you can arrange home charging, the battery benefits as much as your wallet does. What a home charger needs.

The mountains

The Gudauri and Kazbegi roads are not a threat to the battery. Climbing uses a lot and descending gives part of it back. That is ordinary operation and causes no extra wear. Altitude itself is not a problem either.

What to check when buying used

On an EV the odometer tells you far less than it does on a petrol car. The number that matters is battery health.

• Ask to see the state of health. It is a percentage, read with a diagnostic tool or a dedicated app. A seller who will not show it has answered the question.
• On a Leaf, look at the health bars and the quick charge count. That car reports both directly and they are comparatively easy to read.
• Do not trust the range shown on a full charge. That figure is computed from recent consumption and can flatter the car badly. Only the health reading tells you the truth.
• Ask where the car has lived. An uncooled pack that spent years in a hot country and the same model year from the north are not the same car.
• Look at any repair history. A pack that has already been replaced is not bad news; it is the opposite.

How these cars reach Georgia in the first place is covered separately: importing from America and importing from China.

What the warranty covers

Manufacturers normally warrant the battery for eight years or 160,000 km, and it pays out only if health falls below a set threshold, frequently 70 percent.

Two things follow. First, that threshold is low: a pack at 75 percent is outside the warranty while range is already well down. Second, on a privately imported car the warranty belongs to the market where it was originally sold and often cannot be used in Georgia at all. Check that specifically before buying rather than assuming it.

How to make it last

• Live between 20 and 80 percent. A full pack ages fastest. Charge to 100 when you are about to set off on a long trip.
• Do not leave it full or nearly empty for long. If the car will sit for weeks, leave it around half.
• Park in the shade in summer. For an uncooled pack this is the single most effective and cheapest measure there is.
• Charge slowly where you can. This is not an argument against fast charging. It means that when both are available, slow is kinder.
• Warm a cold pack first. If the car can precondition the battery, use it before a fast charger in winter.

What is not a problem

Plenty of the worry is misplaced and not worth spending energy on.

• The occasional full charge. Charging to 100 percent before a long drive is entirely ordinary.
• Cold. The winter drop in range is temporary and returns in spring. It is not degradation.
• Regenerative braking. Recovering energy while slowing does not stress the pack.
• Driving the car every day. A parked EV is worse off than a used one.

Measured figures for specific models, broken down by mileage, are covered separately in battery wear from 50,000 to 200,000 km.

Frequently asked questions