04 / Battery
1,240 cycles run · every car carries the log
The battery test, and what its numbers are worth
One expensive part decides whether a used electric car is a bargain or a liability, and it is the one part a buyer cannot see. So we cycle it, log it, publish it, and hand you the raw test alongside the asking price.
Average state of health
94%
across the current stock
Lowest on the lot
89%
2019 Nissan Leaf, disclosed and priced in
Highest on the lot
100%
2020 Chevrolet Bolt EV
Cycles run in our bay
1,240
cell-level logging on each
The method
One cycle, five answers.
A full charge and discharge cycle with cell-level logging: state of health, per-module deviation, DC charging curve, thermal behaviour and reported range against the EPA figure.
Step one
State of health
The pack is charged to full and discharged under load. Capacity measured against the figure the pack held when it was new, expressed as a percentage. That single number leads the report and the listing.
Step two
Module deviation
Cells age at different rates, and the weakest module decides what the whole pack can do. We log deviation module by module, so a pack with one tired module is identified rather than averaged into a comfortable middle.
Step three
The DC curve
The car is charged from 10% to 80% on equipment that can supply more than it will accept, and the rate is logged as it rises, plateaus and tapers. This is the figure that decides how a road trip feels.
Step four
Thermal behaviour
Pack and coolant temperatures are watched through the cycle. A pack that heats fast under DC charging, or that cannot hold its temperature in traffic, is telling us about its cooling hardware, not its capacity.
Step five
Reported range against the EPA figure
Then the car is driven: a 60-mile mixed loop, with the month and the outside temperature recorded. The rated figure and the measured figure both go on the listing, because the gap between them is what a buyer actually experiences.
State of health, every car
Measured, not read from a display
- 2020 Chevrolet Bolt EV
- 100% of new · 97% of EPA on our loop
- 2022 Hyundai Ioniq 5
- 97% of new · 95% of EPA on our loop
- 2021 Toyota RAV4 Prime
- 96% of new · 93% of EPA on our loop
- 2021 Volkswagen ID.4
- 95% of new · 99% of EPA on our loop
- 2021 Tesla Model 3
- 94% of new · 91% of EPA on our loop
- 2020 Kia Niro EV
- 93% of new · 97% of EPA on our loop
- 2018 BMW i3s
- 91% of new · 94% of EPA on our loop
- 2019 Nissan Leaf
- 89% of new · 92% of EPA on our loop
Health is capacity: how much energy the pack still holds against the day it was built. The second figure is different — how far the car went on our own loop against its EPA rating. They do not move together, and the reason is in the next section.
What it means
Capacity, stated plainly
A car at 100% of new capacity has lost almost nothing a driver would notice. A car at 89% has lost real capacity, and we say so on the listing, in the price and in the defect log rather than hiding it inside an average.
What it does not mean
A verdict on the car
Health is one measurement on one day. It does not tell you how the car was charged, how hot the climate was, or how the next owner will treat it. It tells you what the pack held when we ran the cycle, which is the only honest thing a dealer can state.
Module deviation
A pack is only as good as its weakest module
Averaged capacity can look healthy while one module lags behind the rest. Under load the management system protects the weak module by pulling power from the whole pack, which shows up as a slower charge, a shorter run at speed, and a range estimate that falls faster than the percentage on the dashboard.
We log deviation module by module. Where it sits outside our tolerance, the car does not reach the lot and you never see it listed.
Why we log it
It explains the strange numbers
Two cars with the same state of health can behave completely differently on a fast charger. The difference is usually one module, and the only way to see it is to watch the cells through a full cycle rather than read a single figure off a screen.
What we publish
The finding, not just the average
When deviation is worth knowing about, it appears in the defect log with its severity and what we did about it. The quiet version of this information is what makes used electric cars feel like a gamble; publishing it is what makes them arithmetic.
On the road
Why a peak figure alone is meaningless
A charging peak is a moment, not an experience. The 2021 Tesla Model 3 carries the highest peak on this lot at 250 kW and takes 31 minutes from 10% to 80%. The 2022 Hyundai Ioniq 5 peaks lower at 232 kW and does the same run in 18 minutes. If you buy on the peak figure you buy the wrong car.
Peak power against time spent charging
10–80%, logged in our bay
- 2022 Hyundai Ioniq 5
- 232 kW peak · 18 min
- 2021 Tesla Model 3
- 250 kW peak · 31 min
- 2021 Volkswagen ID.4
- 125 kW peak · 38 min
- 2018 BMW i3s
- 50 kW peak · 42 min
- 2019 Nissan Leaf
- 100 kW peak · 45 min
- 2020 Kia Niro EV
- 77 kW peak · 60 min
- 2020 Chevrolet Bolt EV
- 55 kW peak · 69 min
The honest caveat
Health does not predict your range on a Tuesday.
Two figures, and on this lot they disagree. The 2019 Nissan Leaf holds the lowest health here at 89% and still returned 92% of its EPA rating on our loop. The 2021 Tesla Model 3 carries a pack 5 points healthier and returned 91%. Same loop, same month, same outside temperature.
The tightest run against a rated figure came from the 2021 Volkswagen ID.4 at 95% health, not from the healthiest pack here. Weight, power, tyres, heater use, motorway speed and how full the pack was when the loop started all move the measured number.
Health tells you how much energy the pack holds. The loop tells you what the car does with it.
Read both, and plan around the worse of the two.
Replacement pack, current cost
Fitted, as quoted today
- 2020 Chevrolet Bolt EV
- Covered by recall
- 2021 Toyota RAV4 Prime
- $6,400
- 2019 Nissan Leaf
- $9,800
- 2018 BMW i3s
- $11,200
- 2020 Kia Niro EV
- $11,800
- 2021 Tesla Model 3
- $13,500
- 2021 Volkswagen ID.4
- $15,200
- 2022 Hyundai Ioniq 5
- $16,800
Published so you can do the arithmetic before you buy: the cost of a pack against the price of the car, and how many miles you would have to drive for the difference to matter. Where the honest answer is that a replacement is not worth it, we write that on the listing instead.
Warranty on the pack
Transfers with the car
-
2021 Tesla Model 3
8 years / 120,000 miles from first delivery — transfers
-
2022 Hyundai Ioniq 5
10 years / 100,000 miles on the battery — transfers
-
2021 Volkswagen ID.4
8 years / 100,000 miles on the battery — transfers
-
2020 Chevrolet Bolt EV
New pack fitted under recall 21V-650 — 8 years / 100,000 miles from replacement
-
2021 Toyota RAV4 Prime
10 years / 150,000 miles on the hybrid battery — transfers
-
2020 Kia Niro EV
10 years / 100,000 miles on the battery — transfers
-
2019 Nissan Leaf
8 years / 100,000 miles on the battery — transfers
-
2018 BMW i3s
8 years / 100,000 miles on the battery — transfers
The federal battery warranty — 8 years or 100,000 miles on most cars sold here — belongs to the car rather than to the first owner, so it follows the pack to you. The manufacturer documents go in your file, and the shortest warranty on this page is the one to read first.
Battery / report
Ask for the full test log on any car
State of health, module deviation, the DC curve, pack temperatures and the measured range — the same file our own buyer reads before the car is priced. The car with the weakest pack on the lot right now is a 2019 Nissan Leaf at 89%, and its log is available on request like everybody else's.
Answer within four business hours, from the technician who ran the battery test.