E-bike battery and range

The three numbers on every battery spec

Almost every e-bike battery in this market is described the same way: a voltage, an amp-hour figure, and sometimes a watt-hour figure. Most buyers glance at the first two and move on. They are the two least useful numbers on their own.

Volts (V)

Voltage is electrical pressure. It is set by how many cells the manufacturer wires in series, and it broadly determines how much power the system can deliver without pushing dangerous amperage through the wiring. Most bikes in the $600–$1,200 band use 48V, because 48V pairs sensibly with a 1000W-class motor. Cheaper or lighter bikes often use 36V; some high-power bikes use 52V or more.

What voltage does not tell you is how far the bike will go. A 48V battery is not a big battery. It is a battery at a particular pressure, and it may be tiny or enormous.

Amp-hours (Ah)

Amp-hours measure charge — roughly, how long the pack can supply one amp before it is empty. This is closer to a capacity figure, but it is still incomplete, because an amp-hour at 36V carries less energy than an amp-hour at 48V. Comparing a 36V 20Ah pack with a 48V 15Ah pack on amp-hours alone gets you the wrong answer.

Watt-hours (Wh)

Watt-hours are energy: volts multiplied by amp-hours. This is the fuel-tank number, and it is the one figure that survives comparison across brands, voltages and price points. If a brand does not print it, do the multiplication yourself. It takes five seconds and it is the most valuable five seconds of the entire buying process.

Three bikes, worked through

The AMYET line makes a clean illustration because all three bikes run at the same voltage, so the amp-hour figure is doing all the work.

• AMYET V9-G60 — listed as 48V 20Ah. 48 × 20 = 960Wh. AMYET publishes the 960Wh figure directly.
• AMYET EB26 — listed as 48V 15Ah. 48 × 15 = 720Wh.
• AMYET S8 — listed as 48V 25Ah. 48 × 25 = 1200Wh.

Now the comparison that a spec sheet hides. The G60 and the EB26 are both "48V" bikes with 1000W-rated motors and the same 1500W peak claim. On a comparison table they look like near-twins. But 960Wh against 720Wh is a third more stored energy — 240 watt-hours, which on a mixed ride is worth something like eight to ten extra miles.

The prices AMYET lists are $689 for the G60 and $669 for the EB26. That works out at roughly 72 cents per watt-hour against roughly 93 cents. The EB26 buys you 26-inch wheels and a steel frame for that money, which is a legitimate trade — but it is a comfort trade, not a value trade, and the specification sheet does not make that obvious. Our G60 vs EB26 comparison works through it properly.

The S8 at $1,049 for 1200Wh is about 87 cents per watt-hour, but the per-watt-hour figure is the wrong lens there: that bike also carries a second motor, hydraulic brakes and full suspension, and two driven wheels consume energy faster than one.

Turning watt-hours into miles

A watt-hour figure only becomes useful once you divide it by a consumption rate. Watt-hours per mile is the e-bike equivalent of miles per gallon, and unlike a manufacturer range claim you can estimate it honestly from how you actually ride.

For a heavy fat-tire e-bike — which is what all three AMYET bikes are — consumption typically falls into three broad bands. These are general figures for the category, not measurements of any specific bike:

• Roughly 15–20Wh per mile. Lowest pedal assist, a lighter rider, flat ground, around 15 MPH, no wind, properly inflated tires. This is the band manufacturers quote their maximum range from.
• Roughly 22–28Wh per mile. Moderate assist, mixed terrain, an average rider, some stopping and starting, some hills. This is where most people actually live.
• Roughly 35–45Wh per mile. Throttle-heavy riding, a heavier rider or cargo, sustained speed near the bike's ceiling, hills, cold weather or soft tires.

Applied to the three packs, as estimates only:

• 960Wh (G60): ÷ 18 ≈ 53 miles gentle; ÷ 25 ≈ 38 miles mixed; ÷ 40 = 24 miles hard.
• 720Wh (EB26): ÷ 18 = 40 miles gentle; ÷ 25 ≈ 29 miles mixed; ÷ 40 = 18 miles hard.
• 1200Wh (S8): ÷ 18 ≈ 67 miles gentle; ÷ 25 = 48 miles mixed; ÷ 40 = 30 miles hard — and the S8 has two motors, so the hard-riding band is the one to plan against if you use both.

Notice how closely the middle band tracks what AMYET publishes. Their EB26 listing gives about 30 miles on throttle alone against up to 60 with pedal assist; 720Wh ÷ 30 miles is 24Wh per mile, which sits exactly where you would expect throttle riding to sit. That consistency is a reason to take their numbers more seriously than most. The mechanics of why the headline figure still overshoots are covered in why claimed range is never the range you get.

What is inside the pack, and why nobody tells you

Two 960Wh packs can behave very differently. Watt-hours describe how much energy is stored; they say nothing about how well the pack delivers it, how gracefully it ages, or how safely it fails.

Inside a typical e-bike battery are dozens of cylindrical lithium-ion cells — usually the 18650 or 21700 format — wired in series to reach the voltage and in parallel to reach the capacity. A 48V 20Ah pack is commonly thirteen cells in series by four or five in parallel, somewhere around fifty to sixty-five cells in total. A battery management system sits alongside them, balancing cells, cutting off at low voltage and preventing overcharge.

Cell brand matters and is rarely disclosed

Cells from established manufacturers such as Samsung, LG, Panasonic or Molicel are held to tighter tolerances than unbranded ones. They hold rated capacity more honestly, sag less under load, tolerate more charge cycles and behave more predictably when abused. Premium brands advertise their cell supplier for exactly this reason.

Most budget brands do not name their cells, and AMYET is among them — their listings state capacity, removability, and in two cases an IP rating, but not a cell manufacturer. That is not evidence of a bad pack. It is an unknown, and it is worth treating as one. If the cell supplier is unpublished, the practical substitutes for that information are the safety certification, the warranty term, and whether the brand sells replacement packs at all. We explain how we weigh unpublished specifications on our how we review page.

Removable or integrated

A removable pack unlocks from the frame with a key and lifts out. An integrated pack is sealed into the downtube and charged in place. Both designs are common, and the choice affects daily life more than most specifications do.

Removable wins on three practical grounds:

1. You can charge indoors without the bike. If you live up a flight of stairs, the difference between carrying a seven-pound pack and wheeling a seventy-pound bike is the difference between charging every day and charging when you can face it.
2. Replacement is a purchase, not a repair. When the cells degrade in year four, a removable pack is a part you order. A sealed one is a service job.
3. You can store it at a sensible temperature. A battery left on a bike in an unheated garage through winter, or in direct summer sun, ages faster than one kept indoors.

Integrated packs win on looks, on frame stiffness and often on water ingress, because there is no connector interface exposed to road spray. All three AMYET bikes are listed with removable packs, which for a bike in this weight class is the sensible choice.

Charge time and what it tells you about the charger

Charge time is one of the few specs you can reverse-engineer. Energy divided by charging power gives time, so if you know two of the three you know the third.

AMYET lists 5–8 hours for both the G60 and the EB26. Take the G60's 960Wh: filling it in six hours needs roughly 160 watts of charging power, and at around 48V that is about 3.3 amps. Filling it in eight hours needs about 120W, or roughly 2.5A. So the claim implies a charger somewhere in the 2–3A region, which is standard for the category.

There is a detail worth noticing here. The EB26's pack is 25% smaller than the G60's, yet AMYET quotes the same 5–8 hour window for both. With an identical charger the smaller pack should fill in roughly three-quarters of the time. The likeliest explanation is that 5–8 hours is a generic figure applied across the line rather than a measured one for each bike. It is a small thing, but it is the kind of small thing that tells you how precisely to read the rest of the sheet.

AMYET does not publish a charge time for the S8 at all, though the listing does mention dual charging — two ports, which on a 1200Wh pack is a meaningful convenience if it means two chargers can work at once.

Faster is not always better

A 5A fast charger will fill a 960Wh pack in around three hours, and some riders buy one. The cost is heat, and heat is the main thing that ages lithium cells. Charging at a moderate rate, and letting the pack cool before you plug it in after a hard ride, is worth more over four years than the two hours you save on any given evening.

Lifespan, cycles and what actually kills a pack

Battery life is measured in charge cycles, where one cycle is a full charge's worth of energy — two half-discharges count as one. A decent lithium-ion e-bike pack is typically rated for somewhere in the range of 500 to 800 cycles before it falls to about 80% of its original capacity. Cheaper cells reach that point sooner.

For a rider doing 15 miles a day on a 960Wh pack, a full cycle might take two or three days, which puts 500 cycles somewhere in the region of three to five years. That is a rough envelope, not a promise, and it assumes the pack is treated reasonably.

The four things that shorten it

• Heat. The single biggest factor. Charging a hot pack, storing a bike in a sun-baked shed, or leaving it in a car boot in summer all accelerate capacity loss.
• Running to empty. Deep discharges stress cells. Habitually arriving home at 2% is harder on a pack than habitually arriving at 25%.
• Storing at 100%. A pack left fully charged for months degrades faster than one left at 40–60%. If the bike is going away for winter, part-charge it and check it every couple of months.
• Cold. Cold temporarily reduces available capacity — often 20–30% below roughly 40°F — and charging a pack that is near or below freezing can cause permanent damage. Bring it inside and let it warm up before plugging it in.

None of this requires effort. Charge to full when you are about to ride far, stop at 80% when you are not, keep the pack indoors, and do not charge it straight off a hot climb. That is the whole discipline.

Replacement packs and the cost of ownership

The battery is the most expensive component on the bike and the only one guaranteed to wear out. Any honest sum for what an e-bike costs over five years has to include a pack.

Across the US market, a replacement 48V pack of this size typically runs somewhere in the low-to-mid hundreds of dollars — a substantial fraction of what a $689 bike cost in the first place. We are not quoting an AMYET figure here because they do not publish a replacement price we can cite; treat the general range as a planning number and confirm the actual cost with the brand before you buy.

Three questions worth asking any brand before ordering:

1. Do you sell a replacement pack for this exact model, and at what price?
2. How long do you commit to stocking it? A bike whose pack is discontinued in year three is a bike with a three-year life.
3. Is the pack a proprietary shape or a common frame-mount format? Common formats have third-party alternatives; proprietary ones do not.

This is one place where a removable pack and a brand that sells spares is worth more than a slightly better specification elsewhere. When we set out the case for each bike on our best AMYET e-bikes page, the availability of parts is part of it.

UL 2849, UL 2271 and IP ratings

Two safety standards get quoted on e-bike listings and they are not interchangeable.

UL 2271 covers the battery. UL 2849 covers the bike.

UL 2271 is a standard for the battery pack itself. UL 2849 is broader: it covers the complete electrical system — pack, charger, controller and motor tested as one. Most lithium fires are not caused by a cell failing in isolation but by a mismatch somewhere in that chain, which is why UL 2849 is the more meaningful claim. A listing that says "UL-certified battery" is describing the narrower standard, and a listing that says "UL 2849" is describing the whole bike.

This has stopped being an abstract question. New York City's Local Law 39 requires that e-bikes and their batteries sold or leased in the city meet the relevant UL standards, and beyond any specific statute a growing number of landlords, building managers, employers and insurers now ask for UL 2849 before they will let a bike be stored or charged inside. If you live in a flat, this specification may decide where the bike sleeps.

IP ratings

An IP rating has two digits: the first for solid particles, the second for water. IP65 means dust-tight and protected against low-pressure water jets from any direction. IP54 means protected against limited dust ingress and against splashing water. Neither means submersible, and no IP rating on a battery says anything about the rest of the bike's electronics.

AMYET lists the EB26 battery as IP65 and the S8 as IP54, and does not publish a water-resistance figure for the complete G60. In practice all of these are rain-capable and none are pressure-wash capable. Never jet-wash an e-bike near the battery interface, the controller or the motor cable entry.

If you want the power side of the specification sheet decoded in the same way, read our motor wattage guide, and if you are still narrowing the field, our how to choose an electric bike guide puts battery capacity in order against everything else.