How the EZ Rider Dual Battery Ebike Conversion Kit Works: Range, Weight and Charging

DUAL BATTERY UK ROAD-LEGAL 250W UK + US

The Quick Answer

The EZ Rider is a 36V, 250W front-hub kit that ships with two LG-cell packs: a 7Ah unit and a 15Ah unit, 22Ah in total. That is 252 Wh plus 540 Wh, or 792 Wh nominal. Both packs are 36V, so the second one adds stored energy, not voltage or speed.

KirbEbike quotes 40–60 miles with both packs fitted, using pedal assist at the 15.5mph limit on mixed terrain. That works out at about 13–20 Wh per mile. Use that band, not two added-up range claims, to decide whether your ride needs one pack or both.

How Does the EZ Rider Dual-Battery System Work?

The front wheel is replaced by an EZ Rider 36V 250W geared hub motor (50 Nm, 3.8 kg as a wheel), which is powered by a 36V 14A smart FOC controller and TFT colour display. The power is provided by two 36V lithium-ion packs with LG cells: a 7Ah pack and a 15Ah pack. Fitting is a front wheel swap which includes both batteries and clicking two waterproof connectors together, and the installation bracket already has both connectors integrated.

7Ah + 15Ah: What the Two Battery Sizes Mean

Amp-hours measure charge; watt-hours measure energy, and energy is what decides range. Multiply voltage by amp-hours:

Nominal figures. See our Ah vs Wh guide for more.

Which Pack Is Which

In KirbEbike’s product photos, the 7Ah pack is the handlebar unit, the same unit used on the original single-battery EZ Rider. It carries the colour display, the charging port, an activate button and the system connector, and the display shows battery voltage, speed, assist level and mileage. The 15Ah pack is a separate locking case for the frame.

Why Both Packs Must Be the Same Voltage

Two packs can only share one controller if the system is designed for it, and both packs must sit on the same voltage platform. On the EZ Rider both are 36V and both come in the kit, wired through KirbEbike’s own harness. Do not add, swap or combine packs from other systems, and do not attempt your own parallel wiring.

Dual Battery vs Single Battery: What Changes for Range?

The second pack triples the stored energy of the original 7Ah kit: 792 Wh against 252 Wh. Whether that triples your range depends on how you ride.

252 Wh vs 540 Wh vs 792 Wh Combined

Why Two Range Claims Should Not Simply Be Added

Range is energy divided by consumption, and consumption changes with speed, hills, wind, temperature, rider weight and how hard you pedal. Two range claims made under different conditions cannot be added. Work in Wh per mile instead: at 13.2 Wh per mile the full 792 Wh lasts 60 miles; at 19.8 Wh per mile it lasts 40.

What Conditions Support the 40–60-Mile Claim?

KirbEbike states the conditions: both batteries fitted, pedal assist at the 15.5mph limit, mixed terrain, with rider weight, hills, wind and temperature changing the result. It is a pedal-assist figure; you are contributing effort the whole way. Two owner reviews line up with it: one reports “around 60 miles” from the dual setup, and one rider on the older 7Ah-only kit reports 20–30 km (12–19 miles) per charge with a child seat at assist levels 2–3, which is about 13.5–20 Wh per mile.

Range Scenarios for Real Commuting

Short Urban Commute: Carry One Pack or Both?

Up to about 10 miles round trip, the 7Ah handlebar pack covers the ride with a reserve at typical consumption. One owner uses the original single-pack kit for a 6 km ride to a train station with a big climb home, and takes the unit off to carry onto the train.

20–30 Mile Round Trip: Where the Second Pack Helps

Here the 7Ah pack alone is not enough. The 15Ah pack covers 20 miles comfortably; at 30 miles it is enough only at low consumption. Fitting both turns a tight margin into a comfortable one, which matters on cold days and against headwinds.

40–60 Mile Day: What Has to Be True?

You need both packs and steady, efficient riding: moderate assist, sensible pedalling and few hard climbs. At the top of the consumption band, 792 Wh runs out at 40 miles. Plan a charge stop for longer days rather than relying on the 60-mile figure.

Range vs Weight: Is the Second Battery Worth Carrying?

What the Kit Weighs

The motor wheel weighs 3.8 kg. KirbEbike does not publish separate weights for the 7Ah and 15Ah packs. As reference points, KirbEbike’s other 36V 15Ah pack (sold with its 500W/750W kit) is listed at 2.5 kg, and Swytch lists its MAX+ handlebar pack at 2.1 kg. A second pack is a real addition to carry, so leave it off for rides that do not need it.

Where the Batteries Sit on the Bike

The 7Ah unit sits on the handlebar bracket, so its weight is part of the steering. The 15Ah pack goes on the frame, where its mass sits lower and more centrally. Check the frame space and the removal path before fitting; our frame-fit guide covers the three checks.

Low and Central Weight vs Handlebar Weight

Weight low in the frame affects handling least; weight on the bars or high on a rack is felt more in steering and when lifting the bike. Leaving the frame pack off for short rides keeps the bike light; leaving the handlebar unit off is not an option, as it carries the display and controls. See our battery guide for placement trade-offs.

How Charging the Two EZ Rider Batteries Works

One Charger, Two Packs

The kit includes one 36V 4A charger with a 100–240V input and UK, US, EU and AU plugs. Use only that charger, and charge each pack as KirbEbike’s instructions describe; do not use splitters or third-party chargers.

7Ah vs 15Ah Charging Time

From empty, a charger cannot finish faster than Ah ÷ amps. Lithium-ion charging slows near full, so real times are a little longer; top-ups are proportionally quicker.

Charging Checklist

• Use only the supplied or KirbEbike-authorised charger
• Charge on a hard, dry, ventilated surface away from escape routes
• Stay nearby while charging; do not charge while asleep
• Do not charge a damaged, swollen, unusually hot or wet battery
• Let a warm pack cool before charging

From UK government and US CPSC battery guidance (GOV.UK; CPSC).

EZ Rider System: Fit, Installation and Road Use

Universal vs Brompton Fit

Tyre and inner tube are not included. Gears and rear wheel stay as they are. Maximum load is listed as 100 kg. Measure first with our wheel and dropout guide.

250W Front Hub + 36V 14A FOC Controller

The motor is rated 250W with assistance stopping at 15.5mph (25 km/h), which is the Great Britain limit for an electrically assisted pedal cycle (DfT). A bike fitted this way needs no registration, tax or insurance, and riders must be 14 or over (GOV.UK). The optional thumb throttle is not road-legal in the UK, as KirbEbike notes. In the US, the federal definition covers motors under 750W and 20mph on motor power alone (16 CFR § 1512.2); state and local rules on where you can ride vary.

What the 20-Minute Installation Involves

KirbEbike puts fitting at about 20 minutes: swap the front wheel, mount both batteries and click the two waterproof connectors together. Fitting the pedal-assist sensor can mean removing a crank, which takes longer on some bikes. The kit includes tyre levers, a wrench, hex keys and cable ties, and it is fully reversible.

Lightweight Conversion Options Compared

Each maker’s published figures, November 2026.

For a factory benchmark, Bosch’s DualBattery for its smart system combines up to two batteries for a maximum of 1,600 Wh (Bosch). According to Bosch, the battery with the greatest charge is used first until the two batteries are equal, after which both discharge at the same rate, and charging operates in reverse (Bosch). It's a full bike system, not a conversion kit, but it demonstrates the level of detail to which you can expect to be able to ask any dual-battery system supplier.

Dual Battery vs Bigger Single Battery: Which Is Better?

When Dual Batteries Make Sense

Variable commutes, weekend rides much longer than weekday ones, and riders who want to take the handlebar unit off and carry it indoors or onto a train.

When a Single Battery Is Simpler

Short, predictable routes, minimal cable management, or riders who never need more than one pack’s energy. Our battery collection lists single-pack options.

What to Check Before Buying a Dual Battery Ebike Conversion Kit

Electrical Compatibility

Both packs must be on the same voltage platform, the controller must accept the full-charge voltage, the battery current rating must cover the controller, and the method of combining the packs must be the manufacturer’s own. See our BMS amps guide.

Mounting Space and Removal Path

Template both packs, check steering and fold clearance on folding bikes, and make sure each pack can be removed without loosening its mount.

Charger Compatibility

Use only the charger approved for those exact packs. A matching plug does not prove electrical compatibility.

Your Real Route

Multiply your round trip by a realistic Wh per mile, add 20% for hills, wind, cold and battery ageing, and compare it with each pack’s Wh. Our range calculator does this for you.

Conclusion: Two Packs Are Worth It When the Second One Solves a Real Problem

The EZ Rider’s second pack takes the kit from 252 Wh to 792 Wh, three times the stored energy of the original, on the same 36V, 250W, road-legal system. At the 13–20 Wh per mile implied by KirbEbike’s claim, that covers 40–60 miles; the handlebar pack alone covers shorter rides.

Carry both when your ride needs more than about 250 Wh, leave the frame pack off when it does not, and charge with the supplied 4A charger only. Measure your fork and your route before ordering.

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