dogeTune

BATTERY BUYING GUIDES

Buying a battery? Don’t buy the wrong one. Check these four things first.

Before you pay for any e-bike or scooter battery, check four things: the fit, the controller, motor and plug, the charger, and what’s inside. Each one has a short guide below.

Not sure which one? Send the photos and your bike model, and we’ll check with you.

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A used-battery listing screenshot: a pack on a person's lap, priced S0, with a seller description saying they know nothing about it
A real used-battery listing: S$140 for a “60V” pack, and the seller says they know nothing about it. The main photo shows no label. Seller name covered.

The four checks

CHECK 1

Will it fit the space?

Not sure how to measure the space for your battery? Pick the one that sounds like you, and send us what it asks for.

SCENARIO 1

I can measure my own frame

Send us a detailed drawing of the space, with every length, width and height written on it. Mark anything that sticks into it.

A hand-drawn battery case sketch with depth, width and height written across the top
A drawing a customer sent us: depth, width and height written at the top, each side marked on the sketch.
A battery pack photographed on foam with the length of each side marked on the photo
A customer photo with the length of each side marked on it.
A pencil sketch on grid paper of a battery shape with its side lengths
A rough sketch on grid paper: the shape and lengths are there. Add the unit, mm or cm, next to each number.

SCENARIO 2

I have the bike, no battery, and measuring is not my thing

Send us three photos of the frame, each in a flat top-down view, with a tape measure laid in the shot for scale. We trace the inside of the frame for you, then design a battery to fit it.

A bike frame with a tape measure run through the frame triangle under the battery box
What you send: the frame, with a tape measure for scale.
A photo of a bike frame with the inside of the frame traced over it in CAD, with dimensions
What we do: trace the inside of the frame over your photo.
The traced frame space with a battery cell layout designed inside it
Then we design the battery inside the traced space.

SCENARIO 3

The original battery is dead

Measure its length, width and height, and send us the three numbers. Hook the tape hard against the edge, so the reading starts at zero.

A battery pack with a tape measure laid along its length
Length: a tape measure laid along the pack, from one end.
The hook end of a tape measure held against the edge of a battery pack
Hook the tape hard against the edge, so the reading starts at zero.
A tape measure stretched across the width of a battery pack, its hook held at the edge by a hand
Width: the tape across the pack, the hook held against one side.
Send us your drawing, photos or numbers

Which battery fits my bike?

CHECK 2

What controller, motor and plug does your bike have?

Send us a photo of the label on the controller, a close-up of the plug on the battery lead, a photo of the bike, and the motor wattage. The controller label shows the model, the voltage range and the current rating. The plug shows what the battery has to connect to. Together they let us match the battery to what your bike pulls. The motor wattage is on the motor sticker or in the bike’s listing.

The battery numbers · Photos that help · Which battery fits my bike?

A bike being worked on at a job site with its controller and wiring exposed
Send a photo of your bike too, like this one from a job on site, so we can see where the controller goes.
Close-up of a Fardriver ND72360 controller label showing model, line and phase current and voltage
Close-up of a Fardriver ND72360 controller label: model, 190A line current, 360A phase current, 72V.
Two QS8 plugs on braided leads with a QS8 dust cap beside them
Two QS8 plugs on braided leads, with a QS8 dust cap beside them. A close-up like this lets us check a connector.

CHECK 3

Does the charger match?

A plug that goes in is not the same as a charger made for that battery. Check the label on both before you switch on.

Same plug, different charger?

A pack label showing 72V 20Ah, 20S6P, 50G 21700 cells and full charge 84.0V
A pack label that spells it out: 72V 20Ah, 20S6P, 50G 21700 cells, full charge 84.0V, max charge current 6A.
A charger label showing model 72V5A, output 84.0V and 5.0A
A charger label to match against: model 72V5A, output 84.0V and 5.0A. Its output voltage should equal the pack’s full-charge voltage.
A 109.2V 5A charger with an aviation connector and a mains plug adapter
Not this one: a 109.2V 5A charger. Its label shows output up to 109.2V, far above the 84.0V that 72V pack charges to. The plug fits the socket, and it is still the wrong charger.

CHECK 4

What is built inside the pack?

A big number printed on the BMS does not rate the rest of the battery. Ask what the current actually has to pass through.

Big number on the BMS · Cells vs complete battery

Battery cells in a clear case on a bike frame, joined by soldered wire links
Cells in a clear case on a bike frame, each tied to the next by soldered wire links.
Battery cells joined by soldered wire loops under yellowed masking tape
Cells joined by soldered wire loops under yellowed masking tape.
Our battery pack with welded strips across the cells, insulation boards down the side and leads out of the top
Ours: strips welded across the cells, insulation boards down the side, leads out of the top.

THE GUIDES

Ready to look at batteries?

Pick the kind you need, or ask us first.

An electric motorcycle frame with a battery mounted in it

Bike batteries

Find your bike model and the batteries that suit it.

A finished triangular battery pack made for a frame, with its label

Custom & conversion

Odd-shaped space or a conversion? Start here.

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