Downtube Batteries for Electric Bikes, 36V – 52V
A downtube battery mounts on the frame's diagonal tube, on a metal bracket fixed into the bottle-cage holes, and comes off with a key for charging or for security. It is the most widespread format on electric bikes and on kit conversions, because it does not take up the frame triangle and leaves room for a bottle, a pump or a frame bag.
Every model below is a lithium-ion pack with an integrated BMS, a USB port, a key lock and a charger included. In stock in Romania.
The Downtube Batteries in the Range
| Battery | Energy | Estimated range | Recommended kit |
|---|---|---|---|
| 36V 15Ah | 540 Wh | 50–65 km | 250W – 500W |
| 36V 20.5Ah | 738 Wh | 65–85 km | 250W – 500W |
| 48V 17.5Ah | 840 Wh | 60–80 km | 500W – 1500W |
| 48V 22.5Ah | 1080 Wh | 75–90 km | 500W – 1500W |
| 52V 24Ah | 1248 Wh | 75–95 km | 1000W – 3000W |
Compatibility is set by voltage, not capacity: all batteries of the same voltage fit the same kits, and the amp-hour rating only changes the range. Always compare in watt-hours (Wh), not amp-hours, when choosing between two different voltages.
When to Choose Downtube and When to Choose Triangle
Downtube is the default choice for conversions up to 1500W and for ordinary MTB, trekking or city bike frames. It fits quickly, comes off without tools and looks like a production electric bike.
Move to a triangle battery if you need more than 1000 Wh in a small frame, if you want the weight as low and as central as possible, or if you are fitting a high-power kit where the bike's balance matters.
Not sure which voltage you need? See the full comparison of the whole range on the electric bike batteries page, with energy, range and the recommended kit for each model.