A spare e-bike battery is a bigger shipment than most people expect, and the number that decides everything is watt-hours, not pounds. A common 48V 14Ah pack works out to about 672 Wh, and the line for an ordinary lithium-ion battery mailed by itself sits at 100 Wh. We read that line from USPS's own tariff and ran a real e-bike battery through our own checkout on 2026-08-19 to see what happens next.
An e-bike pack is usually light enough to mail. It is the energy inside it that hits the ceiling first.
Watt-hours are volts times amp-hours, printed or stamped on almost every e-bike pack. The arithmetic below is ours; the 100 Wh line is the standalone lithium-ion ceiling USPS and the Section II air rule both use.
| Common pack | Watt-hours | Against the 100 Wh line |
|---|---|---|
| 36V, 10Ah | 360 Wh | 3.6× over |
| 48V, 10Ah | 480 Wh | 4.8× over |
| 48V, 14Ah | 672 Wh | 6.7× over |
| 52V, 17.5Ah | 910 Wh | 9.1× over |
None of these packs are heavy in carrier terms — most weigh 5 to 9 lb, comfortably under a typical parcel weight cap. Weight is not what stops a spare e-bike battery from mailing like an ordinary spare laptop or tool battery. Watt-hours are.
USPS Publication 52, section 349.244, covers a lithium-ion battery mailed without the equipment it powers — UN3480. Read from pe.usps.com on 2026-08-19: each cell must not exceed a watt-hour rating of 20 Wh, and the battery itself must not exceed 100 Wh. The mailpiece is capped at 5 lb, and section 349.244(e) sends it by surface transportation only, unless both ends of the trip are inside Alaska. Section 349.244(c) requires a DOT-approved lithium-battery mark on the address side naming UN3480, plus the text “Surface Mail Only, Secondary Lithium Batteries – Forbidden for Transportation Aboard Passenger Aircraft.”
A spare cordless-drill battery or a spare laptop battery generally clears that 100 Wh line without much trouble. An e-bike pack, at 360 to 900-plus Wh depending on the bike, does not come close. The 5 lb weight cap in the same rule is usually the smaller obstacle; most e-bike packs would clear it on weight alone if the watt-hour line were not there first.
FedEx's own how-to-ship-batteries page, read 2026-08-19, states that “FedEx Office Print and Ship Center locations do not accept regulated battery shipments, with the exception of lithium battery shipments meeting Section II IATA regulations” — the same watt-hour class USPS caps at 100 Wh per battery, 20 Wh per cell. It does not describe a retail path for a pack larger than that.
UPS's how-to-ship-batteries page, read the same day, does not publish its own watt-hour figure. It directs shippers to the federal 49 CFR Lithium Battery Guide for Shippers and the IATA Battery guidance document, and names the UPS Hazardous Materials Support Center, 1-800-554-9964, for anything outside the routine case.
Neither carrier's consumer-facing page describes an ordinary retail label for a battery this far past 100 Wh. Both route the question to a dangerous-goods desk rather than a checkout box, which matches what our own test found.
Rather than guess, we ran a real e-bike battery through SMKlog's own checkout: 8 lb, packed in a 14 × 5 × 4 in box, described as a spare 48V 14Ah lithium-ion e-bike battery pack, no bike — about 672 Wh — from Berkeley Heights, NJ 07922 to Los Angeles, CA 90001. Captured against production on 2026-08-19.
| Description quoted | Box | Result |
|---|---|---|
| Spare 48V 14Ah lithium-ion e-bike battery pack, no bike | 14 × 5 × 4 in 8 lb packed | No rate returned |
No price came back, on either the parcel side or the freight side. That is the same outcome the 100 Wh line above predicts for a pack this size, and it is why this page cannot show a price the way our other item guides do. What SMKlog does price is the battery still sitting in the bike, described below, and a spare cell or tool battery small enough to clear the 100 Wh line on its own.
Everything above covers a battery shipped by itself. A battery still mounted in the bike's frame or down tube ships under UN3481, not UN3480, which is a different regulatory class but not a shortcut around the review step: our own checkout routes a boxed e-bike with a pack over 100 Wh to manual review too, the outcome our electric bike shipping guide found for a Rad Power RadCity 5 Plus, and it is the shipment most people actually want when they search for this. See the lithium battery label guide for how the UN3480 and UN3481 marks differ, and the how to ship a bike guide for what an ordinary pedal bike costs once the battery question is out of the way.
Wh ratings vary by manufacturer and pack size; check the label on the actual battery rather than assuming one of the four examples above matches it exactly.
Multiply the volts by the amp-hours. A common 48V 14Ah pack works out to 672 Wh, and even a smaller 36V 10Ah pack is 360 Wh. Both are several times past the 100 Wh ceiling that applies to an ordinary lithium-ion battery mailed on its own.
Not at that capacity. USPS Publication 52, section 349.244, caps a lithium-ion battery mailed without equipment (UN3480) at 100 Wh and the mailpiece at 5 lb, sent by surface transportation only. Read from pe.usps.com on 2026-08-19, that 100 Wh line falls well short of a typical e-bike pack.
Not at a retail counter. FedEx's own site, read 2026-08-19, states that FedEx Office Print and Ship Center locations do not accept regulated battery shipments except lithium battery shipments meeting Section II IATA regulations — the same 100 Wh class USPS caps out at. UPS's how-to-ship-batteries page, read the same day, does not publish its own watt-hour figure and instead points shippers to the federal 49 CFR Lithium Battery Guide for Shippers and its own Hazardous Materials Support Center.
Zero rates. We ran an 8 lb, 14 x 5 x 4 in package described as a spare 48V 14Ah lithium-ion e-bike battery pack, no bike, from Berkeley Heights, NJ to Los Angeles, CA through our own checkout on 2026-08-19. Nothing priced, which is the outcome the published 100 Wh line predicts for a pack this size.
It is a different regulatory class, but not an automatic label. A battery installed in the frame ships under UN3481 rather than UN3480. Our own checkout still routes a boxed e-bike with a pack over 100 Wh to manual review rather than an instant ground rate, the same outcome our electric bike guide found for a Rad Power RadCity 5 Plus. See that guide for what the shipment costs once it clears review.