Quick answer: Compare e-bike battery energy in watt-hours (Wh), not amp-hours (Ah) alone. For a nominal specification comparison, multiply the battery's voltage by its amp-hour capacity: Wh = V × Ah. Two batteries can have different Ah figures yet the same Wh rating. That does not make them interchangeable or guarantee the same riding distance.
When one product page says “15 Ah” and another says “20 Ah”, the larger number can look like an obvious advantage. Before choosing between them, put both batteries on the same energy scale. This guide shows the calculation, its limits and the questions to ask before buying.
Read the unit beside each number
| Unit | What it describes | How to use it |
|---|---|---|
| V — volts | The battery's stated nominal voltage. | Use it with Ah when comparing rated energy. |
| Ah — amp-hours | Electrical charge capacity. | Compare it directly only when the nominal voltage is the same. |
| Wh — watt-hours | Energy capacity. | Use it to compare the energy ratings of different batteries. |
| W — watts | Power, rather than stored energy. | Keep a motor's power figure separate from battery capacity. |
Battery manufacturer Renogy explains the Ah-to-Wh conversion: multiply voltage by amp-hours. For this comparison, take both values from the battery specification for the exact configuration you are considering. Do not substitute a charger's output voltage or mix figures from different product versions.
If the manufacturer already publishes Wh, record that figure alongside V and Ah. A calculation from rounded labels may differ slightly from a documented energy rating. A larger unexplained discrepancy is a reason to ask the seller for clarification before comparing or ordering.
Same Ah does not necessarily mean the same energy
Consider two illustrative battery specifications:
- 36 V × 15 Ah = 540 Wh
- 48 V × 15 Ah = 720 Wh
Both labels say 15 Ah, but their calculated energy ratings differ by 180 Wh. The 720 Wh figure is one-third higher than 540 Wh. That is an arithmetic comparison of rated energy, not a claim of one-third more range.
This is why an Ah-only shopping filter can mislead. Before deciding that two batteries are equivalent, find the nominal voltage for each one. If one listing omits it, the comparison is incomplete.
Different Ah figures can describe equal energy ratings
Now change the first example:
- 36 V × 20 Ah = 720 Wh
- 48 V × 15 Ah = 720 Wh
The 20 Ah option has a higher charge-capacity number, but both calculations produce 720 Wh. Choosing it solely because “20 is bigger than 15” would miss the voltage difference.
These are teaching examples, not a comparison test or a recommendation to swap batteries between bicycles. Equal Wh ratings also tell you nothing by themselves about pack dimensions, weight, charging arrangements or the condition of a used battery. Keep those questions on your shortlist instead of treating one number as an overall quality score.
Apply the calculation to a current TTGO specification
The TTGO F7 in Off White provides a concrete example. Its current product page lists a 48 V, 15 Ah battery and a 720 Wh capacity. Multiplying the published voltage and Ah figures gives 720 Wh, consistent with that listing.
Those are manufacturer specifications, not an independent battery-capacity measurement. They help you compare the F7 with another complete e-bike whose battery data is clearly stated; they do not establish how far either bicycle will travel on your commute.
When comparing configurations, keep the exact model, selected variant and source date together. If a seller changes a battery option, revisit the figures. If two sections of a listing disagree, ask for the specification supplied with your intended order rather than choosing whichever number looks more attractive.
Why Wh cannot tell you the distance on its own
The energy rating is one input. Distance also depends on how the bicycle uses that energy. TTGO's F7 product FAQ identifies riding speed, terrain and rider weight among the factors affecting range.
For a useful comparison, ask whether two advertised range figures were obtained with comparable assistance, rider and luggage loads, terrain and riding conditions. A low-assistance journey with regular pedalling is a different scenario from a demanding route with more motor support. If the test conditions are missing, record that gap instead of treating the largest distance as a promise.
Write down your own requirement separately: the distance between dependable charging opportunities, the hills on the route and what you normally carry. Then ask the manufacturer how its range information relates to that use. A Wh calculation can explain a label; it cannot validate an untested route.
Capacity comparison is separate from replacement compatibility
Do not buy a replacement pack just because its Wh value matches the old one. The bicycle's electrical system, battery mounting, connections and intended charger must all be considered. A similar-looking case or matching voltage alone is not confirmation that a replacement is suitable.
The UK Office for Product Safety and Standards advises using manufacturer-recommended batteries, chargers and replacement parts. Ask the bicycle manufacturer to confirm the exact approved part for your model; do not improvise an adapter or modify a battery to make a numerical match fit.
For a TTGO replacement enquiry, our guide to preparing an e-bike support request explains the model information and existing evidence to gather. Send the relevant details through the official contact page.
A comparison sheet you can use before purchase
Create one row per actual product configuration, using these columns:
- Model and variant: identify the bicycle and battery option being offered.
- Nominal V and Ah: copy the labelled values together.
- Published Wh and calculated Wh: note whether they agree, allowing for stated rounding.
- Range conditions: record the assistance setting, route and load, or mark them “not stated”.
- Ownership questions: check handling, the intended charging arrangement and the approved replacement route.
This keeps an unresolved specification visible. It also prevents a larger energy rating from crowding out practical questions such as whether the bicycle fits your storage space or whether you can handle it comfortably.
What if the listing gives only one battery number?
If it gives only Ah, ask for nominal voltage or documented Wh. If it gives only Wh, you can compare the stated energy, but still need model-specific information for charging or replacement. If it gives only W, confirm whether that number describes the motor rather than the battery.
Before deciding: put the figures into Wh, check that they belong to the same configuration, and keep range and compatibility as separate questions. That makes the comparison useful without asking a battery label to tell you more than it can.
Specifications and sources checked on 7 October 2026. Generated illustrations explain the calculations and planning questions; they are not product tests or demonstrations of battery compatibility.
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