Battery capacity

jerry m · Feb 17, 2025

Hi All,
Whats the correct way to measure the wattage of a giant energypak frame type battery?
The actual battery has 5 female contacts so wouldnt have a clue which are used.
Originally the bike was 375w but the lbs says they fitted a 500w one under warranty, but i havent noticed any difference.

Stihldog · Feb 17, 2025

Wattage is calculated, not measured. Voltage x Current = Watts.
I’m not sure of the connection configuration of a Giant battery. Sry, can’t help any more than that.

Stihldog · Feb 17, 2025

jerry m said:
Originally the bike was 375w but the lbs says they fitted a 500w one under warranty, but i havent noticed any difference.

I can interchange a 500w battery for a 625w on my Trek Rail. There’s no noticeable difference in torque. But there is a difference in time, if the demands on the motor are the same.

Peddle assist is somewhat controlled by you. Mode selection, your energy applied (which can be calculated in watts)to the peddles/motor, duration of torque applied etc. each motor can be different though.

irie · Feb 17, 2025

Stihldog said:
I can interchange a 500w battery for a 625w on my Trek Rail. There’s no noticeable difference in torque. But there is a difference in time, if the demands on the motor are the same.

Peddle assist is somewhat controlled by you. Mode selection, your energy applied (which can be calculated in watts)to the peddles/motor, duration of torque applied etc. each motor can be different though.

As you, we have both. Use 500Wh in winter but will probably switch to 625Wh for longer summer rides especially when we go to France for our summer holiday late June/early July (before kids break up for their summer break).

CraigR · Feb 22, 2025

What difference were you expecting? Changing the battery wattage will only extend how far you can ride, not how the bike performs, as it is just a bigger battery with more juice. I don't know what bike/year you bike is, but most Giant EBikes have the ability to adjust the torque, percent power applied at each setting level, etc... within the Giant app. None of this depends on the battery size, but increasing these setting may cause the battery to drain faster or slower, but will change the performance of the bike.

jerry m · Feb 22, 2025

Stihldog said:
I can interchange a 500w battery for a 625w on my Trek Rail. There’s no noticeable difference in torque. But there is a difference in time, if the demands on the motor are the same.

Peddle assist is somewhat controlled by you. Mode selection, your energy applied (which can be calculated in watts)to the peddles/motor, duration of torque applied etc. each motor can be different though.

I should have made it clear.. i realise the power isnt any different. Its the extra mileage on a full charge that hasnt really changed.
My normal rides are around 50 km and elevation gain usually between 700 -900 mtrs. The juice left at the end really hasnt increased.

CraigR · Feb 22, 2025

Are you looking at the LEDs on the bike or reading the percentages in the App? The lights on the bike are in 20% increments so one battery might be at 21% and the other could be at 39% and the same led would be on. There isn't that much of difference between 375w and 500w. What does the app tell you for the battery percentage after riding with both batteries assuming you are doing the same ride, same gears, same power levels, etc....

Stihldog · Feb 23, 2025

I can compare the Trek Rail 625w, and the Fuel EXE 360w. They both have similar amounts of battery power left after similar rides. The big difference is my personal wattage output on the Fuel EXE is higher. Although I can’t scientifically measure this …it is how I feel. If I use different modes on either bike then power remaining is different.
Not sure if that makes sense.

Battery capacity

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