Battery life in AH's

[Brannenthompson1]

Does anyone know the standard for a 15ah battery what is the 15ah ie all batteries are sold in amp hours but what should you get when using it on your E Bike for instance I seem to be getting about 9ah between 42 and 32v but if I had a 10ah battery would I only get 6ah as in two thirds of the stated amp hours or should you get the full 15 or 10ah that are advertised between 42v fully charged and 32 volts minimum. The question is should I see 15ah being used between full charge and 32volt cut off? Is there an industry standard for the usable amp hours a battery makes. Its driving me crazy Because my watt meter is telling me I'm using around 9ah between full charge and 32v, I have a 36v 500w hub motor with 22amp max controller my battery specs are
Nominal Capacity 15 Ah
Nominal Voltage 37 v
Cell Inside Li-ion 3.7V 2600mAh
Configuration 10S5P
Standard Charge Current 3 a
Max. Charge Current 15 a
Protected Circuit Board(BMS) GLBR-Li10S1505-BMS
Continue Discharge Current 15 a
Peak Discharge Current 30 a
Full Charged Voltage 42V
Charge Cut-off Voltage 42.5V
Discharge Cut-off Voltage 25V
Battery Net Weight 3.7 kg
Life Cycle 800

 

[flecc]

The amount of capacity you get is dependent on the rate of current draw, the makers rating usually being at a low rate of draw. E-bike batteries are often worked quite hard so don't reflect the maker's rating in practice.

Some while ago A to B did some repeated tests on a powerful e-bike to empty the battery each time. Starting with using minimal power, they gradually stepped up the power used on subsequent trips to measure the amount used each time.

The nominal 10 Ah battery returned a declining set of results from 10 Ah down to just over 7 Ah realised. So what you are seeing is normal.
.

 

[Nealh]

Most manufacturers use a basic/standard capacity test for rating cells which in turn relates to the possible max battery Ah with cells in parallel.
To quote max possible cell capacity they use a meagre discharge rate of 0.2a and drain the cell to about 2.8v.
For ebike use we are never going to discharge that low and the discharge amp rate is always far more then 0.2a, so what you are experiencing is fairly normal.

 

[Woosh]

Cell Inside Li-ion 3.7V 2600mAh
Configuration 10S5P

stop torturing yourself!

10S = 31.5V to 41.5V
5P with 2600mAH = 13AH

The 15AH is usually made with either Samsung 2900mAH (14.5AH) or Panasonic 18650F 3000mAH cells.

 

[Deleted member 4366]

That's right. Nominally, it's a 13ah battery. It should give close to that at a constant current of around 5A, but if you run everywhere with full power, you can lose around 20%.

Cheap wattmeters aren't always reliable and expensive ones often need calibrating with the correct shunt value before they give correct results. You can get a good estimate of its accuracy by checking between the charger and the battery. During say a 4 hour charge with a 2 amp charger the first two hours should give 4 amp-hours.

Finally, there's the condition of the battery. Does it charge to at least 41.5 volts? How old is it?