You can’t measure capacity while charging, especially not for this 1.5V type. Ah is a stupid unit anyway for our applications.
Thank you !!
Absolutely, but they are measuring energy put into the cell. I assume they use the same method when doing a discharge. (?)
Note that Ah is a unit of charge, while Wh is a unit of energy. They’re not the same thing.
Plus, to compare battery energy capacities with Ah properly, it must be for the same voltage (which obviously isn’t the case for 1.5V vs 3.7V cells), same discharge rate, etc.
As for measuring energy when charging vs discharging, there are inefficiencies which means the total energy put in is more than what will be available to get out.
Maybe this ChatGPT explanation will help:
Ah (ampere-hours) and Wh (watt-hours) are both units used to measure electrical energy, but they represent different aspects of that energy.
Definitions:
Ah (Ampere-Hours): This unit measures electric charge. It indicates the amount of current (in amperes) that can be supplied by a battery over a specific period (in hours). For example, a battery rated at 1 Ah can theoretically supply 1 ampere of current for 1 hour.
Wh (Watt-Hours): This unit measures energy. It represents the total amount of work done or energy consumed over time. It is calculated as the product of power (in watts) and time (in hours). For example, a device that consumes 1 watt of power for 1 hour uses 1 Wh of energy.
Relationship:
The relationship between Ah and Wh can be expressed as:
Wh=Ah×V
where V is the voltage of the battery. This means that to convert ampere-hours to watt-hours, you need to know the voltage.
When to Use Each:
Use Ah when you are primarily concerned with the capacity of a battery in terms of how long it can supply a certain current. This is particularly useful in applications where the current draw is relatively constant, such as in battery specifications.
Use Wh when you need to understand the total energy available from a battery or the energy consumption of a device. This is more relevant when comparing the energy efficiency of devices or when planning energy usage over time.
Challenges and Limitations:
Ah Limitations:
- It does not account for voltage, so two batteries with the same Ah rating but different voltages will have different energy capacities.
- The actual capacity can vary based on discharge rates, temperature, and battery chemistry, making Ah a less reliable measure in some scenarios.
Wh Limitations:
- It requires knowledge of the voltage, which may not always be readily available or constant, especially in systems where voltage can fluctuate.
- It can be less intuitive for users who are more familiar with current measurements rather than energy consumption.
In summary, Ah is useful for understanding battery capacity in terms of current, while Wh provides a more comprehensive view of energy consumption and availability. The choice between them depends on the specific context and what aspect of electrical energy you are interested in measuring or comparing.
We do not use an assumed voltage or current (which is the method most chargers adopt). Instead, we use real-time sampling of current and voltage for integration to calculate the energy value. For LI150 batteries, during the charging process, due to the conversion rate differences in the internal integrated chip, there may be some discrepancies in the actual ENERGY. However, during discharging, it simulates real-world applications with a load, so the ENERGY measurement is accurate.
I never use charge cycle numbers whether A or W as any kind of a metric for cell capacity. Actually I have warned agaist doing that several time on BLF. My question was based on only having charged the 1.5 V cells and noticing the charger listed mWh instead of mAh for the cumulative charge. Then I wondered about the derivation for the metric and how it was calculated. Sorry if you misunderstood my question.
Maybe this is why we almost universally use mAh when testing capacity for cells in flashlights. We want to know how long a cell will run our lights at some specific current draw over time (Ah) It is also the way cells are rated by the manufacturer for the most part. It is even included in many cells as part of their identification number (30T, 40T, etc.), Though I do see more cells that include mWh in much smaller print on their labels, at least recently.
Anyway, my questions have been answered. At least I know that the information I want is available, even if it is not the default view. If I had designed the UI, I would have had the mAh on the main screen for consistency. But that is just a preference.
At least there will be consideration of tailoring the LISP function for different battery types. Which is very good! I will look forward to a firmware with this change…
Thanks again @enova18650.com .