Percentage Question

[donv]

If I show available range as "Rated" (in the US, anyway), I believe this to show, based on a certain energy usage rate, how much energy is in the battery.

Now, if I switch to percentage, what is the percentage showing? Is it showing percentage of original capacity, or percentage of available capacity?

In other words, if I have a 5% degradation in the capacity of my battery, will it charge to 100%, or just 95%?

Presumably the rated range would show the degradation (or else I would never know it's happening), but is it reflected in percentage as well?

 

[TexasEV]

The percentage is the percentage of your battery capacity, so it will always charge to 100%.

 

[donv]

So, in other words, if you only looked at percentage you would never know about battery degradation?

The percentage is the percentage of your battery capacity, so it will always charge to 100%.

 

[Chipper]

So, in other words, if you only looked at percentage you would never know about battery degradation?

Correct.

 

[kennybobby]

It's just an indicator like a fuel gauge, F = Full (100%) E = Empty (0%).

If you drive fast on the highway, hard acceleration starts or lots of hills to climb you get less miles of range for a Full 'tank' than easy starts and slower city speeds, just like any car behaves.

If you want to know actual capacity, then you would need to make a calibrated measurement following a specific test procedure.

If you wanted to determine degradation then you would make this calibrated measurement periodically and plot the capacity versus time or versus number of charge-discharge cycles.

 

[ecarfan]

So, in other words, if you only looked at percentage you would never know about battery degradation?

Yes I think that is correct. It is a percentage of how much rated range you have at that moment out of the maximum possible range you would have if the battery was charged to 100% at that moment.
It cannot be used to measure battery degradation. If you want to estimate degradation, compare a current maximum range on a full charge to what it was at some earlier point in time.