Guess-o-meter or battery capacity

Which is more practical for determining range?

Well the Guess-o-meter does give you a range estimate (battery capacity only tells how many electrons are in the tank).

You just have to keep in mind that the Guess-o-meter's guess is based on your most recent "tank". Thus if you drive for 25mph for an entire charge, the next time you charge up the GOM will show some ridiculous value like 200 miles. Likewise if you drive 80mph for a charge the GOM will show something like 50 miles in range (and indeed while you are driving those two extreme examples you'll see the GOM value change on the fly: When going 25 mph over time you'll see the GOM value rise, and at 80 mph you'll see it drop dramatically).

Its really just knowing how you've driven and what the GOM's guess really is. Also note that the GOM guess gets a bit more accurate the closer to empty you get.

The math just is how much electricity you consume (wH/mile) vs how much you have (capacity) the GOM is doing the math for you.

If you wanted you could do your own GOM math: turn on the enhanced trip meter and divide the capacity remaining by the wH/mile average the trip is showing you (so if it showed 3.4 kWh consumed and 250 wH/mile you could estimate: ((19 - 3.4)*1000)/250 = 62 miles left to go).

I didn't take me very long to get used to how the GOM calculates and to be able to use it on a daily basis...

After 2 years of owning the car, I am noticing that the battery capacity is about 16.2 kWh. What is the best and accurate way to get the battery capacity?

After a full charge reset, I watch the kWh used when the battery shows 50% available. I see 8.1 kWh used for 50% battery.
What have others observed? Is this normal degradation after 25 months or I need to get it checked out?

Cheers.

focussed said:

After 2 years of owning the car, I am noticing that the battery capacity is about 16.2 kWh. What is the best and accurate way to get the battery capacity?

Click to expand...

The best way is probably the "heater run-down test" using the enhanced trip meter.

Here's how...

• Start with a fully charged car.
• Turn on the car.
• Reset the trip meter. (Be sure to use "enhanced" mode which displays net kWh used.)
• Turn on heater to "HI". (Best to use max fan, and leave windows down.)
• Then, let the car run battery down to 0% by making a bunch of hot air. (This will take a couple hours or more -- but do check on it regularly.)
• When finished, note the total kWh displayed by the meter -- this will be your total usable battery capacity.

This works because the trip meter counts all electricity used, even to run things like the heater, not just that used to move the car.

In this case, the electricity will be used only by the heater, but the total kWh used when the battery reaches 0% will naturally reflect the total usable capacity.

focussed said:

After 2 years of owning the car, I am noticing that the battery capacity is about 16.2 kWh. What is the best and accurate way to get the battery capacity?

After a full charge reset, I watch the kWh used when the battery shows 50% available. I see 8.1 kWh used for 50% battery.
What have others observed? Is this normal degradation after 25 months or I need to get it checked out?

Cheers.

Click to expand...

I would say that the displayed state of charge is not completely linear wrt remaining capacity. It seems like SOC changes more rapidly (per kWh used) initially, then levels off. E.g. if I try to estimate capacity from energy used between 100-80% SOC, I might get ~16 kWh. If I estimate from ~60-30% SOC, it might be >20 kWh.

You are right about that. In my case, it would drop very fast for the few few miles and then more gradually afterward. I have the impression, but not certain, that this became more pronounced as the battery aged.

Heater run down test as described above is the best test I know of.

kate spade iphone 5c case I have the same question

Most practical range method is that when it's warm you have about 75-80 miles range and when it's cold it's you have a max of about 50 miles. With the usual variations on that depending on driving type. Beyond that, when you are down to about 20-30 miles left, the GOM will pretty accurately tell you if you will make it to your destination or not assuming you know how far it is to your destination.