No, It’s Real: EV Range Down

would be interesting to find out, maybe not a bad idea.

 

Has your range changed at all?

 

Are there any difference in your daily average kwh/mile records in the past few weeks?

Posted via the PriusChat mobile app.

 

Miles per kWh, I meant.

Posted via the PriusChat mobile app.

 

Preliminary data does not look good:

The traction battery appears to have lost (6.15-5.90) / 6.15 = 4%. This is bad. However, I noticed the traction battery was only accepting ~14.8A instead of the 16A when the battery was new. . . .

Expand your browser window to see the two, EV JuiceNet, screen captures:

• First one is at Propst, Pratt Ave., on two legs of three phase, 210 VAC.
• Second one is at home on both phases of 240 VAC.

Bob Wilson

 

3 days worth of data? 4% is well within the noise considering temperature, AC use, etc. What am I missing...

 

You count funny.

Bob Wilson

 

Looking at the graph above I guess I count funny too.....

 

Source: George Orwell - 1984 - Part 3, Chapter 2

. . .
O'Brien held up his left hand, its back towards Winston, with the thumb hidden and the four fingers extended.

'How many fingers am I holding up, Winston?'

'Four.'

'And if the party says that it is not four but five -- then how many?'

'Four.'

The word ended in a gasp of pain. The needle of the dial had shot up to fifty-five. The sweat had sprung out all over Winston's body. The air tore into his lungs and issued again in deep groans which even by clenching his teeth he could not stop. O'Brien watched him, the four fingers still extended. He drew back the lever. This time the pain was only slightly eased.

'How many fingers, Winston?'
. . .
'How many fingers, Winston?'

'Five! Five! Five!'

'No, Winston, that is no use. You are lying. You still think there are four. How many fingers, please?'

'Four! five! Four! Anything you like. Only stop it, stop the pain!'
. . . ​

Of course if you count from 0, there are 3:


Bob Wilson

 

I see 72 or 73 hours worth of data, depending on whether I start at 0 or 1

 

Anyway...

 

the first year or two, i lost about 15% of pip range. isn't that fairly standard for lithium?

but i do think the software will limit battery capacity to some degree in intense heat.

i have no bwilson data to back up my claims.

 

I don't understand how they keep all those individual cell in balance. With my RC battery packs with just three cells
it is important to do a balance charge every now and then. How do they keep all these cells in balance because the battery is no better than it's weakest cell.

 

there is a bms (battery management system), it does a pretty good job.

 

I know but thee isn't much information about it. As time goes on the Li-ion batteries will fail with age and cycles and this will look like the Gen 2 forum. You guys with the PIP will be up to bat some day.

 

absolutely. toyota doesn't give much away, but i think a few really bright ee's have done some exploring over the years.
isn't that the nature of batteries, or is there a better way?

 

After reviewing the literature, the bulk of the papers are aimed at microscopic effects such as compounds blocking cathode access and lithium plating. These are separated from independent variables I can control. Stepping back, there are three independent variables:

• temperature - using time of day scheduling
• rate - using the amp setting
• partial discharge - raise the lower SOC by enabling HV before running battery out

The temperature test used the coolest part of the day, just before sun rise, and we are seeing a rapid and significant loss of capacity.

The next test will limit the charge current to half of the 14.7 A measured. So I'll configure the JuiceBox to limit current to 7 A and enable charging two hours earlier, 2:00 AM instead of 4:00 AM.

Partial discharge is harder since measuring the effect requires a full discharge. What I'll probably do is set a target of 10% to switch from EV to HV mode. Do this for a week and retest to full discharge. This has the effect of further limiting cathode depletion during discharge.

Bob Wilson