Traction Battery - Volts, Amps & SOC%, kWh, Rated Range

[TonyWilliams]

I just did a full range test on #2496:

10,800 miles

Full charge to Turtle mode

116.4 miles
2.9 miles per kWh from
40.14 kWh calculated burn +/- about 0.5
39.4 kWh reported net burn from CAN bus (48.2kWh burned, 9.3 kWh regen)
0.5 kWh estimated remaining usable energy (1.4% * 39.9kWh)
41.8 kWh advertise useable when new at room temperature

1.4% SOC
2.992v - 3.096v - minimum / maximum resting cell voltage
278.72v - resting pack voltage (92 series configuration)
30C - 32C - minimum / maximum cell temperatures


39.9 / 41.8 = 95.5% capacity from new (4.5% loss, however full charge was only 97-ish%)

4.2 - maximum cell voltage during regen
4.14 - maximum observed resting voltage (I believe 4.15 is probably specification)
2.5 - educated guess minimum cell voltage before auto shutdown


Edit: 8 October 2014

42.063kWh - Full charge reported by the CAN bus
50.0kWh - estimate of "from the wall" power required

84% charger efficiency @ 40 amps / 240 volts

 

[fromport]

I just did a full range test on #2496:

Is that the one you are going to QC today ?

 

[TonyWilliams]

I just did a full range test on #2496:

Is that the one you are going to QC today ?

We will probably do #2496 and #1134.

 

[fromport]

We will probably do #2496 and #1134.

Exciting, please keep us posted.
A photo would be nice as well

Q:
you wrote about an empty battery pack:

278.72v - resting pack voltage (92 series configuration)

From a quick glance over some of the chademo specs that is freely available on the net,
a chademo is imho a huge programmable powersupply.
I assume they won't start with a charging voltage of 390 volt of a full battery pack.
do they gently increase the voltage until a certain amps/kW is reached and they gradually increase
the voltage during the charge ?

 

[yblaser]

From a quick glance over some of the chademo specs that is freely available on the net,
a chademo is imho a huge programmable powersupply.
I assume they won't start with a charging voltage of 390 volt of a full battery pack.
do they gently increase the voltage until a certain amps/kW is reached and they gradually increase
the voltage during the charge ?

The charger is a current regulated source. See http://www.chademo.com/05_protocol.html

 

[n3ckf]

showing the linux boot text going by on the screen when you power it on pretty much ruins the first impression...

au contraire, mon ami.... that reassures me that its not built on some version of embedded WIndows!

 

[n3ckf]

oh and i've never seen that screen "No driving power avialable". When mine turtled (the one time i've done that) i didnt get that screen. But i was only turtling for 0.9 miles mostly flat. so maybe i didnt get down as far as you did).

 

[james]

Hi,

This might be a little off topic but would running the traction battery all the way down to turtle be good for it? I know some batteries have memory issues and it helps to run them down from time to time.

Also, are there a general rules regarding good battery treatment for longevity?

thanks
james

 

[TonyWilliams]

Hi,

This might be a little off topic but would running the traction battery all the way down to turtle be good for it? I know some batteries have memory issues and it helps to run them down from time to time.

Also, are there a general rules regarding good battery treatment for longevity?

thanks
james

Lithium batteries don't have memory issues. The best place for the battery is charged to 50%, then kept cool. That's ideal.

Anything that isn't the above is "bad" for the battery.

 

[TonyWilliams]

I have assumed for sometime that the RAV4 EV used 2900ma cells. A little background; the Tesla Roadster used 2600ma cells, as did the Smart ED, and as did the prototype RAV4 (using two 18kWh Smart ED packs).

RAV4 EV has to have a 45kWh-ish battery to be able to offer 41.8kWh usable when new, and we know there are 4416 cells in Rav4 EV. Divided into the 7104 cells that are in a 85/90kWh Tesla Model S = 0.6216 ratio.

0.6216 * 85kWh = 52.8kWh, so clearly the two cars do not share the same 3100-3400ma cells used in Model S. We knew that.

So, 45kWh divided by 52.8kWh is about 85%

85% of 3100ma cells = about 2600ma.

So, just swapping the cells from the 90kWh car (3400ma) will provide a 30% boost in range.

Take the cells from your current RAV4 and use them for a home battery backup.

It's looking more and more like RAV4 EV uses 2600ma cells.

 

[smkettner]

Trouble is by the time a new battery is needed due to loss of capacity I probably just want a new car for the price.
Have to see when the time comes.

 

[TonyWilliams]

Trouble is by the time a new battery is needed due to loss of capacity I probably just want a new car for the price.
Have to see when the time comes.

Oh, I'm quite confident any new, long range battery will be FAR lower cost than an equivalent RAV4 EV replacement car.

Plus, if you don't want the car, somebody else will. It won't just disappear.

 

[ground_gainer]

Trouble is by the time a new battery is needed due to loss of capacity I probably just want a new car for the price.
Have to see when the time comes.

Oh, I'm quite confident any new, long range battery will be FAR lower cost than an equivalent RAV4 EV replacement car.

Plus, if you don't want the car, somebody else will. It won't just disappear.

Seems to me the $13K out of warranty repair danger for the motor/computer issues will never go away and could put a big damper on someone wanting the car later.

 

[smkettner]

What do the cells cost? I see $6 but probably less for 4,416. Still $26,496 or even half that would be a lot to spend on an EV with iffy reliability.
I assume these are special for Tesla that are unprotected. Are they even available?
Assembly and swap would have to be another $2,000+?

 

[TonyWilliams]

Trouble is by the time a new battery is needed due to loss of capacity I probably just want a new car for the price.
Have to see when the time comes.

Oh, I'm quite confident any new, long range battery will be FAR lower cost than an equivalent RAV4 EV replacement car.

Plus, if you don't want the car, somebody else will. It won't just disappear.

Seems to me the $13K out of warranty repair danger for the motor/computer issues will never go away and could put a big damper on someone wanting the car later.

Why does the car have $13k in repairs? That's not what it will cost to put new bearings in the motor, for example. The other bits can likely all come from a salvage car, or a Model S. The cabin heater is shared with the plentiful Nissan LEAF.

 

[TonyWilliams]

What do the cells cost? I see $6 but probably less for 4,416. Still $26,496 or even half that would be a lot to spend on an EV with iffy reliability.
I assume these are special for Tesla that are unprotected. Are they even available?
Assembly and swap would have to be another $2,000+?

Nobody will pay that price !!!

 

[jimbo69ny]

This isn't available yet, but "next year", I suspect we will make this available to you. Lots of work to do.

Have you done any work on this project Tony? I am looking for options to monitor vehicle and battery stats. Id love something like this, but for EVs.
https://play.google.com/store/apps/details?id=org.prowl.torque&hl=en