Nissan Engineering Team Visit Dec. 3rd: Recap

[evmike]

I specifically asked Mark about Chademo vs. SAE L3. He said Nissan is staying with Chademo.

In a separate thread it looks like they will be adding inductive charging under the vehicle in 2014.

[highcountryrider]

Let me add that I think we have found out what a Gid is; it is the estimate of OCV by conversion from measured amps and volts.

Sorry, what is OCV in this context?

[palmermd]

Sorry, what is OCV in this context?

open circuit voltage. The only time this used is when the car has been at rest for some time (length?). Once you start driving, The car does not know the OCV, but can make an approximation by counting amp hours consumed among other calculations to provide the current state of charge for the battery while in use. Once you turn the car off and let it rest, the computer can then get another reading of the OCV when you start your next trip.

[lemketron]

Sorry, what is OCV in this context?

open circuit voltage. The only time this used is when the car has been at rest for some time (length?). Once you start driving, The car does not know the OCV, but can make an approximation by counting amp hours consumed among other calculations to provide the current state of charge for the battery while in use. Once you turn the car off and let it rest, the computer can then get another reading of the OCV when you start your next trip.

Would this imply that if you've been driving for a (long) while and/or the battery is low and you want to get a more accurate estimate of DTE, that you might (pay attention to your driving speed for a few miles to smooth your average consumption, then pull over and) shut the car off and "reboot" it?

Would that be sufficient to get a good, new OCV (and thus DTE) reading, or does the car really does have to be "at rest for some time"...?

[Christopher]

Sorry, what is OCV in this context?

open circuit voltage. The only time this used is when the car has been at rest for some time (length?). Once you start driving, The car does not know the OCV, but can make an approximation by counting amp hours consumed among other calculations to provide the current state of charge for the battery while in use. Once you turn the car off and let it rest, the computer can then get another reading of the OCV when you start your next trip.

I find this particularly interesting in that I sometimes will come back out to the car after stopping somewhere briefly on the way home to discover that I suddenly have noticeably less charge remaining than I had when I parked it a half hour earlier. It is of course particularly noticeable when I stop with just a bar or two of charge left because I come back out and discover the remaining bars entirely gone and immediately get the out-of-charge warnings. I had wondered if turning the car off and on *caused* a loss of charge (to fill the brake backup power capacitor or something) -- and that perhaps it was safer to head straight home rather than trying to squeeze in another errand if my charge was getting low. Interesting to think that perhaps part of what I'm seeing is just a correction of the previously estimated state-of-charge.

[TEG]

Yes, I think they were suggesting that we don't put ultimate faith in "GIDs" as the system may periodically make "corrections" based on new measurements it is able to make, particularly when you are stopped.

[astrorob]

i have noticed that the DTE does change after powering down and back up again, but usually the car has sat for a while between the power-off event and power-on event. in light of what Kadota-san said, this makes sense. as for how long the battery has to be at rest, i suppose we'd just have to experiment with power cycling the car over longer and longer periods to try to figure out at what point the computer starts trusting the OCV. of course this could be dependent on battery temperature so the length of the trip and the ambient temperature could have an effect on the interval.

[highcountryrider]

Thanks.

So the Gid is computed OCV then, based on what has been withdrawn from the battery, load,
temperature, etc.?

Sorry, what is OCV in this context?

open circuit voltage. The only time this used is when the car has been at rest for some time (length?). Once you start driving, The car does not know the OCV, but can make an approximation by counting amp hours consumed among other calculations to provide the current state of charge for the battery while in use. Once you turn the car off and let it rest, the computer can then get another reading of the OCV when you start your next trip.

[TEG]

Any discussion of how Nissan can assist in US DC Charge infrastructure development?

They have helped by making less expensive hardware, and CHAdeMO chargers are finally getting their UL approvals.
*but* the costs to install and operate them is proving prohibitive for many attempts. Basically I was told that the USA situation is very frustrating since the power infrastructure is controlled by lots of little power companies each with their own ideas of how to bill and control hook up to "their" grid.

The point was made that Oregon & Washington have generally been more reasonable and roll-outs are underway there, but California is a bit of a mess right now.

[TEG]

Great meeting and a definitive no answer regarding an upgrade for a 6.6kw leaf charger on existing LEAFs. But we knew that:)

Oh, they had an answer... no. They mentioned all the wiring harness changes, etc.

I think I heard that the 6.6kW will actually be in the front of the vehicle, with the layout of the components under the front hood being somewhat redone for the next model refresh.

BAYLEAFs made the point that one of our primary interests in this dialog is to do what we can to help them sell more cars. In that regard, I think we don't really know what we are doing, so hopefully Nissan can "steer us" if they think there is some way we can help. So with that said, I am mindful of the concern that "talking up" a future model too much could hurt short term sales as we don't want to make someone go into "wait and see" mode.
So, for anyone on the fence, little future improvements might be accompanied by a price increase (but hopefully not), so waiting could be a mistake!

6.6kW will be a nice little improvement, but many people are doing just fine even with only 3.3kW