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Re: Power use at a stop light

Posted: Wed Nov 10, 2010 3:29 pm
by smkettner
23doctor wrote:if the Leaf is sitting still at a stop light - assuming that the climate control is OFF - in READY MODE, the only power consumption is being drawn from the lead acid battery (low voltage). the traction motor requires no high voltage current in the idle state.

in other words, leaf sitting still (climate control OFF) is no different than any car sitting with ignition in ACC

-n-
So you are saying the creep is not powered until the brake is released?
So does the brake disable the throttle to prevent "powerbrake" ?

Where is the info from.... documentation or test drive?

Re: Power use at a stop light

Posted: Wed Nov 10, 2010 4:01 pm
by jrhubott
I doubt very much that power is wasted running the electric motor against the friction brakes to provide the "creep".

The system is a control loop and the "creep" is electronically added at low/no speed depending on the position of the brake peddle. At some point the mechanical friction brakes are engaged and all power is removed from the motor. I'm sure that Nissan spent a considerable amount of time blending these things together and providing the "creep" of a automatic transmission car.

I personally wish they wouldn't have did this but it seems to make sense if you want the car to feel like a gas car.

Re: Power use at a stop light

Posted: Wed Nov 10, 2010 6:23 pm
by garygid
In ACC the inverter (driver for the motor) would likely be OFF, but at a Stop, that circuitry would be ON.

Also, Brake lights will be ON, otherwise you would be "creeping".

Re: Power use at a stop light

Posted: Wed Nov 10, 2010 11:55 pm
by planet4ever
garygid wrote:In ACC the inverter (driver for the motor) would likely be OFF, but at a Stop, that circuitry would be ON.

Also, Brake lights will be ON, otherwise you would be "creeping".
But surely brake lights are powered by the 12v battery, which 23doctor excluded from his statement. As for the inverter, would it need more than a couple of watts if no power is going through it?

Re: Power use at a stop light

Posted: Thu Nov 11, 2010 8:51 am
by garygid
I suspect this:
When the LEAF is ON, the HV battery really powers everything, and the 12v battery might even be charging. The DC to DC converter will supply all the 12v power, powering the 12v buss while it is also "maintaining" the 12v battery that is on that same buss.

With the car OFF, the 12v buss will only be powered by the 12v (nominal) battery. Only then, will the 12v battery be supplying power ... to anything ON and powered by the 12v buss.

Re: Power use at a stop light

Posted: Thu Nov 11, 2010 9:19 am
by EVDRIVER
garygid wrote:I suspect this:
When the LEAF is ON, the HV battery really powers everything, and the 12v battery might even be charging. The DC to DC converter will supply all the 12v power, powering the 12v buss while it is also "maintaining" the 12v battery that is on that same buss.

With the car OFF, the 12v buss will only be powered by the 12v (nominal) battery. Only then, will the 12v battery be supplying power ... to anything ON and powered by the 12v buss.

This is correct. The loads will be the alarm, acc switched loads, car communications, etc.

Re: Power use at a stop light

Posted: Tue Nov 16, 2010 7:55 pm
by leafygreen
a little off topic, but regarding creep feature, you can always put on the parking brake while at the light. It will automatically shut off when you step on the accelerator (hill start mode).
This would be my first car without a clutch and I'm not used to keeping a foot on the brake
pedal at a stop light (on flat surface). I guess a little more power needed to engage the parking brake?

Re: Power use at a stop light

Posted: Tue Nov 16, 2010 10:14 pm
by garygid
In manually turning the Parking Brake OFF and ON, there appeared to be a 1 to 2 second delay after activating the parking-lever (lever-switch) before the "parking-brake" LED (on the lever) went OFF or ON.

So, that might be the time needed to pressurize (or depressurize) the parking brake system?

Re: Power use at a stop light

Posted: Wed Nov 17, 2010 2:13 pm
by TomT
There is a motor driven mechanical system to engage/disengage the rear wheel emergency brake (it uses the rear disk calibers and has a mechanical override in the trunk) and a similar system to engage/disengage the front wheel parking brake pawl (it's uncertain how/if this one can be manually overridden). Both take a certain amount of time to operate, thus the delay.

Tom

garygid wrote:In manually turning the Parking Brake OFF and ON, there appeared to be a 1 to 2 second delay after activating the parking-lever (lever-switch) before the "parking-brake" LED (on the lever) went OFF or ON.

So, that might be the time needed to pressurize (or depressurize) the parking brake system?

Re: Power use at a stop light

Posted: Wed Nov 17, 2010 2:21 pm
by garygid
You are saying that you found out that:

The parking brake is mechanical (not hydraulic) and only 2 wheels (not 4)?

Where did the info come from?
Did I miss a source?