Service Battery - user replaceable?

My Nissan Leaf Forum

Help Support My Nissan Leaf Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

Nubo

Well-known member
Joined
May 28, 2010
Messages
6,305
Location
Vallejo, CA
Sounds like the "service battery" will be familiar 12V car battery?

I'm hoping this will be made easy for the consumer to deal with, and easy to replace. A maintenance-free AGM deep-cycle battery in a common size would seem to be ideal, something like those from Odyssey (also sold as Sears Diehard Platinum Plus). Hopefully not some special dealer-only hothouse flower.
 
Why deep cycle? It's never used for "starting the engine". I don't think it is even used for running the headlamps (and if it is, they use a lot less power than any you've had before).

No, I'd be willing to bet we're going to get a wimpy hothouse flower, and probably in a space that won't hold anything bigger than a motorcycle battery. But that's OK, because a motorcycle battery is a lot bigger than a laptop battery, and the power in a laptop is about all you are going to need. Besides, it will always be "plugged in" (via DC/DC converter) to the Leaf's hulking giant battery except when the car is powered down.
 
That brings up a question: 12V outlet(s) in the interior ... are they powered by the main traction battery or the small service battery (which in turn is being recharged by the traction battery and the solar panel) ?
 
In most modern vehicles the 12V outlets are only powered when the key is in the accessory position (or the car is on).

I am guessing that with the Leaf, the same will be true, only I'm expecting the car to either be on or off - there's no need for an accessory mode, and in fact, no key.

If that's the case, then the 12V outlet(s) are powered by the traction battery via the 12V DC-DC converter, with the service battery acting as a buffer of sorts. If the 12V outlets(s) work while the car is off, then that power is coming from the service battery alone.

I suppose it's also possible that the Leaf will allow the service battery to deplete to a certain voltage before recharging it, to avoid constantly trickle charging it.
 
garygid said:
For safety, I do expect an "accessory" mode, similar to full-ON, but the car will still be in "park", with brakes locked, and unable to move.

At the very least, having the EVSE attached should do this. At least until someone hacks the car so they can tow a range extender ;)
 
planet4ever said:
Why deep cycle? It's never used for "starting the engine". I don't think it is even used for running the headlamps (and if it is, they use a lot less power than any you've had before).

No, I'd be willing to bet we're going to get a wimpy hothouse flower, and probably in a space that won't hold anything bigger than a motorcycle battery. But that's OK, because a motorcycle battery is a lot bigger than a laptop battery, and the power in a laptop is about all you are going to need. Besides, it will always be "plugged in" (via DC/DC converter) to the Leaf's hulking giant battery except when the car is powered down.

I was thinking along the lines of what happens if/when you run out of range. You may still need the lights on, access to the Nav/wireless for determining the nearest charge point to be towed to and other support functions, may want to run the fan for comfort, etc.. Not to stoke anyone's range anxiety, but I think it's reasonable to say that the day may come when you need it, and the service battery should probably have a decent capacity and also be tolerant of being run down.
 
I tend to agree with Nubo. There are times when I meet up with people in a parking lot, to go running, for example, and I may be sitting in a hot car for 15 minutes or longer if there is a delay. I would want to be able to listen to my music or audiobook, and have A/C or at least a fan. I'm not technical enough to know what size service battery is needed for that.
 
planet4ever said:
Why deep cycle? It's never used for "starting the engine". I don't think it is even used for running the headlamps (and if it is, they use a lot less power than any you've had before).

No, I'd be willing to bet we're going to get a wimpy hothouse flower, and probably in a space that won't hold anything bigger than a motorcycle battery. But that's OK, because a motorcycle battery is a lot bigger than a laptop battery, and the power in a laptop is about all you are going to need. Besides, it will always be "plugged in" (via DC/DC converter) to the Leaf's hulking giant battery except when the car is powered down.

Deep cycle batteries are designed for applications where the battery is used for long periods of time, starter batteries are not designed to cycle as deep and usually have higher peak current capacity. The 12V battery on the leaf does not need to be very big since there is a DC/DC and it does not need to turn a starter or run accessories since the pack can do that. If you run out of range the pack would still be able to power the DC/DC since the 12V system requires very little off the pack, a few amps. having a large 12V battery is a waste or weight on an EV. Every EV I have owned has had a 12V battery similar to a motorcycle battery or slightly larger but never a full size heavy auto battery.
 
Rat said:
I tend to agree with Nubo. There are times when I meet up with people in a parking lot, to go running, for example, and I may be sitting in a hot car for 15 minutes or longer if there is a delay. I would want to be able to listen to my music or audiobook, and have A/C or at least a fan. I'm not technical enough to know what size service battery is needed for that.

For those things it won't matter what size the service battery is, but it will eat into your range.
 
Just very roughly, my Lexus hybrid will run the AC for about 15 minutes on its 0.5kWh battery, so maybe 2kW consumption for the AC maximum?
 
Assuming the 2kW estimate for the A/C load, during an hour (driving or sitting) it would take about 8% (of the original 24 kWh) in the battery pack.

Thus it would "cost" (use up) about 8 LA4 miles, or perhaps 5 freeway miles.

About 12 (or 10) hours to use up a "full" 24 kWh battery pack.
 
From one of the Perry interviews, IIRC, AC in Leaf is quite efficient. Heater is the bad boy. I plan to heat Leaf before leaving home and if possible before leaving office. Ofcource, Seattle doesn't exactly get bone chilling cold, though the number of heating days a year is quite high (we are still heating the house in June).
 
evnow said:
From one of the Perry interviews, IIRC, AC in Leaf is quite efficient. Heater is the bad boy. I plan to heat Leaf before leaving home and if possible before leaving office. Of course, Seattle doesn't exactly get bone chilling cold, though the number of heating days a year is quite high (we are still heating the house in June).


How does that work out though. Your car is still attached to the EVSE, sure, but does it still draw power from the grid even outside your scheduled charging times?
 
I think Nissan (Perry?) gave estimates of A/C cutting range by avg. 10% and heat 20%. I am very interested in this because I use A/C 12 months out of the year.
 
mwalsh said:
How does that work out though. Your car is still attached to the EVSE, sure, but does it still draw power from the grid even outside your scheduled charging times?

You can program your car to heat up / cool down - also send a message from phone. I guess the car will start the AC and draw current from EVSE for that ...
 
The cooling/heating "events" do not need to be "scheduled", but could be "now" events. The car can tell if it is connected to an EVSE, and can "tell" the EVSE to turn "ON" or "OFF". When ON, the EVSE closes its contacts to supply voltage to the car. The car then decides how much current to draw, for whatever purpose.

Preparing to leave a mall, intending to arrive at the car in 10 minutes, one might ask the car to turn on the Air/Heat, presumably without requiring the car to be attached to "shore" power.

Will the car be smart enough to tell you things like, "If you take more than 20 minutes to get here, you might not make it home."?
 
Back
Top