cwerdna
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Re: Scheduling method 2 keep ur 12v battery charged while va

Wed Jun 20, 2012 2:20 am

leafydragon wrote:Off-topic suggestion, the Leaf looks surprisingly "low-tech" under the hood, because of the lead-acid-battery.
I understand the need for separate low-voltage pack for safe operation of accessories and safety stuff with the traction battery disconnected.
But how about using NiMH or LiFePO4 packs (with suitable charge circuit and discharge protection logic)?

viewtopic.php?f=37&t=4819

'13 blue Leaf SV w/premium package (owned)
'13 blue Leaf SV w/QC + LED & premium packages (lease over, car returned)
'06 Prius

Herm
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Re: Scheduling method 2 keep ur 12v battery charged while va

Wed Jun 20, 2012 3:22 am

I still want the small windmill that pops up into the airstream and drives a generator.. you deploy that when its windy :)

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TomT
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Re: Scheduling method 2 keep ur 12v battery charged while va

Wed Jun 20, 2012 7:55 am

I left my Leaf unplugged for a month when I was on vacation last year. When I left it was at 6 bars. When I returned it was at 5 bars and everything was fine. So, to me, it is a non-issue.
But yes, leaving it plugged in does cause an issue unless you program the charging timer accordingly. I would not be adverse to calling it a bug...

As to the 12 volt battery, one word: Cost.

leafydragon wrote:Wait a minute, from what I understand of the 12V batt vacation-depletion problem, it is the fact that a charger is left plugged into the car, will either inhibit the 5-day charging of the 12V batt, AND/OR will cause additional draw on the 12V batt whenever the charger is plugged in.
This would be a design flaw.

Off-topic suggestion, the Leaf looks surprisingly "low-tech" under the hood, because of the lead-acid-battery.
I understand the need for separate low-voltage pack for safe operation of accessories and safety stuff with the traction battery disconnected.
But how about using NiMH or LiFePO4 packs (with suitable charge circuit and discharge protection logic)?
59,991 miles/12 bars/289 Gids/68.54 AHr/101% SOH/101.64% Hx 7May15 w/ new Lizard (barely made the warranty).
71,770 miles/12 bars/256 Gids/59.04 AHr/88% SOH/87.92% Hx 3Mar16 at lease return.

Now driving a 2016 Volt Premier. Model 3 reserved.

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gbarry42
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Re: Scheduling method 2 keep ur 12v battery charged while va

Wed Jun 20, 2012 11:39 pm

The criterion for charging the 12V battery is, that any time the traction battery is connected, the inverter is powered up and the 12V battery can be charged. The LEAF, like the Prius, (and possibly others) has a set of relays that completely disconnects the traction battery from the outside world. That's the main reason the 12v battery is needed to "boot up" the car: It's the only power present when the car is off. Connection events include:

- Putting the car in Ready mode
- Charging the traction battery
- Activating climate control remotely
- Periodic intentional recharge of the 12V battery.

Not sure if I missed any. The wild card, as I learned during the Tesla Affair, is
- Thermal management activity.

The LEAF doesn't have any of that, which is why it can be left alone for months at a time. The early Tesla roadsters, on the other hand, got quite a bit of press, since they tended to running stuff from the traction battery even when just sitting. Later models have firmware that is rather less eager to keep everything running all the time. Their thermal management was the significant drain, to the tune of 200 watts or more. I don't know if the Volt does any thermal management after the car is turned off. This would be a consideration, if so.

I did the routine suggested in the original message, a few weeks ago. Mostly is was on a "just to do it" basis, since I was only gone for a week. But I wanted to come back to a charged battery, so I arranged for it to charge each night for an hour and a half at 120V. I started from 50% charge, and I got pretty close--on the final night it was already at 80% so it just kicked off again. And it was ready to go when I got there.
And there goes the first capacity bar! At 24,000 mi on 9/9/2013.
Second bar at 30,500 mi on 2/7/2015.

DarkStar
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Re: Scheduling method 2 keep ur 12v battery charged while va

Thu Jun 21, 2012 8:25 am

What voltages are owners seeing on the 12 volt battery when the vehicle is powered off and the DC to DC Converter isn't running (and solar panel covered on SL models)?

I'm seeing about 12.3 volts at rest, which is considered only about 70% charged. Unfortunately I didn't measure the battery when I first got the car, but there was some discussion that the grabby brakes were being caused by a low 12 volt battery which got me checking things out.
Mikiko (2011 Nissan LEAF ETEC) Status:
Reserved: 04/20/10 | Ordered: 10/01/10 | EV Project Blink Installed: 03/22/11 | Delivered: 03/25/11 | VIN: 568

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Herm
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Re: Scheduling method 2 keep ur 12v battery charged while va

Thu Jun 21, 2012 10:16 am

DarkStar wrote:I'm seeing about 12.3 volts at rest, which is considered only about 70% charged.


Thats not good, you sure the battery is under load?

DarkStar
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Re: Scheduling method 2 keep ur 12v battery charged while va

Thu Jun 21, 2012 11:36 am

Herm wrote:
DarkStar wrote:I'm seeing about 12.3 volts at rest, which is considered only about 70% charged.


Thats not good, you sure the battery is under load?

Under load (with a battery tester), I'm seeing about 11.8 or 11.9 volts. Definitely lower than it should be.
Mikiko (2011 Nissan LEAF ETEC) Status:
Reserved: 04/20/10 | Ordered: 10/01/10 | EV Project Blink Installed: 03/22/11 | Delivered: 03/25/11 | VIN: 568

Oregon Electric Vehicle Association | Electric Auto Association

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Ingineer
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Re: Scheduling method 2 keep ur 12v battery charged while va

Thu Jun 21, 2012 12:44 pm

TomT wrote:The 12 Volt DC-DC inverter can provide something like 100-150 amps (I forget the exact number now) so jumping is possible there too. I did exactly that with a friend's truck last winter, in fact.
The Leaf's DC-DC converter can supply up to about 1.7kW or 135a. This unit takes ~400v power from the traction battery and makes approximately 13 volts. (varies according to charge requirements of the 12v aux battery) It should be able to power up to 1.5kW of external load with no problems, provided most of the accessories are left off.

It operates ANY TIME the main battery contactor is closed, so this means when the car is in Ready, or anytime there is actual charging taking place over J1772 or CHAdeMO.

One interesting thing is, unlike the 12v system on a ICE car, there is almost no voltage sag. The DC-DC converter is a high-frequency switch mode converter, so it can respond very fast to high current surges, whereas a normal ICE car alternator cannot, and it's also RPM dependant for maximum output.

WARNING: NEVER connect anything directly to the negative post of the Leaf's 12v aux battery! This is a current sensor and doing so will disrupt the charging system! (Connect all accessories to the body ground, or, if high-current, the black wire screwed to the top of the DC-DC JB. (Behind the inverter)

Here's a picture during testing:
Image

While Nissan doesn't condone it, you should have no issues jumping another car with the LEAF. Be absolutely sure to get the polarity correct, and connect the ground on the LEAF to the DC-DC converter, NOT THE BATTERY (-) TERMINAL!

Procedure: Connect the red/black jumpers directly to the Pos/Neg terminals of the dead car's battery first, then connect the red directly to the LEAF's Pos battery terminal, and then finally, connect the black jumper lead to the case of the DC-DC. The DC-DC is the large aluminum box behind the "engine looking" inverter. You can easily see the black negative terminal on top of it, which is a good place to grab. Once jumping is complete, disconnect in reverse order. Be very careful not to short the jumpers together when removing them from the LEAF.

The LEAF's DC-DC converter is about as powerful as an alternator on any normal car, and should charge a dead ICE battery enough to start it in a few minutes. No need to "rev" the LEAF! =)

-Phil
Easily Learn Electricity HERE! - - - - Website: http://evseupgrade.com/ - - - - Like us on Facebook: EVSE Upgrade

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JeremyW
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Re: Scheduling method 2 keep ur 12v battery charged while va

Thu Jun 21, 2012 1:18 pm

DarkStar wrote:I'm seeing about 12.3 volts at rest, which is considered only about 70% charged.


That's concerning if true. Lead acid batteries develop sulfation (lead sulfate crystals on the plates impeding current flow) if they sit too long at a partially discharged state. Lead acids love to sit at 100% all the time. This makes them perfect for the float application and partially why Nissan went with it instead of something newer for the house battery. You can give it a float charge and it will be happy for years.

However, I do ask what kind of multimeter you are using to read the voltage. Some of the no-name brands are notoriously inaccurate. :) I'd check with another meter just to be sure. You should be seeing something around 13.5 to 14.1 during float/charging. My guess is the meter is off by a few hundred millivolts, and the DC/DC is fine.

Jeremy
Former 2012 SL leasee 6/23/12 - 9/23/15
Now driving Honda Fit EV, License plate: CHADEMO
2000 Honda Insight for long trips

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Ingineer
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Re: Scheduling method 2 keep ur 12v battery charged while va

Thu Jun 21, 2012 1:30 pm

DarkStar wrote:What voltages are owners seeing on the 12 volt battery when the vehicle is powered off and the DC to DC Converter isn't running (and solar panel covered on SL models)?

I'm seeing about 12.3 volts at rest, which is considered only about 70% charged. Unfortunately I didn't measure the battery when I first got the car, but there was some discussion that the grabby brakes were being caused by a low 12 volt battery which got me checking things out.
This is quite normal, as the battery is NOT ever truly "at rest" as there are internal loads in the Leaf. Temperature will play a role in the voltage, but generally any voltage over 12v while the Leaf is "off" is fine. To perform an actual open-circuit test, you'd have to pull off the negative connection, allow the battery to rest for at least 20 minutes, then read the voltage. At 77F it should be at least 12.4v. (assuming near fully charged) If you perform this test after a main battery charge then the 12v should be near fully charged.

-Phil
Easily Learn Electricity HERE! - - - - Website: http://evseupgrade.com/ - - - - Like us on Facebook: EVSE Upgrade

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