Scheduling method 2 keep ur 12v battery charged while vaca

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scottf200

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In my Volt VIN 01234 <actual>
Does the LEAF have a scheduler with sort time increments (ie. 15 minutes). Below is a thought I had on the Volt and thought it was applicable to the LEAF as well. If not let me know and I'll delete this thread:

We know even if plugged in that the 12v battery is only charged when the main 360v battery is also actively being charged. Given that ...

Re: Scheduling method to keep your 12v battery charged while on long trip

* The Volt charging scheduler does 15 minute increments (I just hopped in the Volt to see the incr units. I assume the MyVolt.COM is the same)
* You can charge "off_peak" OR "mid_peak"+"off_peak" as a combo. These are just esoteric names assigned to some hours.
* It has a weekday and a weekend scheduling component.

What if you used this combination to have normal (non-vaca) charging to be "mid_peak".

What if while down_south or on a long_vaca that you set to "off_peak" charging only. And you set the weekend only "off_peak" as an example to do ONE 15 minute charge. This would keep the 12v battery battery topped off. Plug into the 120v charger on the lower 8amp setting even if you have a 240v charger. Run the Volt down to say 5 EV miles or whatever before you leave.

"Automated" food for thought. Hope that makes somewhat sense. A little hard to explain and I'm not that good at it <grin>!

I vote they build in a "vacation charging" schedule so it just wakes up for a couple minutes a day or every 3rd day.
 
The Leaf's 12 volt battery requirements are somewhat different than the Volt's due to its different EV architecture. But yes, if the car is left alone, the inverter will come on every 5 days to top up the battery from the main pack. If the car is outside and it's an SL, the solar panel will also keep the battery topped up.

Does the LEAF have a scheduler with sort time increments (ie. 15 minutes). Below is a thought I had on the Volt and thought it was applicable to the LEAF as well.
 
TomT said:
The Leaf does not have to ever start an ICE as the Volt does so its 12 volt battery requirements are different.
Not sure I follow this comment but the 12v battery in the Volt is *just* to "boot" the computers. The 360v battery and the generator motor would start the ICE/GG. Volt has *no* typical "starter motor" like on a conventional car.

On the other hand, the 12v battery in the Volt is good sized (CCA) as you can jump other cars from it easily and with the Volt "on" the APM will let the 360v charge the 12v so you can jump the neighbors 4x4 truck in the dead of winter.

TomT said:
But yes, if the car is left alone, the inverter will come on every 5 days to top up the battery from the main pack. If the car is outside and it's an SL, the solar panel will also keep the battery topped up.
Good to know. I was under the impression that the 12v battery was only charged when the main battery was also being charged. Thought I read LEAF post on that.
 
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.

scottf200 said:
On the other hand, the 12v battery in the Volt is good sized (CCA) as you can jump other cars from it easily and with the Volt "on" the APM will let the 360v charge the 12v so you can jump the neighbors 4x4 truck in the dead of winter.
 
What happens if the car has been parked with the main battery pack depleted - yes, I know it never actually is supposed to go to zero because the BMS does not allow that - and then is later started? Yes, it has no starter per se, but the generator motor still must be fed sufficient power to turn over the generator's ICE to start it up, and that clearly requires more power that simply booting the Leaf. The motor/generator still assumes a starter's function, no? I assume that is why the Leaf's 12 volt battery can be smaller...

I don't pretend to know all the inner working of the Volt any more than I know the ones of the Leaf, even though I have studied the Leaf service and training manuals in great detail...

scottf200 said:
TomT said:
The Leaf does not have to ever start an ICE as the Volt does so its 12 volt battery requirements are different.
Not sure I follow this comment but the 12v battery in the Volt is *just* to "boot" the computers. The 360v battery and the generator motor would start the ICE/GG. Volt has *no* typical "starter motor" like on a conventional car.
 
TomT said:
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.
OK. I guess I was remembering this thread that stated "The User Manual states that a LEAF cannot be used to jump another vehicle":
http://www.mynissanleaf.com/viewtopic.php?f=9&t=6707" onclick="window.open(this.href);return false;

I have not read the whole LEAF manual, however.
 
TomT said:
What happens if the car has been parked with the main battery pack depleted - yes, I know it never actually is supposed to go to zero because the BMS does not allow that - and then is later started? Yes, it has no starter per se, but the generator motor still must be fed sufficient power to turn over the generator's ICE to start it up, and that clearly requires more power that simply booting the Leaf. The motor/generator still assumes a starter's function, no? I assume that is why the Leaf's 12 volt battery can be smaller...
I'm fairly certain that the Volt's generator (running as a starter) can only be powered from the high voltage battery, so would never put a load on the 12v battery. But of course even "fully discharged" the main battery still has many times as much power (wattage) as any 12v lead acid battery ever has. So your hypothetical problem would never really exist.

Ray
 
scottf200 said:
TomT said:
But yes, if the car is left alone, the inverter will come on every 5 days to top up the battery from the main pack. If the car is outside and it's an SL, the solar panel will also keep the battery topped up.
Good to know. I was under the impression that the 12v battery was only charged when the main battery was also being charged. Thought I read LEAF post on that.
There's an issue where if the car is left plugged in on a charge timer, it seems to prevent the every 5 day 12v charge from happening. So, you want to avoid leaving it plugged in while sitting for long periods, or use a battery tender. The LEAF manual recommends charging it to 80%, leaving it unplugged, and then charging the car every 3 months while storing.
 
How long are you on vacation?

Otherwise you can set LEAF timer to charge 10 minutes once a week and it will top up the 12v battery at the same time. I suggest starting with low state of charge and 80% setting.

It seems to work fine for those that have done it.
 
smkettner said:
How long are you on vacation?
Otherwise you can set LEAF timer to charge 10 minutes once a week and it will top up the 12v battery at the same time. I suggest starting with low state of charge and 80% setting.
It seems to work fine for those that have done it.
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.
Am I mistaken?

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)?
 
leafydragon said:
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)?
http://www.mynissanleaf.com/viewtopic.php?f=37&t=4819" onclick="window.open(this.href);return false;
 
I still want the small windmill that pops up into the airstream and drives a generator.. you deploy that when its windy :)
 
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 said:
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)?
 
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.
 
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.
 
TomT said:
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:
pic


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
 
DarkStar said:
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
 
DarkStar said:
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
 
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