charging while in "ready" mode ?

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RustyShackleford

Well-known member
Joined
Jun 24, 2019
Messages
157
Location
central NC
I am wondering if it's feasible and safe to charge a Leaf (via the charging cord plugged into a 120vac outlet) while the car is in "ready" mode.

The reason I ask: I have rigged my car so that I can connect an 120vac inverter to the Leaf's 12vdc system, and use that inverter to drive some essential loads in my home (per the "my Lead-to-home thread https://www.mynissanleaf.com/viewtopic.php?t=13097).

I also have a grid-tied solar PV system, which uses an SMA SunnyBoy inverter, which has the "secure power" (SPS) feature where it's able to supply 1500watts or so of 120vac power even when the grid is down (if the sun is shining). I've tested plugging the Leaf charging cord into the SPS outlet, and indeed it does work to charge the car (albeit very slowly).

So what I'd like to do (during outages longer than a day) is run my essential loads off the "Leaf-to-home" 120vac inverter that's connected to the Leaf's 12vdc system, and also top off the Leaf's battery from the solar inverter's SPS outlet during the day. The issue is, can I do both simultaneously ? I'd rather not have to take the car out of "ready" mode, thus de-activating the Leaf-to-home and cutting power to my essential loads, while I'm charging from the solar; especially since that's when it's most likely to be hot and thus I'd like the refrigerator to be powered.

One answer might be "just try it", but I'd rather have some idea if it's safe (as far as damage to the Leaf) first.
 
What I suggest instead is that you have a 'buffer battery bank' that can provide home power for a few hours while the Leaf is offline and charging. This bank would be connected to the Leaf's 12 volt system. It would be safer for the car to go this route.
 
RustyShackleford said:
So what I'd like to do (during outages longer than a day) is run my essential loads off the "Leaf-to-home" 120vac inverter that's connected to the Leaf's 12vdc system, and also top off the Leaf's battery from the solar inverter's SPS outlet during the day. The issue is, can I do both simultaneously ? I'd rather not have to take the car out of "ready" mode, thus de-activating the Leaf-to-home and cutting power to my essential loads, while I'm charging from the solar; especially since that's when it's most likely to be hot and thus I'd like the refrigerator to be powered.

One answer might be "just try it", but I'd rather have some idea if it's safe (as far as damage to the Leaf) first.

You can technically, but it comes with a warning. In the example that you gave, the power is out too long, but it is bright and sunny. What to do with all that extra power.

First, Leaf has to be off; you have to plug in the Leaf to your Solar so that it starts charging. While it is charging like this, technically the DC to DC inverter is running the 12V system. You can tap the power via your Leaf powered AC inverter so basically the solar is "charging and running" the AC at the same time. Now, the warning part. The sun goes behind the clouds and shuts off the charging to the Leaf. When that happens, Leaf shuts off the DC to DC inverter and basically, your 12V battery is left to power that AC inverter all by itself. You will drain the 12V battery quickly to dead if you have a large load running (say like a Fridge or Heater or something) and give yourself a world of headaches with a depleted 12V battery that can't start the Leaf back up. :(
 
knightmb said:
First, Leaf has to be off; you have to plug in the Leaf to your Solar so that it starts charging. While it is charging like this, technically the DC to DC inverter is running the 12V system.
Wow, really ? I thought the DC-to-DC converter only worked in "ready" mode.
The sun goes behind the clouds and shuts off the charging to the Leaf. When that happens, Leaf shuts off the DC to DC inverter and basically, your 12V battery is left to power that AC inverter all by itself. You will drain the 12V battery quickly to dead if you have a large load running (say like a Fridge or Heater or something) and gives yourself a world of headaches with a depleted 12V battery that can't start the Leaf back up.
Yeah, I think that makes this an unacceptable solution.
 
LeftieBiker said:
What I suggest instead is that you have a 'buffer battery bank' that can provide home power for a few hours while the Leaf is offline and charging. This bank would be connected to the Leaf's 12 volt system. It would be safer for the car to go this route.
So my little Leaf-to-home 120vac inverter is connected to the buffer battery bank, and it's simply directly connected to the Leaf's 12vdc system (no charge controller or anything) ? So basically, unless I manage to drain this buffer, I won't drain the Leaf's 12v battery and be stuck (as @knightmb describes). I'm essentially just beefing up the Leaf's 12v battery. Do I have that right ?
 
RustyShackleford said:
knightmb said:
First, Leaf has to be off; you have to plug in the Leaf to your Solar so that it starts charging. While it is charging like this, technically the DC to DC inverter is running the 12V system.
Wow, really ? I thought the DC-to-DC converter only worked in "ready" mode.
Yeah, otherwise, your 12V battery (which isn't a lot of capacity), would run dead powering the coolant pump for the charger, radiator fans if it's a really hot day, the EV computer, all while charging. That's part of those "charging loses in the system" you hear about when charging an EV, a little extra power needed to run those systems while it charges takes away from the total energy that goes into the battery.
 
knightmb said:
Wow, really ? I thought the DC-to-DC converter only worked in "ready" mode.
Yeah, otherwise, your 12V battery (which isn't a lot of capacity), would run dead powering the coolant pump for the charger, radiator fans if it's a really hot day, the EV computer, all while charging. That's part of those "charging loses in the system" you hear about when charging an EV, a little extra power needed to run those systems while it charges takes away from the total energy that goes into the battery.
Oh I see. But the DC-to-DC converter is on only when charging. Got it.
 
the DCDC is turned On during pack charging;
and while in Ready when the 12V aux needs charging or the windshield wipers are running;
and it can come on when the car is Off and detects that the 12V aux is low.
 
RustyShackleford said:
LeftieBiker said:
What I suggest instead is that you have a 'buffer battery bank' that can provide home power for a few hours while the Leaf is offline and charging. This bank would be connected to the Leaf's 12 volt system. It would be safer for the car to go this route.
So my little Leaf-to-home 120vac inverter is connected to the buffer battery bank, and it's simply directly connected to the Leaf's 12vdc system (no charge controller or anything) ? So basically, unless I manage to drain this buffer, I won't drain the Leaf's 12v battery and be stuck (as @knightmb describes). I'm essentially just beefing up the Leaf's 12v battery. Do I have that right ?

Yes, you do.
 
Good discussion, but I believe it still doesn't answer the question: what happens if I start charging (using 120vac) and then put the Leaf in "ready" mode (or vice versa) ? This would eliminate the need for an additional 12v "buffer" battery, and also eliminate the risk of draining the Leaf's 12v battery (unless the traction battery is also drained).
 
RustyShackleford said:
Good discussion, but I believe it still doesn't answer the question: what happens if I start charging (using 120vac) and then put the Leaf in "ready" mode (or vice versa) ? This would eliminate the need for an additional 12v "buffer" battery, and also eliminate the risk of draining the Leaf's 12v battery (unless the traction battery is also drained).

In all that, you are right, no one answered the question. :lol:

If you put it in standby mode while charging and then charging is lost, then the DC to DC will also shut-off. Standby mode will also auto-shutoff after some time (15 minutes on Gen 2 ? ) That still could lead to a depleted 12V battery if don't shut off your AC inverter quick enough.

There is a *trick* you can do with the Gen 1 (haven't tried it on my Gen 2) where you put it into standby mode (two power button presses without the brake pedal pressed in to put it in drive mode) and if you get the 12V battery voltage low enough in standby mode, the DC to DC will kick on to charge the 12V back up. This makes the center blue light come on and blink while doing this. During that time, power up your AC inverter and make sure you have a load of at least 100W so that the 12V battery never fully charges and it keeps the DC to DC active as long as power is being used.
 
RustyShackleford said:
Good discussion, but I believe it still doesn't answer the question: what happens if I start charging (using 120vac) and then put the Leaf in "ready" mode (or vice versa) ? This would eliminate the need for an additional 12v "buffer" battery, and also eliminate the risk of draining the Leaf's 12v battery (unless the traction battery is also drained).

You can't put the car in READY mode while charging the pack--it doesn't want to let you drive away with the cord connected and charging.

For the same reason, you can't plug in an EVSE to activate charging while the car is in READY mode.
 
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