How long will it take the DC/DC converter to charge a dead 12v battery?

[R1200RT]

I am sure there is no parasitic drain. I installed the Antigravity battery monitor to track what is going on with the 12v. It drops overnight because, it never gets recharged by the DC to DC converter when my wife drives to her work and back home. I am under the impression with my 2013, it will never get charged unless the battery sensor of the Leaf sees the battery below 12v. The Antigravity monitor confirms this when it shows the odd spike into the 14.x volt range, but this only happens once every 2-3 days, sometimes the entire week. And this just kills the 12v on my Leaf.

The only sure fire way of getting the 12v charged that I know of so far besides the windshield wiper trick is to plug in the Level 1/2 charger. Yes I know I can connect a trickle charger to the 12v, but that's a nuisance to have to drag 30ft long extension cable to the curb where she parks her car.

 

[GerryAZ]

You either have a parasitic load that needs to be found and eliminated, a really weak 12V battery, or there is something wrong with the LEAF's computers/network or DC-DC converter. The DC-DC converter should be hitting 14-14.5 volts each time the car is turned on (into ready to drive mode) and then drop to float voltage of about 13 volts (which is still enough to charge the battery) after a little while. The same thing happens during traction battery charging--the DC-DC converter starts at about 14 volts and then drops back to float voltage of about 13 volts while actively charging.

I had to replace the OEM battery in my 2019 after about 27 months of use. I drove to a construction site and opened/closed the doors frequently throughout the day to get tools while it was parked. The computers draw extra power when they wake up each time the doors are opened/closed so the weak battery became discharged during the day. I suspect the voltage of the weak battery dropped suddenly so the computers could not close the main contactor to charge the battery while parked. I had to jump start the car when I was ready to go home. I drove about 6 miles home and the battery took enough charge to start the car when I tested it in the driveway. I purchased an Optima Yellow Top deep cycle battery (Group Size 51R) and installed it that evening because I did not want to take any chances. The new AGM battery has plenty of capacity to handle the frequent door opening/closing when I drive to construction sites (it has been in service for about 14 months so far).

 

[R1200RT]

As stated before, there is no parasitic draw. It's the 2013 DC to DC algorithm where it only kicks it up to 14.x bolts when the battery voltage has dropped below 12 volts. If needed I can post graphs from the Antigravity monitor app.

In the process now of installing a AGM battery.

 

[R1200RT]

Here is a link from Antigravity Monitor APP: https://photos.app.goo.gl/B42yJ1fsRvLehtta6 Basically you'll see 8 trips of which 3 show voltage from the DC to DC converter kicking up to the recharge voltage of 14.x volts. With my wife driving 1 mile each way to/from house to work, this type of poor 12v management easily results in a sulfated battery because, it's left sitting below 50% SOC.

As you can see, it has nothing to do with parasitic draw.

 

[lorenfb]

Here is a link from Antigravity Monitor APP: https://photos.app.goo.gl/B42yJ1fsRvLehtta6 Basically you'll see 8 trips of which 3 show voltage from the DC to DC converter kicking up to the recharge voltage of 14.x volts. With my wife driving 1 mile each way to/from house to work, this type of poor 12v management easily results in a sulfated battery because, it's left sitting below 50% SOC.

As you can see, it has nothing to do with parasitic draw.

Have you actually checked for a draw? Just monitoring voltage won't exclude an excessive current draw.

 

[R1200RT]

Stating again now for the 3rd time. YES I HAVE CHECKED FOR A DRAW

 

[lorenfb]

Stating again now for the 3rd time. YES I HAVE CHECKED FOR A DRAW

Please let us know how you actually did it, i.e. there might be some insightful info for all.

 

[R1200RT]

Connected my DVM in series between the NEG terminal and NEG post. Is it accurate? No as I did not use shunt resistor as I do not have one. I measured 70ma. What's driving all of this is the fact the 2013, cannot speak to someone else's 2015+, where the DC to DC converter is not firing up each time we start the vehicle. Are the 2015+ doing a better job? Don't know.

The current battery in the vehicle is the 2nd one. I nursed the original factory unit from 2013 until 2022. I was regularly taking the caps off twice a year to refill with distilled water. The acid levels were dropping due either to TX heat or just being recharged from a low SOC by the DC to DC converter.

The current battery is a Walmart Everstart Maxx. I am now on a regular basis running desulfation on it every 3-5 months. The DC to DC algorithm does not work with flooded lead acid batteries. Flooded lead acid batteries expect and require they be recharged after they have been used to start a vehicle. They DO NOT like to stay long below 80-90% SOC.

I am in the process of installing a deep cycle AGM that will handle the long duration between each 14.x spike from DC to DC converter.

It would be interesting to know if truly the newer generations the DC to DC converter does fire up to 14.x each time the vehicle is started as that would help the community.

 

[R1200RT]

Adding more data to this. I have driven 30 minutes at a stretch and it never ever kicks it up to 14.x volts, it does keep it around 13.x volts to maintain. So I know it's not time based as some suspect. I use both the Leaf Spy Pro and Antigravity App, and when I see Leaf Spy Pro drop down to 11.6-11.8 volts that's when the DC to DC converter kicks it up to 14.x volts. And it only does that for about 1-2 minutes. During that 1-2 minutes I am not able to often see as I am driving what the amperage is for the 1-2 minute duration. But I suspect that it's not really enough to fully recharge it back to 100% SOC. Even on trips where the voltage climbs to 14.x volts, the SOC after the trip is usually between 50%-70%.

 

[LeftieBiker]

Have you used the wiper trick? If everything is normal, then turning the wipers on, or even just 'blipping' them once, will boost the accessory system voltage to 14.4 volts or so. It stays up for about a minute, but running the wipers continuously (even in intermittent mode) will keep the voltage up.

We also take lots of very short trips, and in Winter at least the voltage, as displayed by an accessory port voltmeter, is usually up around 14. We aren't dunces here, not on a good day anyway, and it really seems as if you have a malfunction. The wiper test should tell you that.

 

[lorenfb]

Adding more data to this. I have driven 30 minutes at a stretch and it never ever kicks it up to 14.x volts, it does keep it around 13.x volts to maintain. So I know it's not time based as some suspect.

I still have my 2013, and the battery charging voltage goes to about 14.2 like my 2019 (40kWh).

I use both the Leaf Spy Pro and Antigravity App, and when I see Leaf Spy Pro drop down to 11.6-11.8 volts that's when the DC to DC converter kicks it up to 14.x volts. And it only does that for about 1-2 minutes. During that 1-2 minutes I am not able to often see as I am driving what the amperage is for the 1-2 minute duration. But I suspect that it's not really enough to fully recharge it back to 100% SOC. Even on trips where the voltage climbs to 14.x volts, the SOC after the trip is usually between 50%-70%.

I had the Antigravity device connected to my 2013, and it appeared to be causing a current drain exceeding
over 100ma resulting in a dead battery after about a week. I then removed it, and no more dead battery problems.

 

[R1200RT]

Adding more data to this. I have driven 30 minutes at a stretch and it never ever kicks it up to 14.x volts, it does keep it around 13.x volts to maintain. So I know it's not time based as some suspect.

I still have my 2013, and the battery charging voltage goes to about 14.2 like my 2019 (40kWh).

You don't specify whether or not the 14.2 is happening on every drive? I know with my 2013, it's not happening on every drive. If you view my graph further above, out of 8 drives, only 3 drives we see 14.2 volts.

I had the Antigravity device connected to my 2013, and it appeared to be causing a current drain exceeding
over 100ma resulting in a dead battery after about a week. I then removed it, and no more dead battery problems.

Does not matter. The topic title is "How Long will it take .....to charge a dead 12v battery". Your perception/fact the Antigravity device is a parasitic drain is not the topic. In fact if the DC to DC converter goes up to 14.2v each time I started the 2013 Leaf, the parasitic drain you bring up is irrelevant as the recharge would mask over the drain. But as I stated before, at least with my 2013 Leaf, the vehicle DOES NOT kick up to 14.2 volts on each start up. And that's a big issue. I have said enough already about battery technology and how the DC to DC converter is not compatible with certain battery technology.

 

[GerryAZ]

My 2011 would jump to about 14 volts every time the car was started and then drop to about 13 volts after charging current into the battery dropped below a threshold which was around 6 to 8 amperes. My 2015 would jump to about 14 volts every time and then drop to about 13 volts when the charging current into the battery dropped below about 3 to 6 amperes. The 2019 stays at 14 volts until the charging current drops below 2 to 3 amperes. In all cases, the charging voltage stayed (stays) near 14 volts (depending upon temperature) until the current dropped (drops) below the threshold. Therefore, the voltage stays high for extended time if the battery is deeply discharged.

If you want to measure parasitic load, you need to connect your ammeter to the battery terminal and the cable while they are still connected and then disconnect the cable so that the circuit is never broken. If the computer modules are not sleeping, they will go dormant when the power is interrupted briefly. This will reduce the measured parasitic current.

 

[lorenfb]

Adding more data to this. I have driven 30 minutes at a stretch and it never ever kicks it up to 14.x volts, it does keep it around 13.x volts to maintain. So I know it's not time based as some suspect.

I still have my 2013, and the battery charging voltage goes to about 14.2 like my 2019 (40kWh).

You don't specify whether or not the 14.2 is happening on every drive? I know with my 2013, it's not happening on every drive. If you view my graph further above, out of 8 drives, only 3 drives we see 14.2 volts.

I had the Antigravity device connected to my 2013, and it appeared to be causing a current drain exceeding
over 100ma resulting in a dead battery after about a week. I then removed it, and no more dead battery problems.

Does not matter. The topic title is "How Long will it take .....to charge a dead 12v battery". Your perception/fact the Antigravity device is a parasitic drain is not the topic. In fact if the DC to DC converter goes up to 14.2v each time I started the 2013 Leaf, the parasitic drain you bring up is irrelevant as the recharge would mask over the drain. But as I stated before, at least with my 2013 Leaf, the vehicle DOES NOT kick up to 14.2 volts on each start up. And that's a big issue. I have said enough already about battery technology and how the DC to DC converter is not compatible with certain battery technology.

My 2013 always goes to 14.24 volts. Sounds you have a problem! Good luck in finding the "big issue".