mpostma
Member
Hi,
FYI: this is my first post on this forum. I would like to share some findings and find out some more info about how the 12V battery is charged.
I understand that the 12V battery is basically charged by the DC/DC converter from the traction battery. That can happen both while the traction battery is charged, but as wel during a normal drive cycle.
Last weekend I found by Leaf completely dead. Only a red symbol for the key system was flashing and the luggage compartiment could be opened. The car was connected through the AC charger inlet to a charge box.
I found out that the 12V battery only held around 6V. Deeply discharged. After recharging with a seperate battery loader I found it has 76% capacity left. It was not really bad, but getting worn, the guy from a a battery shop said. A normal car would start with it, but it might getting problems in future.
I put in another spare battery, which was somehow discharged but otherwise in good condition.
I tried to find out if the car would charge the 12V battery, but it did not at that time. only 13V on the poles in Ready mode, with selector in Park.
After that I did some measurements with that temporary battery.
After a day at work: connect via the nissan app and start a a preconditioning cycle. When arriving at the car, open bonnet and measure the battery. At that time 14.4V. Perfect charging voltage.
When coming home after half an hour of driving. Leave the gear selecter in Reverse. Handbrake on. Measure: at that time it was 13V.
Then I put on all 12V function I could imagione. Main headlight, fog light, rear fog light, seat heatings, max defrost on the windscreen, etc...
Still 13V. Appears to me that the DC charger must be fully operable, but it decides to not charge the 12V battery but only satisfy the demands of the 12V body system.
AFter that I put in the new battery I purchased. That one was somehow discharged when I bought it. Stand alone it delivered 12.4V at the poles. When I put it in it gave 12.3V (poles connected to the car system). Then I started a charge cycle. Now, it measured 14.4V at the poles.
So the car has at least some smart logic that decides when it will charge the 12V battery. Otherwise it will keep 13V at the poles which is not enough to charge, but it won't discharge either. So I regard that as a good neutral Voltage that will neither drain nor charge the 12V battery.
Still I am puzzeld why the 12V battery was not observed and charged while the traction battery was charging during the weekend and why it allowed the battery to drain completely. Since it was not really broken (as lead batteries can experience a sudden death with internal shortcut) I "would" had expected the car to initiate a charge cycle to keep the 12V battery charged
Does anyone have a description of this charging characteristic? Or is it just as "unsmart" as one might experience with other functions. That there is simply not a smart charging strategy or there is a bug that allows the 12V battery to drain. In that case I would like to understand which conditions might trigger the 12V battery not being charged.
I have read some topics about problems in earlier Leafs (2012) and that it should be pretty fine in newer (post 2013) Leafs, but I just want to be sure that the new battery holds a bit longer. Understand which habits I should evade.
BTW. I think 5 years of lifetime is still short for a lead acid battery. It has a production date from early 2014 so it must almost be the original battery.
FYI: this is my first post on this forum. I would like to share some findings and find out some more info about how the 12V battery is charged.
I understand that the 12V battery is basically charged by the DC/DC converter from the traction battery. That can happen both while the traction battery is charged, but as wel during a normal drive cycle.
Last weekend I found by Leaf completely dead. Only a red symbol for the key system was flashing and the luggage compartiment could be opened. The car was connected through the AC charger inlet to a charge box.
I found out that the 12V battery only held around 6V. Deeply discharged. After recharging with a seperate battery loader I found it has 76% capacity left. It was not really bad, but getting worn, the guy from a a battery shop said. A normal car would start with it, but it might getting problems in future.
I put in another spare battery, which was somehow discharged but otherwise in good condition.
I tried to find out if the car would charge the 12V battery, but it did not at that time. only 13V on the poles in Ready mode, with selector in Park.
After that I did some measurements with that temporary battery.
After a day at work: connect via the nissan app and start a a preconditioning cycle. When arriving at the car, open bonnet and measure the battery. At that time 14.4V. Perfect charging voltage.
When coming home after half an hour of driving. Leave the gear selecter in Reverse. Handbrake on. Measure: at that time it was 13V.
Then I put on all 12V function I could imagione. Main headlight, fog light, rear fog light, seat heatings, max defrost on the windscreen, etc...
Still 13V. Appears to me that the DC charger must be fully operable, but it decides to not charge the 12V battery but only satisfy the demands of the 12V body system.
AFter that I put in the new battery I purchased. That one was somehow discharged when I bought it. Stand alone it delivered 12.4V at the poles. When I put it in it gave 12.3V (poles connected to the car system). Then I started a charge cycle. Now, it measured 14.4V at the poles.
So the car has at least some smart logic that decides when it will charge the 12V battery. Otherwise it will keep 13V at the poles which is not enough to charge, but it won't discharge either. So I regard that as a good neutral Voltage that will neither drain nor charge the 12V battery.
Still I am puzzeld why the 12V battery was not observed and charged while the traction battery was charging during the weekend and why it allowed the battery to drain completely. Since it was not really broken (as lead batteries can experience a sudden death with internal shortcut) I "would" had expected the car to initiate a charge cycle to keep the 12V battery charged
Does anyone have a description of this charging characteristic? Or is it just as "unsmart" as one might experience with other functions. That there is simply not a smart charging strategy or there is a bug that allows the 12V battery to drain. In that case I would like to understand which conditions might trigger the 12V battery not being charged.
I have read some topics about problems in earlier Leafs (2012) and that it should be pretty fine in newer (post 2013) Leafs, but I just want to be sure that the new battery holds a bit longer. Understand which habits I should evade.
BTW. I think 5 years of lifetime is still short for a lead acid battery. It has a production date from early 2014 so it must almost be the original battery.