12v battery keeps going dead

[Codeman333]

When I first bought this car a year or so ago, the 12v battery kept going dead. At first I assumed it was a bad battery and I replaced it, but the problem remained. Then after much trial and error I discovered it only happened if the car was left plugged in to the charger, which was a level 1 device that plugged into an ordinary outlet. I decided to put in a level 2 charger and when I did the problem went away. I guess the original charger has some sort of problem. Has anyone else experienced this?

 

[GerryAZ]

The 12V battery is being charged when the traction battery is actually charging or when driving the car. You should unplug the charger after the car is fully charged because there is higher residual current draw from the 12V battery when the car is plugged in but not charging than when it is not plugged in.

 

[TronJockey]

The Leaf normally applies a 13.0V float charge to the 12V accessory battery (this is via the DC-DC inverter when the car is on). This jumps up to 14.35V for roughly 90 seconds each time you start the car. So, the majority of the time the 12V battery sees only a 13.0V float charge. This may not be sufficient to bring back a battery that has seen a heavy discharge (as happens with a gasoline car if you've left the headlights on). This is especially true during very cold winters. Also, as mentioned by GerryAZ above, there are likely one or more relays being held on (drawing current) by the 12V accessory battery during L1 and L2 charging. This would present a "parasitic" current draw and could be enough to drain a 12V battery (especially if already weakened) if done every day and with the charging cable left connected.

 

[dhyatt]

When I first bought this car a year or so ago, the 12v battery kept going dead. At first I assumed it was a bad battery and I replaced it, but the problem remained. Then after much trial and error I discovered it only happened if the car was left plugged in to the charger, which was a level 1 device that plugged into an ordinary outlet. I decided to put in a level 2 charger and when I did the problem went away. I guess the original charger has some sort of problem. Has anyone else experienced this?

Sounds like a 12v automotive problem often a ground or a cable problem.. Check the voltage across the posts make sure its 13v, check voltage across the terminals (not the posts) make sure no voltage drop. Make sure your new battery is not defective... a 12v with comparable size and posts on the same place (make sure polarity matches on the posts.... I mean positive on the right and neg on left...or vise versa..whatever our cars are.)