12 Volt Battery

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wehey

Member
Joined
Oct 7, 2017
Messages
9
Would anyone know what the minimum voltage the 12V needs to be at to start the Leaf?
Mine sits at about 12.4 in the summer and as low as 12 in the winter, which I know is a sign of a tired battery.

I do carry a lithium battery pack with me.....just in case

Just wondering if anyone knows the answer??
 
Something in the vicinity of 12.2 volts for a reliable start. Below 12.5 volts and you have a seriously undercharged battery.

There are at least three topics on the 12 volt battery. Please merge this one, Moderators.
 
I used to listen to the radio while in Accessory mode for hours at a time (it would timeout after an hour (going to Off mode), but I would then immediately turn back to Accessory mode again). One day it was VERY funky restarting, so I realized I must have depleted the battery too far, so I stayed in On mode to recharge the battery. I did not have a voltmeter at that point to document how low the voltage had dropped.

After that experience I bought an Innova Battery Tester (Model # 3721) that fits in the 12v power receptacle so that I could constantly monitor the 12v battery (except in Off mode). I have since never driven the battery to much less than 11.8v, so I can't answer the OP's question, but I can hazard a guess from my previous experience that 11.5v is not too low. Maybe around 11.0v is too low to start.
 
Various charts exist of 12v auto battery % of charge, and generally look like this:

100% is 12.6v
75% is 12.4v
50% is 12.2v
25% is 12.0v

In an ICE, it is possible to have a battery in the 11.5v region and still crank the engine sufficiently fast to start it.

Given that Nissan had difficulty in coming up with an appropriate charging process for the 12v battery, and had to design a protocol for the minimum acceptable charge level for activating the start and run states, we can't assume too much about the controlling logic/software.
Best to monitor the battery to make sure it doesn't routinely drop below 11.5v.
 
wehey said:
Would anyone know what the minimum voltage the 12V needs to be at to start the Leaf?
Mine sits at about 12.4 in the summer and as low as 12 in the winter, which I know is a sign of a tired battery.

I do carry a lithium battery pack with me.....just in case

Just wondering if anyone knows the answer??
Click to expand...

A very weak battery will experience voltage drop under load; so the resting voltage may seem reasonable but as soon as you demand some amps the voltage can sag to the point where the systems aren't happy and start throwing DTCs. Even though LEAF doesn't pull anywhere near the amps of an ICE starter motor, voltage sag can still bite you; I had it happen.

A load test is the proper way to reliably assess the health of the 12V battery. For an ICE car, running the starter essentially serves as a load test every time you drive the car. You generally know when the battery is in decline by the gradual onset of sluggish starts. In an EV the battery can become feeble without giving any hints along the way and then one day the dash lights up like Apollo13. ;)
 
Nubo said:
wehey said:
Would anyone know what the minimum voltage the 12V needs to be at to start the Leaf?
Mine sits at about 12.4 in the summer and as low as 12 in the winter, which I know is a sign of a tired battery.

I do carry a lithium battery pack with me.....just in case

Just wondering if anyone knows the answer??
Click to expand...

A very weak battery will experience voltage drop under load; so the resting voltage may seem reasonable but as soon as you demand some amps the voltage can sag to the point where the systems aren't happy and start throwing DTCs. Even though LEAF doesn't pull anywhere near the amps of an ICE starter motor, voltage sag can still bite you; I had it happen.

A load test is the proper way to reliably assess the health of the 12V battery. For an ICE car, running the starter essentially serves as a load test every time you drive the car. You generally know when the battery is in decline by the gradual onset of sluggish starts. In an EV the battery can become feeble without giving any hints along the way (i.e. the resting voltage seems adequate) and then one day the dash lights up like Apollo13. ;)
Click to expand...
 

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