Leaf Spy AHr max by battery size

[DaveinOlyWA]

Dave,

I am sure you know, but as a reminder, the auto up/down functions must be relearned after power cycling (disconnecting/reconnecting) the 12V battery. Open window and hold open control for a few seconds; then close window and hold close control for a few seconds to relearn.

Hmmm, ok, I thought it was a LEAF Spy thing but it is back to working w/o any enabling process. As far as the back wiper boosting the battery? Tried it, doesn't work. I verified car was not in hiccup mode by turning on front wipers. The one thing I am seeing is the voltage is over 14 but the current is very low? Is this another failing battery symptom or simply how the LEAF works?

Speaking of the battery disconnect thing. Previously when I disconnected the 12 volt, I lost all my radio presets. That doesn't happen any more. The only thing I lost was trip a, trip b and drive computer info.

 

[GerryAZ]

Leaf Spy shows the voltage of the 12V battery and current flowing into or out of it. If the 12V battery is well charged, the current into the battery will be very low even at 14 volts. Typically, the current will increase for a little while when you turn the wipers on and the voltage increases from 13 to 14. After a little while, the charging current will drop back to about what it was at the lower float voltage once the battery is fully charged.

 

[DaveinOlyWA]

Leaf Spy shows the voltage of the 12V battery and current flowing into or out of it. If the 12V battery is well charged, the current into the battery will be very low even at 14 volts. Typically, the current will increase for a little while when you turn the wipers on and the voltage increases from 13 to 14. After a little while, the charging current will drop back to about what it was at the lower float voltage once the battery is fully charged.

Ahh, ok. Well I topped the battery off this morning because it was at its customary 11.98 volts so probably still pretty full. I was seeing .03 amps so almost nothing really. I will have to pay attention to it on Tues morning when it will likely be back to 11 something volts again...

 

[LeftieBiker]

As far as the back wiper boosting the battery? Tried it, doesn't work. I verified car was not in hiccup mode by turning on front wipers.

Ok, thanks.

 

[SageBrush]

If the 12V battery is well charged, the current into the battery will be very low even at 14 volts.

Why does it happen ? Physics, regulation, or both ?

I've been kinda sorta under the impression that current is dictated by (delta V)/R

 

[LeftieBiker]

If the 12V battery is well charged, the current into the battery will be very low even at 14 volts.

Why does it happen ? Physics, regulation, or both ?

I've been kinda sorta under the impression that current is dictated by (delta V)/R

Regulation by the charging system.

 

[GerryAZ]

The DC-DC converter provides a regulated voltage (about 14-14.5 until current into the battery drops below a threshold, then about 13 with exact values depending upon ambient temperature and LEAF model year). The battery will absorb current until its internal voltage matches the charging voltage, but the actual difference in energy storage between 13 and 14.5 volts is not much for a battery in good condition. Therefore, increasing the charging voltage to 14.5 after the battery is stable at 13 will cause current to flow into the battery for a short time and then the current will drop to almost the same value as it was at 13 volts (because the battery is fully charged). The current may be higher if the battery has some deterioration so the extra energy flowing into the battery causes gassing and heating.

 

[SageBrush]

The DC-DC converter provides a regulated voltage (about 14-14.5 until current into the battery drops below a threshold, then about 13 with exact values depending upon ambient temperature and LEAF model year). The battery will absorb current until its internal voltage matches the charging voltage, but the actual difference in energy storage between 13 and 14.5 volts is not much for a battery in good condition. Therefore, increasing the charging voltage to 14.5 after the battery is stable at 13 will cause current to flow into the battery for a short time and then the current will drop to almost the same value as it was at 13 volts (because the battery is fully charged). The current may be higher if the battery has some deterioration so the extra energy flowing into the battery causes gassing and heating.

Thanks. How about current ? Is that regulated, or only battery physics ?

 

[GerryAZ]

DC-DC converter provides regulated charging voltage so current flowing into the battery is limited by battery physics.

 

[SageBrush]

DC-DC converter provides regulated charging voltage so current flowing into the battery is limited by battery physics.

Cool.

Am I on the right track in thinking that a dV Vs I graph would be a fair indicator of 12V battery health ?

 

[nlspace]

...
Ahh, ok. Well I topped the battery off this morning because it was at its customary 11.98 volts so probably still pretty full. I was seeing .03 amps so almost nothing really. I will have to pay attention to it on Tues morning when it will likely be back to 11 something volts again...

The reason that the current is so low is that you have a sulfated battery that will no longer accept a charge. It is either worn out and old, or damaged by standing at a below-full voltage.

If it is not too far gone then you might recover somewhat using a charge up to 14.4, then held there sufficiently long to raise the specific gravity of the electrolyte.

Easiest way to increase the DC/DC output voltage is to disconnect the current sensor on the negative terminal.

 

[lorenfb]

...
Ahh, ok. Well I topped the battery off this morning because it was at its customary 11.98 volts so probably still pretty full. I was seeing .03 amps so almost nothing really. I will have to pay attention to it on Tues morning when it will likely be back to 11 something volts again...

The reason that the current is so low is that you have a sulfated battery that will no longer accept a charge. It is either worn out and old, or damaged by standing at a below-full voltage.

If it is not too far gone then you might recover somewhat using a charge up to 14.4, then held there sufficiently long to raise the specific gravity of the electrolyte.

Easiest way to increase the DC/DC output voltage is to disconnect the current sensor on the negative terminal.

A better approach, i.e. avoiding excessive system charging currents, is to turn the wipers on, (Vcharging ~= 14.5 volts).