Leaf accessory battery dead

Hello all,

Our leaf (2014) has a mostly dead accessory battery. The battery is 6 years old, and I found the solar panel was pretty dirty. I also was out of town so the leaf was plugged in the entire time but not driven.

To my question:

Wondering if the panel will top off the battery enough to have it be reliable?
Does the leaf charge this battery once in a while?
Wondering that since the car was plugged in that maybe the battery is ready for replacement.

Thanks in advance!

Rob

6 yr old battery needs to be replaced...once it goes dead at that age its done!

Do not risk your car electronics over a faulty failed battery.

bonro001 said:

Our leaf (2014) has a mostly dead accessory battery. The battery is 6 years old, and I found the solar panel was pretty dirty. I also was out of town so the leaf was plugged in the entire time but not driven.

Click to expand...

As mentioned, a 6 year old 12V battery is probably ready for replacement.

But it is well known (with dozens of reports on MNL) that leaving a LEAF plugged in and not driving it will cause it to kill the 12V battery. The charging circuit doesn't charge the 12V correctly, and (IIRC) leaving the EVSE attached keeps the electronics live, with a load on the 12V.

If you need to leave car for a period of time (weeks), do not leave the EVSE connected. You should also leave the traction battery under 80% charged. (the exact range has been debated many times, most recently here: Long term EV storage procedure, but "under 80%" includes all the values people have suggested)

Thanks for the advice and confirmation. I will go in search of a new battery today!

-Rob

The original battery group size is 51R. The "R" designation refers to the orientation of the terminals, which is important for fitment.

There is room in the tray for a larger battery than a 51R

You can take some measurements, especially the height is important....

But of course the Leaf requires much less capacity than the stock 12v battery (no "cranking" required). My Leaf functions quite well on a 20AHr LiFePO4 12v battery.

Capacity is measured a number of different ways.

CCA are completely irrelevant in our EVs. Crank starting a conventional car requires very large current flow (many hundreds on a cold day) for brief time periods, just a few seconds typically. That is a very different requirement from what our cars need. CCA is defined as the number of amps a battery can supply, in theory, at 0 degrees F for 30 seconds without dropping below a set voltage. I mention it here for newbies who are dealing with EVs for the first time. Clearly not relevant to our needs.

Batteries built to supply large CCA values are physically different from batteries optimized for sustaining output under lower loads for longer time periods. The latter batteries are a better fit for our cars.

Look instead for "reserve time", usually quoted in minutes, or amp hours (Ah). Reserve time is defined as the number of minutes the battery can supply 25 amps before dropping below a set voltage at 80 degrees F. Amp hours are usually quoted at the "C20" rate, meaning the number of amps the battery can supply for 20 hours before dropping below a set voltage at 80 degrees F. Lower CCA, however, is not a bad thing.

Capacity is not a fixed, linear thing - higher loads draw down a battery disproportionately faster than small loads do - it's not linear. Furthermore, the same battery tested under lab conditions will perform differently from charge to charge. So it pays to understand what standard capacity is being rated for when considering different batteries, and also to recognize that batteries are not so deterministic as one might expect.

bonro001 said:

Hello all,

Our leaf (2014) has a mostly dead accessory battery. The battery is 6 years old, and I found the solar panel was pretty dirty. I also was out of town so the leaf was plugged in the entire time but not driven.

To my question:

Wondering if the panel will top off the battery enough to have it be reliable?
Does the leaf charge this battery once in a while?
Wondering that since the car was plugged in that maybe the battery is ready for replacement.

Thanks in advance!

Rob

Click to expand...

Your battery died because it was left plugged in. This caused the electronics in the car to remain at a high state of readiness which increased the power drain on the 12 volt battery.

The normal process is to leave the traction battery at 50% or so UNPLUGGED. It will be fine for months. Without mentioning how long you were gone, your 12 volt battery may not have enough life left to recover. Replacement is likely

frontrangeleaf said:

Capacity is not a fixed, linear thing - higher loads draw down a battery disproportionately faster than small loads do - it's not linear. Furthermore, the same battery tested under lab conditions will perform differently from charge to charge. So it pays to understand what standard capacity is being rated for when considering different batteries, and also to recognize that batteries are not so deterministic as one might expect.

Click to expand...

See Peukert's law.

Oilpan4 said:

frontrangeleaf said:

Capacity is not a fixed, linear thing - higher loads draw down a battery disproportionately faster than small loads do - it's not linear. Furthermore, the same battery tested under lab conditions will perform differently from charge to charge. So it pays to understand what standard capacity is being rated for when considering different batteries, and also to recognize that batteries are not so deterministic as one might expect.

Click to expand...

See Peukert's law.

Click to expand...

The Cliff's notes version is that you can only use roughly half of the capacity of a lead-acid battery, and the greater the drain on said battery, the lower the available capacity.