How many CCA are required to start the Leaf??

So like many others, my 12V battery has been exhibiting some problems. If anyone can give me some additional information and wouldn't mind taking a minute or two to read this I would greatly apperciate it:

Here's a summary of what has happened:

1) Some warning lights were coming on, and I suspected that it was due to 12V battery problems. I used a battery maintainer to fully charge it about two weeks ago.

Question 1) Should you disconnect the 12V battery from the Leaf if you charge it with a battery charger/maintainer? I am wondering now if I possibly broke my battery maintainer or if (worse), I did some damage to the Leaf DC/DC converter using a battery maintainer (read on for further explanation)

The first time using the maintainer last week took about an hour to get it to full (its a multi stage charger)


Four nights ago, I started getting the brake warning light again which I attributed to the 12V battery and I assumed it was getting low again ( or wasn't going through its 5 day DC/DC top up charge in time etc)

However this time, after stopping at a quick charge station on my way home, the battery was completely dead and the car would not start! (First time this happened)

A guy who happened to be at the quick charge station said it happens to him occasionally and he had a lithium booster pack but it didn't start the car! I assume because the battery was completely dead. I had to have emergency roadsid come out and everything came on immediately once the jumpers were hooked up to his huge truck battery.

So this leads me to ask how much is needed to start the Leaf in terms of cold cranking amps?

But ther's a bit more (thanks for bearing with me this far, hopefully this is going quick)

So after getting the Leaf home, I hooked up the battery maintainer charger and it read completely dead and filled it all the way back up from 0%. It took about 2 hours.

At this point I"m assuming all is good and that I'll just check it every few days w/ the maintainer to "fill in" in case the Leaf's five day cycle for topping off the battery falls short etc.

Big problem though. A few nights later I go to hook up the maintainer and the first time, it reads that its almost full, and just tops it off over a couple minutes (went from 95% to 100%). But then it starts acting strange and resetting. Right when it is supposed to start analyzing the battery, instead the battery charger keeps resetting as if there was a lapse in power or a safety mechanism was triggered etc.

The next day I go to hook up the charger again and it again says the battery is completely dead and starts charging from 0%. it got to 13% and then again the battery charger reset, and after that it woudlnt start again ( it kept resetting). However, I am pretty sure the 12V was not completely dead because all the lights and everything was working fine even w/ the car completely off.

So I am thinking at this point that I should be fine as long as I carry my portable power pack with me, but the problem is the jumper cable assembly (multi pole housing) broke and I can't find a replacement for it. I can, but it looks like it might be cheaper to just get one of these newer, smaller, lighter lithium ones.

But can a Lithium powerpack /jumpstarter start the Leaf if its completely dead (i.e. the 12V?)

And my next question, is, could I just hook up my jumper cables directly to the poles on the 20AH Universal battery that is inside the Powerpack that I have now? The reason I ask this is because you don't turn the Powerpack on to use the jumpstarter and B) since the Leaf shouldn't require nearly as many CCA's as a normal gas car, I am wondering if the 20AH universal booster battery would be sufficient.

If anyone knows A) about how many CCA's the Leaf needs to start the system, and B) if there is anyway to manage the DC/DC charging system to ensure that the 12V doesn't die, I would be most grateful!

At this point I am just hoping to get this taken care of as easily as possible. I am somewhat against going out and buying a new battery after all the stories I hear about "drains" on the 12V.. which might lead one to believe that since the 12V battery isn't used for all the much anyway once the car is started, it might be better to just have a powerpack charger for those times when the 12V dies.

Again, the wealth of knowledge and experience here is highly appreciated, any brief thoughts or responses are welcome!

Your 12v battery obviously needs to be replaced: why not just do it?
I doubt you would want to spend the $$, but I replaced my 12v lead acid battery with a 12v LiFePO4 "drop in" replacement (search for threads/posts in my name) over 2 years ago and haven't had a single 12v problem since.
To answer your question: while the 12v battery that ships with the Leaf is ~40A, I replaced it with a 20A 12v Lithium that more than handles the load of the Leaf. And a tip: never leave your Leaf "plugged-in" and not charging for more than a day at a time.

I think your 12v battery is hosed and is causing all of this. Take the battery in and have it tested.

How many Cold Cranking Amps? Zero.

Get a new battery already. As said above, there is no cranking (cold cranking amps) of a starter on the leaf...

To answer a few other questions: you don't need to disconnect the battery from the car to charge it. Just avoid connecting the negative lead to the battery - use a bolt on the inverter stack (the thing that looks like an ICE with no exhaust pipes) for the negative. I connected semi-permanent maintainer leads to the battery and that ground, and ran it into the charge port compartment, making it easier to connect the maintainer. Once a lead-acid battery fails, just topping off the charge won't revive it. The fact that your maintainer only took an hour to charge the battery (I assume it's a fairly small unit?) indicates that your battery has little capacity left, assuming that the battery is in fact dying.

TonyWilliams said:

How many Cold Cranking Amps? Zero.

Click to expand...

I'm going to say 1. At exactly 0 it probably doesn't have the right voltage.

How many watts does the high voltage disconnect relay need to connect the pack? Gotta be a few watts at least? For what a half second?

TonyWilliams said:

How many Cold Cranking Amps? Zero.

Click to expand...

CCA IS a well-defined term, but some parts of the LEAF will not function properly (brakes, certainly!) if you manage to draw the voltage down to 7.2V. As such, the CCA rating will need to be significantly higher than the number of amps needed to operate the car.

I suspect about 30A are needed to run the vehicle and pull in the contactor, so I suspect a CCA rating over 100A will be necessary to start the LEAF in very cold weather.

You could probably close the contactor with less than 1A as long as the cars lights and accessories are off. The car needs little to close the contactor and activate the DC/DC. Since you can't really drive the car without the contactor closed the 12V system would never draw a high amp rate at all unless there was a HV failure while driving. Most LEAF LV issues are related to voltage sag and the way the car reacts to that bad battery load. The car really does not have any high amp stationary loads.

EVDRIVER said:

You could probably close the contactor with less than 1A as long as the cars lights and accessories are off. The car needs little to close the contactor and activate the DC/DC. Since you can't really drive the car without the contactor closed the 12V system would never draw a high amp rate at all unless there was a HV failure while driving. Most LEAF LV issues are related to voltage sag and the way the car reacts to that bad battery load. The car really does not have any high amp stationary loads.

Click to expand...

You need your foot on the brake to start the car, so brake lights will be on at the very least (LEDs help!). That's likely several amps right there. If you also have headlights on, you could easily get above 30 amps. (Not that I advise that, but it is a real condition that can occur, so the battery must handle it.)

The LED tail lights and head lights pull little and even the halogens would likely be about 10A. I doubt the car draws even near 20A with lights and the foot on the brake. Certainly easy to measure.

I measured that. Curiosity kills

Anyway Leaf does draw between 20-30A for one second. Ambient temperature does not have any effect.
Even before pushing the button there is already some discharge 5-15A. Some of that goes to
modules that are awake and some of that for brakelights, interior lights.


350W is of power will let the Leaf to wake up normally.
1 second after pushing big red button button 12V battery charging will engage.

I'm pretty sure 12V 7Ah UPS battery will do the trick in emergency but failed 12V main battery might have
to be disconnected temporarily (one terminal) because if it is heavily discharged or shorted it will
eat up all those amps. 7Ah UPS battery can keep my home PC running for many minutes and it draws
about 200-350W too.


CCA 30A

As folks are saying in different ways, CCA is not an issue for LEAF, as any car battery ever made has far more current-delivery capability (when new) than LEAF needs to "start up". Cold-cranking-amps is meant to show how many amps the battery can deliver at cold temperatures. This is important for ICE vehicles where the starter motor can pull 100, 200, 300 or more amps, especially in very cold temperatures where the engine oil has thickened. It's a tough job for a starter battery because the highest demand for current happens when the battery is cold which is the worst time to be asking for a lot of current.

Unfortunately a lot of battery manufacturers love to tout the CCA, and ignore an equally important number - Amp-Hours. That's a measure of how much total energy the battery can deliver, usually over 20 hours. Often a larger CCA will correlate with more Amp-hours but that's not always the case. They can be conflicting design goals.

For LEAF, since CCA is largely irrelevant, the Amp-Hour rating is the key. Since the car likes to put a drain on the battery when parked, a larger amp-hour rating means the car can sit unattended for more days with less of a percentage discharge. Deep-cycling is hard on lead-acid batteries. This is also a reason why deep-cycle batteries are better suited for this car, imho.

LEAF has startup problems due to insufficient voltage, not CCA. By the time the battery can't deliver enough voltage to start a LEAF, whatever CCA capacity it had, has already been completely destroyed. This can be from a one-time discharge event, in which case a good charge of the battery can set things right. But for non-deep-cycle batteries, draining to zero often damages them. Then the weak battery is more susceptible to the next drain, etc... Often the first instance of "failure to start" is the opening salvo of a recurring problem that is only solved by replacing the 12V battery. Ideally, a load-test should be performed if the battery has run down. This will tell whether or not the 12V should be replaced.

My "regular" battery is a 20A LiFePO4 (search my name+12v for threads/posts), and I have lived with a "temp" 9A lead acid battery in between swaps. Doesn't take much to get a Leaf going.

I have left my 2015 Leaf parked for 45 days and it started fine. After 63 days I had to give the 12v battery a charge.