Car wouldn't start, now does after charging. What happened?

[VitaminJ]

15 minutes. But what would that have to do with anything? I've charged three completely dead 1000CA bus batteries at the same time at a lower current than what my alternator can put out in even colder weather and still could get 14V.

Yes we're talking about batteries and current flow, so what would a time component have to do with that

Seriously though, because if you put the jumpers "across" the Leaf's multimeter then the Leaf will see the higher voltage of the jumper and the car will start up.

If you put the jumper "inside" the multimeter the Leaf will still only see the stock 12v's voltage and will not work until your jumper has charged the 12v up enough to make it happy.

A lead acid at single digit temperatures will take on charge very slowly and the voltage will not jump as much compared to a warm battery.

By all means check your ground point but I think you will find that's the wrong tree to bark up.

 

[IssacZachary]

Ya, I say let's leave it there Vitaminj. There's too many things here that don't make sense. Like a slow charging battery not getting up to voltage? If the battery is dead flat and slow charging the charging voltage will spike up to charging voltage instantly and stay there (high internal resistance E=IR). But an extremely thirsty, quick-charging battery would pull down the voltage as it charges (low internal resistance E=IR).

 

[VitaminJ]

Haha, it makes perfect sense. Get a digital voltmeter and take a look yourself. I don't know why this is so controversial, I learned this from reading MyNissanLeaf.com :lol:

 

[VitaminJ]

Here's what the US Corps of Engineers thinks about your "extremely thirsty" theory:

A low rate of charging due to low temperatures has two other
adverse effects: first, subsequent starting attempts will be seriously
hampered unless extra charging time is allowed, and second, the
operator may be deceived as to the actual state of charge of the
battery since the battery charger will indicate a very low charging
current going to the battery, which would usually indicate a full
charge.When a battery is in an extremely discharged state, it does
not readily accept a high current charge. It may appear to be taking
a charge, but it will only be taking the charge on the surface of the
plates. In this case the battery should be charged at a very low rate
for a long time, say, 25-30 hours

 

[IssacZachary]

Here's what the US Corps of Engineers thinks about your "extremely thirsty" theory:

A low rate of charging due to low temperatures has two other
adverse effects: first, subsequent starting attempts will be seriously
hampered unless extra charging time is allowed, and second, the
operator may be deceived as to the actual state of charge of the
battery since the battery charger will indicate a very low charging
current going to the battery, which would usually indicate a full
charge.When a battery is in an extremely discharged state, it does
not readily accept a high current charge. It may appear to be taking
a charge, but it will only be taking the charge on the surface of the
plates. In this case the battery should be charged at a very low rate
for a long time, say, 25-30 hours

That's exactly what I'm saying. A cold slow charging battery will exhibit a high voltage as it's being charged. E=IR. Voltage is equal to the current multiplied by the resistance. The colder and slower the charging the higher the resistance. The higher the resistance, the lower the current and the higher the voltage.

Yes, I need a voltmeter to make sure my connections are correct. But saying that a cold, slow-charging battery that's being charged will exhibit a low voltage doesn't make any sense whatsoever.

 

[GerryAZ]

The Hall Effect current sensor at the negative terminal of the 12-volt battery has nothing to do with this. A loose connection somewhere would cause the failure to start regardless of the battery voltage. It is possible that the connection at the current sensor was loose, in which case the car would start if the booster battery negative cable was connected to chassis ground.

 

[LeftieBiker]

Seriously though, because if you put the jumpers "across" the Leaf's multimeter then the Leaf will see the higher voltage of the jumper and the car will start up.

If you put the jumper "inside" the multimeter the Leaf will still only see the stock 12v's voltage and will not work until your jumper has charged the 12v up enough to make it happy.

Ah, right, the current sensor. I had no idea what VJ was talking about in the above. No, that shouldn't do anything but at worst affect how the car charges the battery, but not how jumping it would charge it.

 

[VitaminJ]

Ah, right, the current sensor. I had no idea what VJ was talking about in the above. No, that shouldn't do anything but at worst affect how the car charges the battery, but not how jumping it would charge it.

How do you think the Leaf measures the voltage of the 12v battery in the first place. It is not only a current sensor, it is also a voltmeter.

 

[VitaminJ]

That's exactly what I'm saying. A cold slow charging battery will exhibit a high voltage as it's being charged. E=IR. Voltage is equal to the current multiplied by the resistance. The colder and slower the charging the higher the resistance. The higher the resistance, the lower the current and the higher the voltage.

No. The voltage will be lower. Go do it yourself. The text I quoted states exactly the same. E=IR, there are three variables. If resistance is higher then current or voltage, or both, will be lower. Based on the text I quoted, both current and voltage will be lower in low temperatures and that is common knowledge about lead acid batteries you have it plain backwards sorry to say.

Yes, I need a voltmeter to make sure my connections are correct. But saying that a cold, slow-charging battery that's being charged will exhibit a low voltage doesn't make any sense whatsoever.

Get your voltmeter first


More from that document from the US Army Corps of Engineers (that you clearly didn't read):

-The amp-hour capacity and voltage under even light loads
are seriously decreased.
-Charging becomes difficult and inefficient.

The last two of these difficulties arise from the greatly increased
internal resistance of the battery at low temperatures. As the
temperature falls, the electrolyte becomes increasingly viscous, and
the chemical processes at the plate surface are not only slowed by
direct temperature effects but also are hampered through slow
diffusion of the reactants due to the increased viscosity of the
aqueous medium. This results in a slower rate of both charging and
discharging. Figure 7 shows the apparent power reduction of a fully
charged battery at low-temperatures

And finally, what happened that made your car finally start? You plugged it in for a few hours, just as what's needed to charge up a cold, dead lead acid battery.

 

[VitaminJ]

Ok. So I got the battery tested. Battery condition is:

GOOD.

I'll try cleaning up all the connections this weekend. Right now I just cleaned up the already clean looking battery terminals with a wire brush.

I couldn't find my DMM so I'll be lugging around my big analog voltmeter. Right now it showed almost exactly 12V with the car off and almost exactly 13V. Of course this thing isn't the most accurate thing in the world, so it could be a bit more or less than that.

If you read around this forum (I have) you will find dozens of posts where people with the Christmas tree dash took their battery to get tested and it "Passed." Well guess what they're problems remained until they replaced the 12v battery with new. You will see countless posts on this forum about 12v batteries dying in Leafs causing word-for-word exact same problems you typed in your original post.

If your voltmeter was halfway accurate and it measured exactly 12v with the car off, guess what bub the lead acid battery is a gonner. You can bring it back for a short while by desulfating it with a maintenance charger which will probably get you through the summer and into next winter.

There is a member on this forum who has a quote in their signature or types it in every thread he posts in going along the lines of "NEVER connect anything directly to the Leaf's auxiliary battery posts!!!!" but I guess I'm the only one who read it!

Funny, I never stepped foot in a Leaf until 3 months ago and now I know more about these cars than people who have owned them for half a decade!

 

[IssacZachary]

No. The voltage will be lower. Go do it yourself. The text I quoted states exactly the same. E=IR, there are three variables. If resistance is higher then current or voltage, or both, will be lower. Based on the text I quoted, both current and voltage will be lower in low temperatures and that is common knowledge about lead acid batteries you have it plain backwards sorry to say.

I'm sorry Vitaminj, but I'm going to have to call you out on this one. Either we're not talking about the same thing or you really don't know very much about electricity and batteries.

I'm talking about a discharged lead acid battery on a Leaf being charged via jumper cables off of a running ICE car.

If you're talking about the same thing you don't make any sense. I don't need a voltmeter to know what's supposed to be going on. For one, because I've charged lead acid batteries and used voltmeters on them a countless number of times. And two, because of the math.

You can take a completely dead lead acid battery that's at 0V, hook it up to a 14V charger, and it will have 14V instantly across its terminals. It's not going to go slowly up from 0V, to 1V, to 2V... etc. Hell! You could throw a 24V charger on there and you'd instantly have 24V.

If your voltmeter was halfway accurate and it measured exactly 12v with the car off, guess what bub the lead acid battery is a gonner.

Let's say it was 12V when I was jumping it. The ICE charges at 14V. If the ICE is at 14V, and I have jumper cables totaling 0.006 ohms (4AWG at 10 foot twice) them the current through those cables would be 333A. But of course the maximum current draw of the alternator is 105A putting the voltage differential between the two batteries not more than 0.6V (Leaf 12V, ICE 12.6V. Ok?)

Now I highly doubt that the voltage was 12V and that the car wouldn't start at that. Normally an ICE won't start off of less than 9V. I'd imagine the Leaf to be at least 10V. So at 10V, that would be less than the 1,000CA battery on the Golf. At 10V the amperage would be close to that 333A without the alternator. Put the alternator back into the equation and if what you say is true, the charging voltage of the Leaf battery is still going to be around 10V, too low to start the Leaf, we're looking at a charging current of around 400A.

400A feeding what? What device on the Leaf would draw the charging voltage down that much? It's utterly preposterous, illogical, makes no sense whatsoever.

The references you are using talk about a single battery system by itself, not a bad battery and a good battery connected together or a battery being charged from an external source. Therefore they aren't very relevant and furthermore I don't see and reference to voltage. Which really wouldn't matter if it did since we are talking about hooking up three different voltage sources together at the same time, not just one by itself.

The Hall Effect current sensor at the negative terminal of the 12-volt battery has nothing to do with this. A loose connection somewhere would cause the failure to start regardless of the battery voltage. It is possible that the connection at the current sensor was loose, in which case the car would start if the booster battery negative cable was connected to chassis ground.

Now this makes the most sense. A bad connection somewhere, even if it were a bad jumper cable connection and a dead Leaf battery.

I might test the lead acid battery capacity myself if I get the time. But I'm still leaning towards a bad connection somewhere. Maybe I got it when I cleaned up the battery terminals. I'll definitely try that negative ground cable at the frame, as well as the DC converter connections.

 

[LeftieBiker]

I'll definitely try that negative ground cable at the frame

That's how you should always do a jump start - even with a Leaf - because the slight risk of hydrogen explosion is still there, and because of the current sensor (never called a "multimeter" until yesterday!) on the negative terminal. You can use the part of the inverter stack that looks like an ICE valve cover as a ground.

12 volt batteries can act as giant resistors and still not charge, but that's only when they are actually dead. Viable batteries will absorb charge and the voltage will go up pretty quickly while connected - it's the available amperage that really lags.

 

[IssacZachary]

I'll definitely try that negative ground cable at the frame

That's how you should always do a jump start - even with a Leaf - because the slight risk of hydrogen explosion is still there, and because of the current sensor (never called a "multimeter" until yesterday!) on the negative terminal. You can use the part of the inverter stack that looks like an ICE valve cover as a ground.

12 volt batteries can act as giant resistors and still not charge, but that's only when they are actually dead. Viable batteries will absorb charge and the voltage will go up pretty quickly while connected - it's the available amperage that really lags.

Exactly! Last connection on frame, but because of possible explosion, not because the 12V battery will be low on volts.

 

[VitaminJ]

Either we're not talking about the same thing or you really don't know very much about electricity and batteries.

You can take a completely dead lead acid battery that's at 0V, hook it up to a 14V charger, and it will have 14V instantly across its terminals. It's not going to go slowly up from 0V, to 1V, to 2V... etc. Hell! You could throw a 24V charger on there and you'd instantly have 24V.

These two sentences are perfect together Sorry but you're completely wrong! Especially if it's very cold!

Let's say it was 12V when I was jumping it. The ICE charges at 14V. If the ICE is at 14V, and I have jumper cables totaling 0.006 ohms (4AWG at 10 foot twice) them the current through those cables would be 333A. But of course the maximum current draw of the alternator is 105A putting the voltage differential between the two batteries not more than 0.6V (Leaf 12V, ICE 12.6V. Ok?)

You are mistaking the maximum current draw, with the actual current draw. And if your Leaf refused to start your 12v battery must have been lower than 12 volts.

Now I highly doubt that the voltage was 12V and that the car wouldn't start at that. Normally an ICE won't start off of less than 9V. I'd imagine the Leaf to be at least 10V. So at 10V, that would be less than the 1,000CA battery on the Golf. At 10V the amperage would be close to that 333A without the alternator. Put the alternator back into the equation and if what you say is true, the charging voltage of the Leaf battery is still going to be around 10V, too low to start the Leaf, we're looking at a charging current of around 400A.

The Leaf does not "start" like an ICE car. In an ICE car if the battery turns the starter motor, it starts. In the Leaf, if the computer detects the right voltage, it starts, if it doesn't it doesn't start. It's digital, not analog. An ICE car takes a huge current to start, the Leaf just needs the computer to see the "right" voltage. Completely different animal.

400A feeding what? What device on the Leaf would draw the charging voltage down that much? It's utterly preposterous, illogical, makes no sense whatsoever.

Yes, you are completey misunderstanding my entire posting history in this thread. I would understand why you call it illogical if you are not following.

The references you are using talk about a single battery system by itself, not a bad battery and a good battery connected together or a battery being charged from an external source. Therefore they aren't very relevant and furthermore I don't see and reference to voltage. Which really wouldn't matter if it did since we are talking about hooking up three different voltage sources together at the same time, not just one by itself.

Cold = lower voltage universally across all batteries.

Now this makes the most sense. A bad connection somewhere, even if it were a bad jumper cable connection and a dead Leaf battery.

I might test the lead acid battery capacity myself if I get the time. But I'm still leaning towards a bad connection somewhere. Maybe I got it when I cleaned up the battery terminals. I'll definitely try that negative ground cable at the frame, as well as the DC converter connections.

Well considering it's been a few days and you literally haven't done anything on your car but post on the internet, I seriously doubt you will check your ground :mrgreen:

 

[VitaminJ]

12 volt batteries can act as giant resistors and still not charge, but that's only when they are actually dead. Viable batteries will absorb charge and the voltage will go up pretty quickly while connected - it's the available amperage that really lags.

Or when the temperature is very low, as it was in this case, single digits Farenheit. Thanks for agreeing with me, I know it was hard to do!

 

[VitaminJ]

Exactly! Last connection on frame, but because of possible explosion, not because the 12V battery will be low on volts.

No, you put it on the frame so that the Leaf's voltmeter sees the jumper's higher voltage and not the 12v battery's weak voltage. Once the voltage is right, the DC converter comes on, the Leaf takes over the 12v duties, you remove the jumpers, and the car drives away.

Or you connect them directly to the batter terminals (even though there are 100s of posts on this forum saying NEVER do that) and you will have to wait for the battery to take on charge and come up to a voltage the Leaf is happy with. If it is warm out, that will be almost instantly, if it is cold it can take a long time.

 

[IssacZachary]

I rest my case. Vitaminj just doesn't get it. Sorry, no offense. You just don't make any sense. I say drop it because I won't ever believe that connecting a discharged, perhaps bad little battery to a healthy big battery and a running alternator would slowly charge up in voltage.

 

[VitaminJ]

I rest my case. Vitaminj just doesn't get it. Sorry, no offense. You just don't make any sense. I say drop it because I won't ever believe that connecting a discharged, perhaps bad little battery to a healthy big battery and a running alternator would slowly charge up in voltage.

And that is fine fine fine. You don't have to believe it. It's 60 degrees right now otherwise I'd make a video and prove it to you. Maybe I should put my old lead acid battery in the freezer and make you a video after work. I'm not sure why I am putting more effort into fixing your car than you are though! :lol: Must be because I like fixing things. Like the 4 or 5 Leafs I helped dealer's jump start before I test drove them. Or maybe it's my profession in technical support that makes me not want to give up on stubborn customers.

 

[IssacZachary]

And that is fine fine fine. You don't have to believe it. It's 60 degrees right now otherwise I'd make a video and prove it to you. Maybe I should put my old lead acid battery in the freezer and make you a video after work. I'm not sure why I am putting more effort into fixing your car than you are though! :lol: Must be because I like fixing things. Like the 4 or 5 Leafs I helped dealer's jump start before I test drove them. Or maybe it's my profession in technical support that makes me not want to give up on stubborn customers.

Please do try. Leave lights on till discharged as much as you please. Put in freezer overnight. Take out. Put jumper cables on it from running car. Measure voltage at freezing battery's terminals. Is it the original discharged voltage (i.e. 9 or 10V) or the charging voltage (i.e. 13.5 or 14V)? The world may never know.

Now I feel like a Tootsie pop.

 

[VitaminJ]

Yep I will. The catch is that I did this like 5 weeks ago when I was getting my other car running after it has been off the road for 2 years so I already know how it will play out