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Discussion Starter · #1 ·
So my X has been out of commission for a while now. I only drive it a couple times per week and I dunno if it's the cool weather or what, but if I don't drive it within 3 days it dies on me.

I've got a trickle charger that I use to top it up, but I've been trying to figure out what could be causing this. I've had the battery tested in 3 places and they all say it's awesome (Diehard Platinum).

The alternator 'barely' passes.

So I've been thinking the alternator isn't fully charging the battery, but I decided to do a parasitic draw test.

I followed the instructions from this video, which is really well done:
http://www.youtube.com/watch?v=KF1gijj03_0

I do exactly as he does - set my multimeter for 10 Amps, disconnect negative battery cable and clamp the multimeter leads to the negative terminal and the negative battery cable.

When I first do this there's a slight 'surge' in activity that measures around "0.80" on the multimeter. I figure this is when the dash flickers, the ECM is booting back up, whatever.

After a few seconds everything settles down and the amps sit at around "0.15" plus or minus 1.

So that to me seems like a relatively low draw. I pulled a bunch of fuses and nothing affected the multimeter.

So - Is theory number 1 correct? Alternator isn't charging the battery enough and so it just drains down and dies after driving the X for awhile?

Or am I performing the parasitic draw test wrong? I thought for sure it would be my offroad lights or something, but I have all of those accessories going through relay's and switches - and when I pull their fuses, nothing happens.

Thoughts?
 

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0.15 amps is less than 2 watts worth of power. Nothing. The truck ought to be good for a few weeks at that if the battery is good.

You can take the battery to PepBoys and they'll test it for free.

Start the truck up and measure the voltage across the battery terminals - it should read 13.6 volts.

Shut the truck off and it shouldn't drop below 12.6 volts.

Do the lights dim when you let the truck idle? Does the dash lights dim when you turn the headlights on? - these are indicators of the alternator struggling to keep up. If the alternator is bad the truck will not get enough current even while running.

The Xterra is kind of high tech in that there's a module on the negative lead that measures the current draw and adjusts the output of the alternator to match. This is done in the name of energy efficiency likely saving 0.05 miles per gallon. If there's a problem with that module or the circuit behind it the alternator might not be charging the battery.
 

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Discussion Starter · #3 ·
Thanks Paul - I did as you advised, and the voltage works out exactly.

So, now I'm at a loss! I have two sets of off road lights, I'm wondering if maybe there's an issue with them since I tried turning them on, and all of a sudden they don't work. Fuses are good, which is making me think the relay's are bad - even though I can hear them 'click' off and on along with the switch. Ugh.

I'm going to keep digging. I managed to get a cheap Coleman solar battery maintainer I'm going to keep in the X for the time being and see if that helps at all, but that's clearly a band-aid at best.
 

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You know you have a draw. You know it kills the battery. Forget the amount for a second.

Hook up your meter and start pulling fuses one at a time until the draw stops. Then you'll know which circuit is shorting. You'll really narrow down the problem. If you can leave that circuit interrupted, or disconnect when you park for the night, you can learn whether the problem goes away.

Then focus on that circuit testing wires for a short to ground.
 

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try fully charging the battery with an external charger, if it still is dead after 3 days of sitting, the battery might be bad. but the cause of the bad battery could be the barely working alternator, causing the truck to have to pull from the battery, discharging it while it should be charging it.
 

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Discussion Starter · #8 ·
try fully charging the battery with an external charger, if it still is dead after 3 days of sitting, the battery might be bad. but the cause of the bad battery could be the barely working alternator, causing the truck to have to pull from the battery, discharging it while it should be charging it.
Done that. Battery still died after a few days :(

I's super frustrating. Battery testings says it's good, alternator testing says "technically good but not great". Current draw is very low. A couple random accessories don't seem to be working. Makes me want to rip the thing apart.

Surf, with your inverter - is your negative cable attached to the battery post? I'm wondering if it's something to do with the chip / circuit thing that is attached to the negative terminal.
 

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Charge it up
Unhook the battery.
Wait your magic 3 days.
Hook the battery up and see if it starts.
Yes, battery OK
No, you have a drain.

Alternators can have an internal leak and pull a battery down. But usually faster then 3 days. Try unhooking the alternator and see if that takes out the .15A draw. I believe that can be done at the battery.

Anything aftermarket? I have seen GPS tracking systems suck batteries down. Stereo amps that don't fully shut down also do it. Some aftermarket alarm systems are power pigs as well and on all the time. I don't trust any aftermarket electrical items.
 

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Discussion Starter · #10 ·
Did that - Battery was OK.

Definitely have some aftermarket stuff. Pulled all the fuses on them, no change. But, a few of them have stopped working in general making me think it's their relays or something. Maybe it's a bad ground somewhere.

I'll try disconnecting the alternator when I get a chance and see if that changes anything.

Charge it up
Unhook the battery.
Wait your magic 3 days.
Hook the battery up and see if it starts.
Yes, battery OK
No, you have a drain.

Alternators can have an internal leak and pull a battery down. But usually faster then 3 days. Try unhooking the alternator and see if that takes out the .15A draw. I believe that can be done at the battery.

Anything aftermarket? I have seen GPS tracking systems suck batteries down. Stereo amps that don't fully shut down also do it. Some aftermarket alarm systems are power pigs as well and on all the time. I don't trust any aftermarket electrical items.
 

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Done that. Battery still died after a few days :(

I's super frustrating. Battery testings says it's good, alternator testing says "technically good but not great". Current draw is very low. A couple random accessories don't seem to be working. Makes me want to rip the thing apart.

Surf, with your inverter - is your negative cable attached to the battery post? I'm wondering if it's something to do with the chip / circuit thing that is attached to the negative terminal.
No, but its irrelevant when the truck is off. The device on the the neg cable is a current transformer (CT) which is there as an ammeter to measure current but its only reading when the truck is on. You can go ahead and disconnect your inverter completely to see if your draw goes away. You might want to do that with all your add-ons to isolate the problem.
 

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Discussion Starter · #12 ·
No, but its irrelevant when the truck is off. The device on the the neg cable is a current transformer (CT) which is there as an ammeter to measure current but its only reading when the truck is on. You can go ahead and disconnect your inverter completely to see if your draw goes away. You might want to do that with all your add-ons to isolate the problem.
Thanks, that's the plan today. So where did you ground your inverter? I attached mine to the negative post because the inverter manual said it should be, so I figured I'd go with that. But I know our system isn't necessarily 'typical' with the CT device.
 

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Thanks, that's the plan today. So where did you ground your inverter? I attached mine to the negative post because the inverter manual said it should be, so I figured I'd go with that. But I know our system isn't necessarily 'typical' with the CT device.
I originally had it to neg bat post, but when I went to dual batteries I stuck it to body ground near the batteries for conscience while I was I installing some other grounds.
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Discussion Starter · #14 ·
I originally had it to neg bat post, but when I went to dual batteries I stuck it to body ground near the batteries for conscience while I was I installing some other grounds.
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Cool. I may as well do that while I'm in there messing around. I'm planning on dual batteries at some point in the future too anyways.
 

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Haven't tried that yet. But, I did have it charged and put it back in the X but did NOT hook it up. Let it sit for a few days, and it held it's charge.
I thought you were hooking it back up but if it was just sitting there unconnected and it held then it is not the battery.

Go back to the stock battery connections, no accessories and see what happens. If it still dies then you know its not an accessory. If you have too much corrosion it can also cause issues.
 

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Discussion Starter · #18 ·
I thought you were hooking it back up but if it was just sitting there unconnected and it held then it is not the battery.

Go back to the stock battery connections, no accessories and see what happens. If it still dies then you know its not an accessory. If you have too much corrosion it can also cause issues.
Thanks. It's a sealed battery (diehard platinum) so thankfully there's basically zero corrosion. Connections at the posts are solid as a rock.

But yes, I'm going to go through and trace every wire back and see what's going on. Just need the time to do it (and some warmer weather would be nice).
 

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Discussion Starter · #19 · (Edited)
Edit - NM.

Measured voltage across terminals, got 12.45, figured it wouldn't crank - it did, without skipping a beat.

Then I moved the inverter cable to the body ground. Fired up the X and it showed only 13.1 volts. Shut it down, tightened the ground bolt, and it's back up to 14.3-14.7 charging.

So - we'll see how it goes. About to take her out for a run to the landfill, then picking up a friend at the airport. Lots of driving so I'm hoping to see a charged battery by the end of it.
 

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Haven't tried that yet. But, I did have it charged and put it back in the X but did NOT hook it up. Let it sit for a few days, and it held it's charge.
In the truck, out of the truck, doesn't matter. Only relevant factor is having the battery unhooked during that time.
 
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