Mazda Miata question
- Thread starter PJumper
- Start date
Blister
Well-Known Member
If you have and know how to use a DC ammeter, check current draw with all accessories turned off. If it's more than the milliamps normally drawn by stereo or other electronic memory features, start pulling fuses until the current draw lowers noticeably. Could be something as simple as the trunk or under hood light switches fail and that light can stay on, out of sight, out of mind, or it could be an unintended ground, or faulty electronic device that can be tricky to isolate. Good luck.
Is this checked by removing the ground cable and testing between the terminal and battery post?
I vaguely remember doing this with a test light back in my jalopy driving days.
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Hodr
Guest
Is this checked by removing the ground cable and testing between the terminal and battery post?
I vaguely remember doing this with a test light back in my jalopy driving days.
If the expected power draw is low you could get away with running a multimeter (or ammeter) that way. Though usually for higher power situations you would use a calibrated shunt and meter.
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Hodr
Guest
Any reason not to use a deadman switch and cut power to the battery when the car isn't in use, I mean other than resetting the clock and pre-sets on your radio? Might be cheaper/easier than trying to diagnose the actual issue.
EDIT-----
Just re-read the OP and realized it died while he was driving, rules out parasitic draw unless there was a good deal of time between when the battery was replaced and when this happened (time enough to build up sulfates to the point that the battery won't take a charge).
If the battery is new, check the cables for corrosion. When the car is running, make sure the alternator is putting out > 14v (check at the battery terminals).
EDIT-----
Just re-read the OP and realized it died while he was driving, rules out parasitic draw unless there was a good deal of time between when the battery was replaced and when this happened (time enough to build up sulfates to the point that the battery won't take a charge).
If the battery is new, check the cables for corrosion. When the car is running, make sure the alternator is putting out > 14v (check at the battery terminals).
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PJumper
New Member
Alternator putting 14V at the alternator post, however is not reaching the baterry.
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Hodr
Guest
Alright, then if I were you I would pull the line from the alt to the battery (if easily done), or just run another new line if the old one is hard to get to.
glhs837
Power with Control
Not to belabor the point, but you are saying when you read across the battery terminals, you are not seeing that 14v? Should be easy to track back then. Usually not a lot between the alt and the battery. I think the first thing to look at is the ground cable from the battery to the chassis.
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Hodr
Guest
I read his response as having checked both at the alt (14v) and at the battery (<14v). I assumed he would have already checked the ground.
Definitely check that first (check negative battery terminal to chassis, looking for close to 0 ohm). If its good, then just run you a 10 gauge cable from the alt to the battery and be done with it.
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Blister
Well-Known Member
Do not just run a 10 awg wire from the alternator to the positive battery post!!! The 80 Amp fuse on page 27, between the the Alternator and battery, is there for a reason.
http://www.yorbalindamiata.com/images/wiring/99sys.pdf
The only good part of that idea is that an unfused 10 wire that gets accidentally grounded between the Alt. and Battery would probably burn open on a 12 volt system before it sets the car on fire.
If you are knowledgeable enough to use the diagrams in the link, and some simple troubleshooting techniques, carry on and have fun. If not, suck it up and pay someone who is.
http://www.yorbalindamiata.com/images/wiring/99sys.pdf
The only good part of that idea is that an unfused 10 wire that gets accidentally grounded between the Alt. and Battery would probably burn open on a 12 volt system before it sets the car on fire.
If you are knowledgeable enough to use the diagrams in the link, and some simple troubleshooting techniques, carry on and have fun. If not, suck it up and pay someone who is.
H
Hodr
Guest
Ohh look at Mr. Safety Schmafety over here with his fancy diagrams and fuses.
Seriously though, use a fuse like Blister says.
I forgot to call it out specifically as I assumed someone working on their own car would understand that connections to the battery are fused. But if you're asking online for advice, that assumption was probably incorrect.
Seriously though, use a fuse like Blister says.
I forgot to call it out specifically as I assumed someone working on their own car would understand that connections to the battery are fused. But if you're asking online for advice, that assumption was probably incorrect.
Not to change the subject but.
I have an older vehicle to when sits over a few days the battery is dead.
Took the battery in for load test and they said it was good.
Alternator voltage checks good.
Now I am try to diagnose for key off battery drain.
I found this: http://www.aa1car.com/library/battery_runs_down.htm
Will try it this weekend, but any other good checks?
Edit:
And prior to this happening I smelled something burning and noticed the radio doesn't work.
But I was thinking when something burns up it would create an open. I can check that by pulling the fuse.
I have an older vehicle to when sits over a few days the battery is dead.
Took the battery in for load test and they said it was good.
Alternator voltage checks good.
Now I am try to diagnose for key off battery drain.
I found this: http://www.aa1car.com/library/battery_runs_down.htm
Will try it this weekend, but any other good checks?
Edit:
And prior to this happening I smelled something burning and noticed the radio doesn't work.
But I was thinking when something burns up it would create an open. I can check that by pulling the fuse.
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GWguy
*
Misfit
Lawful neutral
That's what my brother used to ask about my Subaru BRAT.
I had a buddy that had one of those. I'd ride in one of the seats in the bed crusin' on the weekend. I can't believe I'm still alive.
