battery drain, while driving - not fun
03-31-2016, 12:13 PM
#1
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battery drain, while driving - not fun On the highway yesterday my battery drained from 13 volts to 8 volts in a matter of 3 terrifying minutes.
First the stability, abs lights came on, then I watched the volts decrease 13.8 volts downward... .1 volt at a time over the course of several minutes... somewhere around 10 volts the battery light came on... then everything started freaking out around 9 volts... then at 8 volts the gauges and center console went dark...
with no breakdown lane in sight traveling in traffic at highway speed I was waiting for the car to just die, blood pressure rising as the volts fall... and then everything lights back up, the car keeps running fine, and the volts go instantly back to 13.8.
WTF?
A few weeks back my battery cable was rubbing on the headers, which caused an intermittent loss of power but this was a smooth and precipitous decrease in voltage .1 volt at a time... not a short, at least I don't think...
Any ideas?
First the stability, abs lights came on, then I watched the volts decrease 13.8 volts downward... .1 volt at a time over the course of several minutes... somewhere around 10 volts the battery light came on... then everything started freaking out around 9 volts... then at 8 volts the gauges and center console went dark...
with no breakdown lane in sight traveling in traffic at highway speed I was waiting for the car to just die, blood pressure rising as the volts fall... and then everything lights back up, the car keeps running fine, and the volts go instantly back to 13.8.
WTF?
A few weeks back my battery cable was rubbing on the headers, which caused an intermittent loss of power but this was a smooth and precipitous decrease in voltage .1 volt at a time... not a short, at least I don't think...
Any ideas?
Last edited by idrvarocco; 03-31-2016 at 12:21 PM.
03-31-2016, 02:13 PM
#5
On The Tree
I cast my vote for alternator as well. I had this happen to me in a drive through on my base 06 before I got rid of it. Was fine a couple weeks after the occurrence then went out completely with a nice loud grinding noise.
03-31-2016, 03:33 PM
#7
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I haven't had any issues with my alternator but it seems these guys have. I have had a bunch of issues with the batteries though. You could always have the battery tested just to rule that out and then dig in for the alternator.
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03-31-2016, 03:49 PM
#8
If you've swapped incandescent lights for LEDs, added laser jamming hardware, or installed more/better fuel pumps, your battery troubles are probably caused by the alternator. If you look at the amperage vs RPM/temperature curves for the stock alternator, your power problems will suddenly make sense. It had very little margin compared to the bone stock system.
My 240A Mechman puts out more power at 800 RPM than the stock alternator did at peak RPM. Even though my daily drive to work is only 15 minutes, I haven't issues with my Deka ETX20L battery (15.5 lbs, 310 CCA, in service since 2014). My favorite part about the Mechman system is the AVBM II, which allows me to compensate for voltage drop to the battery in the trunk. With it, I can dial in my charging voltage to the maximum recommended by the battery manufacturer.
The higher system voltage and greater low-RPM amperage results in better continuous-time fuel pump performance and helps the engine stay alive at very low RPM where ignition system voltage and fuel pump speed would otherwise decrease to unacceptably low levels.
My 240A Mechman puts out more power at 800 RPM than the stock alternator did at peak RPM. Even though my daily drive to work is only 15 minutes, I haven't issues with my Deka ETX20L battery (15.5 lbs, 310 CCA, in service since 2014). My favorite part about the Mechman system is the AVBM II, which allows me to compensate for voltage drop to the battery in the trunk. With it, I can dial in my charging voltage to the maximum recommended by the battery manufacturer.
The higher system voltage and greater low-RPM amperage results in better continuous-time fuel pump performance and helps the engine stay alive at very low RPM where ignition system voltage and fuel pump speed would otherwise decrease to unacceptably low levels.
Last edited by FuzzyLog1c; 03-31-2016 at 04:12 PM.
03-31-2016, 03:53 PM
#9
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If you've swapped a bunch of incandescent lights for high power LEDs, your battery troubles are probably caused by the alternator. If you look at the power/RPM/temperature curves for the stock alternator, your power problems will suddenly make sense.
My 240A Mechman (downside: ridiculously expensive) puts out more power at 800 RPM than the stock alternator did at peak RPM in cold climates. Even though my daily drive to work is only 15 minutes, I haven't issues with my Deka ETX20L battery (15.5 lbs, 310 CCA, in service since 2014).
My 240A Mechman (downside: ridiculously expensive) puts out more power at 800 RPM than the stock alternator did at peak RPM in cold climates. Even though my daily drive to work is only 15 minutes, I haven't issues with my Deka ETX20L battery (15.5 lbs, 310 CCA, in service since 2014).
Thanks, guys. Sounds like I need a new alternator. Good looks, Fuzzy!
03-31-2016, 04:07 PM
#10
04-01-2016, 10:19 AM
#16
The luminous efficiency of LEDs is far greater than incandescent bulbs, but in automotive applications, users rarely replace incandescent bulbs with LEDs of the same wattage and lumen output.
For instance, I replaced my reverse and turn signal bulbs (which were 25W, IIRC) with 80W LED units. My reverse lights are now brighter than conventional halogen headlights. I took the same approach with every single incandescent bulb in the car, and as a result, the peak power demand of the lighting system went up by hundreds of watts.
For instance, I replaced my reverse and turn signal bulbs (which were 25W, IIRC) with 80W LED units. My reverse lights are now brighter than conventional halogen headlights. I took the same approach with every single incandescent bulb in the car, and as a result, the peak power demand of the lighting system went up by hundreds of watts.
04-01-2016, 10:23 AM
#17
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The luminous efficiency of LEDs is far greater than incandescent bulbs, but in automotive applications, users rarely replace incandescent bulbs with LEDs of the same wattage and lumen output.
For instance, I replaced my reverse and turn signal bulbs (which were 25W, IIRC) with 80W LED units. My reverse lights are now brighter than conventional halogen headlights. I took the same approach with every single incandescent bulb in the car, and as a result, the peak power demand of the lighting system went up by hundreds of watts.
For instance, I replaced my reverse and turn signal bulbs (which were 25W, IIRC) with 80W LED units. My reverse lights are now brighter than conventional halogen headlights. I took the same approach with every single incandescent bulb in the car, and as a result, the peak power demand of the lighting system went up by hundreds of watts.
04-01-2016, 07:54 PM
#20
Don't mistake watts for lumens. And nobody's making a 150W part. If you want the brightest thing on the market, you need to be looking at the 60W Cree XB-D units.
Even then, you have to understand that Cree LEDs are binned into 20-25 separate categories based on their efficiency. Cheaper manufacturers pick the lower binned parts. I'm a generation back, but my reverse lights are plenty bright for 30% tint. So whatever you get should be good enough.
https://www.ebay.com/itm/2X-60W-Brig...lTrnBS&vxp=mtr
Even then, you have to understand that Cree LEDs are binned into 20-25 separate categories based on their efficiency. Cheaper manufacturers pick the lower binned parts. I'm a generation back, but my reverse lights are plenty bright for 30% tint. So whatever you get should be good enough.
https://www.ebay.com/itm/2X-60W-Brig...lTrnBS&vxp=mtr