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Battery drain issue

Sandman

Sandman

New member
I've got a battery drain issue where by lunch time my car is tough to start but once cranked it's all good. I've looked over the battery cables and can't find anything wrong with them and I did a drain test by hooking my meter between the battery ground cable and terminal while pulling fuses and never saw any differences. I didn't do a detailed look but I did a quick glance around the engine bay and the wires looked good. I'll get in there this weekend and really look everything over. Also I've read something about the alternator diodes going bad and pulling power but I disconnected the alt entirely and no change. It is pulling about .144 amps, I'm assuming that's to high. What else can I do to find this?

edit:

I forgot a bunch of info there. The battery is new, starter is new, alt is the stocker @ 170K miles, the battery grounds are clean, I pulled fuses from both fuse panels, and the meter I'm using is a regular Fluke with the probes.
 
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Yeah that's way too much. I think the acceptable amperage is somewhere around 30mA. You pulled the fuses under the hood too? What are you using to measure amperage? If it's a clamp meter you can clamp around the wire after the fuse block under the hood and see if it's not there.
 
lets start off simple.

how old is the battery? have you tested it with a battery tester? one that puts a load on the battery to test the cca? parts stores do this for free.

next simple test is to test the battery power car off, should read 12 volts, no less. then start the car re test the power at the battery, it should be as high as 14 volts.

then of course the battery connections and grounds could be dirty or corroded. clean them up. wire brush does a nice job.
 
I forgot a bunch of info there. The battery is new, starter is new, alt is the stocker @ 170K miles, the battery grounds are clean, I pulled fuses from both fuse panels, and the meter I'm using is a regular Fluke with the probes.
 
un hook the battery, test the volts. then put it back on re test car off. there shouldn't be more then a .7 amps or something like that draw off the battery. any more and its gonna kill it.

have you added a new radio or gauges lately?
 
I was going to question why you were measuring in A, not mA, but it's a Fluke, should still be pretty accurate.

25-50 mA is considered normal for most cars.

http://www.diagnosticnews.com/featured/parasitic-battery-drains/

That might be of some help.

If every fuse has been removed and there is no drop, the issue might be along the main battery wire.

Try removing it at the starter and at the alternator and see if there is any change. One at a time of course.
 


I went ahead and removed the alt cable and I'll see how it is in the morning.

I'll really get into the cables tomorrow, if they're bad it's a good enough reason to upgrade them.
 
battery cables do go bad. especially if you can see the copper wire showing through broken insulation on the cable or its ends.

not that they would drain the battery but you loose a lot of the currant to the starter and it acts like a dead battery.
 
The GM spec for a drain is 50 mA. The normal reading I get on a good system is 15-30 mA. It takes about a 300 mA drain to run down a battery enough overnight for it to not start. If you have a 144 mA drain it will take 2 or 3 days for the battery to run down enough for it to not start. You said the battery is new, was it doing this same thing before you replaced the battery? You could still have a bad battery. I have also seen relays intermittently stick causing a high drain at times.

I assume you know how to use your meter correctly to check amps and the fuses in your meter are good. It sounds like you probably have a larger drain than you are detecting.
 


I think he's reading it right. There aren't a whole lot of ways to do it wrong, and flukes are known to be accurate. He hasn't mentioned that it's gone completely dead yet anyway. Just noticing it was touch to start. He's on the right track, and we'll know this weekend.
 
I had it hooked up right.

After leaving it unhooked all night it was still tough to start. Another guy suggested unhooking the battery completely and seeing not it itself is bleeding off.
 


its a box with 2 jumper like cables on it, it reads the volts, then they hit a switch and it draw on the battery like a simulated engine start, but it take way more power, if it dont hold in the cca range of your battery it failing. you should have a battery rated for 600 cca if na and 625 iirc for the sc engines.
 
Check the voltage to be sure. "Hard to start" shouldn't be a substitute for an OCV (open circuit voltage) test aka battery state of charge. Yes if it's 12.6v at night completely unhooked from the car, and in the morning it's something like 11.5v it's definitely bad.
 
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