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Current to ground


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rjbmed
New User

Dec 9, 2017, 9:09 AM

Post #1 of 7 (387 views)
Current to ground Sign In

I have probably a dumb question, 2007 Toyota Hilux 2.7L 4Cyl, have been having intermittent battery drain, now worsening. I can disconnect the neg battery cable, and test from ground cable back to battery, and read 12.6 VDC, I disconnected the alternator and had the same results. The only thing I notice is that the alternator does not move off of 13.9 VDC when running, at idle or with RPM's, I live a few hours from the nearest garage, so, any help would be greatly appreciated


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 9, 2017, 9:28 AM

Post #2 of 7 (379 views)
Re: Current to ground Sign In

They don't sell this by that name anymore to the US but shouldn't matter. For now your readings of what you did are acceptable depending on what you left on or how long you waited presumable checking for a "parasitic drain" - know that most vehicles draw some power when just disconnected the way you tested and if you aren't finding battery low and better reads 12.6V overnight or hours later that's fine nothing wrong!


You came for a reason no doubt so will need a DVOM digital volt ohm meter is best. Check the same as the battery cable to battery you did and watch it drop to almost no draw or know it's excessive follow this procedure listed below.........


> http://autoforums.carjunky.com/...THE_BATTERY_P186624/


T



rjbmed
New User

Dec 9, 2017, 9:38 AM

Post #3 of 7 (374 views)
Re: Current to ground Sign In

My meter just reads voltage, Amps AC, from what Ive read I need a better meter to solve this, but you say its normal to read voltage with the battery disconnected?, thats not current going to ground?, if I connect the battery, (just replaced), it will draw down in a few hours. I didn't want to risk damaging something by driving to town, but that would be the best option.
Thx


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 9, 2017, 10:19 AM

Post #4 of 7 (371 views)
Re: Current to ground Sign In

Normal when disconnect just voltage: Yes for a while if there's a very strong draw even hood light or open door with interior lights on but should drop off of 12.6 is about perfect for an automotive battery.
Test your meter also on other known things see how close it is like a 9V household battery or in comparison with another meter it struck me as unusual when running it stayed the same normally if you turning on lights, a blower it would drop and recover with higher RPM but never drop below 13V when running nor over about 14.7V nor really stay there long.


You can also watch while cranking shouldn't drop excessively or indicates low battery amps available if you see lower than 9V for even a second your battery isn't strong enough give it a break for some extreme OR you hadn't started it in many days it might and be normal.
Not all mean a problem some have a clear reason or one to be found.


You didn't say if this was leaving you stuck and not starting over this over some time requiring charging it up if so do use a charger till full charge always best don't make alternators work any harder than they do anyway.
Just FYI - know that "lead-acid" batteries are NOT meant to be run low like other types (cell phones and such) it harms them to run low either quickly or just shortens the life of one.


In brief - get a DVOM as said for more detailed info for checking things and learn the milliamps meter of it many things will require fractional draws more than just volts,


T



Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Dec 9, 2017, 11:52 AM

Post #5 of 7 (367 views)
Re: Current to ground Sign In

Yes, you need a better meter and a better understanding of electrical current measurements. You need a meter that not only reads amps but reads in the milliamp scale.



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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.



rjbmed
New User

Dec 9, 2017, 4:41 PM

Post #6 of 7 (352 views)
Re: Current to ground Sign In

Thanks for the help,


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Dec 9, 2017, 9:26 PM

Post #7 of 7 (342 views)
Re: Current to ground Sign In

Good luck. You may NOT have a problem if this still starts and shows what you've observed already but still get a DVOM just useful to have. The only concern I have so far is you see the same higher voltage when running all the time? Alternators don't do that it really would go up and settle down to a area around what you posted not stuck exactly there the system isn't really meant to be that specific if so (it's not) it would be fine there none do that it's your meter,


T







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