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Use which ammeter to test for a battery drain?


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Mark2465
Novice

Oct 4, 2019, 1:24 PM

Post #1 of 6 (1586 views)
Use which ammeter to test for a battery drain? Sign In

Somewhere, there's a constant drain on my car battery. The post at
http://autoforums.carjunky.com/...THE_BATTERY_P186624/
tells us how to find that drain, and requires an ammeter.
A normal car battery has 40 to 90 amps.
Most multimeters say they can measure up to 10 amps current.
If I try the procedure in that above-mentioned post, will I melt my multimeter?
Do I need to get a more powerful ammeter?
Any particular brand / model that you might suggest?
Thanks very much.
Mark2465


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Oct 4, 2019, 2:12 PM

Post #2 of 6 (1572 views)
Re: Use which ammeter to test for a battery drain? Sign In

? "Milliamps" not AMPs a battery can put out.
Look at your device for that setting then it's spelled out in link you referred to pretty dang well,


T



Mark2465
Novice

Oct 4, 2019, 7:30 PM

Post #3 of 6 (1562 views)
Re: Use which ammeter to test for a battery drain? Sign In

Yes, Tom, I understand that the post mentions a 50 mA draw as being too high.
I THINK that's irrelevant to my question.
My question is about a normal car battery having 50 amps,
and my multimeter measures only up to 10 amps.
I AM referring to the AMPS that a car battery normally puts out.
Will I melt my multimeter if I hook it up?
Sorry if I didn't word it adequately the first time.


(This post was edited by Mark2465 on Oct 4, 2019, 7:43 PM)


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Oct 4, 2019, 11:25 PM

Post #4 of 6 (1538 views)
Re: Use which ammeter to test for a battery drain? Sign In

If you mean load testing a battery by amps you would put a load on it (I don't do that in for real loads myself with a machine) like most commonly the starter motor is the expected highest load a vehicle's battery should have to sustain.
The rating of that should be on a battery so use the starter as the load and watch how long voltage also keeps holding is in counting seconds but don't crank engines more than 10 seconds then give it a cool down time of minutes - by a watch it harm it.


CCA = what it can do at 32F vs 80F is bragging rights on them the actual power drops a LOT by lower temps.


Rather than beat on power of a battery out side of cranking an engine what is your issue first then let's find the excessive drain but first begin with a fully charged battery.


Testing other than that isn't accurate info for much of anything.


Back to your specific issue: Is your battery going low without the vehicle (machine) or what being on?
What type of vehicle, model year, engine size.
What type of battery are you looking to test! That will matter too. Flooded lead/acid is the most common used in automotives for starting an engine. If other than that there are and new specs for other uses,


T



Mark2465
Novice

Oct 5, 2019, 9:33 AM

Post #5 of 6 (1518 views)
Re: Use which ammeter to test for a battery drain? Sign In

Thanks for the replies, Tom. I apologize. . .
I thought this was just a generic question, not needing vehicle specifics.
2007 Mitsubishi Outlander, 3.0 L V6 gas engine.
The battery is only five months old,
an EverStart Maxx-24F lead acid unit with 750 CCA from Walmart.
This vehicle is rarely driven, nowadays.
It often sits idle for a week at a time.
Sometimes 10 to 12 days, and that's when the vehicle won't start.
It's quite a Slow drain.
Three months ago, I went on a trip, and the vehicle sat for two weeks.
It started right up after that parked time. This problem is a new thing.
I think I am now realizing that, because I want to test the Drain on the battery
when the engine is not running, there will be Very Little amps going thru the system:
only enough to drain the battery after an extended period of time.
I do not intend to try Starting the vehicle during this test.
Thus, I think it will Not fry the multimeter.
Well, that's the hope, anyway. Unsure
So far, I have fully charged the battery, and disconnected the negative cable.
I think I'll go run the test. Wish me luck. Cool


Tom Greenleaf
Ultimate Carjunky / Moderator
Tom Greenleaf profile image

Oct 5, 2019, 10:03 AM

Post #6 of 6 (1512 views)
Re: Use which ammeter to test for a battery drain? Sign In

OK: A 3.0 engine takes some power to crank if you really had the full 750 (you don't) it would crank for 30 times just long enough (few seconds) without some reason or on purpose (don't do that) disable engine but crank it as a test.
It did go too low on you is now important. Wallyworld will be happy to give you another if it went low enough it already caused some harm without fancy checking! A few of those will kill a good one.


Sub note if applicable to you: If temps where it goes VERY low or dead reach about 25F a stone dead battery will freeze inside - that ends that one. Most don't crack open anymore but can short inside your testing isn't going to show that.
It's a pull the fuses trick find which circuit drains in excess.
Myself and dozens of machines, vehicles: I use battery maintainers simply don't use everything they would be dead if too long. Some vehicles will fuss at 10 days or so is making it worse.


A problem is low all the time the alternator works like all get out gets hot in maxing out to charge it up to a norm isn't good for it can trickle drain after being too hot too many times too - ping pong game of which wrecks the other.
Find which circuit OR > This is new so double check silly things like reading lights anywhere and automatic light, glovebox type things, trunks, hatches, hood light if open. Your call - I just take the bulbs of that stuff you can get a decent flashlight for $2 bucks works better anyway.
Power ports! There's a spot. You may have many and most may shut off when engine is off, key is out. Just dirt or now 13 year old less than that too are failing constant use for devices. Don't leave anything in those and keep those plugged so nothing can get in.
Go ahead if nothing obvious just found looking now do that test. Get a maintainer if at all possible use it where you park if possible at all 12 days is pushing it IMO and experience.
When you are convinced you found something and it quits the NO START try at 5 days or get someone to.


What I'm saying is dump that battery for another but know until a new one proves itself for a few weeks of no trouble there's risk it's NG too! Why - handling the things is the culprit.


Dept stores will (so do pro parts outlets) rotate stock like groceries, battery is heavy it's annoying and rough handling to do that wrecks them!


BTW of last 3 batts I acquired 1 was totally bad within two days just semi worked, checked and wouldn't hold voltage up with any load not a car another machine thing,


Tom (sorry for my too usual novels on a subject it still matters to pay attention to silly stuff)







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