I'm sure one of the Nerdz team will chime in. But the best option, in my opinion, is the 189. The 30 amp one. I use it often. For parasitic draw testing.

The first time I was nervous it wasn't accurate, so I tested it by using my old regular set up of breaking the battery connection and putting my DVOM in between to get the draw reading. I then compared it to the 30 amp clamp, set to 1 amp scale. I also created a draw by flipping open the visor vanity light and other small lights to see if it was reading properly. It does. 

Although no current probe is really well suited for parasitic draw testing the TA189 is the best we have seen.  During our tests we found this probe to be accurate to within 10ma so the 5ma spec is a bit hopeful.  Really nice probe though.

http://www.autonerdz.com/ampprobes.html

Logic, good point and press the zero button when not connected to a wire.

Ray

I would not work with a 9v battery. Charge the battery to 12.8v then load test the battery by load testing it.
Minimum battery cranking voltage is 9.8v.

You should at least make sure the battery is good and the battery terminals are tight and clean before checking for battery drains.

I would ck the alternator voltage and amperage output.

I always do a battery negative terminal to the engine block ground voltage drop test

To test for battery drains, I usually leave the hood open, close the hood switch, remove the ignition key and lock the doors.
Move the key some distance away from the vehicle and let the vehicle sit for an hour before checking for the drain. Max battery drain is usually 50 ma

99.9% of the time, you do not have to record the battery drain overnight.

Ray

If I suspected an intermittent battery drain, I left the hood open in the parking lot all day.

Then every hour or 2, I clamped my amp probe around a battery cable to measure the amp draw.

If you get Tom's TA189, I would connect one lead of a good multi meter in the 400 ma mode to a battery terminal.

Then connect the other lead of the multi meter in series with a test light connected to the other battery terminal.

Let's say the inline ammeter reads 150 ma. Connect the TA189 amp probe any where in that series circuit and the Pico scope should show near 150 ma.

Ray 

Logic wrote on Jan 21^st, 2017 at 5:23am:


You know when you go to a class and one person asks for a verification on a quote made by the instructor and half the class around him think to themselves they are so glad you asked, well maybe this is one of those times.

Could you go into detail on this above procedure, maybe with examples of scope findings and pictures of equiptment used?

Please and thank you 

This one shows a good no load battery voltage of 12.8v on CH A, down to a bad, very low 4.8v cranking.

CH B shows a ground voltage drop of 200 mv

CH C shows the cranking amps and the maximum alternator output amperage of 93 amps on start

Ray

Mick wrote on Jan 21^st, 2017 at 6:36am:


Again, i have always had very good success with diagnosing intermittent battery drains with periodically going out to the vehicle to ck the battery drain during the day without leaving the equipment on the vehicle for any period of time because of the amp clamp reading drift.

Most of the time, the assumption of an intermittent battery drain causing an intermittent no start usually turned out to be a loose or dirty battery connection, especially the GM side battery terminals that look excellent on the outside but corroded on the inside.

Also defective batteries with a bad cell that would drain the battery voltage or a bad starter connection or bad solenoid terminal corroded or burnt connection or a corroded engine block or transmission ground connection, etc

Ray

sorry file type violation

Logic wrote on Jan 22^nd, 2017 at 1:37am:


Can you put the files alone on the drop site?

These screen shots can be useful at time if all else fails

Mick wrote on Jan 22^nd, 2017 at 10:06am:



Yes Mick exactly

Mick wrote on Jan 22^nd, 2017 at 5:16pm:



TXT and 736kb

Logic wrote on Jan 23^rd, 2017 at 3:54am:


Logic
None of them files are any where near that size.

Now that Tom has aloud TXT files could you place it here for me.

Mick wrote on Jan 21^st, 2017 at 6:47am:




Try this first

http://www.ni.com/tutorial/7114/en/

You will see that a current shunt is a very accurately known resistor.

if you measure the voltage drop across this resistor then you can use Ohms law to calculate the current.

A multimeter uses a current shunt.

Every time I reach for fluke to use the current shunt in it the fuse is blown, probably from someone in the workshop using my multimeter for a voltage measurement with the leads in the current measurement jacks....blowing the expensive fuse that requires unscrewing the back of the multimeter to replace..

i'm done with it and use stand alone current shunts along with the Pico current clamps..

there are no batteries, oreintation or drif issues with a current shunt

Mick,

What I have given you is simply a plot of voltage verses time.

We are connected to the positive and negative sides of the battery.

The car has been driven and to the left of Sunday 0:00 when the engine is turned off the gradient of the battery voltage reduction is significant.

The battery then went flat

After the car was restarted and the battery charged the sleep current consumption was normal as seen by the lack of gradient.

What did you theorise from the capture?

Logic wrote on Jan 26^th, 2017 at 10:47pm:


Ok I do see this 

Logic wrote on Jan 26^th, 2017 at 10:47pm:


Thank you for verifying this

Logic wrote on Jan 26^th, 2017 at 10:47pm:


How come the battery voltage when not reducing settles back at 14.05V?

Also for 5 hours before the Sunday 0.00 it pull as low as 7.5 Volts yet rebounded to 13.8 Volts ??????

Mick wrote on Jan 27^th, 2017 at 11:20am:


Yes the battery went flat then the battery of the car was jump started with jumper leads and a spare barttery which was carried in the boot of the car for that purpose.

rayray wrote on Jan 20^th, 2017 at 6:04am:


As well as in the area of where you are measuring.

Sorry Logic this is really illogical to me, don't want to sound offensive but you may have to explain a bit more detail about this software and it's use, haven't you just proven the obvious? the battery goes flat from a current drain? when it happens is irrelevant but are you using this tool to find which circuit is corrupt is what everyone is interested in.

I brought this tool for measuring long term voltage and current but I've never had to use it for overnight graphing
https://moosh.im/mooshimeter/

autosparky wrote on Jan 27^th, 2017 at 8:33pm:




autosparky wrote on Jan 27^th, 2017 at 8:33pm:


Yes I have proven the obvious the battery does go flat….but ….it does not always go flat.

Through logging the battery over a period of days we now no the pattern of when it starts to go flat…otherwise we are just pissing in the wind.

On one of the logging events we put a switch on the alternator output lead so we also now know that the alternator is not the cause.

Yes we are interested in finding the cause, but you must appreciate why I posted here, another tool that we can all use without flattening endless current clamp batteries.

Perhaps I should put this logging devise on either side of of the logging devise leads…then I can calculate the actual current.

If you read your manual for your Mooshimeter that is how they recommend you use the Mooshimeter to measure current.

The BMW IBS (Intelligent Battery Sensor) works in the same way.

Logic wrote on Jan 28^th, 2017 at 12:55am:


The  Calculator did its job but you may want to check your spelling after the numbers

Yahhh by golly. Volts equals amps times ohms.

Mick wrote on Jan 28^th, 2017 at 6:35am:



Don't have to post anything at all if it offends you Mick

Mr. Logic divided his ohms by the volts, rather than vice versa.

ralstig wrote on Mar 3^rd, 2017 at 9:15am:


Drift.

The Amp clamp and not just the one used here are prone to drifting above the zero line.

We always zero the clamp near to the circuit as possible, also snap the jaws open closed a couple of times to get ride of any magnetic build up in the jaws this is known as Degaussing.

After a period of time the zero will rise so the amp clamp will need to be removed from the circuit and the above procedures redone.

Hope this helped