choinga

I've done some searching and read a few posts on this...

I may have a bad battery - I went and bought a new Bosch at Pep Boys and just installed it and I don't seem to be draining that one like the previous one (a POS Duralast...have no idea how long it had been in the car...) but wanted to do some preliminary testing to see what kind of draw I have going with the ignition off.

When I set my Fluke 117 for Amps and put the postive lead on the disconnected negative terminal from the battery and the negative lead on the negative battery terminal, I don't see any measurement at all. (I tried the same thing with the positive leads - same result...)

My Fluke is supposed to measure down to .001 to 6Amps so it should cover the ~60mA range that would be the parasitic draw on the battery (clock, etc...). It just stays on "0.000 Amps".

When I switch to voltage with that same hookup I see around 11.5 volts across that connection. (Interestingly enough, when everything is connected up and I put the test leads on the terminals I get 12.6V across the battery).

I'm certainly no electrician but can't figure this one out. Even with the test leads across the negative terminal it should still conduct electricity correct? When I open the car door or do anything that should get some measurable current across there - I get nothing (and the lights don't come on, etc...).

Any ideas?

JerryW

Are you sure the amps setting is AC -- normally on a meter that stands for Alternating Current. Your Car is DC (Direct Current).

choinga

I have two "A(mperage)" settings - one is for AC and the other is for DC. It doesn't matter which setting it's on - it still just shows 0.000.

Sorry - first post I inadvertantly typed "AC" instead of A for Amperage.

bearone

you're not checking ac amps but dc amp draw.

use the milliamp setting after removing the pos cable.

on my fluke 85 i have to change the hole on the pos cable from the normal position where i measure batt voltage and not sure if your 117 is the same.

87951
95sl320 dd

krystar

make sure u put your test lead in the 10A port on the left , not the other port on the right.

choinga

yes - i have the cable in the left "A" spot and the dial on the A for "DC" setting.

Not sure what you mean by "use the milliamp setting after you remove the positve cable"??

I don't have a milliamp setting - I just set it A for direct current and it gives me a reading in a 0.000 format. So, ideally I should see something like 0.065 on the display if everything checks out.

JerryW

No Prob -- just making sure.

Jusii

Have you checked the fuse in the meter? There should be one inside, easily blown if you accidentally measure current across battery terminals and not in series as you were correctly doing.

V2Rocket

if there were really no amperage there would be no voltage either.



this is what happened. the fuse inside your multimeter is only rated for 10 amps. your battery may be upwards of 600amps which would have nuked the fuse inside. i have a fluke 179 and it is setup the same way.

if you want to measure battery amps you should take it to a car parts store because they have the machinery for that.

Jusii

He's not measuring how much current you can get of that battery, but rather 'idle' current consumption which normally should be something in mA scale. Dash clock, radio memory, possibly alarm.

Used procedure is correct and if the car draws more than 10 amps ignition of, then there's some serious problem.

KuHL 951

When I measure static current drain I use a 0.1 ohm (1mV=10mA) calibrated shunt and the 20mV voltmeter circuit for a more accurate reading. I never seem to have consistent readings using my Fluke 10A auto-ranging ammeter circuit. If you have a really bad short a shunt also prevents overloading the ammeter circuit and blowing the fuse. I have everything up to 250A capacity shunts for testing starting current and most DC electric motors.

bearone

this is my 85 with four connect points at bottom.
far right/pos, volt/ohm
2nd from right/ground
far left/amp
2nd from left/ma-ua

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95sl320 dd

choinga

Thanks guys - I'm pretty sure I blew that damn fuse when I was moving the dial around. I stuck the probes into an extension cord and I get no amperage so we know that can't be right.

Those fuses are hard to tell if they are blown though - you can't see the element inside like a typical fuse...the covering is all hazy...

Oh well, I grab one next time I'm at Fry's. Turns out it was the battery. I figured it was as after letting it sit on the trickle charger all night I could put the key in and turn it to get the electrical on and just sit there and watch the car drain the car from 13v down to 0v in about 60 seconds.

The new Bosch is working great!

bearone

sticking the probes into an ac extension cord measures ac voltage, not amps.

if you have another meter, do a continuity check on the fuses, i never trust a visual ck.

87951
95sl320 dd.