Electrical Short.

[Blue Flame Restorations]

[QUOTE=Hib Halverson;145886]If you connect a volt meter between the batter and ground it will read whatever the battery voltage is.

If you connect an amp meter between the battery and ground you'll read current flow. There should be only a few hundred milamps.

From reading the other posts, I think you understand the procedure of using either a test light or an ammeter then pull fuses.

You might also have a battery which is, itself, shorted.[/QUOTE]

Good point. I had an 84 month battery die today in my Silverado that only had 60 months usage. Had to replace it.

[Paul Workman]

Originally Posted by Hib Halverson

If you connect an amp meter between the battery and ground you'll read current flow. There should be only a few hundred milamps.

Ah, Hib... I believe you meant to say putting an ammeter in series between the battery post and that post's cable connector (have to disconnect the cable from the battery post to do the test). measuring current between the battery (positive) and ground creates a near dead short with the meter in the middle. If yer lucky, all it does is blow a fuse in the meter.

Robert-

because there is a path to ground through the radio and the ECM, etc that keeps the presets, clock, and memory alive, pulling the cable off the battery and then reading voltage will result in a voltage reading equal to battery voltage. If you were to disconnect the pos cable from the battery, and measure resistance between the positive connector and the negative terminal of the battery or to ground, you will see a few hundred ohms, but NOT infinity as there is a closed circuit even with the key off. (Somewhere between 240Ω and 1.2k Ω, after it settles, is normal.)

Back to the ammeter: Reading current between the positive terminal of the battery, and the positive cable connector (removed from the battery) you should have no more than 50mA (GM spec) , and typically 25mA or less. (Also note that when you first make the connection, the current will be considerably higher than that. That is normal. But, as the various capacitors in the electronics charge up (through the meter), the current draw will trickle down to its normal 10-50mA range before leveling off - usually after only 2-4 seconds or so. Once the reading settles, you can assess the normal "at rest" current draw, due to the "always on" stuff.)

The ammeter feature requires some special consideration: Move the read lead to the "10A" port on the DVM and select "A" on the meter BEFORE making connection between the battery post and the cable connector. To make the connections and then sweep the meter selector knob through the various ranges and such will more than likely damage the meter.

And! It is a good practice, once done makeing a current reading, to remove the test lead from the "10A" port on the meter and return it to the normal port. Otherwise you might do what I did yesterday. I forgot to move the red lead back to the normal setting before setting the meter aside. When I picked it up again to this time make a voltage measurement, I didn't notice the mixup until it was too late - and popped the fuse in the meter!

You may already know all dis chit, but I can testify that even if you've been doing "lectric chit" forever, it is easy to have a brain fart and forget to do something a pop a fuse...ask HIB and me how we know!!

P.

[cvette98pacecar]

Originally Posted by Hib Halverson

If you connect a volt meter between the batter and ground it will read whatever the battery voltage is.

If you connect an amp meter between the battery and ground you'll read current flow. There should be only a few hundred milamps.

From reading the other posts, I think you understand the procedure of using either a test light or an ammeter then pull fuses.

You might also have a battery which is, itself, shorted.

That is what I think it is, the amp draw is .0256 which is 256mA. Guessing there is a dead or shorted cell in the battery. Identical to the 91

[cvette98pacecar]

Originally Posted by Paul Workman

Ah, Hib... I believe you meant to say putting an ammeter in series between the battery post and that post's cable connector (have to disconnect the cable from the battery post to do the test). measuring current between the battery (positive) and ground creates a near dead short with the meter in the middle. If yer lucky, all it does is blow a fuse in the meter.

Robert-

because there is a path to ground through the radio and the ECM, etc that keeps the presets, clock, and memory alive, pulling the cable off the battery and then reading voltage will result in a voltage reading equal to battery voltage. If you were to disconnect the pos cable from the battery, and measure resistance between the positive connector and the negative terminal of the battery or to ground, you will see a few hundred ohms, but NOT infinity as there is a closed circuit even with the key off. (Somewhere between 240Ω and 1.2k Ω, after it settles, is normal.)

Back to the ammeter: Reading current between the positive terminal of the battery, and the positive cable connector (removed from the battery) you should have no more than 50mA (GM spec) , and typically 25mA or less. (Also note that when you first make the connection, the current will be considerably higher than that. That is normal. But, as the various capacitors in the electronics charge up (through the meter), the current draw will trickle down to its normal 10-50mA range before leveling off - usually after only 2-4 seconds or so. Once the reading settles, you can assess the normal "at rest" current draw, due to the "always on" stuff.)

The ammeter feature requires some special consideration: Move the read lead to the "10A" port on the DVM and select "A" on the meter BEFORE making connection between the battery post and the cable connector. To make the connections and then sweep the meter selector knob through the various ranges and such will more than likely damage the meter.

And! It is a good practice, once done makeing a current reading, to remove the test lead from the "10A" port on the meter and return it to the normal port. Otherwise you might do what I did yesterday. I forgot to move the red lead back to the normal setting before setting the meter aside. When I picked it up again to this time make a voltage measurement, I didn't notice the mixup until it was too late - and popped the fuse in the meter!

You may already know all dis chit, but I can testify that even if you've been doing "lectric chit" forever, it is easy to have a brain fart and forget to do something a pop a fuse...ask HIB and me how we know!!

P.

Paul, this is exactly what I wanted to know. What are the live circuits on our cars! I knew the radio has the yellow leed which goes directly to a hot connection. I guess I should have went threw the wiring manual and found the circuits which are always hot. I should have done it the easy way, taking readings off the 91, than take readings off the 93.
That is what happens when you try to rush, chit get messed up.

[scottfab]

Originally Posted by cvette98pacecar

That is what I think it is, the amp draw is .0256 which is 256mA. Guessing there is a dead or shorted cell in the battery. Identical to the 91

Point of clarification: If you see ".0256" that's 25.6ma which is not a big deal. If you did a typo and it truly is 0.256 (256ma) and is steady you do have a heavy draw. Time to leave the meter connected that way and start disconnecting stuff until you find the culprit. Do you have any aftermarket electrical stuff?

[Paul Workman]

Originally Posted by scottfab

Point of clarification: If you see ".0256" that's 25.6ma which is not a big deal. If you did a typo and it truly is 0.256 (256ma) and is steady you do have a heavy draw. Time to leave the meter connected that way and start disconnecting stuff until you find the culprit. Do you have any aftermarket electrical stuff?

Good catch, Scott.

Robert: Some meters will auto-range to read in mA directly. How-some-ever, if your meter scale is reading Amperes (not mA), then move the decimal 3 places to the right to convert to mA.

Example: 0.0256A (as Scott points out) becomes 25.6mA - which is well under the GM threshold of 50mA where concern for battery drain comes into play (and is pretty much at the top of the statistical bell curve for "key off" or "keep alive" current draw).

If it is higher than 50mA, leave the meter connected and start pulling fuses, one at a time while looking for a sudden drop in current draw to isolate the circuit(s) with the load. Refer to the FSM to futher isolate the various components that share that fuse.

BTW! What does the voltage across the battery do when you connect your battery charger? It sould jump up a few tenths. (Mine is on a Battery Tender. I just disconnected the BT and measured the (surface charge) voltage, and it was 13.36. Then, reconnecting the charger the voltage bumped up to 13.8. The light on the BT is "GREEN" (indicating fully charged).

My point is, to check the BT while connected to the battery to see if it is in fact working. Just a thought.

Hope this helps.

P.

[scottfab]

I'm going to go out on a limb and guess that it's the battery. I say that because something similar happened to me. A relatively new battery (14mo old) would become useless even after sitting a week or two even with a battery tender on it.

After doing some research into "battery sulphation" back in 2002 I determined the battery I bought must have sat on the shelf for a long time. What happens to cause this is beyond the scope of this thread but the battery turned just fine initially after purchase. Over time it seemed to lose it's ability to pull high amps. Eventually even with plenty of charge time it turned the starter with difficulty. It measured a good 13.7v after charging but.... diminished capacity. Read more if you want at:
http://rollsbatteryne.com/docs/A%20S...%20Battery.pdf
You can also use a device to try and recover a sulphated battery. This is an example.
http://batteryminders.com/battery-sulfation.php
Given enough sulphation the internal current leakage of the battery is higher than the float charger...... the battery drains itself.

If it is the battery and you go for a replacement try to find a car parts or Walmart that has just opened. Chances are they have fresh batteries. Alternatively find a place with high turnover in batteries.

I hope I'm right on this. It's certainly going to be easier to replace the battery than to chase down something draining juice.
Good luck.

[WVZR-1]

If it is the battery and you go for a replacement try to find a car parts or Walmart that has just opened. Chances are they have fresh batteries. Alternatively find a place with high turnover in batteries.

Batteries are date coded these days in generally quite visible areas on the battery, it's wise to confirm the date code of the battery because if 36 months down the road you've a warranty issue and no invoice the date code of the battery is generally sufficient for the application of the warranty. Batteries are generally rotated so a "fresher" battery could likely be the last in the rack! A 75 group battery is pretty popular, you might have a choice of 5 - 7 batteries! Grab the "freshest"!!

[scottfab]

Originally Posted by WVZR-1

Batteries are date coded these days in generally quite visible areas on the battery, it's wise to confirm the date code of the battery because if 36 months down the road you've a warranty issue and no invoice the date code of the battery is generally sufficient for the application of the warranty. Batteries are generally rotated so a "fresher" battery could likely be the last in the rack! A 75 group battery is pretty popular, you might have a choice of 5 - 7 batteries! Grab the "freshest"!!

The only date codes I've ever seen are cryptic. Or they have scratch off pads.
Interviewing the department manager at Wallmart he said they just rotate unsold ones out. The are "reconditioned" and put back on the shelf. And I think they've since gotten out of selling batteries all to gether. The O'Riley's guy I spoke to said they do the same thing. Then a green sticker with a number indicating the month it was last "cycled".
And a local Bi-Mart (coop) does not put acid in them and they sit in the back until inventory is needed. A battery with no acid and sealed will not have a problem. They do not have date codes. They do punch out the year and month on a strip on the top of the battery. Problem at BiMart is the once with acid sit for long periods.

BTW all even the sealed batteries like Optima will develop problems if they sit too long.

[WB9MCW]

I heard from my good friend & mechanic that the cheapo Walmart batteries are actually reused lead innards. Not a melt down and recast lead but actual old plates just being reused.

He claims that is why they crap out so soon.

He said any Interstate Battery guy will confirm this. That was his source and the line he sells.

I have many of the Interstate brand in all my vehicles now and I do have to admit they are good indeed.