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Discussion Starter · #1 ·
Well this chump is stumped. 97 Suburban, 6.5L, 327K original engine and tranny. Quite often after traveling especially at about the 2 week mark I will return to crank the old Suburban and the batteries will be nearly dead. I have no clue what is killing the batteries which are Duralast Gold about a year old. I can close up the truck, disconnect the ground on one battery then check with a meter and have no current draw. Anybody else experience this? If so watcha find?
 

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1997 GMC K3500 dually 4L80 4x4
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You have to have both grounds disconnected and use your amp meter in series in either side. If you only disconnect one cable, the other cable will carry all the current. Hope this helps. The usual suspect on that truck is the radio.

Mac
 

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Discussion Starter · #3 ·
You have to have both grounds disconnected and use your amp meter in series in either side. If you only disconnect one cable, the other cable will carry all the current. Hope this helps. The usual suspect on that truck is the radio.

Mac
hmmm... I will try again Mac thanks.
 

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Easier way is using a digital multimeter set on DC voltage, milivolt scale. Where to measure is each fuse, the recessed contacts on the numbered side.
You are measuring voltage drop over the fuse, it is tiny but anything over 0.000 volts will drain batteries.
Unfortunately, most vehicles have the fuse panel situated to where a door switch will trigger drain. Or security systems etc. But you will quickly find circuits that are draining the battery.
 

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Discussion Starter · #5 ·
Easier way is using a digital multimeter set on DC voltage, milivolt scale. Where to measure is each fuse, the recessed contacts on the numbered side.
You are measuring voltage drop over the fuse, it is tiny but anything over 0.000 volts will drain batteries.
Unfortunately, most vehicles have the fuse panel situated to where a door switch will trigger drain. Or security systems etc. But you will quickly find circuits that are draining the battery.
Okay Keith that is an idea based on Ohm's Law for sure. Actually that is a great idea... will try that. Thanks
 

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Easier way is using a digital multimeter set on DC voltage, milivolt scale. Where to measure is each fuse, the recessed contacts on the numbered side.
You are measuring voltage drop over the fuse, it is tiny but anything over 0.000 volts will drain batteries.
Unfortunately, most vehicles have the fuse panel situated to where a door switch will trigger drain. Or security systems etc. But you will quickly find circuits that are draining the battery.
Be sure to turn radio,heater off . Also dome light override. I have a 95 that will go dead just like yours after 2 weeks. Sometimes if I forget to turn radio off I will come outside to Led Zeppelin blasting!
 
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1995 Chevrolet Silverado Z71 6.5 TD
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You can use an amp meter or an amp clamp. If using an amp clamp just make sure you have the clamp facing in the direction of flow. With your DVM set on amp setting disconnect the ground cable from the batt to test. Then put one lead on the negative post of the batt and the other one on the ground cable. and see what your parasitic drain is. If it's good then check the other batt using the same procedure. Here maybe this will help..https://shoptoolreviews.com/automotive/diagnostic-testing/parasitic-battery-drain/34587/
 

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Discussion Starter · #8 ·
Be sure to turn radio,heater off . Also dome light override. I have a 95 that will go dead just like yours after 2 weeks. Sometimes if I forget to turn radio off I will come outside to Led Zeppelin blasting!
Dancying days are here again as the sumer evenings grow...I said its alright you know it is alright is that the way it should not start... LOL thanks
 

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1995 Chevrolet Silverado Z71 6.5 TD
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Dancying days are here again as the sumer evenings grow...I said its alright you know it is alright is that the way it should not start... LOL thanks
If it's The Wall then let's play it.
 

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Discussion Starter · #10 ·
You can use an amp meter or an amp clamp. If using an amp clamp just make sure you have the clamp facing in the direction of flow. With your DVM set on amp setting disconnect the ground cable from the batt to test. Then put one lead on the negative post of the batt and the other one on the ground cable. and see what your parasitic drain is. If it's good then check the other batt using the same procedure. Here maybe this will help..https://shoptoolreviews.com/automotive/diagnostic-testing/parasitic-battery-drain/34587/
excellent idea will try that thank-you...
 

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First LOAD test (not voltage) test the batteries one at a time.
If it is low, you need to charge it or run the engine so the alternator can charge it.

Do you see the tach (rpm) goes erratic when running or stuck at close to 0?
Then the alternator is bad.
 

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With my truck I was told that a faulty alternator could also be the cause of the current draw. I changed the alternator and the problem went away.
for the record the alternator was charging fine but for some reason was drawing current when the car was off for long periods as well.
the other thing I did was add a battery isolation switch like one from a boat. I actually did that whilst I was waiting for the alternator to arrive. That worked as well.
 

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Do you have an electric brake controller installed for towing a trailer?
 
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Easy to test the alternator for failed rectifier bridge and diode trio with a test light. Disconnect battery, then probe alternator output terminal.
 

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Well this chump is stumped. 97 Suburban, 6.5L, 327K original engine and tranny. Quite often after traveling especially at about the 2 week mark I will return to crank the old Suburban and the batteries will be nearly dead. I have no clue what is killing the batteries which are Duralast Gold about a year old. I can close up the truck, disconnect the ground on one battery then check with a meter and have no current draw. Anybody else experience this? If so watcha find?
I disconnect one battery ground when not using mine, as the batteries have voltage difference, and that drains the good one, also leaving the courtesy light switch in the automatic position, drains the batteries, haven't looked to see why.
 

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You can use an amp meter or an amp clamp. If using an amp clamp just make sure you have the clamp facing in the direction of flow. With your DVM set on amp setting disconnect the ground cable from the batt to test. Then put one lead on the negative post of the batt and the other one on the ground cable. and see what your parasitic drain is. If it's good then check the other batt using the same procedure. Here maybe this will help..https://shoptoolreviews.com/automotive/diagnostic-testing/parasitic-battery-drain/34587/
This is the best troubleshooting advice, for dying batteries. You can also use a test light. Have you tried it yet? "Inquiring minds wanna know"
 

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1997 GMC K3500 dually 4L80 4x4
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The test light will light if there is a high enough draw like a rectifier diode ( 250 ma or so depending on the light bulb) but if it's a smaller draw, the test light will be misleading. An amp meter in series in the isolated ground is bulletproof testing.

Good luck
Mac
 
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