Electrical Drain Question

[MySons68C20]

I went to start the truck yesterday and the battery was dead. After charging the battery it reads 12.4 volts with a running alternator output of 14.3 volts.
I checked for something left on and the only thing I noticed was the turn signals would stay on with no blinking once I hit the turn signal switch.
I went ahead and replaced the flasher with a new hd unit and now they blink/work fine.
My question is would a bad flasher cause a power drain when the engine is off?

[BigBird05]

They shouldn't if the wiring is all stock. You don't have battery power to the turn signals. Does your truck have 4 way flashers? These have battery power and would drain the battery in a matter of hours.

[demian5]

Is horn blown and relay is being activated?

Disconnect the positive cable and put a test light (or regular 12v bulb) between the cable and battery post. Start opening/closing/operating/unplugging things till it goes off. That will probably be your source of the drain. And for good measure charge battery well and let sit a few days. Should hold charge to about 12.4 for a long time.

[Jrainman]

you did not say how old your battery is , I think your battery is boardaline bad because, you said AFTER you Charged the battery, you hand standing volts of 12.4, did you know that a battery to be considered GOOD needs a standing volt reading of 12.5 volts

[rpmerf]

You need to do a parasitic drain test to figure out what is drawing power.

Disconnect the negative battery cable.
Install a multimeter set to 10 amps between the negative terminal and the negative cable.
This reading should be less than 500 milliamps or 0.5 amps. Really, on these trucks it should be less than 0.1 amp.
If it is higher, disconnect things until it drops to find the source of the drain. Disconnect the generator, and voltage regulator. Pull fuses one at a time. When pulling a fuse causes the amperage to drop, the source of the drain is behind that fuse.

http://outintheshop.com/faq/wiring/w...s/image002.jpg
http://outintheshop.com/faq/wiring/w...s/image003.jpg

[Sheepdip]

Originally Posted by rpmerf

You need to do a parasitic drain test to figure out what is drawing power.

Disconnect the negative battery cable.
Install a multimeter set to 10 amps between the negative terminal and the negative cable.
This reading should be less than 500 milliamps or 0.5 amps. Really, on these trucks it should be less than 0.1 amp.
If it is higher, disconnect things until it drops to find the source of the drain. Disconnect the generator, and voltage regulator. Pull fuses one at a time. When pulling a fuse causes the amperage to drop, the source of the drain is behind that fuse.

http://outintheshop.com/faq/wiring/w...s/image002.jpg
http://outintheshop.com/faq/wiring/w...s/image003.jpg

^^^^^^^^^^^^^^^Best Answer To Find The Problem^^^^^^^^^^^

[MySons68C20]

Horn is disconnected and the battery is a 4 year old Optima and has seen little use.
After sitting all last night still shows 12.4 volts.
The 4 way flashers work when I toggle the switch so they seem to be operating correctly.
I'll try the suggested test and report back.
Thanks to all that have replied!

[Steeveedee]

Minimum charge for a lead-acid battery is 12.6V and change. At 12.4 Volts you battery is already discharged a fair amount. Try charging it again (disconnected from the rest of the system) until it gets to 12.6V. Let it sit for a few minutes at a time and check it for charge. It should not drop below 12.6V if nothing is connected. If it does, it's toast. Minimum charging voltage that will bring a battery up to full charge is 13.5V. The reason for it being higher than 12.6V is because it has to stuff the 'trons back into the battery against the wiring and internal battery resistance. Your alternator is charging at 14+ Volts because the battery isn't fully charged at 12.4V, and is charging it up at a rate higher than the 13.5V required to keep it charged.

Go to college on your battery! https://batteryuniversity.com/

[MySons68C20]

Okay, so I'm seeing 75 milliamps on the multimeter testing as described.
I'll go ahead and charge the battery again and see if it makes any difference.
This is an agm battery if it makes any difference.
Thanks again!

[Grumpy old man]

Do you have an aftermarket stereo installed ? They can be the cause of parasitic battery drain from the radio station preset .

[MySons68C20]

Factory radio not installed It is amazing to me how fast the new stereos drain the battery for just the memory function.

[MySons68C20]

The battery is charged and I drove around for awhile. The initial read on the voltage with the battery disconnected is 12.9 volts. I do expect this will drop to 12.5ish overnight but we shall see.

[dmjlambert]

Originally Posted by MySons68C20

Okay, so I'm seeing 75 milliamps on the multimeter testing as described.

I believe a stock-like truck with everything turned off will not draw 75 ma. I recommend connecting the multimeter to read the 75 ma current, and with everything off, remove the fuses one at a time, and see if one of them causes the current to drop to 0 when you remove it. Also in that process disconnect the wire you have plugged into the CIG terminal on the face of the fusebox, if you have one.

Originally Posted by MySons68C20

Horn is disconnected ...

If the horn is disconnected at the horn, you may not know if the horn relay is activated and drawing current. Also unplug the horn relay and check if that 75 ma current draw goes down to 0.

If you have any other accessories, such as phone chargers, GPS trackers, clock, or stuff like that which stays on all the time and may explain the current draw, let us know.

[notsolo]

Slightly off topic, Dmj...can you recommend multi meter for some one electronicly challenged....Thanks Ed.e

[Bigdav160]

A normal electrical draw in these trucks is 0

If you have a modern radio with electronic station presets you might have a 10 milliamp draw (.010 amp). It is suggest with all the computers that modern cars should be under 25 milliamp (.025 amps) although there were a few manufactures that, 10 years ago, were allowing up to 50 milliamps as normal. Battery management is so good on the new GM trucks I have seen it under 10 milliamps.

The suggestion above of 500 milliamp draw as acceptable is wrong. If my battery has a reserve capacity of 60 minutes (example) and a .5 amp drain then the battery wouldn't be able to start the vehicle if left 48 hours.

Tip for using the amp meter function. If you touch the leads of the meter to power and ground (like on the battery) with the leads in the amp position, it will blow the fuse in the meter and will read 0 amps. No matter the function switch position. To test the fuse, set the meter to ohms (omega), insert the positive lead into the volt/ohm port and touch it to the amp port. It should read something. If it reads infinity it means the fuse is blown.

[dmjlambert]

This one is about $6 at Harbor Freight. It is great. It is cheap, in case you fry it, you can just get another. There is a fuse inside for the ammeter function, which is possible to blow, but it is easily replaceable (I've done it).

I have seen occasions where Harbor Freight sends flyers with coupons and this meter is free with coupon, no purchase required. That is how I got mine.

Stores such as Walmart and O'Reilly's Auto Parts have similar multimeters starting at about $8.

[MySons68C20]

Originally Posted by dmjlambert

I believe a stock-like truck with everything turned off will not draw 75 ma. I recommend connecting the multimeter to read the 75 ma current, and with everything off, remove the fuses one at a time, and see if one of them causes the current to drop to 0 when you remove it. Also in that process disconnect the wire you have plugged into the CIG terminal on the face of the fusebox, if you have one.



If the horn is disconnected at the horn, you may not know if the horn relay is activated and drawing current. Also unplug the horn relay and check if that 75 ma current draw goes down to 0.

If you have any other accessories, such as phone chargers, GPS trackers, clock, or stuff like that which stays on all the time and may explain the current draw, let us know.

12.5 volts this morning disconnected....We'll see what it reads after the weekend.
I did blow the fuse on my digital hooking direct to the battery(: fortunately I have a backup!
I will run the test again after the weekend and pass on my findings.
Thanks again!