Anyone familiar with doing a parasitic draw test on our trucks? Battery was dead flat a week ago. I know the battery us fine since i load tester the battery and it was still putting out 900 cca for 45 secs after a full recharge and didnt even drop in voltage. after the test was complete. I have since done a google of how to do a parasitic draw test but i may have blown the fuse in my meter since im not getting any amp draw not even the 50 mma. I conducted the test with the negative lead off , i also tried with the positive lead off and still nothing ? Am i conducting this tests wrong since i know there should be some amp draw but my meter says 0.00 across the board

 

If you unhook the negative battery cable and hook the meter between the negative battery post and the unhooked cable that should be correct. Turn something on like the interior light(just open a door) or the park lights and see if you get a reading.

 

Absoutley nothing , I ll replace the fuse tomorrow and try again.

 

I use a low voltage test light between the positive cable and the battery everything else hooked up. Save the under hood light. If light comes on there is a draw if not then there isn't enought to worry about. Most Fords only draw about 5-10 milli amps with 20 milliamperes being tops. The draw is for keep alive memory circuits in the PCM and radio.

 

So threw in a new fuse this morning and im starting to get some readings now first reading was at 80 - 90 Milli-amps but once the surface charge dissipated i was starting to get a reading of 35-40 Milli-amps draw is this a normal reading from what i understand if its under 50 milliamps i should be good but if what wtroger is saying is tru about the 5 - 10 mill-amp it may be excessive. Like i said i know there should be some draw , i just want to knoe if what i have is excessive for a 5.0L e40d sd setup

 

should be noted that no accessories were turned on at the time of tests should i begin to start pulling fuses or am i okay with the 30 - 40 mill-amp draw

 

I don't know I always use a test light as wtroger mentioned above. If the test light doesn't light you are okay.

 

I dont have a test light so m trying to make due with the multi meter

 

Well, if 20 mA is the top side of the scale and you are getting twice that then there is something amiss.

I'm guessing the reason you ask is it killed the battery in a week of sitting?

As for meter vs. light. The meter will give you the exact amount. The bulb will just let you know visually.

 

is 20 mma all that i should see is this the most , because i have a constant draw of 30-35 mma i also pulled all my fuses will the meter was on and had no change .

 

yes it killed the battery twice overnight after full recharge and load tests , did i mention i work at total battery. its not the battery

 

I have bought new batterys that actually were bad off the shelf.

Easy test: disconnect the battery, let sit for a day, check its voltage and current.

Or use a known good battery in the truck, let sit for 24 hrs.

"Known good" doesn't mean new-off-the-shelf, it means "works OK in another truck".

 

Have you checked the specific gravity of each cell?

Just wondering?

I had a discharge issue with my last '89 F150. I drove it every day for 8 years and never knew it had a problem. Finally got something else to drive and suddenly it wouldn't make it a week without killing a new battery.

 

Listen Im not going to turn this into a bad battery thread , its the same battery i ve had for years. Like i said i work at total battery , i checked all the cells and the hydrometer says there healthy , i out it on a 3000$ load testing machine not the ****ty ones u buy off the shelves at local auto parts stores and it put out 800 cca for 45 secs with is over kill considering that would be a load test for a deep cycle. All I want to know is if 30 mill amps is excessive draw as i know for most new vehicles its 50 millamps

 

not to mention after a week after a full charge the battery still shows a healthy 12.8 volts once the surface charge has dissipated these all point to a healthy battery and adding a new healthy battery to my system would yield the same test results.