camaro4life ss

can some one please give me detailed instructions on doing a parastic draw test. i recently had a prob with my batt draining and then all of a sudden after i charged it, it didnt seem to be draining, but now its getting really low. what should my batt gauge usually be reading on a healthy IROC?

now if i try this parastic draw test and it shows that i dont have a draw, them what could be constantly draining my batt? its not draining quickly but on sunday my batt meter was reading over 13 and now its at around 8? as much as i love this car im really starting to get pissed off with all these problems and i dont want to bring it to a mechanic where they can fix what they think is the problem and for a while the batt stays alright but then after a week or two its low again, then i have to bring it back and waste more money.

how do i test to see how much power the alternator is charging the battery at? and when you turn on your heater/ac or use any of the power options, is the battery meter supposed to drop a little?

this will all help me out a lot for whom ever takes the time to answer.
thanks

Berlinetta00

You will need a multimeter to do these tests. It must have DC volts, amperage, and resistance (ohms).

Parasidic draw test:
With the ignition off, put negative lead (black) on negative post and positive on positive post. Set the multimeter to amps. You should get a reading no larger than .001.

Battery Voltage (open post):
With ignition off, attach leads as above, set voltmeter to Volts DC
Reading should be above 12.3 volts.

Alternator test:
With the ignition on, after having completed the open post voltage test, attach leads in the same manner and again check voltage. If the reading is LESS or very slightly above than that of the open post reading, your alternator is not working properly. You should read at least 13 V.

If your battery is less than 12.3 volts:
-Check the sale date on the battery. If it is near or over four years, replace the battery.
-Visually check the exterior for cracks or damage to the battery case (espacilly around the terminals) if any are found, replace.
-Check the electrolite level, which is done by either sighting the side of the battery for the water level, or removing the caps on the top. WARNING: this is a very acidic substance. Do not spill it, if you do be sure to clean it with a damp rag & baking soda immeaditly.
-If it is a new battery, put it on a charger and load test it at your local parts store.

If your alternator produces less than 13V at a 5-600 RPM idle:
-Check all wiring and connections. Ensure that the leads and connectors are grounded properly and free of corrosion. Make certain that it is connected correctly.
-Bench test it at your local parts store-OR-you can take it apart and test pieces individually, PM me for details.

Hope this helps,

Danno

Sorry guy, you do a current test with the multimeter across the battery as you said and you will draw LOTS of amps. For a parasitic drain test remove one of the battery terminals and insert the meter in series. e.g., one end of the meter will go to the floating(disconnected batt terminal) line, the other lead will attach to the battery. I start usually with the 10 amp scale then drop down depends on the meter. Read the instructions with the meter, you generally must move the positive probe connector to a different plug on the meter to measure current (amps). GM, in a TSB addresses this issue and states that normal parasitic drain for 1995 and up cars/light trucks is less than .015 amps, or 15 ma(milliamps). Remember, interior lights and under the hood light must be off otherwise you will get a high reading. The specs for drain should be pretty close to what GM says even for a TG. To do a simple charging test use the DC volts function of the meter(remember the meter probe lead) and test the battery at rest engine and all lights etc. OFF. A charged unit will read approx 12.6 volts. Start the engine, average DC reading should hover around 14 to 15 volts. Turn on headlights then recheck. The reading should stay about the same, possibly go slightly higher. If it drops your alt is not providing adequate charge. You may want to bring it a little off idle to see the charging. Remember, CHARGE the battery overnight with a trickle setting BEFORE doing any alt testing. As far as drain, the stock battery fully charged has a capacity of approx 75A/hrs. Simply put, you can draw 75 amps for 1hr before it reaches discharge. Whatever drain you measure you can do the math and calculate how long it will take to fully discharge. NEVER try to start the car or run it with the test meter in the AMPS mode. Hope this helps.

82camaro

OK, I have a 8 mAmp draw (just tested it) after I rewired the radio, alarm, guages, tach, amplifier/stereo--it was a huge mess. Anyway, if my calculations are correct, it should be able to set 390 days. Is that about correct? Assuming my battery is about 75000 mAmp's. 15 mAmp draw would be 208 days?

camaro4life ss

ok thanks for the help im going to go try all these.

Danno

No, because there are actually many mitigating factors. GM states a 70Ahr battery with a 30ma parasitic draw will not start the car if left that way after approx 23 days assuming the battery is 90% charged. At 65% 15 days. When the battery loses 40% of charge that is pretty much the point where the car will fail to start. I should have clarified that point. We are really talking about being to start the vehicle. Also, ambient temp changes the batteries characteristics dramatically. If you have only 8ma draw you are more than OK with that, assuming the battery is good and fully charged you should be able to go roughly 75 days before you wind up with a no start condition. It gets very complicated when you take all the variables into account, these numbers are really only general numbers to give you a little insight . One thing I would add is that I use a small wall plug charger with a cigarette plug and go into the cigarette receptacle for exxtended periods of non use. It's a good idea to trickle your battery once a month anyway. My original 89 Delco battery is still in service in a neighbors car, I have trickled every battery I own that way and have almost doubled the time they last. I spent many years as a field engineer for a telecommunications company and many of our transmitter sites were battery backup in the event of commercial power failure. With proper maintenance and charging technique we could average 7-10 yrs in some cases using lead acid batteries.

82camaro

Thanks for the info. I figured that the battery wouldn't be able to start the car after about 50 percent was gone, but it would still power the electronics for that period of time. Like most things, other variables should be included. Like how many times I open the door(turning on the interior light). Or how many times I hop in and listen to the radio.....

Berlinetta00

Are you talking about ability to flow electricity, or voltage, when you say % of charge?

After around 73% of your voltage is gone (9.125 V), assuming that your residual full charge is 12.5 V, the battery would loose its ability to even crank the engine. At 80% of voltage, the engine cranks slowly.

Unless the battery is a deep-cycle battery, you do not have the ability to completely drain the power from the battery (constant 0 volts) and recharge it. This has much to do with the spacing of the cells and the type of electrolite used to produce the electron flow. Even getting a conventional battery down to 40% is risking not being able to recharge it. Deep cycle and gel batteries are an exception, because of their constuction with larger and closer together cells, and a thicker, less viscus electrolite.

If you are talking about the ability to produce amperage, or current flow, the conventional batteries loose this around 50% voltage for low amperage devices (sterio, interior lights, horn), or around 70% (as stated above) for high amperage devices, such as your starter.

Danno: Yes, i was wrong about the amperage test, I was thinking of something else (cant remember what). Your right about the inline on positive cable set-up. You can run a multimeter on Amps with the vechicle running, just be sure to A) read all manufactuer instuctions, and b) set the multimeter to read in the 100 Amp range if you have the ability. The Fluke 78, the most common automotive electrical test meter, is able to operate in Amp mode with the engine running to test total amperage draw or flow of an individual circut. If the reading is too high, the 10 amp fuse in the meter will pop, and that takes all of 1 minute to change.

Hope this helps,

Breadfan

Running the car with your meter in series w/ the b+ post and b+ terminal You will pop your fuse instantly . Your starter is going to pull well over a 100 amps . :nono:

Berlinetta00

Notice I did not say to START the engine with the meter hooked up. Some meters are designed to work in amp mode with the engine running, but it would not be adviseable to test the highest output circut. But like I said, if the amperage is too high, the fuse will pop, no big deal.

-Berlinetta00-

Breadfan

Yeah you still don't put the meter in series with the bat and cable it uses an amp probe that goes around the wire .

camaro4life ss

so i realized today, while i was driving my IROC the battery drained and when i shut off the car it wouldnt start. the alt is new, electric fans arent working(so it appears), ive checked for a short but i didnt find anything(the batt seems to be holding its charge when car is not in use), and worse of all my car heats up and starts to choke when its gettin too warm cause of my fans or maybe water pump not working. what should i do/check? when the car is hot, is it supposed to idle at 3000 when in park? because thats what it did, and when i first turned on the car and started driving, it was driving very nicely, put out all the power its supposed to but then when it got hot it would choke when i stepped on the gas.
please someone help, i really dont want to bring this to a mechanic!

Danno

I was referring to RC, or reserve capacity. In an ideal situation a 75A-12 Delco battery can deliver 75 amps for an hour. Problem is that in an average auto the battery is normally kept around 80-85% at best of capacity in A/hrs. Terminal voltage will generally not change dramatically on a good battery until the RC is almost non-existent. GM has a very well written TSB that takes into account various factors and gives average expectations of a battery's ability to start the vehicle. As far as the meter is concerned I prefer and inductive pickup for anything over 10 amps otherwise the size of the wire you need to work with makes it impractical.

Berlinetta00

Thanks for claring that up. Do you have access to the TSB? Id like to see it. You are right that a magnetic pickup would be better, on top of that, a VAT 40 would be much better for battery/alternator testing if you had access to one.