How much Battery drain is normal ?

Have a 99 cougar, V6 loaded............... battery will go down when car sits for 4-5 days purchased new battery. old one was original. had same problem with old battery, all terminals are clean. Alternator is charging to correct voltage.Belts are good, not slipping Any know problems with this car for this ? Question how much battery drain is normal , And how do you check it with multi meter Thanks

Reply to
Donnie
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try measuring the resistance of the car with out the battery connected... it sounds like you have something pulling it down.

Reply to
Ken Gallo Jr

I reckon there should be practicaly none (or less than 10 mA/one hundret amp of a drain).Watch out for your altarnator rectifer going faulty (often causes the warning lamp to glow slightly). Also check your boot (trunk ) lights .Could be anything. I knew a guy with a Fiat with this problem & it turned out that he had a rear wiper motor that was seized. The average car battery is about 48 Ah so anything (including a small lamp will discharge it in a few days)

Reply to
Joe B

i was just recommending that he check the input resistance of the automobile... if it is not (open) then there is a problem.

connected...

Reply to
Ken Gallo Jr

Ken = clueless

Reply to
Bob

This is the newer, small Cougar, correct? If so, check out

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Try the forums, as there are many knowledgeable people there. The Cougar is just a 2-door version of the Contour/Mystique/Mondeo.

There is also

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Reply to
Andrew Rossmann

Also forgot........... lights will dim slightly when engine is a at redline. Is this a regulator or alternator problem, and could it be part of the battery drain problem ? Thanks for all the help

Reply to
Donnie

would you like to generate an explination for that remark?

you think the battery knows what it is driving? It sees a big resistor. when everything is off.. the resistance should be very high if it is not then there IS a problem.

i think you should get a clue.

I went to school for this i have a clue. Not to mention all the hands on experience.

Reply to
Ken Gallo Jr

heres a test for you... disconnect the "charged" battery from the car and let it sit 6 days.. then start the car with the battery after reconnecting it... if the battery wont crank the car well.. then its a battery problem.. if it does then its a car problem...

this can also be done by checking the input resistance of the car... but forget that.. lets keep it simple...

Reply to
Ken Gallo Jr

Sure, my remark may have been a little harsh but in a nutshell your method will not work on most modern vehicles. There are too many modules that control things like suspension, lights, powertrain, etc. that draw a fair amount of current untill they go into a sleep mode. Some of them like the Lincoln air suspensions for instance stay active for quite a while. The right way to check for a battery draw is to put an amp meter in series between the battery and cable. It's common to see 6 to 8 amps when it's first connected (key off, doors closed) but should come down to 50ma or less before too long.

Try it on your own car if it's less than 20 years old. I think you'll be surprized.

I admit your method would work well on a Model T, how old are you? Bob

Reply to
Bob

Reply to
WcToby

Thanks for the reply... I now understand better what you were trying to have the guy do... I told him to try a simple test... thats disconnect the battery and prove it is one or the other...by leaving the battery sit open with no load and see if it drains.. if it does then its the battery. I would think the 8A is a spike and not a long lasting current draw...

Ive had to reconnect my battery at night time and the arc did not seem like

8 amps.. maybe at most 2 or 3, but thats just guessing.. i never had the energy to put an ammeter in series with my cars battery, especially since my ammeter has a max of 10 amps.. and to do a full test i would have to have the car running and the starter draws quite a bit more then 10Amps.

So if what you are saying is true based on ohms law this guy should read (12V/8A) = 1.5 ohms... i have a very bad feeling that what he reads wil be a lot more then that.

Digital circuits draw very little current and have a huge input impedence. So the car's cpu dont count. The car radio draws a little for memory and presets.. i have not experienced any actuators in cars that activate when the battery is first connected. I would assume that the actuators will activate when the car is running, therefore they are also out of the question. With this being said, i would think the input resistace is a large value.

In any case... i had my way of doing it, you had yours.. yours would always work, mine would work with most cars. I perhaps broke down the problem too simple, and looked at a power source and a load... not thinking this can be a varible load.

i later suggested that the guy disconnect his battery and let it sit not hooked up for 6 days.. see if that mattered.. if it did not then he has car problems .. otherwise its the battery and a weak cell.

Oh yes... and im 23 years of age.

Reply to
Ken Gallo Jr

Reply to
Thomas Moats

you cant measure resistance on a live circuit

Disconnect the battery and mneasure resistance from black lead to red lead on car.... but forget that test... your better of with the other one where you disconnect the battery for 6 days and see the condition

Reply to
Ken Gallo Jr

Reply to
Thomas Moats

Come on guys, get real. You can't measure the 'open circuit' resistance of a vehicle because

  1. there are very often small current circuits working all the time, such as clocks.
  2. There are forward bias semiconductors that will ONLY conduct when the forward voltages more that the forward bias volt drops of the connected circuits.

ALSO, you can't guess the current jumping a gap!

ALSO a car radio commonly has large decoupling capacitors permanently connected to the 12 volt battery, and these cause the flashy sparks that you see when you reconnect the battery.

So, to really find out what is going on, disconnect one of the battery leads and put a DVM set on AMPS mode in series with the battery lead. So the meter should go between terminal post of the battery and the lead that has just been removed. ALSO put the meter in the 10 amps mode otherwise the spark that we have just discussed may blow the internal fuse in the meter.

After things settle down, I wouldn't expect that no more than 10 to 20 milliamps should be consumed. But in very rough terms, you can work out the current taken in the 'OFF' condition. The battery will have an amp-hour figure. And assuming that the battery is in good condition and fully charged, just divide this figure by the length of time taken to drain the battery in hours. Easy really. I think that either the alternator bridge is defective (but in which case the ignition light will be on either when the engine is running, or off, as appropriate) , or a small bulb is on all the time - a light in the trunk may be?

Richard

Reply to
Deadly

Reply to
Thomas Moats

Reply to
Thomas Moats

i did go to school for this.. the resistance should be very high.... now looking at a car as the electrical load.. hes right there are too many things to consider... by the way the only way to measure resistance in a live circuit is to use a shunt resistor or measure the current and then calulate the resistance.. I DARE you to take a resistance measurement of a

480V device while it is running.

If the car was a simple load my method would work perfectly. The car is not a simple load.. it consists of many loads in complex circuits. At first i was thinking of the car as a whole as a lightbulb per say... it is not.. another thing you can do to check the current insted of possibly blowing a meter is to take a really small resistor (.01 ohms) and use it as a shunt... measure the voltage across the resistor.. oh make sure it is 10W or more rated or it will just puff smoke, expect it to get hot.

you know the resistance there and you measure the voltage so u can caluclate the current. If you dont want to damage your meter... not all of us have meters that protect themselvs with fuses.

I admit i was wrong in the beginning.. and i admitted this long before you started asking me questions tom...

i said disconnect the battery and let it sit open circuit.. then try and start the car.. see if it was still no good.. if it was no good then it is obviously the battery.

Now look... i admit i was wrong.. only because i looked at the car as a simple load... in many aspects my way would work fine.. as with an older automobile.

It would be interesting however to see what the input resistance of a car is... i expect it is very high.

Reply to
Ken Gallo Jr

Why, when I can make other measurements?

Why not simply take a voltage drop measurement of lets say the engine ground for one?

You put on a dance to justify your comments..........

"In any case... i had my way of doing it, you had yours.. yours would always work, mine would work with most cars"

What are you going to do when the battery starts the car once, but fails to start the car a second time one hour later? Your theory proves nothing. Again I'll ask you, Would it not be better to check the OCV and SG to find if the battery is good or not? About 10 minuets, not 6 days.

Note, both acronyms are industry standard, you should know them.

No it would not.

You can find the calculated resistance in the engineering schematics, but that does not take in to account for corrosion, ect. Kind of a hint.

Reply to
Thomas Moats

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