Power Drain (electrical)

FX3

New Member
Messages
19
Likes
0
Location
NH
#1
Got a 87 325 Convertable.

If the car sits overnight the battery drains to the point where the car won't start. I have a new battery in it and have pulled almost all the fuses to try and trace this down. Battery

Does anyone have any thoughts?
 

FX3

New Member
Messages
19
Likes
0
Location
NH
#3
it's kept in a garage so not locked. Windows stay up though. I will try that.
I even pulled the keys out of the ignition thinking that might be the reason.
 
Messages
793
Likes
4
Location
Bay Of Islands, NZ
#4
Pull the positive terminal off the battery.

Set up a multimeter/ammeter in series between the battery cable and the terminal.

In a normal situation you may see a very small current drain from a clock or similar.

Pull fuses out at the fuse box one at a time and watch the readings. Note which fuses reduce the current drain. Continue until there is no reading on the ammeter.

Post up here which circuits are causing the drain.
 
Messages
157
Likes
0
Location
chicago
#5
only reason I mention is that my 635 had heated door locks and the whatever was not shuting off and was draining the battery...and it had to do with window lift position...that's all...good luck....cliff
 

FX3

New Member
Messages
19
Likes
0
Location
NH
#6
When I was originally testing I hooked a booster pack to the battery and just put my multimeter probes on plus and minus. It was dropping power .01 volts about every 2 seconds until I had gotten to the fuel pump fuse (started at #1 where it slowed significantly but was still loosing power. I went and put all the fuses back in and pulled a few selective (due to lack of time) like cig lighter/antenna fog lights, fuel pump and one or to others.
Unfortunately I won't be able to get back to the car until after this weekend. I love it when others start projects for me.
 
Messages
984
Likes
1
Location
Australia
#11
Pull the positive terminal off the battery.

Set up a multimeter/ammeter in series between the battery cable and the terminal.

In a normal situation you may see a very small current drain from a clock or similar.

Pull fuses out at the fuse box one at a time and watch the readings. Note which fuses reduce the current drain. Continue until there is no reading on the ammeter.

Post up here which circuits are causing the drain.
Also can be done with a normal test light (If the bulb is bright keep pulling fuses untill it goes dim), but it isn't as accurate as a multimeter.
 
Messages
90
Likes
0
Location
Calgary, AB
#13
Battery drain

Hi there FX3,

It would seem to me that, if there is a drain, it could also be coming from any one of the "hardwired" components (like final stage blower resistor[under dash near heater box], or maybe the a/c pusher fan).
Disconnect the NEGATIVE battery cable, and connect an ammeter in line(series).
Open a door and don't operate anything! You need the car to go to sleep.
After a given time('bout 15 to 20 mins.) the car should go to "sleep". The door lights should turn off and/or the light for the shifter(if you have one) should go off.
At this point, there will still be a draw on the battery, but it should be somewhere under 50 mA (0.05A). If it's higher than that, you have a draw.
start with unplugging the final stage blower resistor to see if the draw changes.
Do not have a booster pack, or a charger connected as they'll give you false readings.

Good luck,
Tiger
 

FX3

New Member
Messages
19
Likes
0
Location
NH
#14
Thanks guys.
Yep have a new battery already. One of the first things I did when I noticed the problem.

I used a battery pack just because i was lazy and didn't want to pull the battery to charge it. I figured power was power. Guess not.

So I will pull the battery charge it and start testing again. One of you sais to pull the POSITIVE terminal and put multi-meter in series. Another said pull NEGATIVE side and do the same. Does it matter what side is pulled?
 
Messages
4,917
Likes
18
Location
Reading,PA
#15
So I will pull the battery charge it and start testing again. One of you sais to pull the POSITIVE terminal and put multi-meter in series. Another said pull NEGATIVE side and do the same. Does it matter what side is pulled?
Does not matter which side. Just observe polarity. But since it is going in series, make sure to get the colors correct. Connect the colors with respect to the BATTERY, not the loose cable end. In other words, if you disconnect the RED + cable, connect the red meter lead to the + battery terminal and the black meter lead to the red + cable end. If you disconnect the BLACK negative cable, connect the black meter lead to the - battery terminal and the red meter lead to the black - cable end.

Also, make sure that the ammeter is capable of carrying at least 5 amps, 10A or 20A is better. You will blow the fuse (or meter) if the current drain is higher than the meter's rating.
 
Messages
793
Likes
4
Location
Bay Of Islands, NZ
#16
There are two schools of thought. The reason Tiger says negative as if you happen to touch the negative lead against a metal part of the vehicle it won't short as vehicles are negatively grounded. Anything connected to the positive side of the battery can short against the body. But as kirby says, it doesn't really matter.

Some modern multimeters don't even care if you connect them the wrong way - they just give negative readings. But follow Kirby's advice and you can't go wrong.
 
Messages
157
Likes
0
Location
chicago
#18
my only point was that 'new' batterys are not always fully charged and the altenator needs a fully charged battery to kick the charge back into the battery.....kind of a catch 22...that's all....good luck
 

FX3

New Member
Messages
19
Likes
0
Location
NH
#19
well I pulled the battery put it on the charger and the charger threw back a defective battery signal. Somehow my new battery is bad. gotta see about getting a new one now. Hopefully I don;t have to spend $100 on another one.
 
Messages
4,917
Likes
18
Location
Reading,PA
#20
Depending on the type of charger you have, specifically a "smart charger", it may be giving you a false indication. Go figure, but a fair number of the smart chargers see a severely discharged battery as bad. In fact, the battery is OK, it's just severely discharged, and needs a big kick in the butt to get the charge going - a kick that some smart chargers can't provide.

Depending on where you bought it, they may want to charge it and test it with their industrial charger, which may well bring it back to life. What that says is what you already know - something in your electrical system is draining your battery.
 


Top