Battery runs down after engine is shut off

[BDSBSS23]

I have tried to find the problem to see why my bug wont start after it runs good. I have checked the starters and it passed all the tests i have tried but still havent found the problems.I checked the switch by hot wiring the wires same sytpoms. I need little more info on how to test the regulator for unexpected curcuits. It would run after i jumped started it with cables and it would rund just fine after i disconnected it. Do you guys think i should get a hard start relay? I would like to know what caused this problems

[Cusser]

Finding Parasitic Electrical drain or short
Put a test light in line between the battery and one of the cables. Pull the fuses, one at a time checking the light after each fuse. When the light goes out, you found the circuit that has the drain. Then trace the circuit and find it. This only works for the bigger electrical drains (You don't put a voltmeter across the battery and look at voltage while pulling fuses. A small current that runs your battery dead will show little-no difference to battery voltage by stopping it when pulling fuses.)
Better, you can use a multimeter/ammeter Set the volt meter to current like the 200mA or 2A or something and make sure the red probe is in the A jack not the V jack. Key off & out of ignition. With battery connected to the car, loosen the nut on the ground cable at the battery lug. Put one multimeter probe on the (-) ground cable fitting. Put the other multimeter probe on the (-) battery lug. Now lift the ground cable off the battery while maintaining the connection (between cable & battery) through the multimeter. The number on the screen will be your parasitic current drain. You want this number to be like 0.050A or 50mA or less. If the number is significantly higher then you start pulling fuses until the number falls down to the 50mA range or less. The fuse that makes it drop has the circuit with the parasitic drain. Then you break out a wiring diagram and go through & unplug all the components on that fused circuit. Put back the fuse and find all components on the circuit & unplug each one. When the parasitic current falls into acceptable range you have just unplugged the component with the drain. If the parasitic drain remains after pulling all fuses then pull the big cable going to the alternator. If the drain goes away then it could be a bad alternator voltage regulator diode. That or it could be a bad alternator rectifier diode.

If you have an ohmmeter, you can disconnect the battery - cable and attach the meter leads one to the battery post, the other to the cable end. Set the meter on amps and see what the draw is. A word of caution: most meters can't handle more than a 10 amps draw without blowing a fuse (if it has one) or damaging the meter. Read what yours can handle. You will also need something to keep the interior lights off when you open the driver door. Your alarm will try to go off when you unhook & attach the leads, so try to get the leads in place before the cable is totally removed, or have the key in the door and ready to shut it off.
Once your all set up, see what the amp reading is. It should be under 100mA, or 0.1A. If you have more, start looking for lights that are on (don't forget the trunk) and then pull fuses one at a time until you find the affected circuit. If your lucky, it will be a fuse that does one thing, not one with 10 items on it. You’re looking for what gives an amp reading of under 50mA on your meter.
Maybe before you get that involved, are you sure the battery is good? Have it charged and tested. Six weeks is a long time for it to sit, but it should have lasted, or at least had something left in it.
The test light method instead of a meter won't work. The light isn't sensitive enough unless your only problem is a large drain. It works fine on my 1971 Triumph, but it has no electronics that are supposed to have power when the car sits like a radio, alarm, computers, or clock.
How to Find a Parasitic Battery Drain
When your car battery goes dead overnight, usually either the battery is at the end of its life span, or you left something on, such as a light. Occasionally something is drawing power that’s not of your doing. This is a parasitic draw, and it can cause the same result as leaving the headlights on: a dead battery in the morning. The test light works only on larger current draws, for smaller ones an ammeter is necessary.
Steps Remove the negative side battery cable from the negative battery terminal.
1. Attach a 12-volt test light between the negative cable and the negative battery post. wait a few seconds to several minutes for the car to go into sleep mode. i.e. when you make the contact with the test light the cars computer systems "wake up" after a bit of time they will go to "sleep".
2. If the test light is burning brightly, something is using too much battery power.
3. Go to the fuse panel(s) and remove fuses, one at a time. Pull the main fuses (higher amp ratings)last.
4. Watch for the 12V test light to go out. The fuse that shuts off the light is the draw. Consult the owners' manual or service manual to find what circuits are on that fuse.
5. Check each device (circuit) on that fuse. Stop each lamp, heater, etc. to find the drain.
6. Repeat steps 1&2 to test your repair. The test lamp should be dark or very dim when battery draw is acceptable.
1. get a good multi-meter that can measure current draw (to at least 10 AMPS)

2. remove negative battery cable, place one lead of multi-meter on negative battery terminal and second lead from multi-meter on negative battery cable. (essentially placing the meter inline between the cable and battery). Set your meter to measure current in the 10 AMP setting and turn it on.

3. record the amount of current draw with the truck at rest (doors closed, every accessory off and ignition off with keys out - never key up during this test, I will touch on this later) in most cases there will be some draw as things like the computer, radio, clock, etc. draw power all the time to keep memory.

4. now, with the meter still hooked up, open the door (does the dome light come on) does the reading on the meter change? If the dome light doesn't come on, then try to manually turn it on...once on does the reading change? If it does, does it change back to what it was when manually turned off, or does it change to something different?

5. now, with the door open and the dome light off, start pulling fuses from the panel in the dash (one at a time) and checking the reading each time one is pulled. after checking the reading, put the fuse back in before moving to the next one.

6. If you go through the whole fuse panel inside the truck and see no changes in readings then move to the fuses under the hood. When under the hood, just make sure you check the main fuse last.

This test will allow you to narrow down your draw search to a specific circuit, so you can focus your time on a small portion of the electrical system without throwing things at it hoping to fix it.

AT NO TIME DURING THIS TEST SHOULD YOU EVER KEY UP THE IGNITION!!! Most multi-meters have a 10 AMP limit on current testing (unless you have spent $400 or more on the meter) and if you key up the ignition you will definitely surpass this 10 AMP limit and (best case scenario) blow a fuse inside the meter or (worst case scenario) blow the meter.



Finding A Parasitic Electrical Drain
Q. Dear Vincent, I have a parasitic drain in my car and I am currently trying to locate it. The general question I have is how should I hook up my multi-meter to the battery? The multi-meter measures AC voltage, DC voltage, and DC amps. I was trying to use it as an ammeter measuring DC amps (I hooked it up in series with the negative battery terminal) but it kept blowing the multi-meter's fuse.

The meter's fuses are 0.5 amp 250 V. Do you see what I'm doing wrong? Is the multi-meter not suitable?
Also, when I hooked the meter up the car was off and all the fuses pulled. I would start replacing the fuses and the meter would never give a reading. Upon inspection the meter's fuse would mysteriously be blown.
Thank you,
Joseph
A. The meter has to go between the positive battery terminal and the positive battery post. Like so:

You need a meter that will handle up to 20 amps DC, otherwise you'll blow the fuse and possibly damage your meter. If you have a meter with multiple ranges, start with the highest range and work down. Most digital multi-meter s are auto-ranging.
I don't know what make and model of meter you have, but it sounds like it's not up to the task. Fluke meters are very good meters, but very expensive. If you look around, you can find a Fluke clone for much less. Some even have inductive amp probes that clip on around the batter cable. You don't need to remove any cables.


if you have an old analog voltmeter do the following. unhook the positive terminal and put it in line between the battery and the cable. It should register a voltage if you have a voltage draw. Unplug your alternator and see of the voltmeter registers different. then go to the fuse block and start pulling fuses, checking the voltmeter after each one. When you get to the right circuit, the voltmeter will go to zero after pulling that fuse. Now you can hunt down where the touble is.

CURRENT DRAINS
Parasitic drains are the small current drains required to operate various electrical systems, such as the clock, computer memory, or alarms, that continue to work when the car is parked and the ignition is off. All vehicles today have parasitic drains and over time will drain all batteries if not driven or charged periodically. The problem is when the parasitic drain becomes excessive, usually over 35 milliamps.
Unwanted battery drain can also be the reason why a battery keeps discharging. Unwanted battery drain can be a result of excessive parasitic drain, or if the top of the battery is wet or has excessive corrosion, it could create a path between the two battery posts, causing a current drain; usually 0.5 volt potential or higher will result in a battery discharge. This is called Case Drain.
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[BDSBSS23]

That sounds like it would solve my problems to battery run downs. I will let you know if it worked.

[BDSBSS23]

what i have noticed so far is that when i use the test light to test the negative side of the battery the light doesnt glow and i have tried to turn on the ignition and even off but nothing. Is that normal?

[Cusser]

If it starts right up when you jump-start it, either you have a bad battery or something is draining your battery to the level where it won't start. When you are trying to crank it (and nothing happens), what is your voltage at the battery then? It should read 9.6 volts or greater or your battery is bad. So if there is no drain, sounds like your battery.

Since a jump-start works, I doubt the hard start relay will help you.
_________________
1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297

[BDSBSS23]

something tells me that it's the altenator. How do i test the alternator to see if it is good or bad?

[classic_bug_lover]

take i believe the positive cable off the battery while the car is running
if the car dies your alternator is bad
somebody correct me if i'm wrong i'm still new to workin on cars

[ainokea]

Sometimes the later bugs have a resistance problem that is causing a hot engine no start. One solution to this problem may just be a wire connection under the back seat, left side. Remove the plastic insulator / connector. cut off the spade connectors, using a yellow butt connector and some heat shrink material, splice the wire ends and weather seal with the heat shrink tube. This may not be the solution to your particular problem, but it will eliminate the hot start problem in some cases but NOT ALL. Ainokea

[ainokea]

one overlooked problem in battery drain overnight could be the memory circuit in a C /D or tape deck. If the deck does not play with the memory disconnected, just connect it to the power in wire. You'll have to reset the player every time you start the engine or want to listen to the appliance. Ainokea

[ainokea]

Here's another easy hot start problem solver that might solve resistance in a bug and most VW's. The bug is the easy one. first, all ACVW's route power to the ignition switch by coming in and connecting to 30 on the lite switch. It then goes to the fuse panel where ignition switch 30 connects. Many times pulling the 30 wire from the fuse panel to the ignition switch and splicing a 10 gauge wire directly from the positive battery terminal to the ignition switch 30 wire will cure many hot start problems by eliminating any start circuit resistance. This procedure is very effective not only for 6 volt systems but 12 volt too. Ainokea

[ashman40]

@BDSBSS23, please provide a bit more info...

Beetle model (STD or SB) and model year? Pre-'71 model years had the battery power running to the headlight switch as a distribution point. Later years had the power running to the fuse box as a distribution point. The headlight became an endpoint.

If you have a voltmeter, get voltage readings at the battery and the fuse box. See how much they differ. Wires in good condition should only reduce the voltage by around 0.1v. So if you are reading significant voltage drops the further you get from the battery your wiring may need some clean up with a wire brush or sandpaper.
Fully charged battery is 12.6v. Below 11.5v you are basically zero state of charge and most high amp devices like the starter will no longer work.
If you don't have a voltmeter, get a cheap one. They are like $10 (or less).

How old is your battery? They don't last forever and the older ones don't last as long as the newer ones. Now days you can get 10years of life from a good battery. It used to be that 5years was a great battery. So if you have an older battery that is over 5years-old, it may just be time for a new battery.

[Chochobeef]

[Cusser]

[Bug53]

[Cusser]

[Eric&Barb]

[h20rider]

I ran a multimeter set to voltage across the negative terminal to the disconnected ground wire. I get a reading of 1 to 1.2 volts. I removed fuses one at a time and still has the same drain, so no secondary circuit short or draw explains this draw. I have no clock or other intentional passive current draws in the vehicle.
Ideas?
Thanks

[Eric&Barb]

[h20rider]

Yes, I’ve done that. No changes. Still the 1.2 v draw.

[Eric&Barb]