525 battery drain

[Unregistered]

Anyone now if my starter motor should have 2 (two) volts running to it at all times? If not, is the problem with the solenoid or the associated wiring?

I know this is basic stuff but I'm a basic kind of guy and know almost nothing of electrics in cars!

[Bimmer Nut Ed]

I'm no pro, but I can't imagine that the started motor should be getting any juice to it when not engaged and active.

[Hector]

the bit of reading I've done in the past, starters rarely go bad.

It's most likely you could have a bad battery or parasitic drain above that of the normal 30 mA that is allowed. Here are some simple things to do to check for this. With all electrical systems turned off, disconnect the negative battery terminal and hook up a DMM between the battery post and the cable. If you read more than 30 mA, then you got a parasitic drain. The next thing is to isolate the probable cause by doing the following: (1) Go to the fuse panel and remove one fuse at a time. Clean the prongs of each fuse and insert back in fuse box. Test for parasitic drain again. If still above 30 mA, then do the same for the relays. It could also be something as simple as (2) glove box light failing to shut off or a drunk light, or (3) two wires with poor insulation that are just barely touching each.

You can further troubleshoot for parasitic drain by checking the load reduction relays. Sometimes these tend to stick. Just turn the ignition off and turn on and off the systems wired to the relays: air conditioner, seat switches, fan blowers, etc, and see if this helps.

Hector

[Unregistered]

Where and with what instrument are you measuring 2 volts at the starter? Tell us some more about this battery drain. When the battery is charged, what happens when you try to start the car? There are some good thoughts in the above post but remember, a voltage measurement by itself can be misleading. Thanks,

Paul

[Unregistered]

I'm no pro, but I can't imagine that the started motor should be getting any juice to it when not engaged and active.

My thoughts as well. 12volts I could sort of understand, 0volts would be what I would expect. I don't know if this means the solenoid is on its way out or not.

Thanks for the reply

[Unregistered]

the bit of reading I've done in the past, starters rarely go bad.

It's most likely you could have a bad battery or parasitic drain above that of the normal 30 mA that is allowed. Here are some simple things to do to check for this. With all electrical systems turned off, disconnect the negative battery terminal and hook up a DMM between the battery post and the cable. If you read more than 30 mA, then you got a parasitic drain. The next thing is to isolate the probable cause by doing the following: (1) Go to the fuse panel and remove one fuse at a time. Clean the prongs of each fuse and insert back in fuse box. Test for parasitic drain again. If still above 30 mA, then do the same for the relays. It could also be something as simple as (2) glove box light failing to shut off or a drunk light, or (3) two wires with poor insulation that are just barely touching each.

You can further troubleshoot for parasitic drain by checking the load reduction relays. Sometimes these tend to stick. Just turn the ignition off and turn on and off the systems wired to the relays: air conditioner, seat switches, fan blowers, etc, and see if this helps.

Hector

Thanks for the detailed reply, Hector. I'll use your info to check out a few things.

I found the fault (battery dead) after leaving the car over night (alarm on) and assumed that the battery had had it. I replaced the battery and everything was fine for approx 2 weeks then it went flat again. I checked the alternator was charging and found it to be in good working order. In order to double check the drain, I removed all the live fuses I could find (under the hood and under the rear seat) so nothing should have had current to it. Then I removed the negative lead and tested the voltage from the lead to the battery post. At this point, there was still 12 volts going through the battery.

This when my wife asked the simple question 'what's that?' and pointing to the box covering the point where you jump start. I replied 'the auxiliary starter post' (that's what I call it anyway) and tested fully expecting to get 12 or 0 volts. This is where I found the 2 volts. Checking down the line, I found the same voltage at the connection to the starter solenoid.

With the ignition off, the only things that work are the clock, radio, interior lights, alarm and seats. I've checked for the bulbs staying on in the glovebox and trunk both of which go out.

By the way, all voltage readings were taken with a DMM using a known good earth.

[Unregistered]

Where and with what instrument are you measuring 2 volts at the starter? Tell us some more about this battery drain. When the battery is charged, what happens when you try to start the car? There are some good thoughts in the above post but remember, a voltage measurement by itself can be misleading. Thanks,

Paul

Paul, Thanks for the advice. I've included more details of the tests I've done in my reply to Hector.

At the moment, I'm unhooking the negative post at night and re-connecting when I need the car in the morning. This doesn't seem to be causing any problems but is obviously not the right way to do things. With the battery charged, the car starts fine. If I leave the battery hooked up, I might get one slow tunrover in the morning or the solenoid will just chatter.

All my tests have been using a DMM and a known good earth.

Thanks

Bob

[Hector]

I'll have to get back to you later as I have to go to a meeting shortly.
Hector



Thanks for the detailed reply, Hector. I'll use your info to check out a few things.

I found the fault (battery dead) after leaving the car over night (alarm on) and assumed that the battery had had it. I replaced the battery and everything was fine for approx 2 weeks then it went flat again. I checked the alternator was charging and found it to be in good working order. In order to double check the drain, I removed all the live fuses I could find (under the hood and under the rear seat) so nothing should have had current to it. Then I removed the negative lead and tested the voltage from the lead to the battery post. At this point, there was still 12 volts going through the battery.

This when my wife asked the simple question 'what's that?' and pointing to the box covering the point where you jump start. I replied 'the auxiliary starter post' (that's what I call it anyway) and tested fully expecting to get 12 or 0 volts. This is where I found the 2 volts. Checking down the line, I found the same voltage at the connection to the starter solenoid.

With the ignition off, the only things that work are the clock, radio, interior lights, alarm and seats. I've checked for the bulbs staying on in the glovebox and trunk both of which go out.

By the way, all voltage readings were taken with a DMM using a known good earth.

[Hector]

Those damn electrical problems can be a pain in the keister. The most important test is checking the parasitic drain current I mentioned earlier. Was it above 30 mA? How did you check the alternator? (Some of the following has been taken from the Bently repair manual.) The alternator should be checked with the battery FULLY charged, which is 12.6 V. Hook up the DMM across the battery and start the engine. The voltage should increase from 13.8 to 14.8 volts. If the voltage does not increase, then there is something wrong with the charging system. If the voltage is lower than 13.8 V, then it could be that one or more diodes in the alternator are blown. If higher than 14.8 V, then there could be something wrong with the voltage regulator.

Just curious, does the alternator warning light, or idiot light come on when you turn the ignition switch to the “on” position without cranking the engine? If the alternator is fine, and assuming the starter is in good shape, there could be something wrong with the instrument cluster but digging into this should be the last resort if all else fails. HTW!

Hector



I'll have to get back to you later as I have to go to a meeting shortly.
Hector

[Unregistered]

Like you, I'm still trying to get my arms around this issue. First, what year is this car? Is it a 1993 525? For 2 volts to appear at the B+ terminal, there must be a hell of a voltage drop betwen there and the battery (assuming a good ground like the ABS housing or the intake manifold). Look for corrosion and/or poor connection at both places. This would indeed apply the lowered voltage to the starter. The full battery voltage should appear at this terminal. After researching that, connect your meter in series as Hector suggests between either the positive battery post and the positive cable or the negative battery post and and the negative cable with the leads in the AMPS jacks and the selector on the current ranges. Observe the current draw and report it here. I'm not sure what the continuous current draw should be but Hector says it should be in the 30 ma range. Let's assume for the moment that the alternator is producing normally. If not, well.....

Paul

[Unregistered]

I was thinking about what you said earlier, that is, when the ignition is off, the clock (is it analog?), radio, and some other things still work. Do you mean that these work with the ignition off and the key out of the switch? I don't think the radio should work but it is possible for the others to be working with the key out since they are a "demand" function. Is it possible that your HVAC fan is also runing at low speed? Make the current draw measurement and see what it says.

Paul