Battery Discharge

[Vista Cruiser 69]

Guys,

the voltmeter suggest me millions of charging Volts, display says 16V but it is 14V, actually. Regardless how many buttons I press, all heater fans and stuff it stands like a president at real 14V even on idle. Which makes me think the generator can't be that bad....

Now, if my wife hasn't moved it for a day or so, now as winter is starting the crank rev is fairly low and it does not sound as it should when you turn the key. He fires up and all - but you can hear it becomes a close thing. If you drove it for 20 minutes and even switched all things on which our wifes tend to when its cold - it does no harm. You make your shopping trips and it always cranks well when turning key.
This makes me think I got a secret consumer stealing energy over time.

Putting an Amperemeter between battery and disconnected cable:
starts up to 1.7 A for 5 sec
stays on 1.5 A for 30 sec
stays at 1 A and does not seem to go down further

Well, 1 A = 12 Watt - which does not sound much but over time it sucks. There is a power lock waiting for a signal and not sure what else is on idle but snipping some energy. There is no Hifi oomph-oomph stuff installed, all stock Tahoe 2001 LT.
Does someone have an idea how high such an energy flow is or should be if the car was completely shut down? I considered this good old "fuse in and out and watch if light goes out" thingy - but times when we had 5 to 10 fuses are over!!!
And - befor some smart arse asks if I considerd the engine compartment lamp
when testing Amperes - yes, i did Thanks for soem thoughts.

Replaced the battery as short term solution some minutes ago but one with standard pole design - aarrgghhh! Took me hours to convert from this GM side screw type, and then plus and minus completely other way round

 

[MO Viet Vet]

Is problem still there after installing new battery and cable connections or started after you replaced them? Is the battery new or just a different one?

 

[Vista Cruiser 69]

Headlight switch blown?

...and another one which showed up today:

All dashboard illumination down, even radio frequency display. When I switch into upper Dome light position -surprise all dash lamps back in full. But this is no real solution driving around like x-mas tree.
Still Tahoe 2001 LT...

Suppose the switch is partly blown with this variable resistor and needs replacement? I'd take the risk of dismantling him but what to look for??

Thanks

 

[MO Viet Vet]

Did you check to see what draw you have when engine is shut off? Amount of milliamps or amps? If large draw does it go away when unplug the alternator indicating a diode problem?

 

[Vista Cruiser 69]

Hi Raider,
changing the battery was the short term solution to this cold cranking issue. The GM Delco battery (Original sparepart) does not look old, preowner changed it soemtime but I do not trust her. I have several batteries around for different cars but that GM pole design hindered me from a quick replacement and check. I'm not yet willing to buy a new GM delco (for king's ransom!) into the blue and find out it was something else sucking it out...
Done it only some hours ago so can't tell if it helped. In addition found that 1 A constant energyflow going out which feels a bit too much. Thanks

 

[MO Viet Vet]

Back when I ran shops I used to only have to deal with milliamp, normal, draw when engine was shut off and only higher if had a real problem draw. Now the allowed draw is higher than that. Get a reading and then see what happens when unplug the alternator. The alternator can charge ok but still have a bad diode.

 

[Vista Cruiser 69]

....and in case I did not write comprehensively. All these Ampere measurments 1.7; 1.5, 1.0A were measured in "all off" mode- incl. engine! As far as I know Diode issue is kind of brutal and digital. If you have it than it discharges in an instant, chragig lamp should lightup as well even ifkey off etc. Can't imagine a Diode can cause this tiny thing here

 

[Vista Cruiser 69]

will anyway have a check with generator unplugged as you suggested and see if still 1A is floating. Nice Sunday winter job!

 

[MO Viet Vet]

The discharge from a failing diode can vary. The draw can be quick or drawn out. The charge light can also be off with key off.