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Fixed - Parasitic Battery Drain

 
  #31  
Old 02-13-2012, 01:06 PM
Lex2002
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Man I hope you track down the source soon. Batteries are pricey. I just had to change both of mine because the truck would sit for weeks without being used and batteries finally died.

Obviously the demise of my batteries is for a different reason that yours.

Nonetheless, this is why I TRIED to get a PriorityStart hooked up, to avoid these types of issues from ruining $250 worth of batteries.

But alas, I havent been able to dedicate the time to figure out the correct connection method with our dual battery set up, despite multiple conversations with the manufacturer. It's my fault for not understanding the wiring logic in the truck, as opposed to being the fault of nice folks at PriorityStart.
 
  #32  
Old 02-13-2012, 01:16 PM
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Anybody know what is considered normal draw on a 2002 7.3 psd?
I tested 210 ma with the alternator connected and 160 ma with the alternator disconnected.
I don't have any aftermarket electronics installed.
 
  #33  
Old 02-13-2012, 01:22 PM
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Originally Posted by MR5x5 View Post
I'm going to pull the glove box and hood light just for kicks. Once I get my kid out of the fridge, I'll see if I can cram him in the glove box to keep an eye on that one too...
I hope you don't get too concerned about the freezer light.

Now don't be making any kidcicles.
 
  #34  
Old 02-21-2012, 02:35 PM
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Update - Stuck at home - raining hard - Passes closed for avalanch work - headed to Idaho - batteries flat in the a.m.

For kicks, I pulled the possitive side of both batteries and checked the current draw... Overscaled my DVM which puts it at over 1 amp. This is goodness. The hunt is on. I narrowed it down to the starter circuit. I pulled the leads off the start relay one at a time. When I pulled the "lower" of the two, the current draw went to zero. More goodness. Checked ohms across the relay and it read "open". Hooked the heavy leads back up to the relay and re-chcked current draw. Draw now at ~1 mA. Odd, whatever was leaking before has now stopped?? Started the truck, shut it off and measured the ohms across the relay again. Still zero.

Ok you smart electron types - what do I have here? A bad relay, or something going on in the starter?

Side question - previously when I measured current leakage I only disconnected one battery and was seeing 35 mA. I figured that my total drain would be approximately twice that - figured low resistance bridge in the meter for current measurement...I'm thinking maybe that was a bad assumption?? Note that today I was also seeing very low draw with one battery disconnected. Disconnected the other and instant overscale.

I still like hammers better than electrons.

Hey, passes are opening in 30 minutes! Got to split.

Cheers,

Mike R
 
  #35  
Old 02-25-2012, 08:26 PM
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Back from Idaho - Update - I took a better measurement. Am seeing 4.5A drain "at the starter relay" I took a chance and replaced the relay - did not fix the problem.

So looking at the hot side of the relay, in addtion to the two wires in the rubber housing/connector that go to either side of the relay, there are two additional "ring lugged" wires on the hot terminal. I'm not finding them on my circuit diagram?? Anybody know what these wires feed?

Looking for ideas - I suppose I could lift the hot lead at the starter and see if the leakage is through the starter.... anybody got any other ideas...?

Thanks,
 
  #36  
Old 02-25-2012, 08:50 PM
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Originally Posted by MR5x5 View Post
So looking at the hot side of the relay, in addtion to the two wires in the rubber housing/connector that go to either side of the relay, there are two additional "ring lugged" wires on the hot terminal. I'm not finding them on my circuit diagram?? Anybody know what these wires feed?

Thanks,
I matched this drawing against my starter relay and they are the same.

You must be referring to #4. I couldn't find them on a schematic either.

This is for a 99 to 01.
 
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  #37  
Old 02-25-2012, 09:05 PM
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Ammeter, (I know, I know...)

Good luck w/this one.
My previous rig (a 1960 F250) had an ammeter that I installed. This greatly simplified identification of the overall state of your batteries and charging system. With everything off and the truck rolling down the road, the needle sat dead center on zero. If I turned the heater fan on, the needle would move just slightly to the right hand side of the midpoint, if I then also turned on the headlights and fog lights, the needle would move significantly to the right and hang there. If I drove for a while like this, and then turned off the headlights and heater fan the needle would swing back past the center and hang slightly to the left of center while the battery charged, ending back on the midpoint after a few minutes. There were several occasions over the years as I fiddled and putzed with this rig that I'd start up in the morning and notice that the needle was sitting just to the left of the midpoint. From this, I could deduce that there was a current draw on the battery from an accessory left on overnight or a misbehaving component.
Recent experience with an electrical problem in my truck has caused me to consider again installing an ammeter.
 
  #38  
Old 02-25-2012, 10:19 PM
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Pason - Thanks - It's the "#4" wires in your schematic that I was referring to. So I can read what it says, but am at a loss for what it means. Engine Control Sensor??? Generator wire - does this imply alternator?

Thx
 
  #39  
Old 02-26-2012, 12:46 AM
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Subscribing....buddies truck has been doing this for years.
 
  #40  
Old 02-26-2012, 11:38 AM
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I don't believe the starter is the issue...I wish I had the charging circuit diagram for the truck, but my cd went belly up a year or so ago (anyone got one?). That wire at #4 is my suspected culprit...the one that goes from the starter relay back to the alternator. It carries battery voltage back to the alternator to excite the rotor so the alternator can then produce electricity. If there was a way for the electricity to get to ground in this circuit it would pull the batteries down when the vehicle was turned off (your 4.5 A draw).

My next step would be to charge the batteries with a charger (or drive) to bring them to full float charge state (around 13.2 vdc....check battery voltage after charging or driving) when you are going to leave the truck for an extended period not running. Then after the charge, disconnect the alternator plug and leave the vehicle. When you get ready to use the truck again (in a few days to a week...whatever time it took to discharge the batteries) plug the alternator back in. If the vehicle starts, then we would know the likely problem is the diode trio...one or more of them is causing a discharge back through the alternator exciter wire coming from the starter relay (#4 in the diagram Payson provided) and the electricity is going to ground at the heatsinks for the diodes.

Another way to check this is when you see the parasitic draw of 4.5 A, disconnect the plug from your alternator and if the current draw collapses to near zero amperage, the alternator is the culprit.

The part that has me confused and our electrical experts might help here is the apparent intermittent nature of the problem (sometimes measuring 35mA parasitic and then 4.5 A parasitic). I see diodes as one-way switches for electricity that lets current flow in one-direction only. They should read open in one direction and closed in the other. I don't know of intermittent diode problems. Someone help here?
 
  #41  
Old 02-26-2012, 12:56 PM
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Originally Posted by MR5x5 View Post
Pason - Thanks - It's the "#4" wires in your schematic that I was referring to. So I can read what it says, but am at a loss for what it means. Engine Control Sensor??? Generator wire - does this imply alternator?

Thx
I am not sure but I have a feeling some EE thought this would be a good place to to connect two wires that are both used to sense/read the voltage.

I'm wondering if one of them is for reading vehicle voltage with a scantol (Engine Control Sensor) and the other for the batt light on the dash. Purely a guess.

Neal's certainly on the right track. An easy test would be to measure the batt voltage and then disconnect both of the #4 wires. Come back a couple of hours later and read the batt voltage again. If there is no significant loss it is one of those wires. To figure out which one just reconnect one at a time and check for voltage loss again. The old "process of elimination".

If it is one of those wires we can try to figure out where it goes.

If not they are at least eliminated as a cause of the drain.
 
  #42  
Old 02-26-2012, 01:04 PM
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Neal - Thanks - Going out to look at things again. My thinking now is that this is not intermittent - but that my intial 35mA measurements were somehow wrong. Note that I get the 4.5A draw with both bats diconnected and the meter in the circuit. I only get the 35mA draw when I put the meter in the circuit with only on bat disconnected...I don't know enought about the meter and associated circuit to know if keeping one of the bats hooked up in parallel with the metered battery imbalanaces the circuit such that the 4.5A draw simply sources from the hooked up bat, hence bypassing the meter??

Headed back out to start again, from the start.... Will recheck the current draw and fuses. Will attempt to isolate the #4 wires as well as the alternator.
 
  #43  
Old 02-26-2012, 01:14 PM
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Originally Posted by MR5x5 View Post
Note that I get the 4.5A draw with both bats diconnected and the meter in the circuit.
I don't see how this is possible...if BOTH batteries are disconnected, how can you get a 4.5A draw ?



Notice on #4 where it says "...and the generator wire"? That is the wire I suspect is the problem (well, probably not the wire per se, but rather the diodes up stream) - I am ASSUMING that this is the wire that carries battery voltage back to the alternator to excite the rotor. If my assumption is wrong...well then my theory collapses. Doesn't someone have the charging system diagram?
 
  #44  
Old 02-26-2012, 03:08 PM
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The draw is with both bats disconnected and the meter place between one bats pos terminal and it's pos cable. (10A meter setting)

Update - looks to be the alt. Both bats unhooked, meter in line with pos side of one bat. Steady 650mA draw. (Not sure where the 4.5A has gone?? May have had one of the doors open and was pulling/reading extra Amps to the dome light??) Disconnect either the 12V cbale to the alt or the 3 pin connector, and the draw goes to less than 100mA. Very repeatable. In fact, if you put an ear on the alt, you can hear it humming with the 3-pin connected. Unplug it, and silence.

Pulled the alt and will take it back the shop that built it to have them give it a once over.
 
  #45  
Old 02-26-2012, 04:14 PM
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Originally Posted by MR5x5 View Post
The draw is with both bats disconnected and the meter place between one bats pos terminal and it's pos cable. (10A meter setting)

Update - looks to be the alt. Both bats unhooked, meter in line with pos side of one bat. Steady 650mA draw. (Not sure where the 4.5A has gone?? May have had one of the doors open and was pulling/reading extra Amps to the dome light??) Disconnect either the 12V cbale to the alt or the 3 pin connector, and the draw goes to less than 100mA. Very repeatable. In fact, if you put an ear on the alt, you can hear it humming with the 3-pin connected. Unplug it, and silence.

Pulled the alt and will take it back the shop that built it to have them give it a once over.
Great news...just great ! If the batteries are charged up I would hook everything back up as it was and see if the batteries get pulled down. I would also take the batteries into a shop and have them load tested BEFORE I hooked the repaired alternator up.
 

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