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Parasitic draw is kicking my van
#779373 July 23rd 2021 5:04 pm
Joined: Feb 2018
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Here is one that I would love some input on this.

Parasitic drain in a1992 Chevy G-20 Mark III conversion van
Note, this is not a high top conversion, nor does it have an inverter or electric couch or TV.

It does have electric locks & power windows & cruise control along with wipers (I have heard that a wiper motor that doesn’t find home position can sometimes still have a draw) but it’s been checked!!

I bought the van about a year ago with a known battery drain. Been stored most of its van life inside with only 66,000 miles on the odometer. The prior owner (I am the 3rd) installed a knife switch on the negative terminal so when parked they could open the knife switch and not allow the battery to discharge.

I have been using my voltmeter and have been trying to find the parasitic drain. Thinking about borrowing another voltmeter to make sure my DMV accurately reading the draw properly (It’s a Fluke, but need to explore options)

This is what I have done.
(Note, I have only found a signal fuse panel (do you know of a hidden one) in the van, and it has the ATO style fuses). I have not found any fuse panel under the hood.

I do plan on taking the battery in to have load tested this weekend. I don’t think that is the culprit but need to eliminate that from the equation. Reason why I say this is because I leave the battery knife switch open and the battery does not drain. Left it open over the winter and then started right up this spring when I closed the knife switch (it sat for 4 months)

1. Fully charged the battery on a slow 2-amp charge overnight (12 hrs.)
2. Hooked my DVM up to the negative terminal (in series) and set DVM to DC amps.
a. Voltmeter can handle 20amps DC, I also have a clamp meter too
3. Made sure dome lights were always off when door was open for testing
a. (Disabled door pop button)
4. I have pulled every fuse in the fuse box and still have a 2-amp to .5-amp draw (left the fuses out too)
5. I have even gone as far as to pull the connections that are not fused out of the top of the fuse panel.
6. I pulled the alternator off the vehicle and tested the alternator using the diode setting
a. My voltmeter showed it failing, so I took to auto parts store and they tested and said it pasted, but a new alt was $100 so I bought and installed (old one was original)
7. For 4 days the vehicle started every morning (let run for about 5 minutes each time)
8. The 5 day the battery was so dead that it would not even click the starter

I am not at wits end but getting close! I am going to check the rear door lock (it’s after market from Mark III and I have a funny feeling on this, and is worth checking at this time, only cause it was the door I used to lock before the battery drained, PS, I know the dome light goes out as I have checked every time (sometimes it’s the simple things that are overlooked that cause the issue I tell people, I don’t want this to be the case in my van) There is an aftermarket keyless entry I had installed 2 weeks ago (but I have left that complete unhooked for the time being until I can find the drain) There is an aftermarket radio installed, but I have pulled the fuse that powers the radio and still there is a draw.

From what I have experienced with this van is that is it intermittent. I was almost positive it was the alternator, but now know it is not and back at the drawing board.

Questions
1. Do you know does the 92 van have a hidden fuse box?
2. Can a starter that works cause a drain?
3. Any direction you can point me in finding the drain?
It’s my plan to work on it again this weekend and look at the rear door lock that unlocks all doors from the rear switch (I don’t know what but think it maybe sticking) I know I could find that fuse that powers the lock/relay and leave it undone for a week to test.


Any input / direction to go next would be appreciated.

Thanks
Bob Maiwald

Re: Parasitic draw is kicking my van
Just4fun1991 #779374 July 23rd 2021 5:25 pm
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I think testing the battery is a great start. I have had a slow drain on my Harley battery for the last year. Granted, way different from a van. It is a chopper so all the extra was removed, rewired with new everything. Battery would be dead within a week of no use. She finally gave up the ghost and wouldn't charge past a certain voltage. New battery, no more issues.

Do you know how old the battery is?


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Re: Parasitic draw is kicking my van
Just4fun1991 #779375 July 23rd 2021 5:28 pm
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Does it have an Alarm? Little red light. Grrrr, Sure radio doesn't still draw for the presets? Radio in the Boat does. Dual Batt. Perko.


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Re: Parasitic draw is kicking my van
Just4fun1991 #779376 July 23rd 2021 7:07 pm
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Its my plan to load test battery Saturday AM.

Keyless was added 2 weeks ago, but I have unhooked the power wire until drain/draw is found.

I am looking into a “thermal image” camera (Flir or Seek IR) but I would like to use that as a last resort.

Bob

Re: Parasitic draw is kicking my van
Just4fun1991 #779378 July 23rd 2021 10:04 pm
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Each and every engine start, can be a 'LOAD TEST' if one has a fast responding voltmeter.

So with such a voltmeter attached directly to battery terminals, crank the overnight cold engine. What was the minimum voltage seen, If it was over 7.6, the engine started.

If it remained in the mid 11's or higher the battery is healthy.

When Voltage falls during cranking to the low 8's, on an overnight cold engine, or worse, a warm one, start shopping for a battery deal.

An actual load test requires loading the battery to 1/2 The cca rating of the battery, and it must maintain 7.5 volts for 30 seconds.

But in reality that is a rather insanely abusive test, when fuel injected engines start in 5 seconds or less.


In your PM you stated you measured a parasitic draw anywhere from 0.5 to 2 amps

YOu cannot measure self discharge of a battery itself via an ammeter.

If you want to test if your battery has a soft short/ excessive self discharge, fully charge it, disconnect it from any potential parasitic draw, then measure the resting voltage. Measure it again in an hour, 12 hours, and 24 hours. If at one hour it stayed above 12.8v, and 24 hours stayed above 12.6v, then it is likely good to go for a while longer.

If it drops to 12.5 instantly when removed from charger, it is either no where near full charged, or is not so healthy but might be OK for 6 or 8 more months. If it drops to 10.7v or less, it has a shorted cell or is just disgustingly sulfated and would struggle to start an engine ever.

If fully disconnected resting voltage remains above 12.7v 24 hours after removing from a charging source then it does not have excessive self discharge, and 90% of the time is still a realtively healthy or better battery.

But it is also possible to have a battery remain above 12.7v 24 hours off the charger, and be incapable of starting an engine.

Voltage is ONLY indicative of state of charge on a battery that is not under a load, and has not been charged or discharged for a period of time. 'Surface charge' a voltage reading shortly after shutdown, almost always misleads one into thinking the battery is more charged/ more healthy than it is, but watching voltage maintained during engine starting removes ALL the mystery, and no need to deal with some halfwit in an Autoparts store.

One can take their tool, and adjust the tension and the surface area the of thr clamps on the battery terminals, and force an OK battery to read weak. 'Good thing we have one right here for sale.....'

Excessive self diacharge can certainly be happening in concert with a large parasitic load, but you say you have measured 0.5 to 2 amps with all fuses disconnected.

And for other readers.

a 2 amp 'trickle charger' for 12 hours, on its best day, can only ever return 24 amp hours into a battery. Most batteries in Vans are no less than 55 amp hours, and a group 27 can be 100 amp hoursm abnd a group 31 uptro 130 amp hours.

This 24 amp hours assumes that the charger is able to bring the battery to, and HOLD the battery in the mid 14v range the entire 12 hours. This is so excrucitaing unlikely to occur, that any statement of truly fully charged, is uttered only by the unexperienced. It takes a ridiculously time to achieve truly fully charged status, and the older and more abused the battery is, the Longer it takes and the more important the 14.5v sought anfd more importantly HELD, for the entire time, is.

putting a 'trickle charger' on a battery is absolutely NO guarantee the battery is indeed fully charged, Not even if the charger's marketing material leads one to believe the CHarger will restore any battery to maximum potential function, then finish off the owner with the best fellatio they ever received.

The most competent of mechanics, seem to be among the most oblivious in terms of the proper care and feeding, and judging the health of, a lead acid battery.

replacing a battery while there is still a significant parasitic draw, is just a guarantee that the new battery's dies prematurely as well.

There is NO need to take a battery to an Autoparts store foir it to be tested. Most just use a tester which puts a small load on teh battery, watches how much the voltage falls, and comes up with a Ohm/ resitance reading, which then correlates to a CCA figure, along with some math to attempt to correct the fact that the battery is likely not being tested at 0F(CCA), or 32F(CA) or 76f(MCA).

As Said one can get vastly different CCA readings from such testers, just by the pressure and surface area the testers clamps are exerting on the battery terminals.

Also a lot of the carbon pile load testers, can only do 100 to 150 amps of load. whereas a true CCA test is 1/2 the CCA rating of the battery, and it must maintain 7.5 volts or higher after providing that load for 30 seconds.

Since fuel injection causes engines to start so quickly, performing this 'tru CCA test' is abusive and can actually push a weak battery over the edge. Which can be a good thing, if one is headed into the wild blue yonder hundreds of miles from the nearest battery vendor.

Put the DMM's leads right on the 'well charged' battery terminals and start the engine.

A truly healthy fully charged battery will remain 11.7v or higher during the 150 to 180 amp load. The load can briefly spike to as high as 240 amps on a gas engine before settling to the 150 to 180 amp range, just to get the engine moving. Diesels can be much higher spike in amperage due to the extra compression.

I have a digital voltmeter on my dashboard, and watch it every engine start.
It only samples voltage 2x per second, but when I ran my last battery to the ground, it was hitting low 8's and high 7's, even on the warm/hot engine, and when it dipped to mid 7's, it cranked so slow it was overwhelmingly obvious that it was no longer to be trusted and should be replaced.

Nobody needs to goto an AP store for a load test.
It's a waste of time and effort, for anybody who can watch a voltmeter on the battery terminals while the engine is cranking.

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Re: Parasitic draw is kicking my van
Just4fun1991 #779420 July 25th 2021 12:00 am
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Update

This morning with battery on charger for 12 hours I took it off. Here are DVM readings thus far

8:30 am. 13.33
9:30 am. 13.03
10:30 pm. 12.88

Tomorrow morning i will take another reading at 8:30 am.

Bob

Re: Parasitic draw is kicking my van
Just4fun1991 #779422 July 25th 2021 3:30 am
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This resting voltage test is not perfect, in terms of determining battery health

A battery can be fully charged, and maintain 12.75+ volts days off the charger, but have a tiny amount of capacity left. This capacity can be so small as to not be able to turn the starter.

I have had one battery pass the resting voltage test at 24 hours, but drop to 10v under any load above 5 amps, then rebound instantly to 12.82v with load removed. That one caused a bunch of cursing as it was in parallel with another battery, and I had to separate them and load them separately to see that one was still good and the other was junk. resting voltage or light loads and it looked fine and dandy



A battery, hot off the charger, that drops voltage quickly, is a sure sign it is not in the good health, especially in warm or hot ambient temperatures. So while passing the resting voltage test is no guarantee the battery is still good/ adequate, failing it is surely indicative that it is not.

very cold battery temperatures and one can easily expect to knock off 0.2v from expected max, and a cold battery not only has to work harder/ provide more amperage to start a cold engine, but it has less overall capacity with which to do so.

Think of an aging or abused battery like a Fuel tank which keeps getting smaller. You can still fill it up, but when new it held '35 gallons', but when it is just barely healthy enough to start the engine it can only hold 2 gallons.

Many people claim their battery is 'still going strong' when it only has '3 gallons' of capacity left, because it still easily starts the engine, then they charge their cell phone and listen to the radio and 'click click'

Measuring voltage during engine cranking on such a battery, would have them rescind such a claim and hang their head in shame, if they had the capability of being honest with themselves.

Re: Parasitic draw is kicking my van
Just4fun1991 #779484 July 26th 2021 9:10 am
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Well, by accident I have a better idea on where the draw/drain is coming from.

Here is my questions.

Does anyone know what these 2 wires that are in the picture power? Also, do you know how one can pull the cover that the arrow is pointing to without damaging the cover? Also, does anyone have a wiring diagram of those connections/wires?

There seems to be a black coating sprayed on the cover. Not sure if that is to prevent corrosion or what?

The 2 wires throw sparks each time they are hooked back up to power. Not just a little spark either. The 2 wires wire into where the smaller lead from the positive cable hooks into the firewall of the van (circled in picture).

If anyone has any input please let me know on how to remove cover and what they power.

Thanks
Bob

[Linked Image from i.imgur.com]

Last edited by Just4fun1991; July 26th 2021 9:15 am. Reason: added
Re: Parasitic draw is kicking my van
Just4fun1991 #780012 August 03rd 2021 10:02 pm
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Well, the weather in Iowa has been a little cooler so I have taken some more time in working on the van electrical drain.

I do have questions for you that are able to give me some input.

I have narrowed down the drain to the HORM/DM fuse.

I am going to guess that DM is DOME light (as the dome lights do not work right now with the fuse out, nor does the horn.

When I close all the doors the dome lights go out(with HORN/DM fuse installed). Could I still have an issue with the dome popper switches?

Does anyone know where the 1992 G20 horn relay is located? (horn works with fuse installed)

ANY THOUGHTS ARE APPRECIATED.

Bob

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