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Astro, CatFish, frscke1, NTvan, Rusty Pancelode
Total Likes: 7
Original Post (Thread Starter)
Parasitic draw is kicking my van #779373 07/23/2021 9:04 PM
by Just4fun1991
Just4fun1991
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
Liked Replies
Re: Parasitic draw is kicking my van #779375 Jul 23rd a 09:28 PM
by Wedgy
Wedgy
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.
2 members like this
Re: Parasitic draw is kicking my van #779378 Jul 24th a 02:04 AM
by wrcsixeight
wrcsixeight
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.
2 members like this
Re: Parasitic draw is kicking my van #780892 Aug 20th a 03:17 PM
by Just4fun1991
Just4fun1991
OK, hope I don't JINX myself or the van. Just wanted to give insight to the next person on issues they could run into and things to look for when having drain issue.


Update! It's been 1 week and van starts like it never has before. Engine/started spins right over and starts right up with battery connected (removed knife switch from battery). In past its never lasted more than 4 days without having to disconnect the battery.

Here are a few of the things I found that caused my issue

1. Biggest issue was the headlight switch (spring corroded out over the years and making contact from time to time) new switch installed $21
2. My voltmeter showed the alternator being weak/bad diode $105 with core
3. Wiring to aftermarket radio (prior owner did no favors in his so called withing)
4. Found a visor had a mirror light that does NOT shut off when cover is closed
5. Last was the battery was an issue/weak (covered under warranty)

time spent, TIMELESS/hours.... But knowing issue is resolved, PRICELESS

The fun part now is going to be cleaning up the conversion van wiring (they bundled 2' of wire in dash for the rear heater controls that can plan on shortening / cut down)

Changing out factory dash speakers while dash is out. Probably install a Double Din radio now with backup camera while dash is out. Just a small mod to make and simple with dash out.

Thanks again for everyone's help/input!!!
2 members like this
Re: Parasitic draw is kicking my van #780013 Aug 4th a 03:28 AM
by CatFish
CatFish
Sent you a PM but I'll copy it here for everyone:


The horn relay should be hanging on (and along side) the wiring harness above the fuse panel. Tough to access.

Both the horn and the dome light circuits are powered all the time.
The horn button simply grounds to complete the circuit and close the relay.
The door switches work in a similar way. They supply the ground connection for the lights.
The power wiring to the horn relay and each of the lights is "hot" direct from the fuse at all times.

Are there any additional lights added by the conversion company? I would suspect the dome lights first.

Here's a pic of the horn relay location. The relay is #4 in the diagram, the fuse panel is #6 and the head light switch is #3.
https://www.carfusebox.com/wp-content/uploads/2017/07/Chevrolet-G20-1994-Fuse-Box-Diagram.gif
1 member likes this
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