What Can Drain the Battery?

Steve83 · Jun 23, 2017

Basic physics: the energy in the battery has to go somewhere - it can't just disappear. Wherever it goes will get warm (or hot). The faster it leaves the battery, the higher the temperature will be. If it was strictly within the ig.sw., the switch would catch fire, so that's not likely. If the switch was staying on, things in the truck would remain on, and you'd see that the switch was ON, so I doubt that's what's happening.

Water (particularly rain) doesn't conduct electricity well enough to drain a GOOD, charged battery in 2 hours. The water would boil away long before the battery even got low. Only the acid on top of the battery case MIGHT be forming a path between the posts, but there shouldn't be any on a new battery.

rjrobin2002 · Jun 23, 2017

I am going to check the starter cable to see if it may be shorting to the frame or engine. I figure it has to be a drain from a large cable.

DirtDonk · Jun 23, 2017

I doubt it. Any single strand from a cable that touches a ground will spark and melt, with (if you're lucky) no superfireworksdisplay that harms things around it.

And besides, the obvious answer to the starter equation is that it's not possible with the old style starters with the relay on the fender. There is no power to the starter.
If there was, it would be the fault of the relay/solenoid itself.

If you have a modern PMGR starter with the power wired directly to it, then something inside the solenoid could be faulty. But my vote for a fast drain like described is the alternator and/or the regulator.

Is the alternator warm when not in use?

Paul

rjrobin2002 · Jun 23, 2017

He does have the upgraded starter with a power cable directly to it, but that is not the cause as I just went out there and looked and unhooked it with the drain continuing. I also unhooked the Alt and the drain continued.

The drain is very inconsistent as he just parked it a week while he was on vacation and it stayed charged.

I check for drains by disconnecting the positive cable and touch it to the positive post slowly and watch the arc and can hear it also. His arc 'drain' is present until the large black wire that heads to I guess the ignition switch is removed.

What should a volt meter be set on to measure the volume of that constant current draw that let's say a radio clock draws? This arc that I can see constantly is about the size of a few grains of salt I can see in broad daylight, I can hear it, and it even makes a small flash of smoke which I feel is more than normal.

rjrobin2002 · Jun 23, 2017

No wires or the starter/Alt felt warm when I was feeling all of them in the engine bay. But the battery was only hooked up for a few minutes.

Steve83 · Jun 23, 2017

rjrobin2002 said:
I check for drains by disconnecting the positive cable and touch it to the positive post slowly and watch the arc and can hear it also.

That's not an accurate test. On a vehicle with any capacitors (inside the PCM, or a power inverter, or a stereo amplifier, or some ignition modules, or some voltage regulators, or...), there will be a spark when power is applied. It's normal for capacitors, and doesn't indicate any parasitic draw. Many small or a few large capacitors will pull a big spark; a few small capacitors will throw a small one. You can't distinguish a capacitor spark from a parasitic draw spark just by its appearance.

rjrobin2002 said:
His arc 'drain' is present until the large black wire that heads to I guess the ignition switch is removed.

The test is only useful if you find out for sure what that wire feeds.

rjrobin2002 said:
What should a volt meter be set on to measure the volume of that constant current draw..?l.

You can't measure current with a voltmeter. Either use an ammeter, or a digital multimeter (DMM) set to DC Amperes. It's safest to start with an ammeter set to its HIGHEST range (usually 5~15A) so that the draw is less-likely to burn the meter's internal fuse. If it registers a usable number, that's the draw. If it registers below 2.0000, turn the range down ONE step at a time until it shows something useful. If it shows some error (like the letters "OC", "OL", or just a "2" at the right side), the current is too high for that meter to read (in that range), or its fuse is already burned. Read that meter's instruction manual, and make sure it has a good battery. Many DMMs require you to insert the test leads into the correct sockets for reading amps, so pay attention to how the sockets are labelled.

Rustytruck · Jun 23, 2017

If its the ignition switch with the key off check the green wire with the red stripe and check the wire to the coil. If power is leaking through the switch these are the most likely suspects as these wires are usually connected to sources that can draw power. You can find the green with red wire in the engine bay by the driver side valve cover and of course you know where the coil is. with the key off there should be no power to these wires.

rjrobin2002 · Jun 23, 2017

I have a multi meter with amp settings, so what is an acceptable amp draw?

I will see if the coil has power with key off and check a bunch of other things for power.

DirtDonk · Jun 23, 2017

The Black wire at the starter relay is the main power to the whole system. So when you disconnected that, you isolated just about everything inside the cab. So your ignition switch is looking more and more suspect, but that's still not the only thing it could be.
But if it's the switch, like Rusty said it could power the Green w/red wire and turn on the voltage regulator. That would definitely create a drain.
You can test that by leaving it all connected and then disconnecting only the connector at the regulator.
If the drain goes away, it's power leaking through the Green w/red wire, OR the regulator itself using the power from the Yellow wire in that connector (always hot) to self-energize. Disconnecting the big Black wire would also have killed power to that Yellow wire, so the regulator could still be suspect.

Maybe other things as well, but those two are the most likely. Easy to test a simple ignition switch and regulator though. Just un-plug 'em!
Actually it's easy to test the switch anyway, but unplugging it would certainly get the job done.

Paul

DirtDonk · Jun 23, 2017

Less than 1 amp I would think. But Steve would likely know for sure.
For factory stuff, well less than that. Maybe less than half an amp? But with aftermarket stereo amps and such, not sure.

Paul

jabshire · Jun 23, 2017

Voltage regulator is the likely culprit.

bronconut73 · Jun 23, 2017

jabshire said:
Voltage regulator is the likely culprit.

I've had them turn out to be the short I was looking for but were somehow still functioning ....

Cheap to experiment. Well worth the investment.

blubuckaroo · Jun 23, 2017

bronconut73 said:
I've had them turn out to be the short I was looking for but were somehow still functioning ....

Cheap to experiment. Well worth the investment.

Yes, the electronic ones are a big improvement, but should always be suspect when you have a battery drain issue.

rjrobin2002 · Jun 23, 2017

I will get him to grab a new voltage regulator and try that.

. The alternative is new but not the voltage regulator, then keep moving forward. He did get jumped off the other day and said it was running horrible the way home, maybe it is coming and going and that day he was driving home the alternative was not charging. I have checked his battery a few weeks ago and the voltage was raising when he gave it the gas from 12.5 to 13.5 or so.

Steve83 · Jun 23, 2017

rjrobin2002 said:
...what is an acceptable amp draw?

The industry standard maximum for passenger vehicles is 50mA (0.050A), but that assumes a lot of factors that may not apply to your eB. Among them: a modern cranking battery, good wiring & charging systems, and that the vehicle is driven frequently. As you cross those off the list, the maximum drops. With an oversize battery or an engine that's easier to crank (smaller displacement, lower compression, worn-out bearings, more-efficient starter), the maximum rises. If you keep a float charger on it, the max. parasitic draw is the charger's nominal output (for as long as the charger is working).

But most modern vehicles I've tested since the early 00s (including new Land Rovers, Jaguars, & Fords at dealerships) actually show closer to 15mA parasitic draw (after all the security & convenience systems go to sleep). Antique vehicles with little or no modern electronics should have about 0 parasitic draw. This is why a THOROUGH description of the vehicle needs to be in the owner's signature. %)

rjrobin2002 said:
I will get him to grab a new voltage regulator and try that.

That's an expensive & frustrating way to fix a problem. TEST it by measuring with your DMM. If it passes, there's no reason to change it, and several reasons NOT to change it.

rjrobin2002 · Jun 24, 2017

A new voltage regulator is $11 from Toms.

His Bronco has a 302 with a modern mini starter, Optima battery, new stock style alt, aftermarket radio with no amp, upgraded headlight harness, and that's about it.

I will get a amp reading, do you disconnect the positive, set it to amps, and put one amp meter lead to the bat and the other on the positive cable and it will test the amp draw?

blubuckaroo · Jun 24, 2017

rjrobin2002 said:
A new voltage regulator is $11 from Toms.

His Bronco has a 302 with a modern mini starter, Optima battery, new stock style alt, aftermarket radio with no amp, upgraded headlight harness, and that's about it.

I will get a amp reading, do you disconnect the positive, set it to amps, and put one amp meter lead to the bat and the other on the positive cable and it will test the amp draw?

You can disconnect either the + or - battery lead and put the meter between the post and clamp.

Steve83 · Jun 24, 2017

I suggest you read the DMM's manual, and browse YouTube for a few videos using a DMM like yours to measure DCA. Mine are (inductive) clamp meters, so I don't have to disconnect wires for HIGH current measurements.

.

There are inductive meters & probes for low-current measurement, and you haven't said what yours is.

rjrobin2002 · Jul 1, 2017

jabshire said:
Voltage regulator is the likely culprit.

Bingo!!!
Amp draw was 3 amps with key off until it was unhooked the yellow wires to Volt regulator and it dropped to zero. Put a new volt regulator on and even with power hooked up it has no amp draw.

What Can Drain the Battery?

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