Hot Rods 12 v Battery problems..

The battery was charged, and the terminals were cleaned Sat. This battery is barely 4 years old. The car has been driven out of town (15 mile road trip) a couple times since then, during the daylight hours. The charging system is working correctly. Today it would not crank over (3rd time in 3 weeks, maybe it doesn't like Tuesdays?), the voltage is below 12.3 volts. This battery is in my wife's appliance ride, but a battery problem is a battery problem.
How do I check for a voltage draw?

Where is the place to buy a good 12 volt battery these days without spending a fortune?

 

Remove your battery and take it to a car parts store. They will check your battery under load.
How many volts are reading at your positive and negative battery terminals with the car running at high rpm?
A good charging system should read close to 13 plus volts.
I’ve bought two batteries from Menards lately. Good price and we’ll see if I can get 3-4 yrs out of them.

 

I have had pretty good luck with Walmart batteries. Easy to get and haven’t had any issues of lasting. Maybe just lucky. Ed

 

Check the current draw (meter on DC amps).
Pull the neg lead and check between it and the neg battery lead. Ie put the meter in series.
Should be less than 50ma, I just checked my OT vehicle, it was at 2 ma

 

You mention wife’s appliance vehicle. If newer, you’ll want the battery to sit for 30 minutes or so before pulling the lead and checking.

 

Thanks guys. When the motor was idling, the voltage read 13.5 volts (high voltage charging system). I currently have the battery out of the car and on the charger. I will give it an hour, then I will put it back in the car to check the voltage draw. If that checks OK, I will cart it off to get load tested.

We have 3 vehicles here, this battery is the newest of any of them. Normally, the batteries have lasted 7 years or more in this car (we have had it for 22 years). I have always bought my batteries from the local farm store and have had pretty good luck, but I'm not impressed with this one. Its suppose to have a 5 year warranty, which probably won't amount to much.

Buying anything from Walmart scares me, I don't even like walking into the store. Menard's might be a go.

 

Current, not voltage.

 

I like Deka/East Penn batteries. Home Depot had them for a while. Sams club changes suppliers and sometimes has them.

 

I was getting 7 years plus of work from my Motorcraft battery’s in my Expedition but one died on me on a Saturday out of town so I picked up a new Walmart and it lasted for 13 months and it’s replacement lasted for 10. I’ve had a Napa in it for 2.5 years now with no issues.

 

So.... about that current draw...

I probably screwed this up, I did put the cable back on and started the motor. The battery voltage while the motor was running was 13.9 volts.
Then I shut it off and disconnected the negative battery terminal. At the point the picture was taken, the terminal was disconnected for about 10 minutes.
I don't understand much about this meter, I know how to read DC and AC voltage, and I can get an acceptable ohm reading out of the ohm scale. But the DC amps is over my head. In this picture I have the dial set at the Highest DC a setting (2000 m). I just checked it again, the terminal has been disconnected for about 20 minutes now, but it is sprinkling out and the battery is exposed to the rain. The scale is running between 246 and 50, but mostly staying at 60-62. I have no idea how accurate this meter is, there is no needle adjustment, but it does have a new 9 volt battery in it.
Do I have an excessive current draw?

 

Set the meter to a lower scale, better resolution. But if I understand you correctly, that would be a 52ma draw. Google your make and model, see what is acceptable.
246 is high. I’ll send you a message

I meant to add that 246ma is near a 1/4amp draw, just for reference.

 

You've piqued my interest there. What happens, or stops happening to the battery after 30 minutes of idle time?

 

We've never met. But at least in some small way I think we're both cut from the same cloth.

 

With the vehicle idling, or with the car shut off.
I’ll have to message you

 

I was ***uming that you meant with the engine off. Just the "Cliffs Notes" version would suffice.

 

If you have a small 12 volt bulb (like a dashboard bulb), put it in series with either battery lead (you can just push the base of the bulb onto the battery terminal post, and touch the lead to the side of the bulb. If it lights up, with everything turned off, you have something drawing current. You can start yanking fuses until the light goes out. This will show you what circuit is still drawing current. If it happens to be one of the "electronic module" circuits, it may be supplying a memory or setting function in that controller. Then as mentioned above, see what the "parasitic" draw is for that vehicle. And remember to turn your meter back to voltage when finished, it will let the smoke out (or just blow the internal fuse if your'e lucky) if you try measuring a voltage on current setting!

 

That doesn't work so good on new cars. When replacing the factory battery on my 2020 Parts Getter III, I was surprised at the arc I got connecting the negative cable. There is a ton of draw on new cars! Have the battery tested outside the car.

 

OK, the update. The car has a few electronic modules. When the car is turned off, voltage is still moving through the system for between 15 to 30 minutes, depending on what stuff is powered by the battery in the car. If you disconnect the battery cable, and check for a current draw before the cycle is complete, it shows a pretty big current draw.

I discovered an hour ago that even with the battery cable disconnected, every time you put the meter leads between the cable end and the post after it was disconnected, you have re-activate part of the system and the meter needle swings for up to 30 seconds before it stabilizes. If I had not read that, I would have never suspected the needle I saw bouncing was bouncing because I activated the memory system by connecting a meter between the cable terminal and the battery post.

I do indeed have a current draw. It is near the top end of the accepted range, my biggest current draw feeds the memory system fuse that powers memory of any device connected to that fuse on car.

At this point the biggest suspect is that the battery does not hold a charge and will fail the load test. Tomorrow may well be battery buying day.

Thank you guys for the help.

 

You don't!
You check for amp draw

You remove the ground cable and use a multimeter on Amp settings as a temporary ground cable.
Don't do anything silly like try to crank over the engine or headlights on.

You can also do this with a headlight bulb and 2 wires [but it doesn't give a reading] I do this when looking for a short circuit or faulty component [the light glows instead of the harness smoking]

Here is an example [black wire to - post , red wire to ground strap] with Amp readings it isn't polarity sensitive.


Same car showing 0.060a draw 60 milliamps [which is sleep mode for that particular car]
The battery is under the plastics [blue arrow]

 

Thank you. We were typing at the same time.

 

Most cars "go to sleep" approx 2-5 minutes of the ignition off and doors closed
The car above [Ferrari] showed a 2 amp draw as soon as I [re]connected the circuit. Then it dropped to 60 milliamps after 2 minutes

 

If you have a fuse block that uses mini fuses, an easy way to check for a current draw is to check the voltage drop across each fuse. So, shut the car off, wait 15 or 20 minutes until the modules shut down, then set your voltmeter on minivolts and touch the leads to each side of the fuse; positive lead to one side, negative to the other. If no current is flowing the meter will read zero. Any fuse in a circuit that is drawing current will give you a reading. You do not have to disconnect anything to do this test. Now that I think of it, it will also work on gl*** fuses.

Also, if you want to know how many milliamps are flowing, here's a chart based on the voltage drop.

 

Hey Kerry!!!

Yes, that’s why I mentioned letting it sit for a period. Shut it off, pop the hood, come back a 1/2 hour later when things have cooled off, the check the draw.
Mine (OT) was just 2ma. But all are different.

 

Computers in modern cars can take quite some time to go to sleep, and things like open doors may prevent them completely. Anything that requires disconnecting and reconnecting the battery will wake things up, so it takes patience to get a reliable measurement after that.

Anyway. A poor connection battery-starter may also cause enough voltage drop to prevent starting, so more than one thing to keep an eye out for.

 

Pulling fuses with the meter in series to the bat is really the best way.

about 20 years ago, I was driving my Fury and the temp gauge spiked. I pulled over and checked it out-nothing hot.
Short, nervous drive home.

Checked and found my memory wire from the aftermarket radio was pulling 11 amps!

-rick

 

Once I got the meter on the correct scale, the draw was .6 Milli amps, which is with in the specs on the car.
The battery failed the load test. I have the new battery installed. My $135 bought a battery with only a 2 year warranty, which was all they had in stock. The out of stock 3 year warranty battery was almost $100 more. I guess that means I will probably be replacing this one in a couple of years.

 

This test saved you the headache of "machine gunning" components at your car.
You need a battery tender for battery longevity

 

For old tech it's quite good. In newer cars where computers will wake up when power to them is restored (by putting the fuse back) and other computers on the same network will be woken up as a result it turns into a major pain in the rear. In those you really want to measure things without disturbing the circuit.

 

This car seldom sits without being used more then 3-4 days. That may be a different story next summer though, she will have two cars to choose from.

 

Those new smart chargers are the cats ***.
No more constant trickle that would cook a battery if it dries out due to heat.