When you measured it with the charger on it and it read 12.6, then you were reading the output of charger BUT the battery will not instantly respond and jump from 12.2 up to the 12.6 but takes time. Maybe too when you measured things,you measured on the battery chargers clips and not the battery posts and then one or more of the connections from the charger to the battery was not good.

When it was up at 12.6 volts and then dropped down to 12.2 then this is telling me you probably need to leave the charger on it a lot longer.

If you charger has a slow charge setting at around an amp or so then this might be more ideal than hot shotting the battery with something like a 40A output. When in doubt see what the battery manufacturer suggests.

After it has been charged with the charger still on it, you might measure 13.0V or so but then once the charger is removed, the voltage will drop little by little until it stabilizes at around 12.6 or so on a good battery and then stay there but if after a while, like overnight with nothing connected to the battery the voltage drops to let's say 10.0V, then the battery probably has an issue.

To charge a battery the charge voltage needs to be higher than the nominal voltage. If the battery is let's say at 12.0 volts and a charger only outputs up to 12.0 volts, nothing will be flowing into the battery.

Jim

 

As Jim has said, the good or new battery should have a no load voltage of between 12.5 and 12.8 volts fully charged.
The first thing to check is the battery in the instrument (VOM or multimeter or voltmeter) you are using to check the car battery as the voltage of the car battery is compared to the voltage of the battery in your instrument to obtain the reading. The more expensive VOM has a battery adjust feature to compensate for old batteries, the cheaper VOM units do not. Don't know about your Fluke.
As Jim said, if you charge the battery, you should be charging at over 13v, just as a good alternator is charging at over 13v. Your Battery Tender has a circuit to limit charging voltage as it is a maintenance trickle charger and is not built to charge a low battery, only maintain a predetermined charge, say 12.5 volts as to not overcharge the battery.
That said, it takes the battery time to lose the residual dynamic charge, so the reading will drop, maybe a couple of tenths, after removing the charger. With no load (no cables hooked up), the battery should not lose any charge overnight.

 

I assume you DieHard battery is a lead acid wet cell type. An AGM type battery puts out a slightly higher voltage when it is fully charged.

12.2 volts on a wet cell means that it is about 45% charged. Your new battery should have been at least 70% charged (12.5 VDC) off of the shelf. Your new battery is either old or has been partially discharged by something. If it is an AGM, 12.2 volts is about 45% charged.

Your battery tender maintains a fully charged battery. It puts out 12.6 volts which is the open terminal voltage of a 12 volt lead acid battery. 12.6 volts is the open terminal voltage of a 100% charged battery. The battery tender is really not a battery charger. A battery charger is able to deliver more current because it produces a higher voltage (about +14 volts).

Your battery tender will never fully charge the battery. It might take a week to bring the battery charge above 45%. You need a stronger battery charger or ask the store to charge your new battery.

 

good stuff guys.that explains alot...

 

My brand new optima sits at 12.16v on 3 different volt meters. Starts and charges just fine. I thought I was having a paracitic loss somewhere and don't. I disconnected the positive and ran an amp test and it was at 0

 

What is the procedure for the amp test?

 

i don't believe you'll ever see a 12 volt battery hold much more than 12 volts even in the best condition. Regular charging systems run more than that to keep the battery topped off. Somewhere around 14 volts is what the alternator supplies. One of the ways to verify charging is to put a voltmeter on the battery with everything connected and running. The voltage should be higher than when the cables are dis-connected.

 

I've had the battery in my 68 show a 12.48V charge after sitting over a Midwest winter with the cables connected all this time AND having a small current draw from the memory/clock circuit from my underseat Pioneer radio. This was measured on April 2017.

I then did another battery voltage test in the spring of 2020 and again after sitting over the winter and the battery was sitting at 12.27. Yep it's lower than from 2017 (down 0.21V) and I'm going to say, right or wrong, it's due to the battery now being older and slightly breaking down.

Jim

 

Measure current by taking the multimeter leads, position them on the meter, black to COM, red to 20 AMPS DC, select meter function for measuring AMPS, and place leads between battery post and disconnected cable from same post.

Doesn't matter with a digital meter as it will measure both directions.

 

Temperature of the battery has an effect of the open circuit terminal voltage. As the battery ages, the internal resistance increases so an old fully charged battery will read less voltage.

Link to optima batteries website:
How do you measure battery voltage?
Fully-charged, our REDTOP batteries (and 34M BLUETOP) will measure about 12.6-12.8 volts and our YELLOWTOP and BLUETOP (except the 34M) batteries will measure about 13.0-13.2 volts. Each manufacturer will generally indicate a range or minimum voltage level for a fully-charged battery. If you are measuring the voltage on another brand of battery and don't know what the fully-charged voltage level should be, it is safe to assume it should be at least around 12.6 volts.

Because there are a multitude of variations (how the battery is made, the age of the battery, etc...) that can factor into what a battery's full state of charge should be, we always indicate battery voltage should be in a range, rather than an exact number. For example, an eight-year old REDTOP that measures 12.57 volts may be fully-charged, while a brand-new REDTOP may measure 12.92 volts. Both are considered acceptable.

Batteries that have just been charged with a battery charger or those that are in vehicles that was just driven may have a surface charge, which will result in voltage readings higher than the true voltage of the battery. Letting a battery sit on a bench for 12-24 hours can allow that surface charge to dissipate. For batteries installed in vehicles, turning the headlights on (with the engine off) for 30 seconds can also remove a surface charge.

This my two month old Die Hard battery. The measurement is not open terminal voltage. The battery cables are still connected. That is why it only reads 12.54 volts. If I take the battery cables off and wait a few minutes the voltage will go up some.

 

Temperature of the battery has an effect of the open circuit terminal voltage. As the battery ages, the internal resistance increases so an old fully charged battery will read less voltage.

Link to optima batteries website:
How do you measure battery voltage?
Fully-charged, our REDTOP batteries (and 34M BLUETOP) will measure about 12.6-12.8 volts and our YELLOWTOP and BLUETOP (except the 34M) batteries will measure about 13.0-13.2 volts. Each manufacturer will generally indicate a range or minimum voltage level for a fully-charged battery. If you are measuring the voltage on another brand of battery and don't know what the fully-charged voltage level should be, it is safe to assume it should be at least around 12.6 volts.

Because there are a multitude of variations (how the battery is made, the age of the battery, etc...) that can factor into what a battery's full state of charge should be, we always indicate battery voltage should be in a range, rather than an exact number. For example, an eight-year old REDTOP that measures 12.57 volts may be fully-charged, while a brand-new REDTOP may measure 12.92 volts. Both are considered acceptable.

Batteries that have just been charged with a battery charger or those that are in vehicles that was just driven may have a surface charge, which will result in voltage readings higher than the true voltage of the battery. Letting a battery sit on a bench for 12-24 hours can allow that surface charge to dissipate. For batteries installed in vehicles, turning the headlights on (with the engine off) for 30 seconds can also remove a surface charge.

This my two month old Die Hard battery. The measurement is not open terminal voltage. The battery cables are still connected. That is why it only reads 12.54 volts. If I take the battery cables off and wait a few minutes the voltage will go up some.

View attachment 273542

Sadly I have NEVER had an optima read that high, even brand new this one read 12.2(on different meters too)

I am going to go measure it really quickly and see what it's reading. I ran it for about 30 minutes yesterday to heat cycle the car(new cam breaking and tightening headers/intake to make sure they are leak free).

When I started the car it was at 12.33v(65*F)
Currently it is at 12.35v(54*F)

 

if there is a draw than remove one fuse at a time until it stops to narrow down the circuit that is the problem and concentrate on that

 

You can do tests like SoCal805 suggests with removing one fuse at a time but if you are using a test light, it might be hard to see a very slight change in brightness should there be two circuits drawing power and then only one fuse removed for the one circuit and the other still powered up. If you had a meter, then you could see the numbers/reading change.

Also be aware that not all circuits are protected by fuses in the fuse block. You can remove all of the fuses in the fuse block and possibly still have a draw if the alternator has an issue, if the external voltage regulator has an issue, or who knows what if someone has added things you might not be aware of like a security system or have added something and not done it correctly and tapped into a circuit like the main feed to the ignition switch and then added sun visor vanity lights that are staying on all the time.

Jim

 

So I bought a meter that can run an amp test. Hooked it up per the article provided by 68rs78z28. Set on the highest Amp setting the reading is 0.76. That's a big draw, right? Anyway I started to remove connections from the interior fuse panel, starting with the non-stock wires that were connected to the middle terminals marked 'acc' (a male terminal) and one that was spliced into the 'ign' wire. I suppose these were being used to supply power for an aftermarket radio and something else. No luck, the draw is still reading 0.76. So now I'll start pulling fuses. Also, how do I test the alternator and voltage regulator for parasitic draw? Thanks again

 

Glad to see you found it is what you suspected... now just finding where the draw is.

I would try to disconnect the alternator to test to see if the draw goes away.

 

I didn't see if you said what alternator you have but most will have a main output stud and now with leaving the battery disconnected, take this cable off of the alternator and wrap it with something to where it cannot touch anything.

Now hook up your meter between the battery post and the cable end that was attached to that post and see what you reading is. If the draw goes down all the way then this is good, but if it only drops some, but not all they way, there is a second or third issue.

If you have a more stock setup with an external voltage regulator and underhood horn relay/key buzzer, these too might be giving you issues.

Also look too under the hood and see if someone might have added a circuit that could be stuck on.

Jim

 

When you disconnect the battery terminals, does it spark? if, yes you have something drawing a load (as you say). Now start with the battery disconnected and remove a light bulb from the glove box, and touch the cable to the battery. No spark, no current draw and you found your problem; have spark reinstall bulb and continue the search. I would start with a trunk/hood and glove box bulbs and see if those switches are bad by checking for spark at the battery.

 

Maybe I missed it but do you have a radio with a clock? Not a lot of draw but enough to take it down if rarely started.

 

						It has an aftermarket radio which I previously disconnected. It was the first thing I pulled. None of my courtesy lights or the dome light work. I will check them next.

 

0.397 amps x 12.5 volts = 5 watts. That is going to be hard to find. If this was your daily driver, you would have never noticed the problem.

I cannot think of anything that draws so little power on these old cars. A small incandescent light might be that small. If you pulled all the glass fuses out of the fuse block, I think all the little lights are no longer in the circuit. It is very possible some of the connectors are dirty and corroded. The dirt will provide a path for the current to leak to ground.

Shown below is a couple of photos of the original wiring harness out of my car. The fuse block is actually three sections that are plugged into one another. One section is the fuse block under the dash. On the engine side, there are two plugs that fasten to the fuse block. One plug is for the lights and the other plug is for the engine. The plugs are located under the brake master cylinder. In the future, if you cannot find the problem, you can separate the three sections from one another. (Do this as a last resort.) After you separate them and you still have a leakage current, then the problem is in the front section of the car.

Below is a photo of an aftermarket fuse block that is below the master cylinder. The two plugs from the engine compartment plug into the fuse block here.

 

While you could have a high current draw and not have issues with it being driven everyday, I would get the draw down to a more acceptable level.

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I've been in the car audio business since the late 70's and I've always liked to see anywhere from 0.00A up to 0.02A of draw with the car sitting there off. I've added radio's, amplifiers, and alarms into vehicles and boats and cannot remember ever going above this.

Since the addition of more electronics on vehicles these the days, you have to watch how you measure things and how long the tests are.

Case in point was a 2010 Chevrolet Express van that I added a new radio and flip down overhead monitor and I measured the current draw with a meter put in between the positive battery post and the positive battery cable end and when this was done the meter measured around 2.19A while the dome lights were on and then when they timed out and went off the current draw went down to 0.68A and then a few seconds later dropped to 0.18A

To me this 0.18 was way too high but then after about 5 minutes with nothing touched on the van, the computer must have done a check as the amperage draw then dropped from 0.18A to 0.02A or so for a split second then rose back up to the 0.68A and then dropped back down to the 0.02A and stayed there until I ended the test 10 minutes or so later.

If I would have measured the amp draw and noted the numbers right at the start and then walked away or disconnected the meter, I would have been chasing my tail wondering what was going on but by letting things settle down and the computer on the vehicle do it's thing, after a while the amp draw was acceptable.

Jim