Question re: 12-volt battery, please?

Julia,

After looking at the picture of your multimeter, what you have is a typical multimeter. It is used for more than one type of electrical measurement.

To measure DC current you use the black side and set the knob on a voltage higher than what you expect. AC measurement would be done the same way, except you use the red side.

With the wires that came with the meter, plug the red one into the "V" plug, and the black one into the "COM" plug.

To check voltage on your battery, simply put the knob on 20 (Black), touch the end of the red probe to the + (positive) side of the battery terminal and the black probe to the - (negative) side. Then just read the number on the meter.

I too agree that your new "Yellow Top" is not fully charged. Go for a long drive in the country, then come back home and let the car sit overnight. Then check the voltages again after the car has set for at least eight hours. You should see better readings then.

Good luck and congrats on the job.

Ron

 

An aside, why are analog multimeters poo-poohed ?

 

Julia,

You might consider taking the original battery to a recycling center, one that buys metal (aluminum cans, scrap iron, etc.) They will pay you cash money for the original battery. I doubt AutoZone will do that, but I could be wrong.

It does not hurt to talk to management, but don't be surprised if they laugh in your face. Most companies today have the attitude that someone else will always come in, so it doesn't matter if they lose you. It is a sign of the times.

Best of luck to you and your new battery.

Ron

 

Good point, why too is it that today the kids can't read analog clocks? Frankly, I prefer analog over digital. Maybe I am just a old school guy or something like that. Sorry for being off topic...

Ron

 

My only complaint is that such multimeters often use 9v batteries. I have dozens upon dozens of AA and AAA nimh batteries and multiple chargers but I have no 9v nimh nor do I have a charger that would accept a 9v battery.

I'm not willing to buy a 9v battery and charger for a device I rarely use. Now if someone would sell a "pack" that would allow me to group 6 or even better 7 aa or aaa batteries together and strap them onto the back of the multimeter it'd be bulky but I could leave the pack empty the majority of the time and fill it up with batteries on the rare occasion that I need a multimeter.

What I do that a multimeter can do I do in one of three ways:

1. P3 Killowatt meter (for AC amps, Hz, volts, watts, VA, kwh, PF)
2. The battery charger (for DC volts) think La Cross BC-900 or similar.
3. for the rarest occassions when I'm working on a dryer or a car part or something else that isn't using a 3 prong plug or AA/AAA battery I grab a multimeter and hope I have a 9v battery with enough charge on it for it to be usefull.

Oh and don't suggest a 9v charger that doesn't display the volts in the battery as then I have to have a working multimeter to check the battery that powers the multimeter. That's the entire chicken and the egg situation I'm trying to avoid and why I loved the La Cross series battery chargers, 90%+ of my mutlimeter use before the lacrosse was me testing a disposable or rechargable battery.

I don't know why others pooh pooh analog meters but for me its all about the power source and how that affects total cost of ownership.

 

What analog meter can you recommend that can accurately read 12V to 1 decimal place - let alone to a higher degree of precision? Usually, an analog meter is rated to something like 2-3% of full-scale accuracy if you are lucky.

A 3% error on a 12V measurement = 0.36V. That is a pretty big error in a situation where 12.9V represents a new, fully charged battery and 12.1V means the battery is discharged.

An analog meter can be relied upon to show that one voltage is higher than another, but it will not necessarily give you a precise reading of the voltage.

Compare that level of error to a decent digital meter. For example, I own the Fluke 87 which is an outstanding handheld unit. The accuracy spec is within 0.1% plus one digit for DC voltage measurements.

Another consideration is the sensitivity of the meter. This is not an issue when it comes to measuring battery voltage, but becomes a concern when performing more delicate measurements.

A digital multimeter will typically place a 10 megohm (1o million ohm) load on the circuit being measured. A cheap analog meter will place a load measured in the tens of thousands of ohms. The latter meter can impose a significant load on the circuit being measured, which means that the measured voltage will be much lower than the actual voltage without the meter loading the circuit down.

Since electronics is a hobby of mine, I own three digital multimeters including an HP lab unit that will provide a measurement to six digits, and two Fluke handheld meters. The reason for having three is that as long as all three report similar findings, I have confidence that they are working correctly.

If one out of the three should report a different finding (which fortunately has not been a problem so far) then I know that one needs help.

 

Thanks Patrick,
I was asking a question, not voicing an opinion.

 

I have had good experience at car stores seeking out female employees. Either they know what they are talking about, or they say they do not know. Much better than wondering if the fellow is competent or BS'g

 

Hi Julia2001- How often does the ICE [engine] come on while performing this task? I have never tried it personally.H

 

Yep. The ICE fires up when the traction battery hits a purple level and (I think) brings the SOC back up to green range.

If my arithmetic is right, the Optima has a useful capacity of 330 wh. If we WAG that the top-off requires 25% of that amount, we are running the ICE for some 80 wh. This suggests that most of the ICE use is to cover the energy consumed by the car just being in ready

 

congrats on the great work julia. even tho i couldn't offer any advice, i felt like i was with you the whole time and learned me some things along the way. thanks everybody, great thread!

 

I will have to add this. Since the topic of analog vs digital meter's came up, I too learned something. Yes, Patrick Wong is correct about the accuracy. Sometimes a old dog (myself) can be taught new tricks.

Source of info: http://www.autoshop101.com/forms/h4.pdf and Multimeter - Wikipedia, the free encyclopedia

I was not aware of the accuracy issue, therefore I have been educated and enlightened and to that I say "Thank you!".

Ron

 

If you purchase a good quality multi meter you will get good accuracy? H

 

If I may paraphrase Pat Wong on analog multimeters, I think he was saying that you can pick any two of inexpensive, accurate and multimeter