What Battery Tester should I buy?

[balticvid]

Hi

I was told that I should have a battery tester that will apply resistance to the battery being tested.
I don't know how this works. I'm not good with any electrical stuff either.
But it has to be cheaper in the long run than dis-guarding batteries when you don't know what condition they are in.

Any ideas?

Thanks, Walt

Might be a good Christmas present. (for me)

 

[Techmedic]

Walt,

Start with a reasonably priced DIGITAL multimeter.
(around $40) I say digital so that you don't have to interpret the different scales on an analog meter. Most importantly, measure the voltage. Secondly, get your hands on the battery's data sheet. (e.g.; go to the energizer web page, "technical specifications" section - it is a good start)
Using the discharge curve of the battery's spec sheet, compare it to the measured voltage of your battery in hand and then you can determine from the plot how discharged the battery is. (e.g.: sheet says that at 1.4V it is about 90% capacity)

Applying a resistance to the battery when testing with a meter is called "load testing" and is really quite useless for dry cells, although it can help a bit if you really know what to look for. It applies mostly to NIMH, lead-acid (car batteries) etc... For alkaline and lithium cells I wouldn't take the extra effort; I don't feel it is worth it.

Start with a digital meter and maybe some spec sheets. Compare voltages with output on a given flashlight. Do your own plot and you will find that new alkaline cells (bright in a light) will deliver about 1.60V and used cells at about 1.15V will appear duller in the same light.

Interestingly, Energizer takes their cells down to 0.9V which they consider dead, but most of us would toss them way before then.

Play and learn! (Safely!!)

Techmedic

 

[milkyspit]

Walt, I posted some info in your other thread, which was closed. (Remember, only start a thread in one place, don't copy the same message to multiple places.)

If you need a cheap DMM, I'm arranging a group buy. Bottom line cost would be in the $8-9 range shipped. PM me if interested.

 

[balticvid]

Where to find a good, or decent Digital Multimeter. Radio Shack?


Thanks for the good info guys.

Walt

 

[Flying Turtle]

Sears has a pretty good selection of DMM's starting at around $20. I have no personal experience with them, but have been tempted.

 

[eluminator]

Radio shack has at least two. Go to their website and search for battery tester.

This is a DMM with built-in tester:
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=22-813

This one appears to be just for alkaline:
http://www.radioshack.com/product.asp?catalog%5Fname=CTLG&product%5Fid=22-093

There are two more shown, but they are out of stock in online store, probably discontinued.

IF you are using NiMH or NiCad and you don't mind opening up the case and re-attaching the springs, the best equipment you can buy, in my opinion, is the C Crane charger with built-in analyzer.

On the other hand, previous posters say load testing alkalines isn't worth the trouble. They're probably right, I don't know. When my flashlight with alkalines gets dim, I replace the batteries. When my radio with alkalines quits working, I do the same.

 

[Empath]

[ QUOTE ]
eluminator said:
On the other hand, previous posters say load testing alkalines isn't worth the trouble. They're probably right, I don't know. When my flashlight with alkalines gets dim, I replace the batteries. When my radio with alkalines quits working, I do the same.

[/ QUOTE ]

Why would they say something like that? I've seen batteries that test great if all you're checking is voltage, yet in service proves near worthless. Load testing is the only way to identify those cells. I've even seen a whole set of newly purchased cells that fail under load.

 

[milkyspit]

Empath's right; load testing is a good idea. It's still not perfect, though, because the load may not be a good match for the device where you intend to use the batteries.

Maybe what the unknown "other posters" meant was that the "load testing" is best done in the device itself, where you're sure to get the exact "load" you intend to use?

You know: if the radio doesn't work, then the batteries failed the "load test," at least for use in the radio...

 

[reviewum]

I've gotten some decent DMM at harbor Frieght tools for $3.00. It is usually $10.00 but is on sale now for $2.99. I really like mine... while there, check this out:

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=30756

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=37809

 

[celler]

What about this puppy. Expensive? Yes, but seems to have the load test capability others are talking about.

Craig.

 

[LitFuse]

I have the ZTS tester, and I really like it. I got it at eBay for $54 shipped, and consider it money well spent. Between my lights and the kid's toys it seems like I use it almost every day. No, it's not cheap, but good stuff usually isn't.


Peter

 

[Overload]

I'm useing a RS 22-802, as I like the digital output instead of a needle. I'm only testing normal alkaline AAs. I'm wondering the battery life question. At what point is a battery effectively dead? Do I need to load test for this? I'm throwing them away at 1v, but would love to have a runtime graph or something showing that at 1.2v the battery has used 67% of it's life or something.
Wondering,
Overload
Colorado

 

[reviewum]

Why Buy a battery tester... Make One!

Okay guys, I don't profess to be an electronics genius like many of you are, but here is what I did:

Homemade Battery Tester

Last night my wife came to me with the age old question, "Do you have a good battery for this?"

I didn't have an answer. I knew I had a box of batteries, but were any of them "good"? I don't have a battery tester in the house, but from my past experience I knew that none of them seemed to work well for all my different types of batteries (alkaline, NiCad, NIMH, etc.). I did some research and learned that the best thing to do is use a digital multimeter and measure the voltage while the battery is under a "load".

I decided to rig something up. I chose to use a small hobby motor as my load. This will run fine from 1.5 volts, but will also run (mind you slower) at lower voltages. While the battery is running the motor you measure the voltage on the battery. I used a power connector from an old PC power supply to insert the test leads from my multimeter and the wires to the motor..

Here it is testing one of my NIMH batteries.

An unexpected bonus to this battery tester is that I can hear the difference in the voltages of the battery. When I started testing a box of batteries I noticed that the whizzing of the motor changed from battery to battery. I could very easily hear the difference between a good, medium, and bad battery and didn't have to look at my meter!

Footnote: I remember as a kid my first experience with rechargeable batteries was in my Tyco Turbo Hopper RC car. I'd run the batteries "dead" but after they sat for a few minutes I could get a little bit of juice out of them. While this was fun with my car, it makes testing batteries more challenging. For example, when I put a NIMH battery in the tester I can get 1.1 volts at first, but as the motor spins I see the voltage drop: 1.0, .9, .8..... and down to the point the motor stops spinning and I'm at about .6 volts.

 

[Wylie]

Re: Why Buy a battery tester... Make One!

Nifty stuff! /ubbthreads/images/graemlins/wink.gif I think a motor is a variable load and may not be your best resistor for the job. Believe me I am no expert and could be very wrong with this but I thought I would chime in anyway. I'm just waiting for Santa and got bored. /ubbthreads/images/graemlins/blush.gif

 

[Doug Owen]

Re: Why Buy a battery tester... Make One!

I, for one, love the motor idea!

Granted it may not be a well understood load, but it is legitimate and repeatable. An interesting option might be a heavy flywheel and a tach circuit with a photo interrupter or similar. Check speed at a couple of points in time as it spools up.

For the graphic amongst us, how about putting a fan on the motor and using it to float a ping pong ball or similar up a clear tube.....

Bravo Ron!

Doug Owen

 

[LightScene]

If you are testing alkaline batteries, then a no-load voltage test will tell you all you need to know. Use the method Techmedic described. A similar method will work for rechargeables - just look at some run-time charts.

If you are testing lithium cells (like 123's), then the voltage won't tell you much, as it will always be near the nominal voltage. In this case, I don't know what the solution is. I do know that if the cell is significantly depleted, the light from a 1 watt luxeon will be less bright. But I have no idea how to calculate how much longer it will continue to function. You can just carry spares and use the old ones until they don't work satisfactorily anymore.

You can get a good DMM from Hobbytron.com for $14 http://www.hobbytron.net/multimetersub.html

 

[milkyspit]

LightScene, one good solution for testing 123 cells is to measure the flash amps. Back in August I posted some information on the procedure... it's over here.

 

[Doug Owen]

[ QUOTE ]
Techmedic said:

Applying a resistance to the battery when testing with a meter is called "load testing" and is really quite useless for dry cells, although it can help a bit if you really know what to look for. It applies mostly to NIMH, lead-acid (car batteries) etc... For alkaline and lithium cells I wouldn't take the extra effort; I don't feel it is worth it.


[/ QUOTE ]

For sure there's a lot of folks who'll offer this advice....unfortunately none of them are battery makers or engineers.

If you really want to know what's up, you should at least consider what they have to say. For instance, Energizer has this to say about their 'point of sales' tester:

"Energizer battery testers are inteneded to indicate general battery condition and will not predict battery life remaining. These testers are loaded voltmeters and use the following loads and minimum "Good" cut off voltages. Becuase of the chemistry of zinc air cells, these testers will not indicate battery condition".

It goes on to list 10 ohms for normal 1.5 Volt cells (all sizes), 1 ohm for "motor drive and photoflash", with a good cut off of 1.1 Volts.

I suspect that if it were really possible to predict remaining lifetime, the makers would capitolize on the oportunity and make some more money on battery sales.

The 'smart money' says 'use only a *loaded* voltmeter, and take the readings with a grain or two of salt'.

Doug Owen

 

[LightScene]

Hi Milky, that was an interesting read. Thanks.

 

[shooter08]

My father had made a simple wire device to hold a flashlight
bulb on one end and the other end was bent to touch the bottom
of the battery. It works surprisingly well for alkaline batts The
brightness of the bulb is directly related to the voltage in
the battery. I have no idea what bulb he used but any screw
in bulb in lower volt ratings will work.

Dave