I want the best battery tester - the one I bought is no good

[michael-piziak]

I want to buy the very best battery tester for AA and AAA batteries. The one I bought off of Amazon is a piece of junk - it says every battery is good even when 3 of my devices say the batteries are dead and the batteries just won't work anymore.

I don't care how much it costs, but I don't want to buy an amp meter or volt meter, I want a simple to use yet very accurate battery tester - that can test alkaline and rechargeable batteries very very accurately.

I thought this Cafe here was a good place to post this. If not, then moderator please move this to an appropriate forum.

Thanks!


Michael

[pqwoerituytrueiwoq]

a voltage meter will not tell you anything useful unless you put a load on the battery

a cheap solution is a battery holder a led and a resistor, then you can make a battery life indicator one like we have on a GBC
for a single cell battery (1.5v) i would suggest ~66Ω
http://www.ebay.com/itm/310654761992 - resistors (using 3 22Ω in series will do)
http://www.ebay.com/itm/221753671824 - AA Battery Holder
http://www.ebay.com/itm/251334280350 - AAA Battery Holders
http://www.ebay.com/itm/261952078097 - 5mm led (longer leg goes to the red wire, the rest does not matter as long as you hook it up)
you could make a bunch of them and sell the extra for $1 each
This will not give you a Boolean Yes/No battery tester, it will give you a analog one, the brightness tells you how much life is in the battery

[michael-piziak]

ok, I'm not into making one.
Can anyone suggest a very good one that is already for sale?

[tgalati4]

The alternative is to buy a cheap voltmeter and stick the leads on the battery when in the device and read the voltage when you turn it on. The only way to truly test a battery is to put a load on it and measure the voltage under load. Most devices shut down at 1.22 VDC per battery. I know this from experience. Which is why rechargeable batteries won't work in most devices. NiCd's and NiMetal Hydrides start at 1.45 and drop to 1.2 pretty quickly, but hold 1.2 for a long time. So rechargeables will only work in devices that have a switch (alkaline or NiCd) or specify rechargeables only.

I have to agree, that making your own tester with various load resistors is really the best tester.

[michael-piziak]

My dad is a retired certified electrician (in our coal mines here in West Virginia).
He has these electricity meters all over the place.

So you need to read the voltage as quick as you can when it powers up ?

Another note, I bought the best rechargeable batteries known, which are Panasonic Eneloops. Check them out, they use to be Sanyo Eneloops (Panasonic bought Sanyo). Had any experience with these fairly expensive rechargeables? I'm using them in an electronic door lock now, and they are the *only* rechargeables that will work in it! A great battery product I think!

Cheers!

[pqwoerituytrueiwoq]

not much involved in making what i described
just twist the resistor wires to each other and same with the led
you will probably need to strip the battery leads before twisting to those
it will look like crap, but it will work

[michael-piziak]

not much involved in making what i described
just twist the resistor wires to each other and same with the led
you will probably need to strip the battery leads before twisting to those
it will look like crap, but it will work

I private messaged you concerning this - I am interested in this.

[tgalati4]

Ask your father how to test a battery's voltage while in the device. Voltage will typically dip when a device is first turned on and then it will recover. The problem with digital devices is that they need to boot up firmware and that takes a lot of power. Once booted, the device can run on a lower battery level, but a weak battery can't provide the boost needed during bootup.

Better rechargeable batteries will have a higher start voltage, but if a device is not designed to use rechargeables, then you won't get the life out of the batteries and the device won't perform as designed. Try a test with cheap alkaline batteries in the lock. How long will they last? The run the same test with your Panasonic rechargeables. Post the results.