GARY'S UK DETECTING.co.uk

Battery Facts

Batterys The Real Deal

Metal detectors need a good power supply

This simple test is on 9volt battery's but the results are the same on AA type

Note :  All the batterys came up as good condition on my battery tester

We all know they kick all out as close to 9 volts as possible, but it is the amps that make the difference when it comes down to the performance of your machine Think of it like a tap which is your machines circuitry...1 amp opens the tap up 25% and 4 amps 100%.

This is a simple experiment using a cheap multimeter...when checking the Amps the numbers will drop the longer you have it connected,so make your check as quickly as possible.

The simple set up

 Energizer kicks out 5.2 Amps

Ever ready 0.41 Amps

Rayovak 0.45 Amps

As you can see the only battery with the real punch is the Energizer,the others are not up to the job,I suspect that the Duracell range may be ok
 

Notes from a reader

Gary, while I think your site is excellent and full of rock-solid comments and data, I must beg to differ with you on your method of testing 9v batteries.

The real-life, real-time issue about battery duration is the load that the circuit places on the battery. No electronics manufacturer in the world would expect a 9v battery to be capable of a continuous current load of 5 amps - that's pure fantasy. I hope I'm not telling you something you already know, but current is not like voltage. A circuit places a current load on a battery, and that load is designed by the circuit designer not to exceed a certain amount. So a particular detector will ask the battery for 50mA or 100mA or whatever, and no more than that. A good battery will deliver 100mA without much of a voltage drop, a crap battery will still deliver the 100mA but with a distinct voltage drop - which (as you found) causes poor detector performance.

A better real-life test of a battery is a simple bench test where you connect the battery to a load (could be several light bulbs daisy-chained) which matches the detector manufacturer's wattage spec for the circuit board. The voltage of the circuit is easy to measure as the test proceeds - a crap battery will allow a voltage drop and have poor time duration, a good battery will maintain correct voltage under load and last a long time. So all I'm suggesting is a more realistic and scientific test. Many metal detector reviewers - including Gordon Bailey - have said that a reviewer has a huge responsibility to get the facts right, as people will be going out and spending hundreds of hard-earned quid on the detectors. I know a battery doesn't cost hundreds of quid, but that's no reason why it shouldn't be tested in the same valid real-life way as detectors.

Incidentally, the world's most powerful 9v battery, the Titanium PowPower, has a max continuous load of 750mAh - which is FAR higher than anything else available. I can't imagine that it lasts long at that load - certainly not hours. There's only so much juice you can pack into the space of a 9v battery casing. Either you have it all quickly (sinking a pint straight down) or you sip at it for half an hour (or whatever) until it's gone.

http://www.amondotech.com/index.asp?PageAction=VIEWPROD&ProdID=1174

What would be VERY revealing is to precisely measure the battery voltage (and possibly even the current load) when a detector is turned on and also as you sweep a field - the current demand of the circuit may even vary with different ground types and detector settings. It will then be trivially easy to sort out the good batteries from the crap. This would be the ultimate real-life dynamic battery test: voltage and amperage data WHEN DETECTING. Interesting huh? Quite easy to rig up the wiring, although an extra person might be needed to hold and read the meters while you're sweeping the detector.

I say all this with the greatest respect - you are vastly more successful than me as a detectorist, probably because I'm now very shy of asking farmers for detecting permission after being cursed by one just for pleasantly asking.

Best regards,

Dominic

Thanks for the info Dominic
Just proves what a prat I am....Gaz