Is it ok to use 2x 9v batteries instead of 8 AA's?

Greetings  [detecting]I was given a Minelab Sterling(fortunate) and didn't receive a manual with it(unfortunate). I have been running 2 9v batteries in the unit and I just found out that it is actually meant to have Two battery holders with 8 AA's. Still seems to work OK, but would like to know if I could be doing damage or hindering its performance?

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Two things come to mind here. The Minelab probably has voltage regulators in it so I believe you're OK as far as the voltage level goes. The 8 AA batteries have around 10 times the capacity of your 9 volt batteries so you will go lots longer with the proper holders and batteries installed. You can find them for under $3.00 each at JayCar, Altronics or Dick Smith's. They come in a variety of configurations all with a snap fitting. Don't pay the $20.00 each that Minelab wants.

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I have been wondering the same thing, i have a old Fisher VLF that i must get around to fixing. It has the same arrangement with the batteries. I have always assumed that they have done it this way for battery life rather than voltage and expect that there will be a voltage regulator on the circuit board. My guess is that the unit will run on 9 volts but I'd only need one 9volt cell or rewire the unit to run two 9 volts in parallel for increased life.
If I ever get it together and make the time to look at this unit I will confirm one way or another what I suspect.
My old V/Uhf signal meter has the same battery arrangement, it takes 8 'AA' batteries. it will run on 9v but the battery will only last about a week, whereas the 8 'AA' will last 5-6 months.

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		Quote:			Posted by xavier
	So now where will your 0v come from?

Where do you think it comes from? No battery.

Actually, since you didn't quote the original message, I'm not sure who you are asking, mate.

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Xavier, he's talking about using two batteries in tandem to give increased current. I believe he left out that he would do that to both sides of the battery circuit and actually use 4 in total.

To Jamjars, I would warn you that doing so will deplete all 4 batteries rapidly when they are not in use. Because each battery is different internally by tiny amounts, one would suck power in tiny amounts from the other. Always. When a battery supplies current to a circuit, or two in parallel do, the current is from the battery to the circuit. When the circuit is out of the equation, the weaker battery will draw current in microamps from the stronger and will drop the voltage until it is now lower. Then, the current will flow in the opposite direction. The end result is heat. Not much, but eventually the batteries would discharge each other. Garrett found this out in their Deepseeker models with the 9v battery trays. The self discharge made the detector appear to be a battery sucker even though the draw was minimal. The fact is that the batteries discharged each other when the unit was off.

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