df batteries

Take two out and put them in a flashlight. Bet you will see the light is dim. That is what my Sand Shark did. These machines measure voltage, not amperage. Amperage is what gives you depth. Try it and tell us what you find out.

It all depends on how long you're using the machine on any given day and how many targets you hit on in a day. If you hit a lot of targets and keep sweeping over the hole to find it you are using up battery by making the machine work.

I usually change mine out at about 30-35 hours. I would think if you go past 35 hours you're pushing it.

Just as a suggestion. I have changed all of my detectors to rechargeable batteries and charge after every long hunt or two short hunts. That way I am never guessing if I have enough charge on my batteries.

I purchase the batteries in bulk on ebay with the highest mAha (milli amp hours) i can find. The last batch of 8 or 16 were 1400 mHa and the cost was $.46 each.

I check the batteries with a volt meter a couple of times a year. Any battery that is lower than the others before charging gets replaced.