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Bounty Hunter Tips

My wife and I own a pair of Time Rangers. I've seen a lot of posts regarding battery drain, even when the detector is turned off and stored for a week or so. The batteries in our own units don't seem to last very long either, so tonite I got out my multimeter and put it in series with each 9v cell. With the detector turned off, I got a reading of several volts on one battery at just a few millamps, and a miniscule voltage reading on the other 9v cell, at a current too small to read.

What this means is that over time, no matter if your detector is used or not, it will drain one of the batteries at a low rate, the second cell is not affected nearly as much.

The loudspeaker is probably the main culprit for excessive battery drain while operating. I'd like to add a volume control, this should help reduce battery consumption while operating. I will probably add my own volume control to the circuit and will get one with a piggybacked power switch so the unit is fully off when I am not using it.

Till then, when my warranty has a little less time left, I'm unplugging one terminal of each 9v cell and swinging it aside so it is not connected. I don't have to remove the connector comletely, just unhooking one side will do the trick.

NOTE: (I did add my own control in series with one of the speaker wires. I ran it out into the extra space in the battery bin, so I didn't need to drill a hole in the case. This seemed to reduce battery drain almost as much as using headphones, and now I don't use the tape to reduce the volume!) See the Time Ranger page for pics.

Hope this tidbit of info helps some Time Ranger and Land Ranger owners!

HH -Ed

Plugging the Battery Drain

by Ed Gerken, Oct. 2001

"About time to wrap up the hunt," I thought to myself, "dinner will be ready soon. As soon as I run to the store to get it, that is!"

Like a dog anxious to find a fireplug, my coil's sweep was increasing in speed and distance with every swing. I didn't have much time left to hunt, knowing that when I returned home, I'd be hanging up the detectors for awhile. The mild weather had lengthened my detecting season by many weeks, but snow was predicted for the following morning. This was to be my last day to hunt, and I was trying to make it last.

I had been testing out my new Bounty Hunter Time Ranger, mentally comparing the day's finds to what I had found here earlier in the spring with my previous detectors. I had a nice pile of clads, and the junk pile was noticeably smaller than usual. Judging by their discoloration and corrosion, I was finding some coins my earlier detectors had passed over. Judicious use of the preset iron discrimination was obviously reducing the number of junk items I had to dig. I was detecting a path towards my car, pleased with the results of my outing.

As my hurried sweeps of the 4" coil scattered the fine gravel, the sun was dipping towards the horizon, and the mercury was sinking as well. Fresh broasted chicken was just a car-hop away, I could almost smell it already. Then just a short drive home through our lovely pine forest to cap off the last hunting day of the season.

My hunt in front of the food concession at the local football field had gone well, and even though the finds had been good and I had plenty of places left to hunt, I was cold and hungry for a good meal, and ready to call it a day. I was almost back to the car, when I noticed that a pair of small portable bleachers had been moved closer to the grass playing field, signalling the change from summertime track meets to winter's football games. "Dinner will have to wait," my inner voice told me,"you can't pass up this chance for a quick search." The ground where the bleachers had sat since last spring lay newly exposed and beckoned my eagerly sniffing coil.

Time wasn't on my side as I hurriedly swung the Time Ranger back and forth. As I neared the end of the row, I stopped to dig a deep signal , and set the detector down, in my haste leaving it turned on. Once I recovered the signal, a gnarly old member of the local population of the "beaver-tailed pulltab," I noticed the Time Ranger's battery monitor had crept down a notch. Usually I turn the Time Ranger off while digging a deep target, as I have noticed it seems to "eat" batteries faster than my other detectors did.

That observation was echoed by comments on the detector forums I had visited on-line. I follow several of the many forums, and enjoy reading reports from users of the same machines as I own. I had noticed several owners were reporting excessive battery drain problems with their Land Ranger detectors, which are very similar to the Time Ranger model that I own.

"Drats!" I muttered out loud. "Add that to the shopping list, and subtract it from my little pile of finds." The tarnished coins seemed suddenly less impressive. Batteries can be expensive, particularly the 9-volt alkalines my hungry detector eagerly eats up. I counted up the day's take and noted it was nowhere near the cost of a fresh pair of store-branded bargain cells.

On that somewhat dimmer note, I packed up my gear and made my way to the store, but discovered the bargain brand was sold out. "Just as well," I reasoned, "it's the end of the season anyway, and I shouldn't leave batteries in the detector all winter." It just makes good sense to remove the batteries from any device when it is not in use. I've cleaned enough crud from battery compartments to remember this lesson, but I usually wait till the end of the season to remove them. Was this a good policy?

On the way home, I pondered my dilemma. How could I make this hobby pay for itself, if the battery costs alone were eating all the profits? I decided that I'd spend the following day indoors by the fireplace, checking for some hard answers about metal detector battery consumption.

With a delicious supper out of the way, and our alarm clock set for 2am, we went to bed early. No, it was not to start testing detectors in the middle of the night! We were rising that early in hopes of catching a glimpse of the annual Leonid showers before the snow showers settled in. While nowhere near the expected two thousand-per-hour meteor storms everyone was predicitng, we did see our share of the estimated 200 or so per hour that actually fell. It was truly an eventful and enjoyable day, and at about 4:30 am, I finally settled in for some serious sleep, all the while anticipating the testing I was going to do the next day.

With a fresh snowfall covering the ground, and an equally fresh pot of hot coffee chasing away the chill, I conducted some tests on 5 of the 7 detectors currently in the house, using an inexpensive digital multimeter. The units I tested were 2 identical Bounty Hunter Time Rangers, a Fisher Gold Bug I, a First Texas DX8500 and a Falcon MD10 pinpointer. All of these machines are powered by a pair of 9-volt batteries. The other two models on hand, an older Compass and a Radio Shack 2000 are powered by multiple AA batteries, so I did not consider them at this time. Some of my assumptions about battery use were borne out by my tests, but I was at times surprised by what I discovered about these various 9-volt units.

From my testing, I determined there are three possible ways to connect two 9-volt cells in a circuit; series, parallel, and independently. A series connection adds the voltage, but not the current, so the detector operates on 18 volts. Parallel connections add the current; the voltage remains at 9 volts, but the current is doubled.

An independent, or "split" supply, is where each cell powers just a portion of the total circuit. To explain this further, a couple of the detectors apparently had one cell primarily powering the audio stage, while the other powered the rest of the circuit. It came to me that if a detector using this battery connection method were to "run down" in the field, perhaps swapping the positions of the two batteries would allow the detector to operate for another few minutes or an hour.

I didn't open the cases and trace wires to verify my therories, I just observed the meter's reaction when I tested the current drains, first on one 9-volt cell, then the other. I was only measuring the amount of battery drain and wasn't too worried if I had the theory down pat. Here's what I learned about battery use in each of the detector models I tested.

BOUNTY HUNTER TIME RANGER- This unit is apparently wired for independent use of the two batteries. I was surprised to find the Time Ranger draws a small amount of current even when turned off. This drain was different for each battery, about 2ma (milliamp) for one cell, and less than a microamp (.001ma) for the second cell. This is a very good reason to be sure to remove the batteries when the detector is going to be idle for any length of time. The drain is low, but always there, and is probably due to the use of flat panel push switches instead of a rotary detent knob with postive-acting switch contacts.

The drain on each cell was measured separately, and increased to about 30-34ma when the unit was turned on. The audio response while detecting an object significantly increased the drain on one 9-volt cell. The current drain was increased only when the unit was "sounding off" with an object under the coil, once the detector became silent, the current returned to normal quiescent levels. During the tests, the drain on the other cell did not vary to any great degree.

In "All Metal" mode, using the speaker increased the current draw to about 80ma, while with headphones plugged in, this figure dropped to about 45-50ma. The operator's manual for this detector recommends using headphones to conserve the batteries, and this test certainly seemed to confirm that.

In "Disc" mode, and with the headphones still connected, the detector consumed about 40-45ma when passing an object beneath the coil, but the current peaks were very brief. Unplugging the headphones, while still passing the object under the coil, increased the draw slightly to about 50 or 60ma. Perhaps the actual current use was lower in the Disc mode, or the transients were too short to be accurately measured by my particular meter.

In both modes, the other 9-volt cell's drain increased from 30ma to about 35ma when detecting an object through the speaker. This did not vary much when modes were changed or headphones were used.

Disconnecting one or the other cell from the unit shut the detector off, but some "juice" was still being applied to the unit from the other cell, as disconnecting, then reconnecting either cell returned the unit to an "on" state without having to press the power button. Both Time Ranger units performed similarly, and use of either the 4" or 8" coil did not appreciably change the figures.

OBSERVATIONS- Disconnect one side of each 9-volt battery when the detector is not in use or remove them from the unit. Use headphones, or minimize the use of all metal mode, especially in really trashy areas. Avoid long, leisurely pinpointing sessions or use your separate pinpointing detector when possible. Primary use of Disc mode may help reduce battery consumption, as batteries tend to survive longer if used in brief spurts, as opposed to constant drain conditions. Since the drain on each battery is different, swapping positions of the two batteries from time to time may help to even out their lifespan. The battery drain observed using the built-in speaker can probably be linked in part to the omission of a volume control. NOTE: I did add my own control in series with one of the speaker wires. I ran it out into the extra space in the battery bin, so I didn't need to drill a hole in the case. This seemed to reduce battery drain almost as much as using headphones!

FISHER GOLD BUG I- The Gold Bug batteries seem to be connected in parallel, as it continued to operate more or less normally with either cell connected by itself and the other cell removed from the detector.

Because of this, my tests on the Gold Bug were performed with only one cell installed. In a parallel connection of two cells, one cell would affect the current reading of the other cell, unless I read both cells simultaneously with two identical meters. In practice, the Gold Bug's current use should remain about the same or a bit lower with both cells connected normally as what I measured on a single cell.

The Gold Bug has a positive click switch that completely shuts off the detector when not in use, so there was no current draw when the detector was off. It had a quiescent (turned on but not detecting an object) draw of about 10-12ma. This increased to about 20-24 ma when the speaker was sounding, and was decreased to about 16ma by the use of headphones. Switching between Auto, Motion and Non-Motion produced no significant change in the current draw.

OBSERVATIONS- The low current draw substantiates what I already knew, the Gold Bug was a mizer when it came to battery use. Lacking even discrimination, this detector doesn't have a display or lots of components that draw current. Use of headphones is not as mandatory as it is with the Time Ranger. Interestingly, the loudness setting did not vary current draw to as great a degree as it did on the other units I tested that also had a volume control. It appears the Gold Bug I could be run with just one good battery in a pinch, but I wouldn't depend on it to be as stable or deep-seeking.

FIRST TEXAS DX8500- This older TR/VLF model is past it's prime, but I tested it for comparison to its more modern cousins. When off, a click switch prevents any current drain. Once turned on, there is a brief surge to about 30ma, after which the detector idles at a very low 7ma. Once a signal is detected however, things change. Passing my test object, a large military knife, beneath the coil gave the highest current use I had yet observed, over 160 ma at times.

OBSERVATIONS- To give the machine some credit, the current draw did vary widely, depending on the setting of the volume control. The lower the better, as far as battery consumption goes. At a low setting of the volume control, current drain was measured at a respectable 10 to 30ma when detecting the knife. Plugging in headphones made no real difference, the volume setting alone was the key. However, since using sensitive headphones requires reducing the loudness setting to a tolerable level, it would in practice increase the battery life.

The DX8500 seems to place one cell in the audio circuit, much like the newer Time Ranger, so it too could benefit from battery swapping. The other cell's draw did vary, but to no appreciable degree. It was the battery connected to the audio circuit that was doing all the work, once a signal was encountered.

FALCON MD-10- A small pinpointing detector, the Falcon was the thriftiest detector to operate of the group. This came as no surprise, as the MD-10 has the simplest design and lowest component count of any of the units tested. It also sports the smallest coil, a mere inch across.

The two batteries are either connected in series or their use is spilt equally in the circuit, I measured equal drain on either cell. It has a click switch which completely disconnectes the batteries from the circuit. Once turned on, quiescent draw was minute at .1ma, and this increased to about 10-20ma when detecting an object. Since the built-in speaker is nothing more than a small headphone driver itself, connecting external headphones made scant difference. There is no volume control to affect savings in batteries by that method, but since the drain is quite small to begin with that is not much of an issue. Since some models of headphones have built-in volume controls, some additional battery savings could be expected from their use.

OBSERVATIONS- I used to turn the MD-10 off between uses. When I power it back up again, retuning it is always a pain. With such a small quiescent current drain, there is no reason it could not be left on for a hunt of several hours. Current use is low enough that alkaline batteries are not needed, inexpensive carbon-zincs can be used with excellent service.

With all my testing now out of the way, and the pile of detectors safely stored for the winter (with all batteries removed), I brought out my little treasure trove once again. It was growing a bit larger in my eyes once again, as I now knew some secrets I would employ next season to extend the battery life in all of my detectors.

There is one more test I have in mind for the next snowfall, though. I'm going to compare the results I got using alkaline batteries with those I obtain with a set of rechareable nickle-cadmiums. Will the lower 7.2 volts obtained from them change my detector's performance, and would their useable life between recharges be long enough for a typical hunt? Hmmm, food for thought. Speaking of food, is there any of that broasted chicken left in the 'fridge? Happy Hunting!


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