Ed in SoDak
Member
I was digging around in my computer's Bounty Hunter Folder and came across this article I wrote in 2001 about how to save on batteries. Thinking I'd submit it to a treasure magazine, like many other unfinished projects, I never got around to actually sending it in. It should probably be updated to include more current models, but I leave that to somebody who owns them! 
The general principals still apply, especially to the Time Ranger.
Enjoy!
-Ed
-=-=-=-=-=-=-=-=-=-
Battery costs draining your wallet? Plug the drain with these simple tips!
by Ed Gerken, October, 2001
"About time to wrap up the hunt," I thought to myself, "tonites chicken dinner will be ready soon. As soon as I run to the store to get it, that is!"
Like an anxious dog sniffing for the scent, 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. Mild weather had lengthened the detecting season by many weeks, now snow was predicted for the following morning, coinciding with the peak of the annual Leonid meteor showers. Like Leonids burning bolides, trailing sparks through the sky, my coil rapidly streaked over the surface, scattering pebbles in its wake. OK, maybe my scans werent quite that fast! But, if this was to be my last day to hunt, I was determined to make it count.
I had spent the day getting further acquainted with my new Bounty Hunter Time Ranger. Now I was mentally comparing the day's finds to what I had found at this same spot earlier in the spring with my previous detectors. I had a nice pile of 20 or so clad coins, mostly dimes and zinc pennies, but 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. Detecting a path towards my car, I was pleased with the results. A couple of hours well-spent.
As my hurried sweeps of the 4" coil scattered the fine gravel, the sun was dipping towards the horizon, and the mercury was quickly sinking as well. Fresh broasted chicken was just a car-hop away, I could smell it already. Then, just a short drive home through our lovely pine forest to cap off the last outing 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 hot meal, and finally 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 impatiently swung the Time Ranger back and forth. I had just five or ten minutes to hunt the 30 foot stretch. As I neared the end of the row, I stopped to dig a deep signal. Setting the detector down, in my haste I left it turned on. Once I recovered the target, a grizzled old-timer from the local population of "beaver-tailed pulltabs," I saw the Time Ranger's battery monitor had crept down to the low end of the scale, calling a halt to any further explorations.
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. That observation was echoed by comments on the detector forums I had visited on-line, where several owners were reporting excessive battery drain problems with their Land Ranger detectors, very similar to the Time Ranger models that my wife Sandy and I own.
"Drats!" I muttered out loud. My little pile of tarnished coins seemed suddenly less impressive. Batteries can be expensive, particularly the 9-volt alkalines my hungry detector consumes. I counted up the day's take and noted the total 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. I'll watch for a sale and pick up fresh ones before spring."
It just makes good sense to remove the batteries from any device when it is not in use. I've cleaned enough corrosion from battery compartments to remember this lesson. I usually wait till the end of the season to remove them, mainly to prevent accidental leakage.
Considering what I had been reading on the forums lately, was I waiting too long to pull the batteries? Another thought crossed my mind. I seldom use headphones while searching, and do a lot of pinpointing and ID checking. Were my hunting methods adversely affecting battery life?
Heading homewards, I pondered my dilemma. How could I make this hobby pay for itself, if the battery costs alone were eating up 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 hit the sack 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 meteor showers before the snow showers took over.
While we saw nowhere near the expected two thousand-per-hour meteor storms everyone was predicting, we did observe 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 eagerly anticipating the experiments I was going to conduct the next day. Any day I get to play with detectors is a good one!
Later in the morning, with the predicted fresh snowfall covering the ground and an equally fresh pot of hot coffee chasing away the chill, I conducted some simple current tests on five of the seven detectors currently in the house, using an inexpensive digital multimeter. The units I tested were two identical Bounty Hunter Time Rangers, a Fisher Gold Bug 1, an old First Texas DX8500 and a Falcon MD10 pinpointer. All of these machines are powered by two 9-volt batteries. The other two models on hand, an older Compass and a Radio Shack 2000 were powered by multiple AA batteries, so I did not consider them in my experiments. Some of my assumptions concerning 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 split. A series connection adds the voltage, but not the current, so the detector operates on 18 volts. Parallel connections add the current, but the voltage supplied to the circuit remains at 9 volts. With an independent, or "split" supply, each cell powers just a portion of the total circuit. To explain this further, a couple of the detectors I tested apparently had one cell primarily powering the audio stage, while the other cell powered the rest of the circuit.
It came to me that if a detector using a split battery supply 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.
To eliminate one variable from my experiments, I used the same pair of batteries in all of the detectors. I didn't open up the detectors and trace wires to verify my theories, I just observed the meter's reaction when connected in series with first one 9-volt cell, then with 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 as a split supply, each battery seems to supply a different portion of the circuit. I was immediately surprised to find the Time Ranger draws a small amount of current even when turned off. This drain was different at each 9-volt connector, about 2ma (milliamp) for one cell, and less than a microamp (.001ma) for the second cell (for any non-techies out there, 1000ma=1amp). This is a very good reason to be sure to disconnect the batteries when the detector is going to be idle for any appreciable length of time, say for several days or longer. The drain is low, but always present, and is probably due to the use of flat panel "soft" switches instead of a rotary detent knob with postive-acting switch contacts.
The drain on each cell was measured separately, and increased in each to about 30-34ma quiescent current when the unit was turned on (turned on but not detecting an object). The audio response while detecting an object significantly increased the drain on just one of the 9-volt cells. This current drain 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 these tests, the drain on the other cell did not vary to any great degree.
While responding to my test object in "All Metal" mode, and using the built-in 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 a little less than it did in All Metal mode. Current fell to about 40-45ma when passing an object beneath the coil, however, the current peaks were as brief as the audio blips in this mode. 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 simply too short to be accurately measured by my particular meter. Still, my meter showed a reduction of some 20 to 30ma by switching to discriminimation from all-metal mode, if the built-in speaker was used instead of headphones.
In either mode, the other 9-volt cell's drain increased from 30ma to about 35ma when detecting an object. This did not vary much when modes were changed or headphones were used.
Disconnecting one or the other 9-volt cell individually appeared to shut the detector off, but some "juice" was still being applied to the unit from the other cell. 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. This seemed to contradict forum posts that typically claimed lower battery consumption with a smaller coil, but my tests were very rudimentary and did not include the 10 coil, which I do not happen to own.
TIPS- Disconnect one side of each 9-volt battery connector when the detector is not in use or remove the cells 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 a separate pinpointing detector when possible. Primary use of the disc mode instead of all-metal may help reduce battery consumption, as batteries tend to survive longer if used for brief moments, as opposed to more 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 while using the built-in speaker can probably be linked in large part to the omission of a volume control. I've always felt my Time Ranger was just a bit too loud. Lacking a volume control, I instead placed a piece of tape over a portion of the speaker opening. This reduced the sound level, but of course not the current used. Perhaps replacing the speaker with one of higher impedance would be a near-painless way to reduce both the somewhat loud response to targets and the battery drain.
-=-=-=-=-=-=-
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 9-volt 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 meters, or opened the case to get a direct connection to the supply lines. In practice, with both cells connected normally, the Gold Bug's current use should remain about the same or a bit lower than what I measured on a single cell.
The Gold Bug has a positive click power switch that completely shuts off the detector when not in use, so there was no current draw when the detector was off. Once turned on, it had a quiescent draw of about 10-12ma. This increased to about 20-24 ma when the speaker was sounding, which decreased to about 16ma with the use of headphones. Switching between Auto, Motion and Non-Motion produced no significant change in the current draw. I got the same readings no matter which bay held the single cell I used in testing.
TIPS- The consistently low current draws that I measured substantiated what I knew from years of experience with the machine. The Gold Bug was a mizer when it came to battery use, and was not too particular about what it was fed, as long as one of the pair of 9-volt cells had a decent charge in it. Lacking even basic iron discrimination, this detector doesn't have a meter, LCD display or any of the added components associated with such features, all of which must draw some current. Use of headphones is not as mandatory to save on batteries 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 that in a pinch, the Gold Bug 1 could be operated with just one good battery and a weaker one, or even just one battery, period, but I did not attempt to verify this. (I've since opened up the Gold Bug and verified the batteries are indeed wired in parallel. Its current draw is so low, it will operate normally using either one or two batteries. There would be an advantage in cold weather to have two batteries installed.)
-=-=-=-=-=-=-
FIRST TEXAS DX8500- This older Bounty Hunter TR/VLF model is past it's prime, but I tested it for comparison to its more modern cousins. When shut 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, well over 160 ma at times. Admittedly, when I took these readings, I had the volume turned much higher than I would set it in normal use.
TIPS- To give the machine some credit, the current draw did vary widely, depending on the setting of the volume control. Lower was much better, as far as battery consumption was concerned. 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 significantly increase the battery life.
The DX8500 seems to place one cell in the audio circuit, much like the newer Time Ranger, so it should also benefit from periodic battery swapping. The other cell's draw did vary, but to no appreciable degree. Once a signal was encountered, it was the battery connected to the audio circuit that was doing most of the work.
-=-=-=-=-=-=-
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 split equally in the circuit, as I measured essentially equal drain on either cell, and disconnecting either cell appeared to shut off the detector completely. It has a click switch which completely disconnects the batteries from the circuit. Once turned on, quiescent draw was incredibly minute at .1ma, and this increased to a mere 10-16ma when detecting an object. Since the built-in speaker is itself nothing more than a small headphone-like driver, connecting external headphones made scant difference. There is no volume control to affect any additional savings in batteries, but since the drain is miniscule to begin with, that is not much of an issue. Since some models of headphones have built-in volume controls, I would expect that current use could be even further reduced by their use.
TIPS- I usually turned the Falcon off when not using it to pinpoint a target. When I powered it back up again, retuning it was 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. It is not as thrifty to operate as a smoke detector, however. I have forgotten to turn it off after a hunt, remembering a day or two later, only to find the batteries depleted. Current use is low enough that alkaline batteries are not needed, inexpensive carbon-zincs can be used with excellent service life.
To get a comparison between my detectors and other battery-powered devices, I also tested an AM/FM radio powered by four C-cells. Quiescent current draw of this unit was about 24ma and increased with the volume setting, to a maximum of about 74ma. I could have continued this part of the experiment for many additional hours, but felt that my tests had done a reasonable job of answering my questions.
A lot of what I learned could be applied to most any detector in use today. Here are some general tips so you can start saving some juice right away. Detectors with complicated displays and soft-touch switches may use more juice at idle and when detecting, and may not power down completely when turned off. So, turn your detector off while digging if it is convenient, and if your machine does not have a click switch, always disconnect the batteries when its not in use for more than a day or so. If your detector has a memory setting, you may want to check to make sure it will not be erased each time the batteries are removed. Rotate the batteries to equalize their life, much as you would a set of tires. If you can control it, keep the volume down to a dull roar and use headphones, especially if the headphones driver is smaller than the detector's built-in speaker. Minimize use of all-metal mode, with its constant audio tone, and keep pinpointing and ID sweeps to the minimum required to determine your target. Instead of buying expensive name brand alkalines, watch for sales to save even more on thriftier store-brands, and finally, try using low-cost carbon zinc batteries in the detectors with very low current draw. Some detectors, such as the Time Ranger, will not operate with carbon-zinc batteries. Other machines, like my Falcon, thrive on them.
With all my testing now out of the way, and the pile of detectors cleaned and safely stored for the winter (with all batteries removed), I brought out my little treasure trove for another look. 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 rechargeable 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? My detectors are on a diet, but a man's gotta eat! Happy Hunting!
The general principals still apply, especially to the Time Ranger. Enjoy!
-Ed
-=-=-=-=-=-=-=-=-=-
Battery costs draining your wallet? Plug the drain with these simple tips!
by Ed Gerken, October, 2001
"About time to wrap up the hunt," I thought to myself, "tonites chicken dinner will be ready soon. As soon as I run to the store to get it, that is!"
Like an anxious dog sniffing for the scent, 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. Mild weather had lengthened the detecting season by many weeks, now snow was predicted for the following morning, coinciding with the peak of the annual Leonid meteor showers. Like Leonids burning bolides, trailing sparks through the sky, my coil rapidly streaked over the surface, scattering pebbles in its wake. OK, maybe my scans werent quite that fast! But, if this was to be my last day to hunt, I was determined to make it count.
I had spent the day getting further acquainted with my new Bounty Hunter Time Ranger. Now I was mentally comparing the day's finds to what I had found at this same spot earlier in the spring with my previous detectors. I had a nice pile of 20 or so clad coins, mostly dimes and zinc pennies, but 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. Detecting a path towards my car, I was pleased with the results. A couple of hours well-spent.
As my hurried sweeps of the 4" coil scattered the fine gravel, the sun was dipping towards the horizon, and the mercury was quickly sinking as well. Fresh broasted chicken was just a car-hop away, I could smell it already. Then, just a short drive home through our lovely pine forest to cap off the last outing 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 hot meal, and finally 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 impatiently swung the Time Ranger back and forth. I had just five or ten minutes to hunt the 30 foot stretch. As I neared the end of the row, I stopped to dig a deep signal. Setting the detector down, in my haste I left it turned on. Once I recovered the target, a grizzled old-timer from the local population of "beaver-tailed pulltabs," I saw the Time Ranger's battery monitor had crept down to the low end of the scale, calling a halt to any further explorations.
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. That observation was echoed by comments on the detector forums I had visited on-line, where several owners were reporting excessive battery drain problems with their Land Ranger detectors, very similar to the Time Ranger models that my wife Sandy and I own.
"Drats!" I muttered out loud. My little pile of tarnished coins seemed suddenly less impressive. Batteries can be expensive, particularly the 9-volt alkalines my hungry detector consumes. I counted up the day's take and noted the total 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. I'll watch for a sale and pick up fresh ones before spring."
It just makes good sense to remove the batteries from any device when it is not in use. I've cleaned enough corrosion from battery compartments to remember this lesson. I usually wait till the end of the season to remove them, mainly to prevent accidental leakage.
Considering what I had been reading on the forums lately, was I waiting too long to pull the batteries? Another thought crossed my mind. I seldom use headphones while searching, and do a lot of pinpointing and ID checking. Were my hunting methods adversely affecting battery life?
Heading homewards, I pondered my dilemma. How could I make this hobby pay for itself, if the battery costs alone were eating up 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 hit the sack 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 meteor showers before the snow showers took over.
While we saw nowhere near the expected two thousand-per-hour meteor storms everyone was predicting, we did observe 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 eagerly anticipating the experiments I was going to conduct the next day. Any day I get to play with detectors is a good one!
Later in the morning, with the predicted fresh snowfall covering the ground and an equally fresh pot of hot coffee chasing away the chill, I conducted some simple current tests on five of the seven detectors currently in the house, using an inexpensive digital multimeter. The units I tested were two identical Bounty Hunter Time Rangers, a Fisher Gold Bug 1, an old First Texas DX8500 and a Falcon MD10 pinpointer. All of these machines are powered by two 9-volt batteries. The other two models on hand, an older Compass and a Radio Shack 2000 were powered by multiple AA batteries, so I did not consider them in my experiments. Some of my assumptions concerning 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 split. A series connection adds the voltage, but not the current, so the detector operates on 18 volts. Parallel connections add the current, but the voltage supplied to the circuit remains at 9 volts. With an independent, or "split" supply, each cell powers just a portion of the total circuit. To explain this further, a couple of the detectors I tested apparently had one cell primarily powering the audio stage, while the other cell powered the rest of the circuit.
It came to me that if a detector using a split battery supply 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.
To eliminate one variable from my experiments, I used the same pair of batteries in all of the detectors. I didn't open up the detectors and trace wires to verify my theories, I just observed the meter's reaction when connected in series with first one 9-volt cell, then with 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 as a split supply, each battery seems to supply a different portion of the circuit. I was immediately surprised to find the Time Ranger draws a small amount of current even when turned off. This drain was different at each 9-volt connector, about 2ma (milliamp) for one cell, and less than a microamp (.001ma) for the second cell (for any non-techies out there, 1000ma=1amp). This is a very good reason to be sure to disconnect the batteries when the detector is going to be idle for any appreciable length of time, say for several days or longer. The drain is low, but always present, and is probably due to the use of flat panel "soft" switches instead of a rotary detent knob with postive-acting switch contacts.
The drain on each cell was measured separately, and increased in each to about 30-34ma quiescent current when the unit was turned on (turned on but not detecting an object). The audio response while detecting an object significantly increased the drain on just one of the 9-volt cells. This current drain 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 these tests, the drain on the other cell did not vary to any great degree.
While responding to my test object in "All Metal" mode, and using the built-in 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 a little less than it did in All Metal mode. Current fell to about 40-45ma when passing an object beneath the coil, however, the current peaks were as brief as the audio blips in this mode. 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 simply too short to be accurately measured by my particular meter. Still, my meter showed a reduction of some 20 to 30ma by switching to discriminimation from all-metal mode, if the built-in speaker was used instead of headphones.
In either mode, the other 9-volt cell's drain increased from 30ma to about 35ma when detecting an object. This did not vary much when modes were changed or headphones were used.
Disconnecting one or the other 9-volt cell individually appeared to shut the detector off, but some "juice" was still being applied to the unit from the other cell. 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. This seemed to contradict forum posts that typically claimed lower battery consumption with a smaller coil, but my tests were very rudimentary and did not include the 10 coil, which I do not happen to own.
TIPS- Disconnect one side of each 9-volt battery connector when the detector is not in use or remove the cells 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 a separate pinpointing detector when possible. Primary use of the disc mode instead of all-metal may help reduce battery consumption, as batteries tend to survive longer if used for brief moments, as opposed to more 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 while using the built-in speaker can probably be linked in large part to the omission of a volume control. I've always felt my Time Ranger was just a bit too loud. Lacking a volume control, I instead placed a piece of tape over a portion of the speaker opening. This reduced the sound level, but of course not the current used. Perhaps replacing the speaker with one of higher impedance would be a near-painless way to reduce both the somewhat loud response to targets and the battery drain.
-=-=-=-=-=-=-
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 9-volt 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 meters, or opened the case to get a direct connection to the supply lines. In practice, with both cells connected normally, the Gold Bug's current use should remain about the same or a bit lower than what I measured on a single cell.
The Gold Bug has a positive click power switch that completely shuts off the detector when not in use, so there was no current draw when the detector was off. Once turned on, it had a quiescent draw of about 10-12ma. This increased to about 20-24 ma when the speaker was sounding, which decreased to about 16ma with the use of headphones. Switching between Auto, Motion and Non-Motion produced no significant change in the current draw. I got the same readings no matter which bay held the single cell I used in testing.
TIPS- The consistently low current draws that I measured substantiated what I knew from years of experience with the machine. The Gold Bug was a mizer when it came to battery use, and was not too particular about what it was fed, as long as one of the pair of 9-volt cells had a decent charge in it. Lacking even basic iron discrimination, this detector doesn't have a meter, LCD display or any of the added components associated with such features, all of which must draw some current. Use of headphones is not as mandatory to save on batteries 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 that in a pinch, the Gold Bug 1 could be operated with just one good battery and a weaker one, or even just one battery, period, but I did not attempt to verify this. (I've since opened up the Gold Bug and verified the batteries are indeed wired in parallel. Its current draw is so low, it will operate normally using either one or two batteries. There would be an advantage in cold weather to have two batteries installed.)
-=-=-=-=-=-=-
FIRST TEXAS DX8500- This older Bounty Hunter TR/VLF model is past it's prime, but I tested it for comparison to its more modern cousins. When shut 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, well over 160 ma at times. Admittedly, when I took these readings, I had the volume turned much higher than I would set it in normal use.
TIPS- To give the machine some credit, the current draw did vary widely, depending on the setting of the volume control. Lower was much better, as far as battery consumption was concerned. 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 significantly increase the battery life.
The DX8500 seems to place one cell in the audio circuit, much like the newer Time Ranger, so it should also benefit from periodic battery swapping. The other cell's draw did vary, but to no appreciable degree. Once a signal was encountered, it was the battery connected to the audio circuit that was doing most of the work.
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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 split equally in the circuit, as I measured essentially equal drain on either cell, and disconnecting either cell appeared to shut off the detector completely. It has a click switch which completely disconnects the batteries from the circuit. Once turned on, quiescent draw was incredibly minute at .1ma, and this increased to a mere 10-16ma when detecting an object. Since the built-in speaker is itself nothing more than a small headphone-like driver, connecting external headphones made scant difference. There is no volume control to affect any additional savings in batteries, but since the drain is miniscule to begin with, that is not much of an issue. Since some models of headphones have built-in volume controls, I would expect that current use could be even further reduced by their use.
TIPS- I usually turned the Falcon off when not using it to pinpoint a target. When I powered it back up again, retuning it was 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. It is not as thrifty to operate as a smoke detector, however. I have forgotten to turn it off after a hunt, remembering a day or two later, only to find the batteries depleted. Current use is low enough that alkaline batteries are not needed, inexpensive carbon-zincs can be used with excellent service life.
To get a comparison between my detectors and other battery-powered devices, I also tested an AM/FM radio powered by four C-cells. Quiescent current draw of this unit was about 24ma and increased with the volume setting, to a maximum of about 74ma. I could have continued this part of the experiment for many additional hours, but felt that my tests had done a reasonable job of answering my questions.
A lot of what I learned could be applied to most any detector in use today. Here are some general tips so you can start saving some juice right away. Detectors with complicated displays and soft-touch switches may use more juice at idle and when detecting, and may not power down completely when turned off. So, turn your detector off while digging if it is convenient, and if your machine does not have a click switch, always disconnect the batteries when its not in use for more than a day or so. If your detector has a memory setting, you may want to check to make sure it will not be erased each time the batteries are removed. Rotate the batteries to equalize their life, much as you would a set of tires. If you can control it, keep the volume down to a dull roar and use headphones, especially if the headphones driver is smaller than the detector's built-in speaker. Minimize use of all-metal mode, with its constant audio tone, and keep pinpointing and ID sweeps to the minimum required to determine your target. Instead of buying expensive name brand alkalines, watch for sales to save even more on thriftier store-brands, and finally, try using low-cost carbon zinc batteries in the detectors with very low current draw. Some detectors, such as the Time Ranger, will not operate with carbon-zinc batteries. Other machines, like my Falcon, thrive on them.
With all my testing now out of the way, and the pile of detectors cleaned and safely stored for the winter (with all batteries removed), I brought out my little treasure trove for another look. 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 rechargeable 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? My detectors are on a diet, but a man's gotta eat! Happy Hunting!
