I bought my Dual Field in August of '09 and have modified it in several ways to allow me to get the most use out of it without creating problems that would destroy the detector!!
Early on I recognized the savings that could be realized by using re-chargeable batteries and the risk of constantly opening the control housing to access the battery-pack.
Up-front I want to say I have never been comfortable with charging batteries while they are in the control housing, otherwise I would have just kept the battery-pack in the detector and installed a water-proof connector allowing charging without opening the housing each time.
As I mulled over the expence of buying off the shelf items that might do the job and the fact that most were kinda light duty for the wear and tear the machine is subjected to the more I decided I needed to find a cheaper/better way!!!
In using the Garrett's XL500PI machines I learned to re-build the internal battery packs and with that experience I felt comfortable creating a custom battery pack that would give the DF 13V or more at full charge for a nice reserve and would use 10, 1.2V off the shelf NMIH batteries.
This would be enclosed in a simple case built of inexpensive plumbing parts available everywhere. Many plumbers would happily contribute a foot of the 2" pvc pipe needed to avoid you having to buy a full length of pipe. (Even though it is not too expensive if you did have to buy it.)
[attachment 240474 8-7-12BatteryPackBuild013.JPG]
[attachment 240476 8-7-12BatteryPackBuild014.JPG]
[attachment 240478 8-7-12BatteryPackBuild015.JPG]
I used short pieces of 2" PVC pipe to build up the side where the tubular housing would mate to the control housing. The cradle shaped pieces were heated and strapped to the PVC pipe housing for a good fit and when cool, glued in place and later shaped into a flat surface with my band saw and bench mounted 6" belt sander for a suitable mounting surface..
Notice the rubber cap is clear of the control housing on the side away from my "working side" and the head of the SS clamp is kept turned to the top to keep it from snagging on anything.
[attachment 240480 8-7-12BatteryPackBuild017.JPG]
[attachment 240482 8-7-12BatteryPackBuild019.JPG]
[attachment 240483 8-7-12BatteryPackBuild021.JPG]
The batteries are joined in pairs via a short, hand fitted spring that clips to the positive terminal of the battery and compresses when they are squeezed together using a quick clamp. (I'll demonstrate in later pics.)
5 pairs are the secured together with a couple of plastic electrical ties.
The battery pairs are enclosed at the join with a 11/4" length of 3/4" heat shrink tubeing bought at a local electronics supply shop. This HS tube is lined with a hot melt glue/sealer by the manufacturer, that binds to the batteries securing the two firmly together solveing the problem of connecting them without unnecessary hardware. (More than enough for 2 battery packs cost me less than $4.00.)
A 3/8" piece of the HS Tubing is used on both ends of each pair as a cushion when the pairs are joined into what will be the battery pack.
This tubing I carefully heated with an electric heat gun, but I have no doubt that some of the more powerful hair dryers would probably do the job.
Just enough heat to shrink the tubing, but not too much or the batteries may be damaged. (A little of the hot melt glue/sealer can be seen oozing out.)
After the HS tube cools off enough to hold in your fingers comfortably the clamp jaws are opened and the join is complete.
Most electronics techs will shudder at my craftsmanship I'm sure, but the resulting battery pack works great!!
The thin copper strips connecting the batteries together in series were pieces of copper tube used in hydronic baseboards for rapid heat transfer to the aluminum fins within the baseboard housing. (Again, more than enough for this project, less than a foot, should be available from any plumber who does heating work for cheap.)
Trimmed to the right size with a pair of tin snips, the copper strips work very well as conductors and firm up the pack too..
Using thin lead solder intended for electrical work, tin all connecting surfaces and make the necessary connections. (I prefer an old Stanley medium duty soldering iron I've had for many years.)
The battery connector was scavenged from an old 9Volt Battery.
Liquid electrical tape covers all surfaces to prevent accidental shorting of the B/Pack.
At full charge the two I built test at 13.5 Volts and after about twelve hours of use tested at 12.5 vots.
The PVC pipe is epoxied to the control housing using some marine epoxy I bought a few years ago when I wanted to build a kayak.
Thickened with glass dust available where the epoxy is sold into a dense paste and liberally spread over the carefully cleaned and scuffed (with coarse sand cloth surfaces) the epoxy seals and secures the construct together.
Using 2 SS 1/4" bolts and rubber washers I fastened the control housing and battery housing after the epoxy cured for maximum security and strength at the join.
The power wire from the new terminal connector was fed through a 1/4 " hole and connected to the detector wires w/ the splices covered with 1/4" HS tube.
The hole was then sealed w/small dabs of shoe goop which I should have allowed to cure before putting in the battery pack. WORD TO THE WISE ----(I was in a hurry to use the DF and later had a hard time getting the battery out even though the was only a tiny 3/16"" spot stuck to the pack!!!)
The synthetic rubber 2" "Fernco Cap" is heavy duty and inexpensive and seals beautifully.
After using the DF for over 10 hours in the water now I have only good things to say about my creation.
And I no longer have to lose sleep over leaks from opening the control housing all the time for changing batteries.
Early on I recognized the savings that could be realized by using re-chargeable batteries and the risk of constantly opening the control housing to access the battery-pack.
Up-front I want to say I have never been comfortable with charging batteries while they are in the control housing, otherwise I would have just kept the battery-pack in the detector and installed a water-proof connector allowing charging without opening the housing each time.
As I mulled over the expence of buying off the shelf items that might do the job and the fact that most were kinda light duty for the wear and tear the machine is subjected to the more I decided I needed to find a cheaper/better way!!!
In using the Garrett's XL500PI machines I learned to re-build the internal battery packs and with that experience I felt comfortable creating a custom battery pack that would give the DF 13V or more at full charge for a nice reserve and would use 10, 1.2V off the shelf NMIH batteries.
This would be enclosed in a simple case built of inexpensive plumbing parts available everywhere. Many plumbers would happily contribute a foot of the 2" pvc pipe needed to avoid you having to buy a full length of pipe. (Even though it is not too expensive if you did have to buy it.)
[attachment 240474 8-7-12BatteryPackBuild013.JPG]
[attachment 240476 8-7-12BatteryPackBuild014.JPG]
[attachment 240478 8-7-12BatteryPackBuild015.JPG]
I used short pieces of 2" PVC pipe to build up the side where the tubular housing would mate to the control housing. The cradle shaped pieces were heated and strapped to the PVC pipe housing for a good fit and when cool, glued in place and later shaped into a flat surface with my band saw and bench mounted 6" belt sander for a suitable mounting surface..
Notice the rubber cap is clear of the control housing on the side away from my "working side" and the head of the SS clamp is kept turned to the top to keep it from snagging on anything.
[attachment 240480 8-7-12BatteryPackBuild017.JPG]
[attachment 240482 8-7-12BatteryPackBuild019.JPG]
[attachment 240483 8-7-12BatteryPackBuild021.JPG]
The batteries are joined in pairs via a short, hand fitted spring that clips to the positive terminal of the battery and compresses when they are squeezed together using a quick clamp. (I'll demonstrate in later pics.)
5 pairs are the secured together with a couple of plastic electrical ties.
The battery pairs are enclosed at the join with a 11/4" length of 3/4" heat shrink tubeing bought at a local electronics supply shop. This HS tube is lined with a hot melt glue/sealer by the manufacturer, that binds to the batteries securing the two firmly together solveing the problem of connecting them without unnecessary hardware. (More than enough for 2 battery packs cost me less than $4.00.)
A 3/8" piece of the HS Tubing is used on both ends of each pair as a cushion when the pairs are joined into what will be the battery pack.
This tubing I carefully heated with an electric heat gun, but I have no doubt that some of the more powerful hair dryers would probably do the job.
Just enough heat to shrink the tubing, but not too much or the batteries may be damaged. (A little of the hot melt glue/sealer can be seen oozing out.)
After the HS tube cools off enough to hold in your fingers comfortably the clamp jaws are opened and the join is complete.
Most electronics techs will shudder at my craftsmanship I'm sure, but the resulting battery pack works great!!
The thin copper strips connecting the batteries together in series were pieces of copper tube used in hydronic baseboards for rapid heat transfer to the aluminum fins within the baseboard housing. (Again, more than enough for this project, less than a foot, should be available from any plumber who does heating work for cheap.)
Trimmed to the right size with a pair of tin snips, the copper strips work very well as conductors and firm up the pack too..
Using thin lead solder intended for electrical work, tin all connecting surfaces and make the necessary connections. (I prefer an old Stanley medium duty soldering iron I've had for many years.)
The battery connector was scavenged from an old 9Volt Battery.
Liquid electrical tape covers all surfaces to prevent accidental shorting of the B/Pack.
At full charge the two I built test at 13.5 Volts and after about twelve hours of use tested at 12.5 vots.
The PVC pipe is epoxied to the control housing using some marine epoxy I bought a few years ago when I wanted to build a kayak.
Thickened with glass dust available where the epoxy is sold into a dense paste and liberally spread over the carefully cleaned and scuffed (with coarse sand cloth surfaces) the epoxy seals and secures the construct together.
Using 2 SS 1/4" bolts and rubber washers I fastened the control housing and battery housing after the epoxy cured for maximum security and strength at the join.
The power wire from the new terminal connector was fed through a 1/4 " hole and connected to the detector wires w/ the splices covered with 1/4" HS tube.
The hole was then sealed w/small dabs of shoe goop which I should have allowed to cure before putting in the battery pack. WORD TO THE WISE ----(I was in a hurry to use the DF and later had a hard time getting the battery out even though the was only a tiny 3/16"" spot stuck to the pack!!!)
The synthetic rubber 2" "Fernco Cap" is heavy duty and inexpensive and seals beautifully.
After using the DF for over 10 hours in the water now I have only good things to say about my creation.
And I no longer have to lose sleep over leaks from opening the control housing all the time for changing batteries.
But just a tad few bits of concern on the battery build that probably aren't too important but either way...