Critterhunter
New member
I thought I warned you? 
If you didn't read the other thread then don't bother with this one, as it's only some minor points of very minor concern that won't even make sense unless you read the other first. I just didn't want to muck up his thread with a long/boring post with obscurely related side details. So read this thread link below first and if you even care then you can read my few bits of advice on the battery pack project. Even after reading that excellent mod thread on a battery project, you'll probably find my response in this thread rather dry and trivial, so you were warned...
http://www.findmall.com/read.php?22,1755835
I didn't want to much up his thread with a super long response, so figured it'd be better for me to respond in a separate thread and just post a link in his battery mod project build to this one for my response, so that anybody who doesn't want to read a longish/technical dive into a few minor points of concern on the project could avoid this message. I would feel guility if I bogged down such a great thread with pics by getting into some trivial stuff in a dragged out way, so if you read his and don't want to read this one on some *tiny* points I don't blame you...
Ingenues and great job! Always like to see people mod stuff. Just got two quick "but maybe" points but please don't feel I am knocking your invention as it looks very sound...
First, if I understand correctly it only sounds like you soldered the external battery ends by the pics of the obvious soldering for that, and the pics of the spring loaded battery contacts from one battery butting up to another at it's end was not soldered but just compressed and used a spring to further insure good electrical connection should the two cells separate partly?'
If that's the case, the two batteries butting ends without soldering together could pose potential oxide shorts over time. The physical nature of removing/installing batteries (even nimhs or nicads as well of course of regular non-rechargeable batteries) makes for any oxide build up potential to have lessor risk as the physical acting of removing/installing batteries will scrub away any surface oxide and insure good contact and connection. By not being able to remove those batteries at the ends where they connect to each other lacking solder, eventually I can see an oxide buildup problem that will result in the battery no longer completing an electrical circuit. It only takes one, so you've got multiple potential spots for that to happen maybe some day. Maybe you did and I missed it (?) but I would have put dielectric grease on those battery ends and that spring to insure no oxide build up. This stuff is often called "boot grease" and sold at auto parts stores meant to coat the internal part of spark plug boots and the spark plug to prevent such problems. If it's applied in a VERY thin coat, meaning wiping off the surface with your hand so it's just a film present, it will do it's job, but if applied to thick it can actually impare the flow of electricity.
This stuff is great to put on say the battery terminals of a battery holder where it makes contact with a detector when installed and such. Or any other physical metal contact points that aren't soldered together and yet won't be subjected to physical action on a semi-routine bases to insure any oxide is scraped off the surface to insure good contact. I always use this stuff on things like sensor plugs on my truck when doing auto repairs. Anywhere an electrical connection is made that won't often be removed and re-installed. Stuff light light bulb sockets in cars and so on. Just make sure to only use a thin film and never glob it on, because in my experience that can stop current flow. It will prevent oxide build up while allowing the current to continue to flow.
That's the very reason why nimh or nicad cells can be bought with electrical soldering tabs on them, as you can solder the two cell ends together and then "fold" the tab down in place so the two cells can also sit flatly against each other. The clearance (or lack there of) of the two cells is no longer critical then, because the two battery solder tabs are of course soldered together.
Lacking batteries that have solder tabs on them, one trick to solder two cell ends together is to load them in a spring loaded contraption made from wood with a channel they both ride in and one cell is spring loaded to "shoot" it's end together with the other stationary battery end very quickly. Heat is applied to both battery ends at the same time (it helps to have a second person and soldering iron for this if you don't have a device that can apply heat to both at once). Once a good flow of fluid solder is on both (you want both ends "wicked" with solder so both solder blobs will instantly "become one") and they are hot enough to connect properly, a doll rod is pulled from one battery to make it immediately travel a very short distance (so as not to cool first) and slam into the other battery, thus making a good connection very fast while the solder is still fluid and the battery ends are still at the proper temperature.
I've built packs lacking soldering tabs, but in order to avoid building such a spring loaded contraption, I just used short wire to connect both ends of each cell and then will but them together. The wire bends easily out of the way (using a small enough diameter just high enough to handle to expected amp draw or so) and the pack is just as compact and as quality of a build as using cells with solder tabs.
Second, I noticed from the pics you seemed to use a lot of heat to insure a good solder point on the external battery ends to connect to each other. While some decent heat is needed to insure good solder flow and connection on these large surface mount metal areas, too much heat can destroy the "battery buttons", meaning the non-metal cloth like "washer" looking things that go around the positive battery nipples to insure no connection is made between the negative part of the circuit and the positive nipple. If that has been compromised due to too much heat you may have at least a cell fail on you down the road.
One final nit pick here, and again I apologize for offering "suggestions" because you should be applauded for such an excellent project and ideas you used...But, I'm not aware of the normal battery pack used stock in that machine. What is the configuration of the stock pack? Meaning, how many cells, what type of battery and were they rechargeables or not? What I'm driving at is I want to know what the expected source voltage is for that machine, because depending on that your "13V or more at full charge" might be pushing the voltage tolerance window of the internal regulator of the detector. If it's at or above the upper window for the expected voltage range that regulator can handle, while it might work fine for a while on a exceedingly hot day you may suddenly find your machine to shut down and not appear to be working anymore.
Linear voltage regulators (which I would expect that machine is using because they are far more cheaper and also far less noisy (which is important to a metal detector) than switching regulators) get rid of excess voltage by converting it to heat that is shunted off an external heat sink found at the head of the regulator. Usually these metal "tabs" on the head of the IC have a hole in them, which a bolt can be put through to connect it to an even larger metal heat sink if needed to bleed off the excess heat (but not always is used). If the voltage is near the upper range or slightly above that window of the specs of that regulator, while it might work fine on most days, a real hot day might push it over the edge. Don't panic though, just turn the machine off and let it cool down for a while and see if it works later, as regulators have an internal thermal overload circuit which will break connection to stop current flow. If you are lucky when the regulator cools down it will re-make that overload connection and work again, but these overloads have a limited life span, and some time will fail to re-connect on the very first break due to overheating.
So, if you don't know the upper range limit of voltage window for the specs of that machine's regulator, and if you don't fear taking the machine apart, then I would open it up and see if you can gleam a number off that regulator to look up the voltage specs on. And, just for extra insurance, if the bolt hole on that regulator's heat sink (if it has one) doesn't have a bolt through it to attach to a large piece of metal, then I would install something (aluminum works great) as a heat sink to that heat sink on the regulator via a small bolt or screw. I think radio shack sells small ribbed heat sinks meant for this very purpose, but much larger than the one that comes built into the regulator. If it does lack an external extra heat sink (or even a bolt hole)...I think radio shack also sells heat sink paste. Apply it to both surfaces of both heat sinks before connecting them, as that will insure even greater heat transfer.
I fly RC electric planes, and one of my "mods" when the ESC speed controls are reaching their max rated amp limits due to the motor and prop I'm using that the ESC controls, one mod I do is to cut away a square of the heat shrink ("shrink", not "sink") that protects the ESC on the heat sink side of it. I'll then apply a little heat sink paste to the aluminum flat surface of the stock heat sink, and then I'll epoxy a external heat sink to that. I apply the heat sink compound in the center, and apply the epoxy around the entire outer area of the external heat sink I'm adding, so the two don't interfere with each other in doing their job. With a ribber external heat sink added to the ESC (which I think I used to get at radio shack), I could often run these ESCs at say 40 amps over there 30 amp limits for extended periods of time with no thermal overload shutdowns. Of course that was also due to the air flow over the ribbed heat sink as the electric plane flew through the air at high speeds.
One more tid bit of useless knowledge... Switching regulators (which I've never heard of using in detectors due to their noise factor) get rid of excess input voltage by simply outputting a pulsed transmission to the device they are powering. They don't need to shunt the excessive voltage off as heat. That pulsing makes them noisy but also very efficient (not really important with detectors) in that they aren't wasting off excess voltage as heat, but rather control the output voltage by quickly pulsing the output to the circuit board off and on. That's what makes them noisy though, and so to limit that noise they need more additional components on the circuit board to try to get rid of it, so not are they more expensive to begin with but also cost more to use due to the extra components needed on the board. I'm not sure, but for that reason alone and also that the noise never seems to be quite entirely gotten rid of, I doubt they are used in any detectors that I'm aware of.
If anything doesn't know what voltage regulators do...They take in a certain window range (not too low or too high) of input voltage (from say your battery on a detector in this case) and then output only a constant stable fixed voltage to the circuit board. The circuit board on a detector needs this static voltage at all times (say 8V) in order to stay in tune and work properly. If the voltage was constantly dropping as the battery drained, the machine would never stay in perfect tuned balance to operate stably. As a small example, let's say a regulator wants a window of about 10.2 to 13V for it's input power, and it's output is a static 9V. What happens when the voltage gets down to near 10.2V? The detector then sounds it's low battery alarm.
OK, final point about the myth of rechargeables giving less performance than non-rechargeables due to rechargeables being 1.2V per cell instead of 1.5V. In a detector, or any device using a voltage regulator...You can now clearly see that so long as the voltage is within the window of voltage range the detector wants to see, the machine is only seeing 9V (as the example per say given above). No amount of extra voltage is going to change the performance of the machine, and in fact one could argue a lower voltage using nimhs or nicads might even be better for the long life of the machine due to less voltage being bled off into the regulator's heat sink (less stress on the regulator on hot days). Final note, modern nimhs or nicads with say about 2500ma or higher capacity will often give 1 to 4 times MORE run time than a store bought non-rechargeable battery. And, a high capacity cell like that may start off with a less starting voltage than a non-rechargeable (which is meaningless anyway), but in fact the nimh or nicad will drop less in voltage as it drains due to it's higher capacity, so it will in fact at a certain point in discharge maintain a higher voltage than the non-rechargeable if that's important to you still for some odd reason.
Either way, didn't want to muck up your thread with a super long boring post and I think you did a great job. Just adding a few bits of advice you can ignore as not important or not. Up to you. Good job either way.
If you didn't read the other thread then don't bother with this one, as it's only some minor points of very minor concern that won't even make sense unless you read the other first. I just didn't want to muck up his thread with a long/boring post with obscurely related side details. So read this thread link below first and if you even care then you can read my few bits of advice on the battery pack project. Even after reading that excellent mod thread on a battery project, you'll probably find my response in this thread rather dry and trivial, so you were warned...http://www.findmall.com/read.php?22,1755835
I didn't want to much up his thread with a super long response, so figured it'd be better for me to respond in a separate thread and just post a link in his battery mod project build to this one for my response, so that anybody who doesn't want to read a longish/technical dive into a few minor points of concern on the project could avoid this message. I would feel guility if I bogged down such a great thread with pics by getting into some trivial stuff in a dragged out way, so if you read his and don't want to read this one on some *tiny* points I don't blame you...
Ingenues and great job! Always like to see people mod stuff. Just got two quick "but maybe" points but please don't feel I am knocking your invention as it looks very sound...
First, if I understand correctly it only sounds like you soldered the external battery ends by the pics of the obvious soldering for that, and the pics of the spring loaded battery contacts from one battery butting up to another at it's end was not soldered but just compressed and used a spring to further insure good electrical connection should the two cells separate partly?'
If that's the case, the two batteries butting ends without soldering together could pose potential oxide shorts over time. The physical nature of removing/installing batteries (even nimhs or nicads as well of course of regular non-rechargeable batteries) makes for any oxide build up potential to have lessor risk as the physical acting of removing/installing batteries will scrub away any surface oxide and insure good contact and connection. By not being able to remove those batteries at the ends where they connect to each other lacking solder, eventually I can see an oxide buildup problem that will result in the battery no longer completing an electrical circuit. It only takes one, so you've got multiple potential spots for that to happen maybe some day. Maybe you did and I missed it (?) but I would have put dielectric grease on those battery ends and that spring to insure no oxide build up. This stuff is often called "boot grease" and sold at auto parts stores meant to coat the internal part of spark plug boots and the spark plug to prevent such problems. If it's applied in a VERY thin coat, meaning wiping off the surface with your hand so it's just a film present, it will do it's job, but if applied to thick it can actually impare the flow of electricity.
This stuff is great to put on say the battery terminals of a battery holder where it makes contact with a detector when installed and such. Or any other physical metal contact points that aren't soldered together and yet won't be subjected to physical action on a semi-routine bases to insure any oxide is scraped off the surface to insure good contact. I always use this stuff on things like sensor plugs on my truck when doing auto repairs. Anywhere an electrical connection is made that won't often be removed and re-installed. Stuff light light bulb sockets in cars and so on. Just make sure to only use a thin film and never glob it on, because in my experience that can stop current flow. It will prevent oxide build up while allowing the current to continue to flow.
That's the very reason why nimh or nicad cells can be bought with electrical soldering tabs on them, as you can solder the two cell ends together and then "fold" the tab down in place so the two cells can also sit flatly against each other. The clearance (or lack there of) of the two cells is no longer critical then, because the two battery solder tabs are of course soldered together.
Lacking batteries that have solder tabs on them, one trick to solder two cell ends together is to load them in a spring loaded contraption made from wood with a channel they both ride in and one cell is spring loaded to "shoot" it's end together with the other stationary battery end very quickly. Heat is applied to both battery ends at the same time (it helps to have a second person and soldering iron for this if you don't have a device that can apply heat to both at once). Once a good flow of fluid solder is on both (you want both ends "wicked" with solder so both solder blobs will instantly "become one") and they are hot enough to connect properly, a doll rod is pulled from one battery to make it immediately travel a very short distance (so as not to cool first) and slam into the other battery, thus making a good connection very fast while the solder is still fluid and the battery ends are still at the proper temperature.
I've built packs lacking soldering tabs, but in order to avoid building such a spring loaded contraption, I just used short wire to connect both ends of each cell and then will but them together. The wire bends easily out of the way (using a small enough diameter just high enough to handle to expected amp draw or so) and the pack is just as compact and as quality of a build as using cells with solder tabs.
Second, I noticed from the pics you seemed to use a lot of heat to insure a good solder point on the external battery ends to connect to each other. While some decent heat is needed to insure good solder flow and connection on these large surface mount metal areas, too much heat can destroy the "battery buttons", meaning the non-metal cloth like "washer" looking things that go around the positive battery nipples to insure no connection is made between the negative part of the circuit and the positive nipple. If that has been compromised due to too much heat you may have at least a cell fail on you down the road.
One final nit pick here, and again I apologize for offering "suggestions" because you should be applauded for such an excellent project and ideas you used...But, I'm not aware of the normal battery pack used stock in that machine. What is the configuration of the stock pack? Meaning, how many cells, what type of battery and were they rechargeables or not? What I'm driving at is I want to know what the expected source voltage is for that machine, because depending on that your "13V or more at full charge" might be pushing the voltage tolerance window of the internal regulator of the detector. If it's at or above the upper window for the expected voltage range that regulator can handle, while it might work fine for a while on a exceedingly hot day you may suddenly find your machine to shut down and not appear to be working anymore.
Linear voltage regulators (which I would expect that machine is using because they are far more cheaper and also far less noisy (which is important to a metal detector) than switching regulators) get rid of excess voltage by converting it to heat that is shunted off an external heat sink found at the head of the regulator. Usually these metal "tabs" on the head of the IC have a hole in them, which a bolt can be put through to connect it to an even larger metal heat sink if needed to bleed off the excess heat (but not always is used). If the voltage is near the upper range or slightly above that window of the specs of that regulator, while it might work fine on most days, a real hot day might push it over the edge. Don't panic though, just turn the machine off and let it cool down for a while and see if it works later, as regulators have an internal thermal overload circuit which will break connection to stop current flow. If you are lucky when the regulator cools down it will re-make that overload connection and work again, but these overloads have a limited life span, and some time will fail to re-connect on the very first break due to overheating.
So, if you don't know the upper range limit of voltage window for the specs of that machine's regulator, and if you don't fear taking the machine apart, then I would open it up and see if you can gleam a number off that regulator to look up the voltage specs on. And, just for extra insurance, if the bolt hole on that regulator's heat sink (if it has one) doesn't have a bolt through it to attach to a large piece of metal, then I would install something (aluminum works great) as a heat sink to that heat sink on the regulator via a small bolt or screw. I think radio shack sells small ribbed heat sinks meant for this very purpose, but much larger than the one that comes built into the regulator. If it does lack an external extra heat sink (or even a bolt hole)...I think radio shack also sells heat sink paste. Apply it to both surfaces of both heat sinks before connecting them, as that will insure even greater heat transfer.
I fly RC electric planes, and one of my "mods" when the ESC speed controls are reaching their max rated amp limits due to the motor and prop I'm using that the ESC controls, one mod I do is to cut away a square of the heat shrink ("shrink", not "sink") that protects the ESC on the heat sink side of it. I'll then apply a little heat sink paste to the aluminum flat surface of the stock heat sink, and then I'll epoxy a external heat sink to that. I apply the heat sink compound in the center, and apply the epoxy around the entire outer area of the external heat sink I'm adding, so the two don't interfere with each other in doing their job. With a ribber external heat sink added to the ESC (which I think I used to get at radio shack), I could often run these ESCs at say 40 amps over there 30 amp limits for extended periods of time with no thermal overload shutdowns. Of course that was also due to the air flow over the ribbed heat sink as the electric plane flew through the air at high speeds.
One more tid bit of useless knowledge...
Switching regulators (which I've never heard of using in detectors due to their noise factor) get rid of excess input voltage by simply outputting a pulsed transmission to the device they are powering. They don't need to shunt the excessive voltage off as heat. That pulsing makes them noisy but also very efficient (not really important with detectors) in that they aren't wasting off excess voltage as heat, but rather control the output voltage by quickly pulsing the output to the circuit board off and on. That's what makes them noisy though, and so to limit that noise they need more additional components on the circuit board to try to get rid of it, so not are they more expensive to begin with but also cost more to use due to the extra components needed on the board. I'm not sure, but for that reason alone and also that the noise never seems to be quite entirely gotten rid of, I doubt they are used in any detectors that I'm aware of.If anything doesn't know what voltage regulators do...They take in a certain window range (not too low or too high) of input voltage (from say your battery on a detector in this case) and then output only a constant stable fixed voltage to the circuit board. The circuit board on a detector needs this static voltage at all times (say 8V) in order to stay in tune and work properly. If the voltage was constantly dropping as the battery drained, the machine would never stay in perfect tuned balance to operate stably. As a small example, let's say a regulator wants a window of about 10.2 to 13V for it's input power, and it's output is a static 9V. What happens when the voltage gets down to near 10.2V? The detector then sounds it's low battery alarm.
OK, final point about the myth of rechargeables giving less performance than non-rechargeables due to rechargeables being 1.2V per cell instead of 1.5V. In a detector, or any device using a voltage regulator...You can now clearly see that so long as the voltage is within the window of voltage range the detector wants to see, the machine is only seeing 9V (as the example per say given above). No amount of extra voltage is going to change the performance of the machine, and in fact one could argue a lower voltage using nimhs or nicads might even be better for the long life of the machine due to less voltage being bled off into the regulator's heat sink (less stress on the regulator on hot days). Final note, modern nimhs or nicads with say about 2500ma or higher capacity will often give 1 to 4 times MORE run time than a store bought non-rechargeable battery. And, a high capacity cell like that may start off with a less starting voltage than a non-rechargeable (which is meaningless anyway), but in fact the nimh or nicad will drop less in voltage as it drains due to it's higher capacity, so it will in fact at a certain point in discharge maintain a higher voltage than the non-rechargeable if that's important to you still for some odd reason.
Either way, didn't want to muck up your thread with a super long boring post and I think you did a great job. Just adding a few bits of advice you can ignore as not important or not. Up to you. Good job either way.
