Battery Thoughts Please...

[gleaner1]

True enough Prof. Unfortunately its difficult to obtain schematics or diagrams. Then one has to know how to interpret them to use them effectively. With training or just self study reverse engineering is the only way to go to discover how a system is structured. However there are certain basic principles that should be followed when attempting to modify an unknown system~ research is one key and basic electrical knowledge another. Never assume Your probably aware of this however.

gleaner: In this old discussion we never got feed back on how the power supply was structured~

The op stated that his battery pack tested at 18v. If the batt pack only has two terminals, then the power supply (batt pack) has been 100% verified.

 

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[Phantasman]

I find all this complaining about battery costs relative. My CoinGt used 8 AA and my LRP uses one 9v. Which costs more to operate? The Whites. Every device I have operates on 9v including my pinpointer. I buy a value pack of 9v that come out to about $3 per (Alkaline). To spend hundreds, even thousands of dollars on detectors and nit pick the difference in cost between two types of batteries (when we are talking chump change) seems a little picky. It's more convenient for me to carry two 9v along with me in my pouch than 8 AA's. Not to mention the added weight.

Most times two 9v are used (like my F2), they are not in series. It can operate on one 9v. But it needs the second to operate the speaker and other circuits that have a higher draw, effectively through it's Ah rating, not it's voltage.. That's why, as the batteries start to die, the speaker is not as loud, etc.

 

[gleaner1]

Radio shack will sell step down circuits. A 18 volt battery has a lot of amps. I'm surprised you didn't melt your detector. I like the new red Duracell battery's.

The amps that the battery will supply to the device have nothing to do with the size of the battery. The amps drawn are dictated by the circuit of the device. As long as you don't change the voltage, you will be okay. The bigger the battery, the more run time you will get. You could hook up a thousand car batteries in parallel and you would still have 12 volts, you could still safely start your car, and your car starter would still draw the same current as if only using one battery. Now voltage, that's the killer. If you hook up 24 volts to a 12 volt system, things start getting smoky.

 

[Rawhide]

Just buy Duracell and be done with it.

 

[DDancer]

gleaner~ post 16 and 21 contradict No its not 100 percent verified and you acknowledge that yourself. Its also my concern and I've pointed out why in my posts. Considering the audio circuit went kaput well that just increases my desire to know the true layout of the circuit.

As to batteries: Well they can be cheap enough and you'll get what you pay for. I've made my own battery packs and regulated power supplies for the simple reason of extending the operation time of the detector in question. I've also made Lithium power supplies to cut down on weight. Its really all in what your aiming for and the author was looking at the operational time verses expenditure on new batteries. Its a great thing to play with and if you have a green streak its less wasteful.

Now gleaner makes a point that the size of the battery has no effect on power draw, ie amp draw, and this is true. However the thought is incomplete. Battery size does have a corresponding effect on how long the battery will maintain operational voltage level relative to how deep the batteries current capacity is.
The example of a bunch of 12 volt batteries in series with the output always being 12 volts is good however add to that one 12 volt battery will last 1 hour before the operational voltage drops below effective use on a given machine and that say 6 batteries will give 6 hours of life before dropping below effective voltage.
This is often seen in the physical size of a battery. But with new battery technologies its not always true anymore.

An 18 volt battery voltage regulated at 9 volts gives the overall effect of paralleling two 9 volt batteries as you are effectively halving total power draw as well as working down from a higher peak input power. The limiting factor at this point is the point of regulation~ are you using an IC regulator which will cut off below 9 volts, a zeiner diode regulator which will cut off at or just below 9 volts, or a simple power splitter using resistors which will continue to work till power is exhausted.
Another limiting factor will be that the 18 volt battery itself will have a dramatic drop off off output ampherage once it dips below a certain point as well. That's just because of the way the battery is built. As I said its an overall effect but one that is interesting to play with and in the end usually does not make any difference as long as the goal is made for what is desired from the power supply.

 

[AugustMoose87]

...Considering the audio circuit went kaput well that just increases my desire to know the true layout of the circuit...

The audio isn't kaput - it still works just fine when I use 2 9v batteries. It is only when I connect my 18v battery to the "outside" positive and negative terminals that I get no audio, telling me that one of the two 9v's serves as both half of the 18v circuit and a seperate 9v circuit. Right now, I am waiting for my current 9v batteries to die so I can test them to see which of them is more drained, since that is likely the "dual purpose" battery.

 

[DDancer]

Ah I read that wrong? Hrm. *shrugs* a simple voltage divider would work just fine when you figure out which set of terminals power the audio.

 

[woof!]

Sorry, I'd have jumped in a lot sooner but I didn't realize this thread was about legacy BH machines until today.


The legacy BH and BH clone machines that run on two 9-volt batteries run the batteries in series, with the audio system running at 9 volts off the first one. Tapped system. I don't like the system myself, but it wasn't my idea. You can't run it off an 18 volt battery, it requires two 9 volts. I've heard of it being done with two 6-cell AA packs.

--Dave J.

 

[DDancer]

Good to know woof Actually what I suggested would work fine~ just need to install a voltage divider, power splitter, for the first circuit.