Fisher F2 Alternative Power Source Question

mh9162013 · Jun 7, 2020

I've successfully removed 9V batteries from my Garrett Carrot (which now uses AAA batteries) and I've started on the process and getting rid of 9V batteries in my Fisher F2.

I've taken the approach if trying to use a single battery to power the F2. A while back, I read from somewhere that the F2 ran off two 9v batteries running in parallel. However, this means that if I use a single battery for the F2, it should work (assuming the single battery has the ability to provide the necessary current). But when I try to use this set up, my battery gets warm. I eventually realized that the Fisher F2 is NOT using a "pure" parallel setup. If it were, it would not be creating a short circuit in my single power source setup.

So my question is: how exactly is the Fisher F2 power wiring arranged? It's not parallel and it doesn't appear to be in series, either.

Any insight would be appreciated.

Thanks!

DIGGER27 · Jun 7, 2020

Not sure but I do know one battery powers the tones and the other powers the rest and they don't discharge evenly.
If you get low in the field simple switching the battery positions will get you another bar or two of battery power for a short time.
I do prefer using cheaper AA's in my F70 but when I used the F2 heavily I usually just bought big packs of 9 volts from Costco which are fairly cheap or caught Bogo sales at CVS or Walgreens and since the batteries lasted 30 hours or so, or more, for me using headphones I never cared much about the cost so much.
Good luck tinkering though, hope you figure it out.

mh9162013 · Jun 7, 2020

DIGGER27 said:
Not sure but I do know one battery powers the tones and the other powers the rest and they don't discharge evenly.
If you get low in the field simple switching the battery positions will get you another bar or two of battery power for a short time.
I do prefer using cheaper AA's in my F70 but when I used the F2 heavily I usually just bought big packs of 9 volts from Costco which are fairly cheap or caught Bogo sales at CVS or Walgreens and since the batteries lasted 30 hours or so, or more, for me using headphones I never cared much about the cost so much.
Good luck tinkering though, hope you figure it out.

Thanks for your insight. From another message board, I just learned that the F2 runs off of 18V (series), but part of the electronics runs off 9V.

And I have a few 9V batteries to spare for now. But I will run out eventually and by the time I do, I want an alternative power source in place. And no, buying more 9V cells is out of the question. So is buying 9V rechargeables, as the whole point is the remove 9V cells from all my metal detecting equipment and switch to a single battery type (will probably be AAA).

DIGGER27 · Jun 7, 2020

mh9162013 said:
Thanks for your insight. From another message board, I just learned that the F2 runs off of 18V (series), but part of the electronics runs off 9V.

And I have a few 9V batteries to spare for now. But I will run out eventually and by the time I do, I want an alternative power source in place. And no, buying more 9V cells is out of the question. So is buying 9V rechargeables, as the whole point is the remove 9V cells from all my metal detecting equipment and switch to a single battery type (will probably be AAA).

That would be 12, 1.5v batteries...a heavy and unwieldy extra weight you will be hauling around.
I don't believe that thing will work right at all unless you feed it the entire 18 volts.
Maybe a battery pack you can belt mount?

I have an old Compass Judge 2 that uses 12 AA's...already a monstrously non ergonomic boat anchor and when you add all those batteries in you can tell the difference.

mh9162013 · Jun 7, 2020

DIGGER27 said:
That would be 12, 1.5v batteries...a heavy and unwieldy extra weight you will be hauling around.
I don't believe that thing will work right at all unless you feed it the entire 18 volts.
Maybe a battery pack you can belt mount?

I have an old Compass Judge 2 that uses 12 AA's...already a monstrously non ergonomic boat anchor and when you add all those batteries in you can tell the difference.

No, not necessary as I will use a voltage booster. I am already using a 9V booster in my Garrett Carrot and it works perfectly. I plan on using the same booster for my F2.

Right now, it looks like I'll use two of these 9V boosters to create two independent power sources (likely 3 x AAA NiMH cells). The problem is the added cost of using two booster circuits instead of 1 and the extra space taken up by the wiring.

My original plan was to use 4 x AA NiMH cells with a single 9V booster circuit. Looks like that won't work, though.

Silversmith45 · Jun 7, 2020

DIGGER27 said:
I have an old Compass Judge 2 that uses 12 AA's...already a monstrously non ergonomic boat anchor and when you add all those batteries in you can tell the difference.

I have two old Tek detectors. An 8500B and a 9000B. They both use 14 AA batteries. They worked well with heavy Duty batteries but were so heavy I had them both converted to Hip mounts.

Fisher F2 Alternative Power Source Question

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