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Gp Extreme With Two 18650 Batteries


bklein

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I took a Fatshark battery pack that holds two 18650 li-ion cells and fed it into a buck converter adjusted to 6.86V output and used it to power my GP Extreme.  I'm testing out a (TDI) Beach Hog coil at the beach.  I have a Barrie Johnson Nuggettfinder MKII that has its own speaker/amp as well as speaker/phones volume controls.  The buck converter has less than a volt dropout so it has a reasonable life of about an hour and a half.  I did run into a problem though - if the coil got too near my scoop the detector overloaded.  Something, the audio amp, the detector, I don't know which, overloaded and went into a low frequency oscillation.  I thought I had fried the detector inputs but I shut everything down, waited a bit, and repowered and everything was fine.  I can't duplicate the issue using an input signal from a signal generator into the Nuggettfinder - which has me scared now.  It happened twice in the latter part of the battery life so maybe this is a factor?   Is the GP Extreme designed to take overloads from large metal or is it at risk of frying?  I bought mine with fried inputs and fixed it - don't want to do that again.

I may move to a buck boost converter, put a 2S battery management circuit on the pack, and use larger 26650 cells which would keep the voltage stable and last longer. 

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  • 2 weeks later...
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Or another thing: I was running a Razorback Beach Hog coil that is meant for the TDI...  I’ve read you can use GPx coils on the TDI but not the other way around.  That would be a shame as then what is available as a bigfoot type coil for GPx? 

 

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  • 1 month later...

I replaced the buck converter with a buck boost. I also replaced the batteries with better cells. Has worked fine since. The Beach Hog is awesome.  Use the fuel gauge on the Fatshark to monitor cell voltage does not get below 3V/cell.

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