TDI Beach Hunter...... Some Basic Beach Tests

[Tony]

I thought I'd copy this from my other thread which was buried down on the second page.......is this okay Steve as I don't want to duplicate if unnecessary?

"Just got back from the beach....in one word.........awesome. Some observations;

It is the deepest detector I have ever used on the beach (in the past 25 years) by running the higher voltage pack.

It is the first time I have ever detected (with any detector, including the Minelab PI's) my gold wedding ring at a measured/buried 18" deep.

The US nickel can be heard at 16" in buried wet sand...but with GB OFF. With GB ON it drops to 12"-13" !

My machine is much deeper with GB OFF across all targets.....the rock solid threshold with GB OFF is unbelievable with no loss of sensitivity.

Even with the coil swept through shallow salt water at max gain and 10us......it is so smooth. I don't know how White's have done it....maybe a new batch of the latest flux capacitors......

I tried with GB on but in clean white sand, there was no perfect GB....it was close but just a slight positive signal as the coil was lowered to the ground...but the depth loss was significant with GB on and slight falsing with higher GAIN. None of this is a problem with GB OFF."

Tony

PS.......on the real deepies (edge of detectability), there is often a one, two and three way signal but not a four way signal if swept from left,right and up and down.

[Tony]

Here are the results of the Panasonic 4 x 18650 cells (3400 mah)

On my Xtar charger, I get very close to the stated capacity which is appreciated (thanks to Panasonic).

I got a comfortable 7 hours operating time (Max GAIN and 10uS) with a just audible THRESHOLD and VOLUME

The pack started out at 16.3v (down from the 16.6v fully charged as I had used it for about 30 minutes)

After 1 hour the pack read 15.7v (a drop of 0.6v)

After 2 hours the pack read 15.20v (a drop of 0.5v)

After 3 hours the pack read 14.70v (a drop of 0.5v)

After 4 hours the pack read 14.20v (a drop of 0.5v)

After 5 hours the pack read 13.65v (a drop of 0.55v)

After 6 hours the pack read 12.55v (a drop of 1.1v)

After 6.5 hours the pack read 11.80v (a drop of 0.75v)

Each battery tested and found to be about 2.95v to 3.00v

In summary, the pack will give about 7 hours of run time before the pack reaches to 12v mark (or 3v per cell).

This is a generous built in safety margin as the low voltage cutoff built into each cell is 2.5v. Some people believe not to discharge below 3v.

As you can see, the first 5 hours discharge is very linear but accelerates for the final 2 hours.

As expected, the depth drops off slightly but only noticeable/measurable at around the 5 hour mark.

This pack will be perfect for in the water as 7 hours deep digging in the water is plenty for me. If on the beach then a battery swap after 5 hours is easy enough.

Tony.

[Steve Herschbach]

Every TDI I have ever seen or heard of, with the exception of the TDI SL that auminesweeper owns, will get better depth and smoother operation with the ground balance off. Ground balance only adds depth when there is enough mineralization present to severely cut performance while the ground balance is off. Then engaging the ground balance regains back some, but not all, of that lost depth.

You do lose the discrimination capability tied to the tones when ground balance is turned off.

Link deleted since Findmall Forum update broke all old links

Effects of Ground Balance on Target Depth?