Battery Power

[Nova]

G`day everyone, i`m from Australia, as someone who does not know much about the technical side of detectors, i`ve been trying to find where i could get some of my questions answered, someone suggested Geotech Forum, so here i am, i hope you guys can help with my first question, so here goes:
As an owner of a SD2200d these machines are very deep over 1metre on the top of a coca cola can, and this was tested in highly mineralised goldfields soil, my question is regarding the battery, the battery will last 6-8 hours,a 6volt lead acid battery, will the battery give sustained depth over this whole period, or will the power and depth decrease as the battery slowly drains?
If so; it would make sense to have another battery and swap after 3 hours use, what do you guys think?

[kt315]

need more info. pics of ML batt will give me some presentation...

what do you guys think?

i think sd2200 is good for to give for geotechers new winter project...

[waltr]

First look at SD2200 schematic:
http://www.geotech1.com/forums/showt...ghlight=SD2200

This shows that the Coil is powered directly from the Battery.

A Lead Acid battery Voltage varies a bit during discharge and this depends on the discharge rate, temperature and the battery construction. You MUST look at the Data sheet for the EXACT battery you are using.
Here is example for a particular sealed Pb battery.
http://www.power-sonic.com/images/po...hManual-Lo.pdf

This Battery does how Voltage well IF discharge is within spec.

So the bottom line is IF you are using a GOOD Quality battery and do not go beyond the recommended capacity then there is only a slight drop in Voltage to the Coil. This will probably not result is a noticeable loss of detector depth.

[kt315]

Australia we know this fact good is sunny country and simplest device solar panel+converter will give you full power.
we still wait pics, walter. pics.

[Andi68]

I agree with waltr.

What is the capacity of the battery?

Is there a board or layout for the SD2000?

[Carlos]

I believe that the sensitivity of the detector should not vary as long as the power supplies of the operational amplifiers remain within their reference values. That lower the voltage of the 12v battery. to 10 v. it does not vary the force against electromotive that induces the coil.
Charles

[homefire]

Not to rob the thread but these could work . Been messing around with some 38120 LiFePO4 Cells. These things can produce some crazy Amperage. 4S have Zero Issues starting a car. They weigh less then half that of a SLA battery. http://www.litrade.de/pub/HeadWay%20...fications1.pdf

[Nova]

Thanks guys, i appreciate your knowledge on this, is very helpful, if you want an idea what the battery looks like, try ebay and type in battery for minelab sd, it`s a rectangle size battery 14 cm wide by 10 cm high by 4.5 cm width.
I guess my point is for all detectors, if the power is not constant for the whole period of battery discharge, then as the day progresses we will be losing depth, and in the goldfields this is not what i want, as i`m hunting deeper ground looking for those big chunks of gold.
What if the battery is 2 years old, nearing the end of it`s life, will this battery still give full power that is required?

[waltr]

Thanks guys, i appreciate your knowledge on this, is very helpful, if you want an idea what the battery looks like, try ebay and type in battery for minelab sd, it`s a rectangle size battery 14 cm wide by 10 cm high by 4.5 cm width.
I guess my point is for all detectors, if the power is not constant for the whole period of battery discharge, then as the day progresses we will be losing depth, and in the goldfields this is not what i want, as i`m hunting deeper ground looking for those big chunks of gold.
What if the battery is 2 years old, nearing the end of it`s life, will this battery still give full power that is required?

As I stated above:
It depends on many factors and you need to STUDY exactly how the Voltage of battery you are using droops during discharge.
There is NO simple answer.

If the battery is old then your must measure the Voltage discharge curve and compare it o the SPEC for that EXACT battery to determine if it is time for a replacement.

Also, as I and others stated, IF the battery is NOT over discharged (still on the more level part of the discharge curve) then there should be NO noticeable loss of depth.
This is a case where comparative Air tests will show if a loss happens. Test with a full battery then after the detector has been run for several hours.
Then you will KNOW instead of us guessing.

Last, The TX power is much less important for depth than a VERY GOOD Receive circuit. For example if you doubled the TX power the depth increase is only about 1/8th.

[kt315]

try ebay and type in battery for minelab sd,
---
please do not send me afar. i asked you pics, i grasp ML used NI-CAD battery in his last but i must see what you have.
also you have to open the batt holder, show us cells and write what every cell gives voltage.
another way we run to LIPO matter and i had know people LIKE this one to disput here but that absolutely does have not relation to your subject.

[Nova]

Thanx everyone, i think u have answered my question thoroughly enough, true Waltr, the best thing to do is measure when battery full then 4-5 hours later measure again, this will answer my question, i guess i believed that this was common knowledge amongst engineers, but i guess it`s just not that simple, like most things in life i suppose.
Anyway thanks all for your replies
Cheers!!!

[waltr]

Thanx everyone, i think u have answered my question thoroughly enough, true Waltr, the best thing to do is measure when battery full then 4-5 hours later measure again, this will answer my question, i guess i believed that this was common knowledge amongst engineers, but i guess it`s just not that simple, like most things in life i suppose.
Anyway thanks all for your replies
Cheers!!!

It is the issue with batteries. These are electro-chemical systems that change over time and each type is different.
For example your Car battery, It starts your car for years but then one cold morning it just doesn't have the poo the start the car.