DURACELL AA BATTERY QUESTION

[Waikiki_Sweep]

Yes, I am taking out 18650 to charge (as well as we need to take out AA to trash).

Charger for two batteries costs $2.5-3 on eBay.

Holder I found starting $1.23



Batteries form $1-2 each.

But I mostly using 18650 cells from broken notebook computers because they are more fit to declared capacity then those you can buy on eBay.



Also you can make your own charger using MAX1555 ic



I do not recommend to use four cells to 12V detectors because it is overshot.
You will have 4.2 X 4 = 16.8 V at max charge.
Three cells are OK. 4.2 X 3 = 12.6 V.

3.7 volts is lower edge of voltage. Full charge is 4.2. I never discharge it to 3.7 volts. I recharge it if it has 3.9 V.

Also you can buy miniature digital voltmeter starting $1.45 on eBay to know your power supply voltage.
Search for "Mini DC 2.5-30V LED Panel Voltmeter".



Just add a "battery check" knob or Reed switch and use magnet to turn it on if you using waterproof case for your detector.

[Carl-NC]

Well wikipedia says this" Primary (non-rechargeable) zinc–carbon (dry cell) AA batteries have around 400–900 milliamp-hours capacity, with measured capacity highly dependent on test"

But elsewhere I found this quote" These are your standard 1.5V AA alkaline batteries from Duracell. Don't even think about trying to recharge these. Roughly 1500mAh per. "

So I'd guess you could count on around 1000ma from a typical alkaline "AA" cell.. So 10 hours at 100ma draw.

Most alkaline AA are 1500-2000 mAh under modest load (i.e. 100mA).

Most carbon-zinc AA are 500-1000 mAh under modest load (i.e. 100mA).

Most rechargeable, whether NiMH or LiIon, are rated 25% above their actual capacity. That is, if the package says 2500mAh, assume it means 2000mAh.

[daverave]

i think Carl i will use a rechargeable battery pack in my next project as i feel the duracell alkaline are unacceptable at 2000 mAh and not cheap to buy.

[daverave]

do you think rechargeables are better for pulse detectors as the internal resistance of the battery is much lower compared to alkaline...maybe a little bit more depth ????

[Carl-NC]

do you think rechargeables are better for pulse detectors as the internal resistance of the battery is much lower compared to alkaline...maybe a little bit more depth ????

In most PI designs battery resistance isn't a limiting factor, if the design is done right using a reasonably low ESR tank cap. So I doubt you will see much difference in depth with different batteries, just different run times and different costs. Generally I recommend rechargeables to people who hunt on a very regular basis, and alkaline to people who hunt on rare occasions. Personally, I really like the Energizer 9X Ultimate Lithium batteries; they do exceptionally well with high current (1 amp) delivery, just not rechargeable .

[6666]

These I like and have ordered some thanks

Mini DC 2.5-30V LED Panel Voltmeter

[Waikiki_Sweep]

You can have more depth if you switch to rechargeable batteries!

How?

If you have literally unlimited power source you can increase pulse width and burn as more energy as you want creating more powerful magnetic field.
Increasing in depth in couple inches will triple energy consumption as I have checked. Not much but who do not want those inches ???
My Surf PI runs at 130 mA instead of 55 mA as it was designed and I like that depth it gives me now.
But if I will use Energizer batteries in such mode for last three years I am detecting up to 10 hours a day everyday
I have no idea how thousands $$$$ I have to spend on batteries by trashing 8 pack every day.
But I am using 3 X 18650 all those years and they can be recharged 500 times. So extra power costs me nothing.

If you have any doubts please read: SAND SHARK OPERATOR INSTRUCTION MANUAL

http://www.tesoro.com/info/manuals/c...arkmanual.html

Set the Pulse Width

The PULSE WIDTH setting controls the amount of signal that the Sand Shark will transmit into the ground. A pulse induction detector works by transmitting a signal and then reading the residual eddy currents that are left on metal items. All of this takes place at approximately 600 pulses per second. Increasing the pulse width allows the detector to transmit longer and create more eddy currents on a metal target. These extra currents are more easily picked up during the receive phase and will therefore increase depth and sensitivity. However, more transmitted signal means more power used in the transmit phase, limiting the battery life. We have marked the best balance of battery life and depth and sensitivity on the faceplate at the mid-position on the PULSE WIDTH adjust knob. You will be able to increase or decease the PULSE WIDTH by turning the Pulse width adjust knob. Start with the detector in the factory recommended position and wave a few targets in front of the coil. Try turning the knob and see what effects it has on depth and sensitivity.

But as result:

SPECIFICATIONS

Battery Requirement ( AA DC (alkaline)
Battery Life (typical) 10 to 20 hours

............

I am sure that good PI detector have to use RECHARGEABLE batteries !!!

[Waikiki_Sweep]

Also if you will go to overclock your Surf PI (increase pulse width) do not forget to add fuse to your schematic. I already have one kit with melted MOSFET

[Mechanic]

Hi Guys,

If you are using li-ion or li-po, make sure you have a good protection cct in place to protect the cells form over current, over charge and over discharge. If you let the cells go below their minimum voltage, the cells will be damaged and no longer hold the same capacity, if at all.

Cheers Mick

[mohandes]

i think seald lead acid is better(just alittle heavy)
buy 12v 7.2amp or higher amp , i buy it and now have 11.5volts but IDX can work(regulator of IDX is 780

[Waikiki_Sweep]

Protect the cells form over current, over charge and over discharge.

Thank you. It is important point!
So you can buy protected cells. They have small control circuit inside. Also such cells may have a little less output voltage.

But in most cases it is not necessary:

over current - fuse
over charge - proper charger
over discharge - detector just stop working at 8.5 volts or so. So turn it off. That $1.45 LED panel voltmeter helps too.

[Praco]

If you go with rechargeable batteries?
I recommend the 'MAHA' charging unit , it is a computer controlled charging unit. With multiple ways to keep your batteries in tip top shape for years!
http://www.mahaenergy.com/mh-c9000/
We still have energizers that are over 5 years old!

The best of:
Alkaline
1. Eveready Gold 2700mah $.50 each
2. Rayovac 2500mah $.56
3. Duracell 2100mah $.95
4. Energizer 2000mah $.89

Rechargeables
1.Energizer 2275mah $2.65 each
2.Kodak 2000mah $2.70
3.Polaroid 2100mah $1.93
4.Rayovac 1400mah $1.50

Hybrid rechargeables (come precharged & cost 1 penny to recharge)
1.Powerex 2700mah $2.96 each
2.Immedion 2100mah $2.95
3.Rayovac 2100mah $2.25
4. Enloop 1900mah $2.95