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Battery question

Andy can

New member
I just got a Vanson charger and 8 nimh batteries for the explorer. It says charge 12 to 14 hours. I did, plugged it in, nothing. I took them out, and put them back in the pack carefully to be sure I hadn't turned one around, .. nope. still nothing. I read the side of them and they are 1.2 volt batteries. Is this normal?
 
Did you plug the charger in, prior to inserting the batteries? This is the proper sequence, but I`m not sure if it would prevent the charger from working if done in reverse.

BTW, I already had a leaky Vanson battery, after the second charging no less. Seems like pretty crummy original equipment for a $1000 detector. I upgraded to Energizer 2500mah batteries and a charger from Sam's Club.

Russ
 
The 1.2 volt batteries seem to run my Explorer XS okay but they won't run my Sovereign GT.
Will they 1.2 run the Explorer II?
 
Been using Energizer rechargables since I've had my EX II and not a problem as of yet! Run them in my Musketeer Advantage too! Mine are all 1.2 volts and work just fine! On a full charge the 2300 mah batteries will run me 14 hours easy! Sounds like you may have got a bad set of batteries or a bad charger. Check things out with an ohm meter and see if things are in order. That would be my first move.
HH Gilly in Illinois
 
Hi Andy,

Both the Energizers and Vansons are 1.2 volt, which I believe is typical for rechargables.

I don`t know how long the 2500s will last, I haven`t been able to burn them down yet, although my longest detecting spree has only been about 3 hours. I apparently don`t need those hi cap batteries but at about $15 for 8 I can`t complain.

They also work well in my various radios and GPS units.

Russ
 
The Explorer and Explorer II take 8 nickle hydrides to work with a total of 9.6 volts. The Sovereign takes 10 of these batteries to work as this is what is in the rechargeable pack of the factorys. The alkaline pack only take 8 of the alkaline batteries that are 1.5 volts apiece, so the 8 nickle hydrides will not work in the Sovereigns.
 
I wonder if the batteries you are trying to charge are dead as some charger will not charge a completly dead battery, this is one of the reasons never run your batteries untill completly dead. The Explorer will shut down before completaly dead, but some like to discharge the batteries with a light bulb and forget them and ruin the batteries.
The other posibitllity is the charger you have is not working, check you outlets and conections.

 
The batteries were brand new in the plastic, as is the charger. 4 red lights were on (indicating they 8 batteries were charging properly). Don't have an ohm meter, but I put them on a small battery tester, there is no place to test a 1.2v so I put them on the 1.5 location, and they all tested around the replace battery stage. Not sure what that is telling me. Thanks for the response.
 
I did put the batteries in the charger before I plugged it in, can't imagine what difference it would make, the charger indicated it was charging ok. I'm thinking of trying them for a few more hours, but it says they can be ruined by overcharging???
 
that came in my sovereign in the 90's - 10 nicads AA's

somewhat heavy

now i have built two 10 packs of AAA's..........nick. med. hyd.'s - work okay........lighter

only difference is the AAA's only last about 6 hours each pack..........

these are all 730 mA's each battery.

 
Rick,

I have always been puzzled about the 1.2V notation. The Minelab manual shows the discharge curve (the battery voltage under load vs. time) on page 92.

The fully charged voltage is 11.4V. This translates to 1.425V per cell

The shutdown voltage is 8.75V. This translates to 1.094V per cell

At 1.2V per cell the battery voltage is 9.6V. One will note that the discharge curve indicates that this voltage is about where the battery is exhausted and begins to fall off rapidly. This suggests that the 1.2V rating represents when most of the battery useful charge has been delivered.

HH,
Glenn
 
A problem that one will encounter at times is an 8 pack compared to a 10 pack. The NICAD batter is rated at 1.5 while these batteries are 1.2. The total voltage is found by 8X1.2=9.6 volts and 10X1.2=12volts. So, eight 1.2 volt batteries will not work for a device that requires 12 volts or will work for a much shorter period of time.

Measure the output voltage of the charger with a voltmeter. The charging voltage for a battery has to be greater than the voltage of the battery because the charging current flows through the battery in the reverse direction of discharge. As an example a 1.2 volt batter connected to a charger that is rated at 1.2 volts will only supply a very small charging current and then only for a short time. A 1.2 volt battery actually connected so the battery voltage is in opposition to the charging voltage. So, 1.2 volts in opposition to 1.2 volts has a total voltage of 0. However, if I have a charger with and output of 4 volts connected to a 1.2 volt batter then the charging voltage is 4-1.2 volts for a charging voltage of 2.8 volts. The greater the difference the more charging current will flow so there is a limit to a safe charging current. A fast charge has more charging current flow in the circuit than a slow charge.

Be sure the batteries are placed in the charger in the correct polarity since the batteries have to be connect so the charge current is from positive to negative. In the detector the discharge current or working current flow is from negative to positive. Also, a battery has a load and no load voltage when measured with a voltmeter. The no load voltage is a quick check but a bad battery will often have a no load voltage that is about correct. However, if the battery is connected to a load and then measured the voltage will be very load. A loaded battery is on that has something connected to it to draw current such as a resistor or other load.

HH, Cody
 
I intended to say a the end of the post that a battery measured under load can be very low compared to the voltage measure with no load. Also, you cannot measure the resistance of battery with an ohm meter. This is a situation where we are interested in voltage and current so need to use a multimeter that can measure voltage and current. I think most technicians would measure voltage and calculate current due to the difference in how they are measured.

HH, Cody
 
Cody,

It has been a while since I designed battery chargers, but I believe that most chargers do not charge with a simple voltage source. The reason for this is that the charging current could be excessive and damage the battery. What is commonly used is a current limited "float" voltage. Therefore, if the cell (or battery) is depleted, then the current limiter determines the maximum current into the cell. As the cell is charging, then the cell voltage will rise towards the "float" voltage. As the cell reaches the "float" voltage then the charging current goes to zero (in this simple charging technique).

Another common charging technique is to use a "trickle" current that continues to flow even after the float voltage is reached.

* When the cell is not completely charged, then the electrical energy into the cell is converted into chemical energy. Since the charging process is not 100% efficient, then there is a portion of the electrical energy that is converted into thermal energy and increases the temperature of the cell to allow for the thermal energy to be transmitted away from the cell. If the charging current is too great, then the temperature rise in the cell can causes damage to the cell. For this reason we have to be careful not to use excessive charging current.

* When the cell is completely charged, then the electrical energy into the cell is all converted into thermal energy and can give rise to cell damage if that continued current is too great. The "trickle" charge is selected to "top off" the charging process without causing damage to the cell. One will note from the discharge curve that charging the cell to the last millivolt does not provide much extra capacity in the cell.

HH,
Glenn
 
Good information. I was thinking of the little wall wart chargers that are not much more than a transformer, few diodes, and a capacitor or two. Not much more than junk in my opinion but will do the job. However, they get the basic ideas across and that is about it.

HH, Cody
 
Nickel-Cadmium and Nickel-Metal-Oxide batteries are both 1.2 volt cells. Alkaline (throw-aways) are 1.5 volt.

Some detectors that are "12VDC" (comes with 12 volt packs) will work, say from 10 volts to 14 volts. Some will work from 9 volts to 15 volts, etc. It depends on the design and the circuitry used. The Quattro and Explorer will work on <9.6 volts (8 pack of 1.2 volt cells), but others may not.
 
Go to this web page ( http://www.nimhbattery.com/mhc401fs_buy.php3 )and check this battery charger out . I have one and its great . You can slow or fast charge . Also does not over charge . Will Trickle charge at the end .
 
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