Brokensignal
New member
I have done the voltage test myself,no-load and under-load.For a 12vdc there would need to be a total of 10-1.2vdc NIMH AA-batteries to total 12vdc.It don't take a brain surgeon to figure this one out!.
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The NIMH AA Recharge-ables Are not Adding Up
- Thread starter Brokensignal
- Start date
Larry (IL)
Well-known member
You are 100% correct. 1.2 X10 = 12 volts. It seems to add up to to me.
If you are asking why only 8 batteries are used in the battery pack for 10 Volt operation, 12 volt for alkaline batteries, it is because most detectors operate at a much lower voltage and the voltage is controlled by an internal voltage regulator. Many of the White's detectors will operate properly down to the lower 8 volt range. I suspect other brands are similar, but not all.
If you are asking why only 8 batteries are used in the battery pack for 10 Volt operation, 12 volt for alkaline batteries, it is because most detectors operate at a much lower voltage and the voltage is controlled by an internal voltage regulator. Many of the White's detectors will operate properly down to the lower 8 volt range. I suspect other brands are similar, but not all.
grumpyolman
New member
Contact this guy and ask for his PDF file. w7el@eznec.com <w7el@eznec.com>
He's a HAM radio guy and knows his electronics. He wrote a fantastic, scientific, detailed. paper about Akalines vs. NiMhs.
Here's how it starts and shows the title to ask W7EL about.
He's a HAM radio guy and knows his electronics. He wrote a fantastic, scientific, detailed. paper about Akalines vs. NiMhs.
Here's how it starts and shows the title to ask W7EL about.
Brokensignal
New member
I take expensive 1.2v NIMH AA batteries and charge for the recommended time and no-load measure the dc voltage reading is 9.6volts to 11 volts.Turn on the detector what do you think the loaded volt measurement drops to.The loaded volts will drop at start of the detector to 9volts,this is not acceptable Yes i know there is a voltage regulator at the start of the detector circuit.Volts are an important part of this equation just as milli-amps are,voltage is the pushing force to make the electrons move.Take a 8-pack of alkaline batteries and measure the no-load voltage,will measure 14vdc to 15vdc starting out,no load,turn the detector on and the loaded volts goes to 12vdc.With the NIMH rechargables i get 3 beeps on a battery check and i can tell the performance is not the same.I am just like others,why can't a rechargeable NIMH-AA-battery be made in a true 1.5vdc rating?.
Larry (IL)
Well-known member
The short version is, the voltage developed across a cell's terminals depends on the energy release of the chemical reactions of its electrodes and electrolyte. Alkaline and carbon-zinc cells have different chemistries but approximately the same emf of 1.5 volts; likewise NiCd and NiMH cells have different chemistries, but approximately the same emf of 1.2 volts. On the other hand the high electrochemical potential changes in the reactions of lithium compounds give lithium cells emfs of 3 volts or more.
The long version, http://en.wikipedia.org/wiki/Battery_(electricity)
The long version, http://en.wikipedia.org/wiki/Battery_(electricity)
grumpyolman
New member
Please..Just read the publication. Frankly...it doesn't have to be 1.5 volts as the functional difference, after a low amp drain in just a short period of time, will show that the Nimhs are producing more voltage and for a longer period of time than the Alkalines. The voltage drop, measured under load, shows that after 15 minutes of use the Nimhs produce more voltage than do the Alkalines. This study is measureable and repeatable. Unless somebody replicates the study and shows an error, IMHO, it's significantly more accurate than somebodys observations and supposiion. For a long time people thought the world was flat and chose not to investigate the research done to prove it different. I too thought the world might be flat until I read this paper. It's NiMH for me from now on. Read it and judge for yourself.
Here's the final paragraph:
The conclusions are that:
1. You can use
Here's the final paragraph:
The conclusions are that:
1. You can use
Larry, a lot of people worry when they switch to nicads, because they can see (if they put it on a battery tester), that the voltage reads a bit lower than a fully charged alkaline. So some persons worry that their detectors will not perform as well, won't have full power, etc... What they don't realize, is exactly what you say: The detector has voltage regulators that limit the voltage to what the detector was designed to operate at, to begin with. So for example, if the regulator controls the usage to be at "1", then it won't matter whether your batteries are putting out 1.5 each, or 1.2 each, etc.... Performance won't be affected till it drops down to below the threshold set by the regulator.
Brokensignal,I'm not sure which detector you will use these batteries.Example 8 AAs rechargeable won't work very well for the Sovereign or Musketeer.Even under full charge expect only a couple of hours duration because you are already well under the 12volt needed for this system.On the other hand the Explorer is fine with this which is a 9 volt system and seem to work even better than the stock rechargeable.Good Luck Ron
Brokensignal
New member
Thank you Ron God Bless You .this is all i am trying to say.Done deal,this could perhaps effect other types or makes of detectors the same way.
Brokensignal
New member
n/t
grumpyolman
New member
OK! Point well taken. There was just some incorrect data being started and I wanted folks to be able to see a real study and judge for themselves. I hate to see someone choose alkalines when NiMhs would work better, longer and are cheaper. The final choice is the owners. I use rechargeables in my Tiger Shark, White's Dual Field, and E-Trac and they work wonderfully. Jim
With 2800mah Ni-Mh batteries the sovereign elite and GT will work as long if not longer than the stock rechargable pack, I agree that you don't have the initial voltage of alkalines but high mah takes a lot longer to discharge and reach the cut-off voltage. I also use them in the explorer/etrac and whites dual field, not tried them in the F75 yet as it came with normal duracell alkalines that i have recharged a couple of times(yes normal alkalines can be recharged too), once they won't charge anymore i will try the ni-mh in that too, also got an alkaline pod for the excali en route so i will try that too and let you know.
Brokensignal
New member
Kered,no way,i had a sovereign,and now have a Musketeer.Did you see what Ron said,i don't think there is anyone that knows more about a Sovereign than him and a handful of others on the Minelab Sovereign Forum(He said it will not work,but maybe for a couple of hours if you are lucky) If you break open a Minelab Sovereign Factory NIMH rechargeable pack,you will see it is built to charge to 14vdc-15vdc not 9.6vdc.If you take a digital volt meter and take a no load voltage reading on the ML NIMH factory recharge pack after charging it up you will get 14vdc-15vdc,this will be the required no load voltage needed for the detector.If you put 8-AA NIMH in the Alkaline battery holder that has a full charge on it and take a no load voltage reading,you will measure 10vdc-11.5vdc on the pack.You are telling me you like this,with a one Thousand dollar metal detector you are going to start the day on less volts than the detector requires?What is wrong with every one.Go to the Minelab Forum.proper voltage level is very important in a metal detector.I don't care about a radio,ham,whatever,this is a metal detector forum.We talk about metal detectors not ham radios!.You really think i am going to put 9.6vdc in a one thousand dollar metal detector that works off of 12vdc you are more nuts than i ever will be.You go on the Sovereign forum,you see how the guys are modifying the Alkaline packs to hold two extra NIMH batteries to run the Sovereign.I am trying to help people here with there detectors.To get off to a good start.You need to come clean with your voltage test.And old man can go talk about ham radios as far as i am concerned.
To start with a no load voltage means nothing, good quality rechargables when charged will give a no load voltage of between 1.35 - 1.45V poor quality cheap ones similar, the difference is when you put them under load, some drop even below the 1.2v and hence won't work, good quality ones don't drop off so much when under load and also the higher the ah/mah the better/longer they will take to discharge to the cut off voltage, its similar to putting a 12v 45ah battery on a truck and see if it will start compared to a 12v 95ah one, the bigger one will spin faster and for longer even though they both give the same no load value, so ok you keep buying alkalines and i'll do it my way with rechargables
HH
HH
SteveP(NH)
New member
When alkalines have been discharged to about 50% of their total capacity their output voltage will have dropped to about 1.2 volts, so for the 2nd half of their useful life they will produce a voltage lower than a nimh battery will. The exact voltage depends on how fast they have been discharged.
The amount of power a device needs to run is measure in watts. The power laws says that watts = volts X amps so you can end up with the same amount of power even at different voltages if the current (measured in amps is different) Here is an example - suppose your detector needs 100 milliamps from each battery in its power pack (to keep things simple we will just use one cell). We need to keep all of the units on the same scale so if we are going to use volts then we need to use watts, so 100 milliwatts is equal to .1 watt so we have
.1 = 1.5 x .66 for alkalines or we can have
.1 = 1.2 x .83 for nimh
both batteries deliver the same amount of power to the detector even though they have different voltages - the only difference is the current required from the nimh batteries is greater. This is a good thing because an alkaline battery doesn't maintain its voltage as it is used. The voltage of an alkaline battery drops as it is used. After about 15 hours of use the alkalines will have dropped down to 1.2 volts, after that they will have less voltage than a nimh battery, as the nimh batteries do (for the most part) maintain their 1.2 volts over their useful charge life.
In fact according the data sheet for energizer batteries when the batteries has used up 50% of its available charge its voltage will have dropped to around 1.2 volts. The same data sheet recommends that manufacturers design their equipment to work until the voltage drops to .8 volt in order to get all of the available energy out of their alkaline battery. You can look at the energizer battery spec sheet here http://data.energizer.com/PDFs/E91.pdf
The amount of power a device needs to run is measure in watts. The power laws says that watts = volts X amps so you can end up with the same amount of power even at different voltages if the current (measured in amps is different) Here is an example - suppose your detector needs 100 milliamps from each battery in its power pack (to keep things simple we will just use one cell). We need to keep all of the units on the same scale so if we are going to use volts then we need to use watts, so 100 milliwatts is equal to .1 watt so we have
.1 = 1.5 x .66 for alkalines or we can have
.1 = 1.2 x .83 for nimh
both batteries deliver the same amount of power to the detector even though they have different voltages - the only difference is the current required from the nimh batteries is greater. This is a good thing because an alkaline battery doesn't maintain its voltage as it is used. The voltage of an alkaline battery drops as it is used. After about 15 hours of use the alkalines will have dropped down to 1.2 volts, after that they will have less voltage than a nimh battery, as the nimh batteries do (for the most part) maintain their 1.2 volts over their useful charge life.
In fact according the data sheet for energizer batteries when the batteries has used up 50% of its available charge its voltage will have dropped to around 1.2 volts. The same data sheet recommends that manufacturers design their equipment to work until the voltage drops to .8 volt in order to get all of the available energy out of their alkaline battery. You can look at the energizer battery spec sheet here http://data.energizer.com/PDFs/E91.pdf
diggindirt
New member
kered said:
Well if you look at the Minelab video, it does show that rechargeable batteries will work fine in the alkaline pack.
The only negative is the actual remaining battery life level will be off due to the circuit looking for alkaline levels from the alkaline pack.
This is because of the different voltages as the detector circuit was designed to monitor the levels based on the type of pack being used (alkaline or rechargeable).
I suppose If you just charge the batteries before going out, they won't quit on the hunt.
Thanks!