NIMH-AA-1.2v-Batteries Are Not Adding Up

[Brokensignal]

I have done the voltage test myself,It would require 10 NIMH-recharge-ables @ 1.2v to = the required 12volts for 12volt detectors.

 

[BarberBill]

That's true, however most detectors have a voltage regulator that adjusts the voltage to a preset level until the battery voltage drops blow that point. Many 12 volt systems actually function at around 9 volts or so. I've seen battery box modifications mentioned on the forums for one of the competition's machines where an extra battery or two (nimh or nicad) is added to bring the voltage up. I've never felt the need for rechargeables as good quality alkalines give many hours of use.
HH
BB

 

[Brokensignal]

Yes BarberBill but the battery go green earth movement is trying to get rid of alkaline batteries.I know the detectors have a voltage regulator at the start of the detector circuit.Both volts and milli-amps are important here.Volts are what gives the milli-amps the driving force in the circuit.If you start out with a weak runner with low energy levels,the performance is not the same as if you start out with a runner that starts out with high energy levels.

 

[Brokensignal]

The Minelab Musketeer or Sovereign will not work but for short a period of time if that with these 1.2v-AA NIMH rechargeables.So perhaps there could be other detectors that could have trouble that are 12vdc detectors with voltage regulators that are near the 9.6 volts dc these batteries put out.8x1.2vdc=9.6vdc no load,put a load on them,what 8.5vdc,You are not kidding me right,you think this is ok?.

 

[BarberBill]

I've asked this before on a similar post -- What is the reason that the rechargeables aren't manufactured at 1.5 volts? Anybody know?
HH
BB

 

[Brokensignal]

Can't you see it,it is a government cover up,and no one can figure it out.But i am getting to the bottom of it.

 

[Furious T]

Brokensignal, it seems that some detectors work ok on rechargeables and some dont. I'm certainly not criticizing you for your concern about pollution with all the batteries that are thrown away, by other people as well as detecorists. The NiMH (Nickel Metal Hydride) rechargeable batteries have a voltage rating which is normally lower than ordinary batteries, as you already know e.g. 1.2 V as compared with 1.5 V and 8.4 V as compared with 9V.

There is also another rationg: mAh, which I suspect, has to do with the length of time that the battery can supply the amount of voltage: AAs can range from 1800 mAh to 2500 mAh, and from my experience (and please believe me, I share your frustration) using anything less than 2500mAh is virtually useless. There may now be batteries with higher mAh ratings, I haven't checked for a while. It can also depend on the detector a bit. With my Cibola, it is hardly worth putting a re-chargeable battery in it, while the same battery will last a little bit longer in my Eldorado U Max.

All which I have written here is just from my personal experience, and not from any in-depth knowledge of electronics, so if there is anyone who wants to correct me or add to what I've said, please go right ahead.

Thought it might help, Brokensignal that you are not the only one who is being frustrated by this developing technology. Sapper.

 

[trueblue]

the higher rated 2500 & 2900 mAh work fine in my Tejon considering it takes 8xAA's rechargable's really save me some $$$ no big deal with rechargables in the Umax dectectors there so fuel effiecient on the single 9vlt Alki

 

[Furious T]

There are 2900s? I'll have to get some to try....thanks trueblue;.

 

[Brokensignal]

Trueblue power x makes 9 volt rechargeables that are actually a 9.6vdc that charges to 11v-12v.The 9 volt batteries i have no problem with.What people are not realizing is when you go get 8-AA-Alkaline batteries to use in you 12vdc detector.You take those 8-AA Alkaline batteries and no-load test the voltage,it is not going to be 12vdc it is going to be higher,roughly about 14v-15v,then the charge voltage will remain around 12vdc longer which is good because you do not want a voltage to go down to say 9vdc,why because this is usually were the cut off to the voltage regulator is at inside the detector,ok.You go get 8-AA-NIMH-rechargeable 1.2v batteries and charge them up,these batteries will not charge higher than 1.2v.ok you know the drill 8x1.2=9.6vdc.This is starting out voltage on a 12vdc detector.Yes i know about the higher Milli Amp hour (mah) batteries.When you cut the detector on the voltage is so close to the voltage regulator inside the detector that the detector may work or it may not,this is called loaded voltage measurement on a devise.This voltage will then drop approx a volt which would now be 8.6vdc on a 12vdc detector.Volts are just as important as amps,the volts are what drives the electrons(amps) through the circuit.Sure these batteries will work in your mag lite,but when you are controlling electronic devices that must maintain a level of voltage to preform right 8.6vdc is not going to preform right or if at all in a 12v designed metal detector.I do have experience with electronics,i worked in the electrical & electronic field for over twenty years.So you can bring out a technical paper out or say they are working fine in your detector,but this is a myth,there is no way!.It don't add up!.And i can guarantee you there are others that have used these batteries in there detectors and looked at the charge meter or listened to it and said this is not right.

 

[trueblue]

Sapper yeah I got some 2900's off EBay vapex brand tassie seller good quality batts well priced ....there've gone in price a bit since I brought mine but they are good quality ...cant say the same 4 the vapex AAA's I'd steer clear off them ...

2900 vapex batts ebay

Brokensignal .....ya got a point there 4 sure I dont disagree , I just figure my Tejon fires up with 4 beeps on fully charged NIMH and well as far as I know operates perfectly get good depth disc is spot'on an all rest of it ..I have used Alki's and didnt find any difference apart from on my pocket ....but there may be ? I cant be sure and have no way testing the theory ? hmmmm interesting discussion sure makes ya think

 

[Brokensignal]

Really it will run smoother with more voltage,even though metal detectors have voltage regulators at the beginning of the circuit,the proper force needs to always be there to run the detector.

 

[trueblue]

hmmmmm after a long hard think Im reckon'ing that NiMH's are just fine my reasoning behind this is :

Ya alkaline batts will after 4 -8 hrs or there about will probly drop in volts to 1.2 or less this is in my Tejon yet may vary as I havnt tested .
now unless ya got plenty a $$ for constant fresh batts ya detector is now gunna be powered by at that ugly 8-9 volt range no ? and given that NiMH ' s discarge at a slower rate...that would mean that after that first 4-8 hrs ya'd be better served by using the NiMH's
thats not to metion the wasteful replacing of half drained batts .
keep in mind I aint tested this theory but I plan to , Im gunna take me volt meter next trip and buy some quality alki's check the volts and see just long it takes then to drain down to 1.2 and below and find the voltage point at whitch my Tejon fails to fire up ......I know that the lil 9volt batts run the Umax detectors just fine at 7 volts ..Ive checked the voltage in 'em before an after use many a time , I had a bounty hunter QDII that ran on 2x 9 volt batts ..the batty alam would go off with not enough power to run the BH and yes I turned the batts every couple a hrs to ensure even draining ..yet these batts would power up and run the 9 volt umax for another 7-10 hrs on each batt.....Ok Im doin a test right now ....just grabbed and tested the volts in a 9volt alki that has been used in the wifes Eldo Umax it tested 8.20 volts ...now I just put in the eldo and turned the detector on after 15 minutes the voltage now measure's 7.85 volt's and the detecor sounds off with 5 beeps on the batt check ....yes it was a short test and a test over longer period would be better keep imn mind the detector was just sittin on the bed quiet no being used for this test ... it does show that the volt power drops off quite quickly and being that the detectors are regulated I really cant see any drawbacks in using rechargables only the opposite $$$$ savings

cheers

 

[Brokensignal]

After all it has been proven by a name brand metal detector company(MineLab) that if you have one of the metal detectors that has a 8-slot alkaline battery holder and you use 8-Nimh in place of the alkalines that the detector will just not work.This to me is why i would never get rid of a good 9v battery detector !.Some of the newer model Minelab detectors are being made to run on NIMH AA batteries such as the X-Terra detectors.But i would be careful of the older detectors that are not designed to work on this type of battery.Another case in-point.I have a digital camera that was designed to run on 2-AAA-alkaline batteries.I buy all types of rechargeable batteries because i am like you i do not want to be wasteful.So i make sure to charge these 2-AAA-NIMH batteries(which will only come in 1.2v,like the AA NIMH) i put these 2-AAA-NIMH batteries in the camera and turn it on to take a picture.The charge meter comes on right away and says dead batteries and the camera shuts down in less than two minutes.I have to keep turning the camera back on to take a picture.What you got for this trueblue? Keep trying to find higher mah rating batteries?You can mess around with low power detectors if you want to but when i go out to remote places treasure hunting i am having a good voltage charge on my detector ! .

 

[trueblue]

lol ... rrrr its a hard one , prehaps its a minelab problem , after all ya sayin quote " the detector will just not work" I take that to mean not power up ....well maybe Tesoro mak'em better cause my Tejon runs fine on NiMH's

It would be good to hear from the Giffards as to whether there12 volt detectors fuction ok on NiMH's prehaps the thread should also be posted on Tesoro's official forum as we'd all like to know the facts

this is an interesting topic Brokensignal

"HH"

 

[grumpyolman]

Brokensignal has posted this concern in several other sections of this forum with the same title. I respectfully think he is in error. Please read the following link. You'll have to find the post from SteveP (NH) and follow his link.

http://www.findmall.com/read.php?18,1036094

There you will find a pdf. scientific report about the discharge rates of Alkalines vs NiMhs and substantiates some of the posts above are correct. After an hour or less of runtime, the NiMhs are producing more voltage for a longer period of time than the Alkalines. It doesn't make a hoot what you're starting voltage is when in an hour the Alkalines are producing less voltage than are the Nimhs.

I just think there is error in the logic stating that the NiMhs wont work because of voltage issues. Evey detector I have owned, plus HAM radios, flashlights, RC receivers, etc., work just fine with rechargeables.

Nicads are weird and you have to take special care of them. NiMhs don't have that 'memory' effect. The recent gripe was NiMhs air discharge when sitting on the shelf and you have to charge them before you can use them. That's been my experience. Some manufacturers now state there are NiMhs that will retain 80% of their charge while sitting on the shelf for a year. I/m gonna try a set on my Sand Shark. Jim

 

[Brokensignal]

I don't need the scientific report grumpy old man.I know how to use a digital volt meter and do simple math.That makes no sense to have all that money invested in the metal detectors that run on 12vdc and start the day off with 9.6vdc.Does this really make sense to you.Think about it grumpy.I can tell you don't like it,but you are trying to make it right in your mined but you can't.It don't add up.If it don't fit you must acquit.You know it is not right but you want it to be right.

 

[grumpyolman]

It's hard to present something new to a closed mind. You are just plain in error even if you can read a digital volt meter. Look at the study I cited and if you still think I am trying to make it right in my mind that's fine. I just hope others will do the investigating and won't be swayed by the erroneous methods and logic you used to arrive at your conclusion. It's not your reading of the voltmeter that is wrong. It is apparent you are not also measuring or considering other factors influencing the operation of the electrical device instead of starting voltage. Use your alkalines. I'll use my NimHs. Jim

 

[trueblue]

The proofs in the pudding , NiMH's work flawlessly in my Tesoro

 

[tvr]

Brokensignals,
The link to the pdf file provides valid information. While the rechargeables do not have the same peak voltage, they do retain their voltage level better than alkaline batteries until they reach a very discharged point. If the regulator cut off for the circuit is below where the load voltage of the rechargeable pack is, then you are OK.

If the Tejon gives you three beeps on the rechargeables, you are above the regulator cut off and should work fine until the charge is essentially gone.

Only reason I say should and not will is that there there are a few really cheap rechargeable batteries that are low quality and have high internal resistance that can get you in trouble since they will appear to be providing the required voltage, but can not provide any real instantaneous current. Pretty much any rechargeable battery that is advertised to be good for digital applications (as in camera or portable video devices) will be good in this application.
tvr