Metal Detecting Forum

After finding out that the AA nimh batteries only coming in 1.2vdc the charge and amp load was not good enough for the Tejon,1.2vx8v=9.6vdc,i used the Tejon with this battery type and it did not preform well.I changed to Alkalines this weekend and so did my luck.

hi brokensignal. as another happy tejon owner, i've heard from a few others out there that rechargeable batteries don't do well in a lot of tesoro units. there are some machines out there that do well with rechargeables - and i don't know why. i just can't bring myself to spend big bucks for a charger and batteries that seldom ever power all the way up and often fail in the middle of a hunt. maybe technology hasn't advanced that far yet. i'll stick with alkalines too.

but, like i said earlier, some machines and people do real good with rechargeable batteries.


the tejon is pretty hard to beat to begin with. i go to home depot and get the 24 packs of double a's for less than 10 bucks. they work good, and last long time! the upside is, when i'm done with the batteries and change them out, they will run all the remotes in the house for months! hh!

They make rechargeable alkalines now dont they??Maybe they would work..Alot of the newer battery types dont have a memory now ,like the one im my E-Trac..I can charge it as little or as much as i like without effecting the length of time it stays charged..I think i saw alkaline rechargables at ace hardware the other day..Ill look next time im there and let you know..Buying batteris can add up fast...Radio shacks batteries are some of the Best!They are as good as duracell and are way cheaper.Good Luck..Happy Hunting



Edited 1 time(s). Last edit at 08/24/2009 08:35AM by NiagracountyNY.

My thinking is if battery life/cost becomes such as to be a concern, then that means I've been detecting a lot YEA! My two bits.
HH
BB

BarberBill the cost is not an issue for me either but i just wanted others to know if they go buy NIMH rechargeable AA batteries thinking they are getting a 1.5vdc battery they are not.The NIMH rechargeables only come in 1.2vdc and i found this out because my Minelab would not even get a threshold tone with these batteries.So i referred to the Minelab forum and they said on certain 12vdc detectors these batteries would not work because the voltage is to low starting out.1.2 x 8 =9.6v.The Minelab is a 12vdc metal detector.And i did notice a shift in performance when i stopped using them in the Tejon.Now for the 9V rechargeable NIMH batteries that i use in the Vaquero is great,they charge to about 11 volts.

After that the voltage actually drops below the 1.2 volts that a nimh battery maintains through out its charge.

Here is a pdf with some graphs of how the battery voltage of alkalines and nimh batteries drops through the service life. So unless you put in new alkalines every 5 hours or so, you will end up with higher voltage from a nimh battery for all but the first 5 hours.

http://www.eznec.com/Amateur/1.5_vs_1.2_Volt_Batteries.pdf

Does anybody have an explanation as to why NiCads and NIMH batteries are 1.2 volts rather than 1.5? Can't they be designe/manufactured at 1.5 volts? I've wondered about this for a long time.
HH
BB

That post from stevenh is worth reading and studying a bit. It was written by a HAM radio person and they know their electronics like we know our detectors. That paper clears up, scietifically, all the myths about Nimh vs. Alkalines. The Nimh wins hands down.

Look up T-Energy. They sell top of the line Nimh AAs and they even sell them in a package deal with good chargers. Usually for less than $20 total I don't know which ones are the super new ones, but there is one manufacturer who states their Nimh will retaing 80% of its capacity after sitting on the shelf for a year. That used to be one of the bad points of the Nimh. It air discharged after it was charged and in 2 months when you needed it, it'd be dead and need to be charged again.

The other myth about Nimhs is when they are getting to the end of a charge they suddenly fail. Look at the graphs from stevennh. They do drop off a bit faster but not the sudden deadness complained about fairly often when battery discussions take place.

Thanks for the good paper that dispells the myths. Jim

Steve(NH) it looks to be a good comparison of the two types of batteries.Minelab forum said different.Such as the battery pack for the Sovereign for instance,is a 12vdc-8-AA Alkaline battery pack,If you check with Minelab they will tell you the NIMH recharge-ables will not run the detector properly due to the fact that 8 -AA-NIMH -1.2vdc will not work or add to the required voltage of 12vdc.If you take a 8-pack AA-alkaline and measure the volts no load will be 14 to 15volts dc to start.NIMH setup =9.6volts-2 more AA's are required.There would need to be a total of 10x1.2=12volts,this is causing some detectorist to modify there detector battery packs.Thanks for the input.



Edited 1 time(s). Last edit at 09/03/2009 09:24PM by Brokensignal.

I might even try some of those high dollar funky lithium batteries.Then i will see what the Tejon will do!.Does this buckle look old? Thanks for the help.

Johnnyl helped me on Wharzit Forum and said it is a colonial shoe buckle.Now if i can find another one i can put them on my shoes and take a walk back in time.

They start out at 1.75v and level off around 1.5. They are really good for detectors. I just bought 40 of them for about 50 bucks. Just put some in my Tejon last night. The regular alkalines that were in there were about 1.4v. I save them for use in other things.

I put Oxyrides in my V3 and it has stayed around 12.66v but I haven't used it much since I put them in. I expect it to stay above 10v for quite a while... time will tell.. When I use the rechargable battery it drops below 10v quickly and below 9v in a hunt.

Those Ultimate Lithium batteries are really expensive, I have not tried them. I need to shop them online, also I wonder where the voltage starts out on them. The 1.7+ voltage on the Oxyrides is a big plus.

J

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Julien in Cartersville, Georgia...

SovereignGT
Tejon
T2
E-Trac
V-3
F75 LTD
Omega-8000
Compadre

I have CDO. It is like OCD but the letters are in order like they should be...

Hi jbow the doctor asked me the other day if i wanted some lithium and i told her that don't sound to good,and could get expensive!.

Thread is a bit old, just wanted to chime in about using LiPo batteries on a Tesoro Tejon. I bought one used off @#$%& with its shaft broken, it was an easy repair since I had one of those chinese cheap detectors which served as a shaft donor for the Tejon. I replaced the 8AA battery enclosure with a 3S (3 cells, 12v in total) LiPo battery. It runs at 12.6V when 100% charged and will go up until 11.5 before I charge it up. The Tejon seems to love it and it gets me a long time between recharges.

Quote
BarberBill
Does anybody have an explanation as to why NiCads and NIMH batteries are 1.2 volts rather than 1.5? Can't they be designe/manufactured at 1.5 volts? I've wondered about this for a long time.
HH
BB

People get hung up on this 1.5v vs 1.2v which is actually 1.25v.
If your device has to run on 1.5v batteries then you would have to change them out and throw them away after about 3 hrs of use!
In MOST all battery powered devices the power supply is above 1.0 -1.1 volt and everything above that is regulated down to the lower range (1.0-1.1 volt).
Keep in mind that in many cases there is more than one battery, and they are likely in series, many they actually voltage is multiplied, x-1 x2 x3 x-4 and so on,
but lets just use the 1.5v vs 1.2v for conversation!
Standard batteries start out at will say 1.5v and steadily decline until they're dead, and dead is somewhere around the 1.0v range.
Well, the rechargeable's don't do this, they start off at 1.25v and stay there though their cycle, then they avalanche (fall off very quickly) so in essence the rechargeable has a much more stable
power output as compared to the standard batteries.
Yes, in a non electronic flashlight the light will be brighter at the 1.5v vs 1.25v but to keep the 1.5v going you have to change the batteries when they get to 1.4v or to say every few minutes, your only
starting off at a higher voltage, your not maintaining it!
Modern electronic devices are regulated to the lower end of the battery, so a 9v device isn't using the 9 volts, its actually operating at 5 to 6volts, so the usable part of the battery is only the power above that.
I had two Tejon's and they run just fine on rechargeable's.
What's really going on here is a mental thing to some point, 1.5v has to be better than 1.2v its more power, but not if the electronic device is not actually operating at said 1.5v.
Its everybody's choice to which battery type they like to use, but I think its good to clear the air of the myths of both!

MarkCZ

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