Why All The Love For 9v Batteries?

[mh9162013]

Thanks for the detailed and informative post - I learned a lot.

I think your point about the low noise circuitry might be one of the best reasons I've ever heard for using 9V batteries. I can imagine how a pinpointer could really benefit from low noise.

 

The leak issue is also a good reason, but easily remedied by using NiMH or lithiums and most modern devices are capable of handing cells with 1.2 to 1.7 nominal voltages.

[EL NINO77]

The 9V battery is still one of the industry standard heads for low current devices ... The only disadvantage I see in 9V Ni-MH rechargeable batteries is the smaller power capacity of 170-mAh up to max. 250 mAh .Classic Alkaline or Lithium 9V batteries - having 3x to 5x higher capacity energy - 600 to 1000 -1200 mAh.

But I believe this difference in power capacity in the near future with the help of li-ion or li-pol technology will quickly equalize ..

[mh9162013]

On 3/23/2019 at 4:27 PM, phrunt said:

Noise on a circuit can cause false signals, metal detectors have noise suppression built into them as much as possible but noise is always an issue with sensitive electronics, pinpointers don't have a lot of space for bulky circuits. 

I will leave it up to manufacturers to decide what battery is best for what application, it's easy to criticize being an end user.

You can buy an F-pulse for your pinpointer if you prefer AA's, it's a good pinpointer and they made it run off AA with a reported 25 hour battery life.

I guess we have to remember the 9v shape is just a form factor, they can use whatever battery storage technology they like in the battery. 

How do you propose you're going to make a 3 x 1.5 volt batteries work in a pinpointer designed for a 9 volt battery? You're going to make your own noiseless booster circuit for in your little battery package and somehow make it fit into the pinpointer along with the batteries and make it perform as well. It would have to perform better or it's a futile exercise.  It just makes no sense.  You'd be better off just buying the F-pulse and you've got what you want without having to make any unusual modifications.

The problem with the F-Pulse is the growing pains its had. Supposedly they're gone, though, but I'm not 100% convinced, especially with so many other options out there (although they use 9V batteries).

There are voltage boosters out there that can easily take 3.6 or 4.8 volts and up it to 9V with about 80-85% efficiency. As for how clean it does so, I don't know and is not something I had thought about. It may fail miserably, kind of like those first edition F-Pulses, or it could work just as well as 9V batteries, but give users the ability to use alkaline, NiMH or lithium (primary) AAA cells in their pinpointers. 

Assuming the noise isn't an issue, making a 3 cell AAA adapter will be a walk in the park. The hard part will figuring out how to fit in in the pinpointer with the least amount of modifications to the battery compartment or end cap. Ideally this can be done with no modifications to the pinpointer itself, but I'm not optimistic. However, I won' t know until I try, hence my WTB post in the classifieds section asking people for busted or broken pinpointers for me to tinker with. Even if I have to McGyver an endcap extension, if it allows me to avoid the 9V battery (and keep the same performance), I'll take it - I hate 9V batteries that much.

[mh9162013]

1 hour ago, EL NINO77 said:

The 9V battery is still one of the industry standard heads for low current devices ... The only disadvantage I see in 9V Ni-MH rechargeable batteries is the smaller power capacity of 170-mAh up to max. 250 mAh .Classic Alkaline or Lithium 9V batteries - having 3x to 5x higher capacity energy - 600 to 1000 -1200 mAh.

But I believe this difference in power capacity in the near future with the help of li-ion or li-pol technology will quickly equalize ..

 

But why? Sure, there's the low noise advantage, but even then, why not design a device so it doesn't need voltage boosting from the batteries?

I wouldn't be surprised if metal detecting tech naturally wants higher voltage. But even if true, lithium batteries are so cheap and easily available  that just a 2 or 3 cell Li-ion or LiPo pack that's built into the device should be easy to design. And another advantage will be forced obsolescence, as lithium rechargeables have limited cycle lifespans. Alternatively, manufacturers could offer battery replacement services for these devices and use it as another money making opportunity.

 

[mh9162013]

Thanks for the suggestion. I may do that if I can't find a suitable donor soon. I'd like to avoid that though, to keep myself from funding counterfeiters but more importantly, to not worry about the slight internal differences that may exist.

[Noah (FL)]

I purchased a 4pk of EBL “9volts” with a charger about 2 years ago to use in my Tesoros and Garrett PP.   They still provide enough power for a couple days of detecting when fully charged.  I’ll have to double check on the maH rating as I’m currently away from home.  

 

[EL NINO77]

8 hours ago, mh9162013 said:

 

But why? Sure, there's the low noise advantage, but even then, why not design a device so it doesn't need voltage boosting from the batteries?

I wouldn't be surprised if metal detecting tech naturally wants higher voltage. But even if true, lithium batteries are so cheap and easily available  that just a 2 or 3 cell Li-ion or LiPo pack that's built into the device should be easy to design. And another advantage will be forced obsolescence, as lithium rechargeables have limited cycle lifespans. Alternatively, manufacturers could offer battery replacement services for these devices and use it as another money making opportunity.

 

Quote

 

Some metal detectors have separate power to the main electronics where the voltage converter ... and the detector's audio output works directly from the battery ...

So the low battery voltage while the detector electronics is working OK, but the audio part is already very weak sound signal ... For my detectors it's TeknetiksG2, and Fisher GoldBug2 ..

9V battery meets the requirements for low power detectors .., and provides another advantage in small size 9V battery and weight -up to 30-50grams..

 

For heavier power detectors .. and utilizing a large number of 6X-8X AA batteries - which means a large weight of 200-300 grams of battery holder is the use of a 2-3 Li-ion battery quite a big advantage ..- High power capacity ..., ... Low weight ... as well as reliability of work / 2-3cells Li-ion compared to 6x-8xAA battery with large current draw /
.. this is a plus .. 

[Geotech]

When I designed the TRX, management wanted 9V, I wanted 2-AA, so I designed it for both. It quickly became obvious that 2-AA was the right answer, so when I designed the F-Pulse it was 2-AA all the way. I won't design for 9V again unless a gun to the head is involved. Even AA seems to be endangered, as more & more designs are moving to rechargeable lithium, many with no dead-battery backup option. Not sure how I feel about that.

 

[EL NINO77]

....I think Fisher Impulse AQ shows the right way using 18650 li-ion Battery as a power source..for very powerful detectors...

[Geotech]

3 hours ago, phrunt said:

Thanks for entering the conversation Geotech I was really hoping you would ? , do you know the reason behind management wanting 9v and what was your reason for wanting AA over 9v?  Your answer here may get a bit over my head so be gentle ?

Management was gun-shy to do anything differently than what others (Garrett, Minelab) were doing. I wanted AA because I personally don't like 9V batteries.