Rechargeable 9v batteries ok for Detector?

[Benjamin52]

I have just purchased a tesoro vaquero metal detector.
I believe in the manual the recommendation is to use 9v alkaline batteries to power it.
I just stopped by a hardware store and saw that several types of 9v batteries are being sold there.
I also saw they sell rechargeable 9v batteries with a recharger.
Before I buy any type of battery I thought maybe I should ask somebody with more experience if rechargeable 9v batteries could damage my vaquero in any way?
I saw they sell rechargeable lithium, li~ion, some other technology and normal (alkaline?) 9v batteries.
Of course I would prefer rechargeable ones because of the cost and for the environment.
So are rechargeable 9v batteries ok for the vaquero? if yes, which kind is the best?

Will my decision have any impact on the detector`s performance? (e.G. could too low voltage mean I loose depth or too high voltage damage the machine?)
I also heard rechargeables will last less even if fully charged?

Thanks for any help and recommendation!

 

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[texasred777]

I've used rechargeable 9v for my detectors, Bounty Hunter 840, Tracker 2D, Tracker IV, and Lone Star, with no problems. The rechargeable ones don't last quite as long; but are a lot cheaper. And, yes, they are easier on the 'environment', i.e. my pocketbook! I'm not familiar with the Tesoro. I started using rechargeable 9v's in my BH 840 in 1981. They were very inferior back then compared to now. I used to buy the Harbor Freight brand in the 1990s. I used all sizes, 9v, AA, AAA, D, and C, for everything from radios to flashlights. I'm presently using some 9v from an Ebay store that seem to be much superior to anything that I've used before. They are rated at 600 mha; the ones that I had from Harbor Freight were rated at 150 mha! I haven't used these new ones much, but they seem to last forever. I believe I paid about/less than $30 for 4 with charger. As far as voltage is concerned, I've not seen a rechargeable that had more voltage than the alkaline, so too much voltage shouldn't be a concern. As far as depth and other performance, I can see no difference.
---UMM, these are just my opinions, but I don't think you can damage your detector using rechargeable batteries. If you are interested in the name of the brand of batteries that I bought from Ebay, PM me and I'll give you the name. So far, I'm well pleased with them.

 

[Benjamin52]

Thank you, texasred for the answer.

Ordering on ebay will be a little difficult because right now I am in Taiwan and I don`t know if they ship them here.. But 600maH sounds impressive, the ones I saw in the store were 160 maH but I know that is only the charge capacity, so the amount of energy the battery can store, so basically it means the less maH, the faster it will run out of juice, but that is not my main concern, it would just mean I`d have to charge them more often or take a spare pair along to my detecting= no problem.

What I am concerned about is the voltage and the chemical composition, mainly because i certainly don`t want to

a)loose performance and depth on my detector due to lower voltage? (some say 9v but really are 8,4) and

b) damage my detector with too much voltage or leaking chemicals if they run out..

So are these legitimate concerns or does the performance not change even if the rechargeable ones are a little less voltage?
Can a detector even get damaged with a little too much voltage?

 

[TallTom]

I'm not an expert on batteries, but here is my experience so far.

I've had no problem using rechargeable 9V batteries with my Tesoro
Silver uMax or my Vaquero. I've used Tenergy 200 mAh ones for my
Silver uMax. When I recently bought my Vaquero, I read that they drained
a 9V battery a bit faster, so I bought some 250 mAh Tenergy batteries
to use with it. All these are NiMH batteries. (Nickel Metal Hydride)

In both detectors, I find that the rechargeable lasts just about half as long
as an alkaline battery. On my Vaquero, an alkaline lasts 10-12 hours, the
250 mAh rechargeable lasts 5-6. (On my Silver uMax, all numbers were
roughly doubled.)

So it's a little annoying that I have to switch batteries so often on the
Vaq, but it's no problem to carry a spare in my pocket, and it's quick and
easy to make the switch. Performance seems to be the same. I assume
most or all metal detectors (other than super cheap ones, maybe) use
a voltage regulator in their circuitry, so they supply the voltage needed by
the device, and then stop when the battery can't supply enough voltage.
I'm no electronic engineer; that's just my assumption.

Yes, I understand also that rechargeable 9V batteries don't really supply
as high a voltage as alkalines, but they seem to work fine. The main difference
I see when detecting is that the rechargeables fade fast when they get near
the end of their charge. The alkalines fade more gradually. So the battery
check on my Vaq gives 8 beeps when fully charged (rechargeable), then slowly
works down to 5-6 beeps over the first 4-5 hours of usage. After that, it
quickly drops down to 1-2 beeps and dies.

I've seen that 300 mAh models are available, but I've never heard of 600 mAh
models. In either case, they might last (a lot? a little?) longer per charge. Maybe the
charge would fade at a more constant rate, too. Just a guess.

Tom

 

[TallTom]

By the way, I always use headphones when detecting, so my estimates for
how long my battery charges last are based on that. Apparently the beeping
into the speaker (instead of headphones) draws quite a bit more power from
the battery, so the battery life is much less when you use the speaker.

By the same logic, if you search for hours and hear very few targets, your battery will
last longer -- the detector doesn't have to drain the battery by beeping all
the time.

I suppose different headphones might differ in how much battery power they
drain, but I've never experimented with that.

 

[Benjamin52]

Thank you, Tom for the extensive and detailed answer.
I figured the headphones would drain less energy, many other people on the forum had mentioned the benefits of headphones also.

So you say that metal detectors would normally have a voltage output-control, which would prevent it from getting damaged if the voltage would be slightly too high.
And you also think the performance would not drop with slightly lower voltage but the detector would just not work if the battery drops below a certain threshold, right?
That`s good news then, I was afraid the wrong battery might damage the machine or I would loose depth if the voltage starts dropping. (I think I read that on some other metal detecting forum, but it must be some kind of superstition then.)

I guess I will get the rechargeable ones then and the 2-slot recharger so to charge 2 batteries before hunting and then have another disposable one in my pocket just in case...
I will never go metal detecting more than 5 hours at a time anyways so I hope I will be fine I was just concerned about the machine and the performance..

 

[TallTom]

Hey, no guarantee from me about non-damage, but so far I've had no problem.
However, I've never used any battery with higher than 9v (to my knowledge).
I'm sure there's a limit where excess voltage could cause damage, but I don't
know where it is.

When the power from the battery fades, I've noticed no performance problem.
I've detected right down until the detector goes dead, and it's found targets
all the way, seemingly with the same sensitivity as a full charge. With my Vaq,
sometimes I get some chattering when the battery is just about to give out.

When that's happened, I've turned off the Vaq for a few seconds, then turned
it back on and listened to the battery check. It's been either no beeps or one
beep when that's happened. So I just put in another fully-charged battery and
continue with no problem. At least once, the chattering did not happen. The Vaq
just wend silent, so you have to beware of that or you might continue swinging
for quite a while before you realize you're getting no responses.

 

[Benjamin52]

Thanks again, Tom.
This is the answer i got from tesoro support:

“Hi Benjamin, the main reason for recommending alkaline type batteries is the extended battery life (15-20 hours) and they seldom leak battery acid. *Rechargeable batteries are fine as long as you dont mind the investment of purchasing a set of batteries and the charger but you might have to switch batteries every few hours.“

I guess if i use rechargeable ones resbonsably and take em out over night it shouldnt be a problem.

No comment on performance from them but i guess it should be fine I might do a comparison air test with an almost empty rechargeable one vs a full alkaline disposable one and keep you guys posted as soon as I get the detector...

 

[TallTom]

Good idea! I'd like to learn the results of that test.

I predict no significant difference between the low-charge rechargeable
and the full alkaline (as long as the rechargeable is still strong enough
to be stable), but I really don't know. Keep us posted!

Tom