Minelab's 12 volt battery pack vs. 9.6 volt NiMh?

[Anonymous]

Minelab's 12 volt battery pack vs. 9.6 volt NiMh?
Posted By: Tony N (Michigan)* (56k48.expression.org)
Date: Wednesday, 23 March 2005, at 5:57 a.m.
Hello fellow lovers of the Explorer!
I have a question that has probably been asked a gazillion times.
I believe (though could be mistaken) that the rechargeable battery pack that comes with the Explorer is 12 volts?
My question is about NiMh rechargeable batteries that when brand new are supposed to be 8 x 1.2 = 9.6 volts.
<span style="background-color:#ffff00;">Do you think I could be getting less performance in my Explorer by using rechargeables that may be maxing at 8 to nine volts due to repeated re-charging? </span>
I have another detector that is supposed to have a shut down feature at around 8 volts. It beeps when it hits that voltage letting you know by beeping. My freshly charged NiMh rechargeables cannot be used in it. It beeps constantly when I install them but does not with fresh alkalines.
Should I purchase another stock 12 volt rechargeable battery pack for my Explorer. And if so, where?
Thanks and HH!
Tony

 

[Anonymous]

My Explorer battery pack says "12v 1500mAh"
And my empty rechargeable pack that you put batteries in that came from Minelab says:
"Use only 1.5V 'AA' Cells" on the lable.
I wonder if this could be part of my problem using 1.2 volt rechargeable batteries for a total of 9.6 volts?

 

[Anonymous]

Comes with a plastic cradle to set the batteries in label up and I've never used alkalines in the extra emergency pack. Nowadays you get 2200-2500 ma batteries as normal. You can even pick up an 8 bay charger to get those batteries done if you don't have the SR charger. I like that charger because it does both the factory battery pack and the NIMH loaded (supposedly alkaline) pack and does them in about 2 hours. You put an inverter in your car and if your battery goes dead on you you can charge the battery most of the way while you go eat lunch. (The last part of the charge takes the extra time as it slows down the rate of charging as it gets near the end.)
What I do... Guvner..

 

[Anonymous]

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[Anonymous]

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[Anonymous]

Tony,
The Minelab manual (page 92)show the discharge curve of the NiMH battery. The completely charged voltage is 11.3V or 1.41V per cell (I measured 1.42V unloaded for a fully charged cell). The 9.6V results after about 12 hours of normal usage. Note that the NiMH has a somewhat lower voltage at full charge than does the alkaline battery, but has a flatter discharge curve.
I have switched to NiMH rechargables for my auxiliary battery. At Walmart you can get Duracell charger for four cells for about $20.00. This charger will charge the cells in about 1 hour. You can by a Duracell set of 8 2500mAh cells for about $10.00 This combination has longer hunting time than the alkalines and saves considerable money in the long run.
HH, Glenn

 

[Anonymous]

is the Guv one of those big chiefs with just a grass skirt on in the old Tarzan movies? <img src="/metal/html/lol.gif" border=0 width=15 height=15 alt=":lol">
The Guv has done me good over the years since I've been here. I say that to let you know that I'm just joking around with your "bwana" statement.

 

[Anonymous]

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[Anonymous]

and it says (it doesn't SAY anything, you have to read it!) 9.6V 1600mAh.
I use the Energizer 2500mAh cells in the "Alkaline" holder, and it works exactly like the Minelab factory pack, but lasts longer.
Most modern equipment uses a switching type power supply so they don't waste anywhere near as much enegy as heat. What this means is, the machine could't care less about the input voltage (whether it's 9.6 or 12V or even a touch higher), it regulates to provide the correct voltage no matter what (within limits) the input voltage is.
Long story made short there is no difference in ExpII performance in even the slightest way when using the "Alkaline" pack with either NiMH, NiCD, or Alkaline, other than the run time determined by the capacity of the cells in question.
Conversely, with a linear regulator, it "throws away" excess voltage as heat. take for example 5 volts delivered to a microprocessor circuit. If we need 200mA at 5 volts, the linear regulator with a 12V input will "throw away" 7V x .200 or 1.3 watts of heat. A switching regulator turns on and off VERY rapidly, and only wastes a tiny amount of heat in the process, giving you much longer life from your batteries than the linear approach.
Those good with math will notice that 5V x .200 = 1 watt, in other words, the linear regulator throws more battery energy away than the (hypothetical in this case) processor circuitry is using!
Your ExpII does not know the different between 9.6V and 12V input because it is using a much more advanced switching regulator.
DAS

 

[Anonymous]

I imagine that is the same case with my Explorer XS concerning the switching regulator?

 

[Anonymous]

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[Anonymous]

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[Anonymous]

but mainly because switching regulators have "arrived" and are in virtually everything now.
It just makes so much more sense to use the battery capacity to it's fullest, rather than throwing so much away.
My numbers (200mA) are complete ballpark, and meant to convey a principal, rather than solid numbers I might have otherwise measured if I felt like taking my machine apart.
Let's put it this way, if any high end metal detector isn't using a regulated supply, it is JUNK. Further, if it isn't a switching regulator, the customer is paying to throw battery energy away in the form of heat. If I thought Minelab would sell me a detector that was designed to waste batteries, I'd find a different manufacturer who understands the concept of engineering in a bit more detail.
<img src="/metal/html/biggrin.gif" border=0 width=15 height=15 alt="">
DAS