Moving from 9v battery to 6 AA batteries.

[Jalm]

Hi friends,

I have a question: is a bad idea to change the normal 9v batteries and adapt a 6 AA 1.5v rechargeable batteries holder in my metal detector ?...9v batteries are expensive (where I live at least) and really they don't last enough, so a bunch of 6 AA 1.5 rechargeable batteries will run for long time.

Thank you.

 

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[airscapes]

9v is 9v so if you can modify it to work with AA then you will be good to go!

 

[texasred777]

I've used 9v rechargeables for years. I find they don't last quite as long a an alkaline; but are SO much cheaper. I try to have at least 2 spare sets with me. My BH MDs use 2 of the 9v. I used to buy the Harbor Freight that were 150 mAh; but found some on Ebay that were 600 MAh; about/less than $30 for 4 with charger. So far, I'm VERY pleased with them.

 

[Jalm]

I've used 9v rechargeables for years. I find they don't last quite as long a an alkaline; but are SO much cheaper. I try to have at least 2 spare sets with me. My BH MDs use 2 of the 9v. I used to buy the Harbor Freight that were 150 mAh; but found some on Ebay that were 600 MAh; about/less than $30 for 4 with charger. So far, I'm VERY pleased with them.

I have done that as well but I think that 6 AA rechargeable batteries, let's say 3000 MAh.each, will give a really long chance for detecting. But I'm not sure if rechargeable batteries are conveninent for such devices since their voltage is a bit lower than normal batteries.

 

[texasred777]

Although there is a slightly lower voltage with rechargeable batteries, I have had no problems except in my digital cameras. After I started buying the 2900mAh and higher, I haven't had that problem. One of my cameras uses a lot of 'juice', especially when using the flash. With other things, radios, keyboards, mice, flashlights, kids toys, etc., I've not noticed a difference with voltage; just the shorter time that they last. They seem to last about 75% as long as an alkaline.

 

[stoneshirt]

Hello.Can I post in here,there is something I don't understand.Alk Bats are 1.5V,Right? And Rechargeable are 1.2V Right? 12V verses 9.6....
Whats the Deal.Minelab ExplorerXS Packs say 9.6V,but when fully Charged they say 12.something is desirable..What does the Machine actually run on?
Ken.

 

[flgliderpilot]

9.6V is the voltage of a dead pack. Charged, it could read up to 12V.

 

[airscapes]

What does the Machine actually run on?
Ken.

Can not speak for other brands but Whites cut off is about 8-8.5v All machines have a voltage regulator in them and require less voltage than the pack can provides, which in the case of anything running on 8AA would be about 8v which would be when each cell has hit 1v and has little capacity left. Remember it is the millamp current capacity that is what the machine runs on not the voltage so to speak. Voltage is the pressure or the electricity, current is the volume of electricity, think of it as water. So if a machine needs 80 millamps of current at 8.5v it does not care if the battery is 12v or 9.6v as the regulator steps the pressure (voltage down). The battery that will last the longest is the one with the greatest milliamp hour rating, as capacity drops so does voltage.
The current generation of high capacity rechargeable AA batteries used with a smart charger work wonderfully. PowerEX 2700 are what I have been using. Just bought a second set of 8 for my extra DFX. Ran them though the "discharge refresh" cycle on the smart charger right out of the box and when done every cell had a capacity of 2700 mha or above.
One reason rechargeables have gotten a bad rap is they were not consistent. On bad cell of 8 will cause your run time to be a long as the bad cell lasts. With a smart charger you can measure the real capacity of each cell and know if you have a bad one. This is why I run the discharge refresh when new and mark the batteries capacity on each battery. After 6 month of use, I will rerun to verify all cells are still equal.

 

[stoneshirt]

flglider,and airscapes..Ha Ha,When I post about my (Machine) Problems,I just assume everyone else is running Minelabs too! Thanks,I will Digest this and carry on.Battery's are just as complicated as some Women I've met.Ken
Seems like I read somewhere,their are some who think that an extra few Volts will increase Depth and such.

 

[airscapes]

Seems like I read somewhere,their are some who think that an extra few Volts will increase Depth and such.

I have read that as well, I would guess if the machine does not have voltage regulation that could be true, but I have not experienced it with any of the whites machines I have owned..

 

[TunnelRat]

I'm wondering if a 12v motorcycle battery carried on the waist could be used to power the md. Since they now make sealed batteries there is no longer a problem with it leaking. You would sure have more battery than energy to swing the coil. It would never run down in the middle of a hunt.

 

[Swaveab]

Jalm, the battery pack is for alkaline batteries that when new are well over 1.5v each and give voltages to the detector at over 13v. The nominal rating of this type of cell is 1.5v and when nearing dead it will fall to below 1.3v per cell. The big disadvantage is the falloff voltage of the rechargeable batteries will fall below the minimum operating point for the detector even though they still have plenty of power they could deliver as when fully charged they show about 1.3 to 1.34v each cell. Theoretically, if rechargeable NiCD or NiMH are to be used the aa slots could be increased to 10 to have the same voltages as given by 8 alkalines, but they don't make such a pack for us to use and even the premade rechargeable packs they sell for it are still just a regular battery pack stuffed with aa NiMH batteries and you can buy these in higher capacities and cheaper than the premade pack.

I too use the Powerex aa batteries as even cheap alkaline batteries get expensive and I carry an extra battery pack with me with more rechargeable batteries in it. The extra pack isn't mandatory as you can just have 8 extra aa batteries with you and change it out, but the less handling to me the better while in the field and you don't want to intermix your batteries as you may accidentally replace all but 1 that was in the old group of aa batteries as an example. Having a dead cell with 7 good cells is not going to give good results and could damage that weak cell. Also, do not mix different battery types or capacities and even identical batteries that differ widely in age or use unless they all are near the end of their life and you're just exhausting them before throwing them away.

In summary, the rechargeable batteries give out sooner only due to their lower inherent operating voltage and are a good way to go if one is knowledgeable about them and their use. For example, they lose their charge very quickly while in storage and I recommend a recharge to them once every 2 months if stored fully charged to start with. Alkalines do last long in the field and one can just toss them and buy new ones if you don't want to fumble around with the rechargeables, but at a higher overall cost.

 

[Swaveab]

TunnelRat, you could use a motorcycle battery for the detectors that take 8 aa batteries, but connecting it will be a feat and carrying it around a bigger feat. They do make sealed types that take that leak risk away, but they are still hard to connect up and carry. If the battery should short out you could have a dangerous circumstance going there. Why bother?

 

[Carl995]

I'm wondering if a 12v motorcycle battery carried on the waist could be used to power the md. Since they now make sealed batteries there is no longer a problem with it leaking. You would sure have more battery than energy to swing the coil. It would never run down in the middle of a hunt.

You could use the smaller gel cells used in alarm systems.

 

[Swaveab]

Jalm, I guess your initial question I side-skirted to a point. You can do the replacing, but do this in as good a manor as is possible. All connections must be quality and insulated from shorts if it fits within the detector and if wired externally take extra care with better flexible wiring and add a fuse at the batteries to insure against accidental shorts. If you're not experienced or knowledgeable enough then stick with the 9v types out there and get the higher voltage and current ratings on them. Don't get the 7.2v types as they are too low in voltage to operate well and even the 8.4v can go low too soon, but are better than the 7.2v types. I got a 9.6v Powerex MHR9V. It's good to just have one in the detector and a spare or 2 on you fully charged so you don't get stuck before ending your hunts. Above all get a good charger for any rechargeable batteries. Those that charge aa batteries should have individual battery charging parameters and not the types that take multiples of 2. Too carry the 9v rechargeable I place it in a small plastic prescription bottle with the locking plastic cap. This keeps it waterproof to a large degree. I place the charged battery with contactors face up to the cap and when dead i put them in face down. No mistakes that way.

 

[NGE]

Thank god for RnB innovations. I bought one for my minelab Etrac. 50 to 60 hours on a pack, only 2 hours for total recharge. Lithium Ion rechargeable pack. nge

 

[fireaero1]

motorcycle batteries would be too heavy. Your hip would be sore and a real pain to bend over. tom in central pa

 

[223Larry]

Dollar tree has four alkali AA batteries for a dollar