9v NiMH Rechargable in Fisher F2?

I read on here back this summer that they can be used, however when I had my F2 I noticed that it's picky about what type of 9v batteries it uses.

I wonder I the Garrett ProPointer can use the 9v NiMH battery?

Do energizer 9v alks work ok?

I use 9v rechargables in my pro pointer, Compadre, and Bounty hunter 202. They last almost as long as alkalines and are RECHARGEABLE. No more buying stupid alkalines. Heck, in 2 years I haven't bought ANY batteries for any of my detecting gear.

Xaquin said:

Do energizer 9v alks work ok?

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Have used Energizer with no problem....

I bought a bunch of rechargeable batteries for my etrac.they have a slightly lower voltage output..but they last a lot longer in time due to the milliamp hr rating.ive hunted 3, six to 8 hour trips and they are still reading half life left on the machine.

This is the answer I received from Fisher.

It is best to use alkaline Batteries because most of the
rechargeable batteries do not provide the full voltage that they are
rated. Thank you for your support.

Julian Alba
Fisher Customer Service
1465-H Henry Brennan
El Paso, TX 79936
1-800-685-5050 Ext 152
(915)225-0333 Ext 152
Fax: 915-225-0336

Clearing up the Confusion over Rechargable Batteries

I spoke with an engineer at Fisher about their CZ-21 metal detector and rechargeable battery use. The information I'm sharing is based on this discussion and my understanding of what I was told. I do have an engineering background but am not an expert in batteries or metal detectors. Although this information is specific to the Fisher CZ-21 there is some knowledge here that is useful to understanding rechargeable batteries for all metal detectors.

The four 9 volt batteries this unit uses are in a series/parallel configuration and the output voltage is 12V. They combine two 9 volt batteries in series for 18 volts then put each series in parallel. The voltage is then stepped down to 12V with a voltage regulator so the operating voltage is not 9V but in fact 12 volts. The metal detector can tolerate a voltage drop down to between 10.5 to 11 Volts before it may malfunction. This means you can use rechargeable batteries. Rechargeable 9 volt batteries typically come as 8.4 volts or 9.6 volts depending how many cells they have. Each cell is 1.2 volts so if you have a seven cell 9 volt battery it is actually 8.4 volts because the cells are in series. An eight cell battery will be 9.6 volts.

The engineer I spoke with recommended the 8.4 volt batteries because they will have less stress on the electronics. 8.4 volts will be adequate because in series it will be 16.8 volts but will be regulated to only 12V output anyway. What is most important is the mAh hour rating of the batteries you use. Typical alkaline batteries have a 600 mAh rating. The reason why most people say their rechargeable batteries do not last as long is because most often they use a battery with a lower mAh rating.

Most NiMH batteries are anywhere from 200-330 mAh which is significantly less than the alkaline batteries. There are lithium ion batteries available with 880mAh ratings and a 8.4 volt output. This should in theory give you 46% longer run time than most alkaline batteries. There are also 550 mAh nine volt batteries that should have run times almost as long as Alkaline batteries.

Another question I see come up is why do the manuals say only to use Alkaline batteries. I believe this is for a couple of reasons. First, if people buy rechargeable batteries without understanding the differences they may be very disappointed if they get some with only 200mAh ratings since their metal detector will probably start malfunctioning by the end of the day due to running out of battery power. Some nine volt batteries only use six cells and are actually 7.2 volt batteries. Some electronics will not operate at that low of a voltage or not for long. Secondly, cheap 'heavy duty' batteries I've heard are more susceptible to voltage fluctuations under load. That could cause a metal detector to act funny.

I hope this helps.

i use 250 mah rechargeables in my F2 with zero issues. tenergy puts em out--the blue ones. they last a long time.

I use the Tenergy Centura 9V 200mAh Low Self-Discharge NiMH Rechargeable Batteries since I purchased the F2. Use them in the Pro Pointer as well, no issues so far.

Patton said:

Have used Energizer with no problem....

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Thats good to hear! just got 4 of them for Christmas this year.

Just to reiterate what others have said, I used rechargeable batteries nimh for years with no issues. I do carry spare batteries with me in my detecting bag so if my detector does go low on charge I change them out. I also keep the batteries on the charger until I am ready to go hunting.

Note: NIMH will lose charge faster in cold weather. I don't hunt in cold weather. If I did ever hunt in cold weather I would use lithium's.

Make sure the charger you have is rated for the type of batteries your charging.