9volt Batteries

Depends on the battery's chemistry.

If using NiMH cells, then yes, 200/250 mah is the kind of capacity you can expect. You can get higher, but you'll need to get a 9V battery that uses lithium cells inside.

Given how lithium cells are about 3.6 or 3.7 volts nominal, these are most likely 2 cells inside with a voltage booster or 3 cells inside with something to step down the voltage. I have no idea what effect that will have on performance of the cells or your metal detector, although I don't foresee it causing a problem.

I've been using Tenegy's low self-discharge NiMH batteries for a bit in my Fisher F2 and they seem to work well. I imagine the lithium versions with 3 times the capacity will give a lot more run time, but I don't know if they'll be more durable. Conventional wisdom says lithium cells don't last as many cycles as NiMH cells. However, I can't say for sure if that applies to rechargeable 9v batteries.

EDIT: Out of curiosity, I looked up some of the Tenergy lithium cells. Looks like they may not have a booster inside. Instead, they just consist of 2 cells for 7.4 nominal volts. However, when fully charged, they probably give around 8.5 to 9 volts. Yet as the batteries deplete, this voltage will drop. I don't know how long your cells can go before the F5 will stop working, though.

mh9162013 said:

Given how lithium cells are about 3.6 or 3.7 volts nominal, these are most likely 2 cells inside with a voltage booster or 3 cells inside with something to step down the voltage. I have no idea what effect that will have on performance of the cells or your metal detector, although I don't foresee it causing a problem.

I've been using Tenegy's low self-discharge NiMH batteries for a bit in my Fisher F2 and they seem to work well. I imagine the lithium versions with 3 times the capacity will give a lot more run time, but I don't know if they'll be more durable. Conventional wisdom says lithium cells don't last as many cycles as NiMH cells. However, I can't say for sure if that applies to rechargeable 9v batteries.

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I'll add to this that I've used the Tenergy Li-ion 9V (500 mAh version) in my F2, and they worked just fine, run for a long time. Haven't used them enough to comment on long term durability.

To the OP, generally speaking, double the mAh rating means double the runtime.

might check some of the other post on batteries. https://metaldetectingforum.com/search.php?searchid=12530444

Still wondering about these lithium batteries and the chargers for them. The devices won’t charge or not compatible with the older recharge batteries? Not sure of which ones to buy, 280, 600,800, etc

demyansk1942 said:

Still wondering about these lithium batteries and the chargers for them. The devices won’t charge or not compatible with the older recharge batteries? Not sure of which ones to buy, 280, 600,800, etc

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It's unlikely your nicad/nimh 9V charger is designed to work on the li-ion 9V batteries, so you would need to purchase a new charger to go with them.

The Tenergy brand is fairly well respected. They're claiming 200 or 250mAh from their nimh 9V, and 600mAh from their li-ion 9V. Be cautious about any brand you've never heard of claiming more than they do.

Thanks for the reply torque and others. I sort of felt this is what was going on with these batteries.

I tried rechargeable batteries when they first came out years ago. They worked great but then they would go dead all at once instead of gradually like normal batteries, usually a long way from your car. I haven't tried any since. I live in an apartment and talked them into giving me the old batteries that they take out of smoke alarms. Most test almost new and work well in my detectors . . . and they are free.

When i got my Garrett "carrot" last November i bought a pack of inexpensive alkaline 9 volt batteries at Harbor Freight.

I have used the pointer a LOT and am still on the first battery.