Batteries/Depth

[gobum62]

I use rechargeable batteries and was wondering if I lose depth? Noticed I am collecting a lot of coins but no deep ones. Have T2, Golden Umax and Ace 250.
Thanks
gobum62

 

[Flintstone]

Hi 62, I use rechargeables and think as long as you get a good charge on them they do fine. I know they go down faster after about halfway down and then you will lose some depth. My detector tells the volts when turned on as long as i have above 9v i do ok. Get a good set of nonchargeable and find some deep targets and mark them, then try the rechargeables and see if there is any difference. Good Luck Flintstone

 

[WV62]

Batteries really don't have anything to do with depth, until you drop below what the detector needs to operate. Your detector has a voltage regulator in it that cuts down the battery voltage and keeps the detector running at full steam. You should have some kind of low battery alert, check your manual. A detector does not work like a flashlight, the lower the batteries the dimmer the light. If it did we would be changing batteries all the time.

Hope this helps,

Ron in WV

 

[MarkCZ]

Well said big brother (WV62)
Its like this, lets say a detector runs on one 9v battery and lets call that "9 Volts" so it has a 9 volt power supply.
If the detector's electronics actually needed "9 Volts" then it would be like the flash light!
But like ALL battery powered electronics, they use a electronic regulator to regulate the voltage down to the electronics actual rating.

So, that would mean that a detector that uses a 9 volt battery is actually running at a much lower voltage, like,
5 volts or possibly 6 volts.

That means that as long as the battery has a voltage range above either 5v or 6v then its still being regulated down.

If the detector actually runs at 6 volts then a 9 volt battery has a 3 volt range of usable power before the detector is running on low voltage.
If the detector runs at 5 volts then a 9 volt battery has a 4 volt range of usable power, ect...

So when you change the battery its not normally really dead, its just down below the electronics usable voltage range.

Mark

 

[Mtnmn]

I'm guessing that if there were any deep coins to be found, then your T-2 would surely reach them. Having moderately high ground mineralization can kill your depth, helping prevent you from reaching any deeper coins. Also a lot of deeper coins can be masked by the amount of trash in the your ground, especially any deep iron.

 

[Critterhunter]

Batteries really don't have anything to do with depth, until you drop below what the detector needs to operate. Your detector has a voltage regulator in it that cuts down the battery voltage and keeps the detector running at full steam. You should have some kind of low battery alert, check your manual. A detector does not work like a flashlight, the lower the batteries the dimmer the light. If it did we would be changing batteries all the time.

Hope this helps,

Ron in WV

BIG THUMBS UP my friend! I've been trying to crush that "rechargeables cost you depth" myth for years. Detectors need a stable static voltage setting to run properly, otherwise they'd be constantly drifting out of tune as the battery drains and drops in voltage. So long as the voltage is above what the regulator needs to operate (say 9 to 12V to put out a static 8V perhaps), then the electronics are not going to see any less voltage or thus less performance using rechargeables. And, when the voltage does drop below what the regulator needs to supply the lower output voltage to the board, that's when your battery alarm goes off when it gets near that. A regulator can't for instance take in 6V and output 10V. The voltage has to be a volt or two higher on it's input then the output static voltage the electronics need to run properly.

Another myth I keep trying to bust is that rechargeables don't give you as long of run times as non-rechargeables. That used to be true years ago with low capacity nicads and nimhs, but with the advent these days of 2500ma and even much higher capacity AA cells, run times for me when I use AA nimhs are actually longer than regular non-rechargeables in many devices I use them in. The nimh may start out at a somewhat lower voltage than the non-rechargeable AA, but as they drain the nimh will hold it's voltage more steady (higher) as it drains, and so at one point in time the non-rechargeable is going to be outputting less voltage than the nimh for a while and hit the low battery alarm sooner.

If anybody is looking to pick up some AA nimhs, get ones at least 2500ma or higher in capacity. High as you can find= more run time. Also, shoot for ones rated with low self-discharge sitting on the shelf after they've been charged. One of the other reasons why people think nimhs or nicads don't give long run times is that they charge them and then weeks later they use them and get a short run time, due to them self-discharging while in storage. There are now low self-discharge nimhs, but do your research as some are better than others at holding up to their claims. Otherwise, if using regular nimhs, if you didn't peak that pack in say a week you better throw it back on the charger to top it off.

Finally, be sure you use a charger that will tell you the batteries have peaked (meaning are charged). And don't super fast charge them at 1 hour or less. Over time that can shorten life and run time. If it's getting hot you are for sure charging too fast. I usually charge at about 1/3rd C (about 800ma for a 2500ma cell, which will take about 3 hours to charge a completely dead battery then) or less. Only if I'm in a hurry will I push 1/2C (two hours to charge) or 1C (1 hour), but make sure the cell is designed to handle that or you've got a ruined battery or worse on your hands. Hot=Bad news. Always charge in a fire proof place too like in the middle of a cement floor.

 

[MarkCZ]

Batteries really don't have anything to do with depth, until you drop below what the detector needs to operate. Your detector has a voltage regulator in it that cuts down the battery voltage and keeps the detector running at full steam. You should have some kind of low battery alert, check your manual. A detector does not work like a flashlight, the lower the batteries the dimmer the light. If it did we would be changing batteries all the time.

Hope this helps,

Ron in WV

If anybody is looking to pick up some AA nimhs, get ones at least 2500ma or higher in capacity. High as you can find= more run time. Also, shoot for ones rated with low self-discharge sitting on the shelf after they've been charged. One of the other reasons why people think nimhs or nicads don't give long run times is that they charge them and then weeks later they use them and get a short run time, due to them self-discharging while in storage. There are now low self-discharge nimhs, but do your research as some are better than others at holding up to their claims. Otherwise, if using regular nimhs, if you didn't peak that pack in say a week you better throw it back on the charger to top it off.

Finally, be sure you use a charger that will tell you the batteries have peaked (meaning are charged). And don't super fast charge them at 1 hour or less. Over time that can shorten life and run time. If it's getting hot you are for sure charging too fast. I usually charge at about 1/3rd C (about 800ma for a 2500ma cell, which will take about 3 hours to charge a completely dead battery then) or less. Only if I'm in a hurry will I push 1/2C (two hours to charge) or 1C (1 hour), but make sure the cell is designed to handle that or you've got a ruined battery or worse on your hands. Hot=Bad news. Always charge in a fire proof place too like in the middle of a cement floor.

And to add to that the NEWER "LSD" batteries are really nice, "LSD"= Low Self Discharge, these have a much greater storage life, some up to a year! That means that not only can you use rechargeable's as main batteries but as backups as well.

Mark

 

[Critterhunter]

Yep, low self discharge nimhs are the way to go these days. Also, people should surf the net and find the battery tech heads who just love testing rechargeables to see how the low self discharge nimhs hold up to their claims. Some don't very well depending on brand.

I've never looked when I had a detector apart but I'd assume they are using linear regulators due to switching regulators generating a lot of on board circuit noise, which is very bad for a detector performance wise. You can tame the EMI of switching regulators (they pulse the power output to control voltage) with other onboard components but that adds to the cost of already more expensive switching regulators versus linear ones.

Only problem with linear regulators is they get rid of excess voltage by shunting it off as heat, and so they have a metal heat sink on them. That's not as efficient as switching regulators but still they would seem to me to be a more perfect solution in a detector for the other issues above. I've seen people talk of upping the voltage on their detectors to try to give them more depth. If the detector is using a linear regulator like I suspect, then you run the very real risk of blowing the regulator or if your lucky it will shut down on it's thermal overload circuit and come back to life once it cools down.

Regulators in general have a rather wide input voltage range. I would suspect one designed to output say 9V can tolerate about a 10 to perhaps 15V or so input power, but again upping the voltage will do nothing performance wise based on the static output to the board that it needs to run stable. I'm running a 3 cell lipo (very light and cheap batteries popular in RC electric plane circles) in my detector, as a 3 cell series pack is perfect at 12.6V to replace the 8AA cells in my detector. I doubt any detector designed to run on 8AAs (12V) will have issues with the extra .6V, but nobody should take my advice on that.

The only real way to tell what your regulator can handle is by writing down the part # and looking up the specs. I never checked new AAs to see but I would suspect that start out a bit above 1.5V per cell anyway. Wouldn't make sense to me that a regulator meant for a 12V power source didn't have some room for play in terms of a bit higher voltage source I wold think. At least all the linear regulators I've ever played with in projects have a rather wide input range ability, but again don't take my word for it.

One of the things I love about nimhs, besides them being super light and compact, is that you can charge them at 1C (1 hour) without stressing the pack, and also that they have just about zero discharge on the shelf so a year later it's ready to roar for the most part. If I do store them long like that though I put them to a sleep charge that is designed to retain long life and capacity while they are stored in a metal fire proof box in my refrigerator.

 

[edjcox]

Lithiums the way to go..

 

[Critterhunter]

Lithiums the way to go..

Lithium Ion has it's perks, but so do lithium polymers. Mainly lipos are cheap and extremely light and compact. They do have some guidelines that need followed though, like not charging above the abilities of the pack (usually a 1C max charge rate), and not draining past 3V per cell (9V in a 3 cell series pack). The cost, light weight, compact size, and also abilities to hold up to high amp draws make them hugely popular among RC electric plane circles for one.

Wanted to correct something I said...

One of the things I love about nimhs, besides them being super light and compact, is that you can charge them at 1C (1 hour) without stressing the pack, and also that they have just about zero discharge on the shelf so a year later it's ready to roar for the most part. If I do store them long like that though I put them to a sleep charge that is designed to retain long life and capacity while they are stored in a metal fire proof box in my refrigerator.

Mean to say lipos here, not nimhs...But modern high capacity low self discharge nimhs are also fantastic in their own right as well.

 

[gprater]

I would appreciate a link to recharable batteries you guys use successfully. Thanks