Need Some Help With Batteries

[Arlin]

Hello All,

I am new to your forum and could use your help. I have a Teknetics Mark 1, which I purchased back in the 80's, and I just pulled it out of storage looking to get back into the swing of treasure hunting. My battery clips are in kinda rough shape and I have seen a post on your forum about doing a mod to change the 8 aa's to a 9v and 2 aa's , and then on the 6 aa's side, they had stated that they put 2 9v batteries on that side. Would 1 9v work on that side or does it require 2? Any help that you could give me would be greatly appreciated. Also, any other mods that you can think of, would you share those as well. Thank you guys, I hope to hear from you soon. Take Care.

Arlin

[PimentoUK]

No experience of the Mark1 machine ... but know my electrics.
The reason that two 9V batteries ( in parallel ) are suggested to replace 6 x AA, is related to current draw, and battery life. One alkaline PP3 may have adequate capacity, but still may not respond well to heavy current demands.
If you use NiMH rechargeable PP3's, they usually have rather modest capacity ( about 180 - 280mAh ) , so you would still likely need two in parallel.
One alternative solution: Use Lithium PP3 rechargeable batteries. EBL seem a good brand. They have two lithium cells in series internally, plus some charge regulating etc electronics. They have a decent capacity ( 600 mAh ), plus can handle higher discharge current rates with no troubles. So only one of them would be needed to substitute the 6 x AA's. The EBL PP3's are commonly sold as a 'bundle' of two or 4 batteries and the 'special' charger.

On the 8 x AA's side: One PP3 and two AA's is a bit ugly, plus the AA cells will outlast the PP3's by a significant amount. I guess weight is the intent of this battery replacement exercise. 8 x AAA would be an obvious solution. A rechargeable pack of 9 x AAA NiMH cells ( or 10 cells ) would also be an idea, though you would have to make / improvise a charger ... not too difficult if you have electrics skills.
Open up a PP3 NiMH, you will typically find 7 small cylindrical cells ( probably 1/3 AAAA ). A bit of surgery to remove 2 cells changes this to 5 cells. Modify two PP3's like this, and you have essentially two 6 Volt PP3's , giving the required 12V when run in series. Again, some simple custom charging arrangement would be needed.

More advanced solutions:
Make a custom 3 cell lithium rechargeable pack to replace the 12 Volt / 8 x AA pack. Electronics skills are definitely needed here, as you will need a 'battery management system' ( BMS ) circuit board to ensure the cells charge up evenly. These are easily found on eBay, 5 dollars or less. But the charger needs some thought. The cells themselves could be rescued from 'used' disposable E-cigarettes ( Vapes ). You may have friends/relatives who use these, ask around.

[Arlin]

Thank you so much PimentoUK, that gives me some info that I needed. I am not that skilled with this, going to some learning for me. 

[Arlin]

Thank you so much PimentoUK, that gives me some info that I needed. I am not that skilled with this, going to some learning for me. 

 

PimentoUK , taking your advice, I looked up the EBL Batteries and wanted to check with you to make sure it's exactly what I need. The 9v EBL's are 650 mAh while the Pallus 9v are 850 mAh. Which ones would you use? Also, The EBL AA batteries are 3300 mWh, would that be a good match for the EBL 9v for the side that takes 8 AA's. I really appreciate your help. Take care and I look forward to hearing from you soon.

 

[PimentoUK]

Hmmm, tricky questions, and setting off my "uh-oh??" alarm too.
The EBL PP3 batteries are 600 mAh. That's what every seller states they are, and it's what their website say, too:
EBL PP3 Li

So if you've seen some claiming to be 650mAh, I'm getting suspicious they are fakes/copies.
Yes, there are now other brands of two-cell Lithium PP3's, and some claim, and may actually be, higher capacity. I'm sure it's possible to squeeze a few more mAh in the box. Trouble is, EBL seem a good brand, and they've been making these PP3's for a while, now. All these other Chinese 'brands' I've never heard of ...
Now.. the AA cells. You got me worried as soon as I read 3300mWh. This is the warning trigger for wierd and wacky stuff. Sure enough, I think you are referring to these things:
Lithium AA

The answer is a big NO. They consist of a lithium cell, ( about 800 mAh capacity ), with some magic electronics board** integrated in the package, to drop 3.7V down to 1.5V.
They are not what you need, they produce electrical interference, and need a special charger.
You just need plain old NiMH ( nickel metal hydride ) rechargeable cells. Any old crepe will do, they will outlast the PP3 easily. Even AAA cells would be OK, as many of them are 900 mAh+ capacity now. You might even have some suitable AA's at home, or maybe a trickle charger for them. I use some pretty low spec NiMH's in my Fisher F75, they still run it fine.
If you in the market for some AA rechargeables, however, the best brand is generally considered to be Panasonic Eneloop. There's a few 'flavours' including the LSD / Low Self-Discharge type, which stay charged up for months on end.

** Buck mode switching regulator

[phrunt]

Can't go wrong with Eneloop. 

Pimento knows what's he's talking about with the above posts.  Great advice.

[Arlin]

Thank you again PimentoUK, that made it clear of what I need. You were correct, I did in fact have some Eneloop Batteries at home that I totally forgot I had. Thats alright, I ordered some extra just in case. You have been a fantastic help and I really appreciate it. Hopefully. someday I'll be able to help you or pass if forward. Take care and may God Bless you PimentoUK. 

[Rad Rocks]

A note on the New rechargeable batteries…

There is some talk going around in regard to the newer Batteries with the built in/On board recharging circuit. Seems that some are injecting noise artifacts into the circuit(Noise). I have heard this from a few people now(Music Industry) and If it affects Audio equipment, I’m fairly confident that it crosses over to Detectors.. Now this apparently does not effect the Old/standard style that has a charging station but the ones that you individually plug the usb into(The charging circuit seems to be the culprit).  I have only heard this and I have not personally experimented with any of it as of yet but it sounds plausible.. This may not be a Big deal but I just wanted to bring it up.. 
 

[PimentoUK]

"This may not be a Big deal but I just wanted to bring it up.. "

It's well-known, hence me mentioning it in my last post:
Quote: "The answer is a big NO. They consist of a lithium cell, ( about 800 mAh capacity ), with some magic electronics board [switching regulator] integrated in the package, to drop 3.7V down to 1.5V.
They are not what you need, they produce electrical interference, and need a special charger.

The idea of just one of these switch-mode regulators is bad, but a pack of 8 of them, for example, is not going to get my vote at all.
For what it's worth, the regulator will likely operate at about 1 Megahertz, so some way above the main detector frequency, but that doesn't stop them potentially causing interference.

For what it's worth, there are many detectors with switching regulators integral to them, everything from an ACE250 to a Teknetics T2 to an Equinox. But if it designed properly, the risk of problems can be eliminated.