Can lithium AA batteries be used in a Minelab battery pack (instead of alkalines?)

I was reading this article:

[shopping.yahoo.com]

Based on this, it seems that lithium AA batteries (specifically, Energizer Advanced) are a much longer-lasting alternative to alkalines (I've never tried lithium batteries). Since 8 AA alkaline batteries (Duracell) only last 1-2 hours in my Minelab Explorer, I was wondering if lithium batteries would last a good bit longer -- and thus do a better job of being a "backup" to my rechargeable battery than alkalines have shown to be...

Steve

As a followup to my own post...

A little research is showing that NiMH rechargeables would possibly be a better option...so any thoughts there on battery type/charger type would also be appreciated.

Steve

Steve, I have been using Sanyo Eneloop NiMH batteries for a couple of months and they work great. I got 8 AA and a Sanyo charger for around 30.00. The only thing I would have done different is pay a llittle extra and get the charger that holds 8 batteries, mine only holds 4.

Steve... i believe you have the SE like me. I wouldnt recommend them if you still have a warranty. I dont know what kind of combined voltage they produce.... but i know the manual says: Rechargeable Lithium Ion can NOT be used because they produce voltage above 13 V. Take a look at the Tenergy 2600's. I think you will find they last a LOT longer than many rechargeables.

Dew

Most detectors have a voltage regulator to prevent any damage from too much juice but but would call Minelab and get it from the horse mouth rather than speculate or perhaps damage your unit.

Thought/Comparison/Tangent = The F70/F75/T2 will operate 43 hours (nominal) on 4-AA alkaline batteries. Hmmmmmm.

There is a difference between Li-Ion rechargeable cells (3,6 V nominal) and the lithium AA sized primary cells, which have 1,5 V nominal voltage. There would be no harm using the "Lithium" 1,5 primary cells.

However I would definitely recommend some of the newer low self-discharge NiMHs.

Steve, if you go with NiMh AA batteries, I recommend the Sanyo Eneloops. Of all the brands I used, they are the most reliable. Read their reviews on Amazon. No other mfg gets such high user praise. Get the low-self discharge variety. Regular NiMH lose significant power when in storage waiting to be used. The Tenergy's have highest mAH capacity as I told you in PM, if you get non-defective ones, they are nice. They last longer between charges. However, IMHO the Tenergy's will not last as long as Sanyo's. They seem to have a much shorter overall lifespan than the Sanyo's. The Tenergy's have a propensity to give up the ghost after about 1 year. Read Amoazon reviews on the Tenergy's. And do get a high quality charger (cheap chargers will shortlife your batteries) that can do 8 batteries at once. Don't recommend the Sanyo 4 cell charger they package with some of their batteries. Takes 8 hours to charge 4 batteries.

OK, thanks all --

Instead of lithium disposables, I'm thinking rechargeables at this point -- NOT lithium ion (thanks dewcon) but NiMH instead; I'm thinking Sanyo Eneloops and an 8-cell charger (thanks TerraDigger and iskirkra).

Terra -- you say "don't get a cheap charger," and my reading also showed (like you said) that the Sanyo charger that comes packaged with some Eneloop AA packs is not the way to go. Instead, I was thinking about this Maha Powerex charger:

[www.amazon.com]

Anyone have any thoughts on that one?

Also -- for any of you using rechargeable NiMH AAs in an Explorer, how long will they run the machine before needing to be recharged, as compared to the Minelab rechargeable battery pack? Longer? Not as long? About the same? Just curious.

Finally, one last question -- assuming the NiMH rechargeables will give at least as much run time as the Minelab rechargeable pack, is there any advantage to using the Minelab pack? I initially considered just buying a second Minelab pack, but at over $100 I started looking at alternatives. Is there ANY advantage to the Minelab pack that warrants paying twice the amount of 8 AAs and a charger?

Steve

Steve----I'll take on your "final question"-----The convenience (less hassle) of a Minelab re-chargeable battery pack & charger (at least to me) is definitely a big plus!-----Is it worth the extra money?---That is up to you (the individual)---to me it is.----They last long enough to do a long days hunt.-----------More than all this---one thing that concerns me the most & it doesn't seem to have been discussed------Did I read your post wrong or did I understand it right that you get 1 to 2 hrs. running time with a battery pack of alkalines?-------If that's the case, you got a FAR MORE serious problem than deciding on batteries and you better get that detector checked out.-----I have the Etrac (which I feel "eats up" batteries faster than any previous Explorers I've had) and as I stated, I get over a days hunt with the Minelab re-chargeable battery packs and considerable longer than that with the alkalines.------------Del

Del --

I agree, the Minelab rechargeable pack and charger is very "convenient." But, I am trying to picture how it would be that much MORE convenient than having an eight-cell charger. As an aside, the rechargeable AA cells would actually charge much faster than the Minelab charger charges the rechargeable pack, and given the much higher mAh rating, (2000 on the Eneloops, 1500 on my Minelab pack) I would think they'd give more run time than the Minelab pack, no?

Anyway, it seems like with an 8-cell charger, the charging would be pretty easy...but maybe not? (I've never used AA rechargeables, so I may be missing something...)

As for the alkalines -- yes, they discharged very quickly in my Explorer, I was shocked. I will try a new set to verify, but I drained them VERY quickly. I almost never use the alkalines for that reason (I only used them once -- when my rechargeable died during a hunt, and I was SHOCKED at how quickly they ran out). I have a friend that hunts with an E-Trac, and he, too, was surprised that that's all I got out of the alkalines (he said he gets considerably more run time than that when using alkalines). I sure HOPE I don't have a problem with my machine; like you, I get a good 8-10 hours out of the Minelab rechargeable pack. I'm not sure what could possibly be wrong with my machine where I'm getting proper "run time" from the rechargeable, but very SHORT run time with the AA alkalines...NASA-Tom, would that make any sense to you? Maybe I had a bad batch of alkalines...

Thanks for the info, Del.

Steve

Steve, get a multimeter (if you don't have one already) and a fresh set of alkalines. Test all batteries beforehand. Run the detector and see if issue replicates itself. Sending you a email to your home email.



Edited 1 time(s). Last edit at 11/14/2011 11:48AM by TerraDigger.

I do have a multimeter, thanks Terra. My dad got me this really nice Fluke multimeter (he's an EE). I barely know how to use it! But, I do have it and will use it! I'm going to use my AA battery pack next time I hunt to see if the issue "replicates."

Thanks much!

Anyone have any opinions on that Maha charger?

Steve

You m;ight also get with someone like Batteries Plus they can build you a cheaper set up than the 1600 ML pack. I used my SE with low disc in trashy parks and was out there for 6 or 7 hours and still had battery left. Ive had my ML pack since i bought the SE when they first came out.... whats that been 3 years and rarely use anything but the ML pack. But i do keep the AA pack in the care with a pack of AA just in case. Im sure it will die some day.... then ill have someone take it apart and build me another.

Dew

Steve...... I'd be willing to bet you had a bad batch of batteries......... OR......... one AA battery went bad and nominal voltage for the entire pack dropped below minimum requirements... in short order.

If you have a good microprocessor controlled charger which can measure the capacity of single cells by controlled discharging, then having 8 AAs in a holder is better than having a pre-made Minelab pack IMHO. As Tom mentioned, one bad cell always ruins the whole pack. But on the other hand, putting the cells in and out mechanically stresses the holder. And also - if you discover a cell going bad after some 100 cycles, you would have to replace it - but it is not advised to mix new and old cells. Maybe have 10 and rotate them in duty? That would take care of it

Anyway, I am using Sanyo 2700 mAh cells I have originally bought for my RC model transmitter. I have used them for a while and then they have been unused in a box for more than a year. They still perform as new If you have a buddy who is building model cars/planes/boats, he should have some knowledge about rechargeable batteries - as the guys really care and a bad cell could mean hundreds of dollars and hours of work lost in one crash. Also, the chargers used by them are of the best kind.

Having the ability to 'load-bank' (test) individual cells is ideal..... with a plethora of available testers on the market. Finding one that is not cost-prohibitive for the application of this hobby... may be worth your time.

Try these sites. Thomasdistributing.com digitaldingus.com imagingresource.com rechargeablebatteryreview.com on thomasdistributings web site look at maha imedion 2400 mah low discharge. Power ex 2700 mah. Chargers maha mh-c204w and other maha 4 &8 cell chargers. The maha batteries perform best including c,d,aaa and 9 volt. Hope these sites help.

Wow, all...thanks for all the great info. Lots to digest, and links to check out (thanks, Sam!)

NASA-Tom -- I think you were right about the "one bad battery" thing. I ran my machine for 4 hours today with AA Duracells, and the battery indicator never moved from showing full charge.

BUT -- running the AA pack today raised an important, additional issue...and this issue will directly influence whether I change course, and buy a second Minelab rechargeable pack, AS OPPOSED TO using one of these other options (AA rechargeables, have Batteries Plus build me a pack, whatever). And that is this...

Today, I would SWEAR I had a major loss of depth using the AA pack. I hunted a new spot, so it COULD have been EMI (silent), or it COULD have been hot ground, but when I'd hit what sounded like a deeper coin, I'd dig -- only to find it much shallower than I expected. I think I have a pretty good feel for my SE Pro, and usually know roughly the depth I'm dealing with (based on how I run my gain) without having to look at the depth meter. Today, however, that "feel" was not there; I had several coins that I was guessing 6-7" on based on the tone, that ended up being 4-5". I don't think I dug a coin over 5" deep today. I definitely got the feel that my machine was not running "optimally" with the AA pack -- even though the machine was showing full battery life.

Now, we are getting into an area where I know almost NOTHING, so I have to ask -- is it possible that the Minelab pack is somehow offering "more power" to the unit -- and that additional power is directly being used advantageously by either the "send" or "receive" circuits of the unit? One one hand, this would seem doubtful -- but on the other, maybe it is possible. I plan to do some test-garden testing to see if my experience today is confirmed in that "controlled" environment. But, I'd like to hear thoughts (NASA-Tom?) as to whether what I think I observed today makes any sense, electrically, to a person much more versed in such things than I am.

To take this further, if this IS the case (the Minelab pack is in some way "optimized" for maximum power/performance in this unit vs. using AAs), then I have issues to consider, with respect to considering use of AA NiMH rechargeables (aren't they lower voltage than AA alkalines?) There is so much here that I don't know, and I HATE not knowing things! But, if today's results are accurate, then I am going to be gun-shy using ANYTHING in that backup pack -- and might just want to spring for a second Minelab pack. Still, I can't IMAGINE that you shouldn't be able to get equal performance from batteries in a backup pack to that you can achieve when using the Minelab NiMH rechargeable pack...any thoughts here?

Steve

Ahhhhhhhhhhh............. The merit of a test-garden is bliss!

I HIGHLY doubt the alkaline batteries were the problem. Any time you feel the batteries are the problem.......... it is quite easy to instantly slide out the AA batteries..... and slide in the rechargeable Minelab pack..... and see if anything changes.

The rechargeable pack provides less voltage than the regular alkaline pack. Voltage and Current is what drives the circuitry. Both packs are 'over-designed' to provide more than ample power............ with plenty in 'reserve'.............. and for long periods of operating time.

ALWAYS test new batteries! ALWAYS test old batteries! Be frugal. You may find that one (of the eight) batteries went 'flat'.... and the other seven are perfectly fine. What are you going to do............................ throw away 7 good batteries? This is not frugal. I (somewhat) do not like to 'mix' batteries........... but it certainly is MUCH more cost effective to find one spare battery to complete the 8-pack........ and .............. preferably............ of comparable voltage.......... if possible.

If you buy a 24-pack of AA's......... you may be surprised as to their individual voltages! ((( Try and match three comparable sets ))).

MH-C9000 wizardone charger has battery matching.lcd display.

Okay Steve, this is not up to Tom's test garden standards. Bury a silver coin in a clean area of your yard to the depth fringe of the Minelab battery pack. Swap out the Minelab for AA's. Play with it. It should give you a rough idea of Minelab pack vs AA. But like I said earlier, get that Fluke multimeter you own out, and check those AA's before testing. If your still getting the depth differences you perceived in the park, perhaps you have a circuitry issue with the unit. But do keep in mind that alkaline batteries do vary in voltage amongst different mfg's. Just because its a alkaline battery don't mean its automatically going to work perfectly. That's why they need to be multimeter'd beforehand. Tom D. would probably have a good idea what it could be if its a detector hardware issue.

p.s. wish I owned a Fluke.....they are sweet.

Steve, I have used some duracell 2650 for a couple of years and they gave good service up to a few months ago where
evidently one or more batteries are going bad as it runs down in a few hours.
While they were good, I could have ran almost 2 full days on one charge.
In no way am I endorsing the duracells, just thought I would give an idea of what to expect on some good fresh rechargeables.

I do wonder if they make throwaways as well as they used to, for sure the Explorer puts a current on them.
If you have good set of alkalines, they should give close to the same performance.

Sam --

Thanks much for that heads-up on the charger. Too bad they don't make a charger/analyzer in an 8-cell configuration.

TerraDigger -- I have that test garden with coins buried at multiple depths, so I plan to check it out tomorrow, the two packs, and see what I find out. Hopefully I don't have a machine hardware or a coil issue, that just coincidentally happened to crop up on the day I used the AA pack -- such that it's not the batteries at all, but the unit or the coil. Also, yes, it is time to break out the Fluke and start checking my batteries. It's funny, I have this really nice multimeter, courtesy of my dad the electrical engineer, and yet barely know how to use it! I guess it's better to be over-armed, than under-armed, though, right?!

Steve(MS) -- sounds like you had an issue with Duracells once resulting in your AA pack running down quickly. That must be what happened (as NASA-Tom also alluded to), as this current batch of batteries are doing fine.

NASA-Tom -- yes, again my test garden is going to show its value! Never thought I'd be checking out BATTERY PACKS in it, but I guess you never know! Anyway, like I said, it's time I break out the multimeter as I agree with the "frugal" thing -- I tossed that whole set of AA batteries when they stopped powering my machine, and now realize it was probably only one bad one that was the issue...and a battery test would have been prudent!

Since you confirm that "current" is what drives circuitry, then I can see that the battery pack was likely not the issue. Need to do some test garden testing.

Along those lines, I guess I can assume that the roughly 9.5 to 10 volts I'd get using 8 fully-charged AA NiMH rechargeables is still "OK?" I think the the "low battery shutdown" level on the machine is 9 volts; as such, I guess I'm good until they drain to 9 volts? Given that the machine's pack is rated at 12 volts, and 8 AA alkalines might start out as high as 13 volts, and with "shut down" I think at 9 volts, I assume that no matter what batteries you use, current supplied to the unit in the 9-13 volt range should result in consistent depth performance -- i.e., you don't "lose depth" as the battery slowly drains, do you? I am guessing the manufacturer would set the "shut off" voltage well above whatever voltage would theoretically start resulting in depth loss?

Steve

Steve, keep in mind that alkalines start high in voltage and have a rather rapid constant linear drop in voltage as they are used. NiMH don't start as high, but they drop slightly in voltage and then "plateau" at a constant (usable) voltage for most of their life. Look over the graphs on the Eneloop test I sent you. That is why the NiMH will work in the Minelab, like they do in my White's/Tek Omega. Lots of Minelab users utilize non-Minelab NiMH batteries with no problems.
There is nothing special about Minelabs rechargeable batteries over a good quality NiMH of equivalent voltage/mAh capacity. If Minelabs proprietary NiMH rechargebles work, so will others. They buy their batteries from the same mfg's we do. They just ain't telling us who they buy from.

Read this FMall post:

[www.findmall.com]

And look at charts here to see how NiMH batteries plateau and alkalines do a linear descent in voltage:

[www.powerstream.com]



Edited 4 time(s). Last edit at 11/16/2011 12:47PM by TerraDigger.

Thanks for that additional info, Terra. I read the FM post you sent...maybe I am over-thinking this (wouldn't be the first time! : ) )

I guess the only question now is to find out if what appears to be a "loss of depth" was due to some other issue (EMI, soil, whatever), or is due to a coil or hardware issue that has just cropped up.

Still curious though, on the theoretical question of whether you "lose depth" as you lose voltage (with ANY battery/battery pack), or if the "machine shut off" voltage level is ABOVE whatever voltage level would be whre you would begin to see a loss in depth/performance...

Steve

Well, if Minelab builds their units to depend solely on voltage for depth, they need to redesign their units. But I don't think they are built that way.
Most good detectors have voltage regulators so that the unit can properly operate within a range of voltage. Tom D. could best answer that question. In my Omega Tek manual, they say NiMH are fine to use, but won't last as long as alkalines. That's because most NiMH batteries have a low mAh rating. Get a high mAh NiMH battery like Eneloop, Tenergy or Duracell etc. and the longevity issue becomes a non-issue. I think Minelab uses 1600/1800 mAh rechargebles. The three brands I mentioned have NiMH that exceed Minelab.
I use a Powerex Imedion 240mah true 9.6v NiMH battery in the Omega and it rocks. Cost me 13.00 per battery, but well worth it.



Edited 3 time(s). Last edit at 11/16/2011 12:34PM by TerraDigger.

When battery voltage becomes too low on the Explorer/ETrac........ the unit will simply shut-off. In the process......... as the batteries are slowly depleting (in voltage and current)......... there is zero loss of depth performance............. all the way down to 'shut-off' voltage. Nearly all modern units operate/function in this capacity. I can not think of any modern detector that loses depth/performance whilst batteries are depleting.

That's what I was hoping/thinking. Thanks guys, good to know.

Steve

Hey Terra --

Thanks so much for the powerstream link; that really sheds light on battery performance (and a number of other things, as well!)

Steve