Weird incident with Rechargeable batteries and my Sovereign:shrug:

[Critterhunter]

That's one of those "THOU SHALT NOT..." things.
You will still not get the actual under load tests unless you can get to the battery terminals with the battery installed. Not gonna happen with a GT. Static voltage test will be about all anyone will get. It will not be quite accurate because the internal resistance of the battery packs will vary from pack to pack. Two different packs registering the same static voltage will not necessarily provide the same voltage under load.

HH

Art, nimh and nicad AAs actually have way more amp handling ability than regular AA non-rechargeables. The amp draw of 50 to 60ma or so of a Sovereign or Excal is miniscule. What you are describing is surface charge or surface voltage, and is only really an issue with devices that draw much higher amp draws. It is possible that a bad cell in a pack could cause this to happen even with the super low amp draw (60ma is super low, but even if you round up to 100ma that's still 1/10th of an amp...hardly nothing for nimhs or nicads), where the pack reads say 11 volts but under load reads say 9.5V, but at such a low amp draw of detectors that would mean a bad cell or a very weak/old/abused pack. Also, I tested mine LVC point on my GT using a 3 cell lipo that is designed to handle 15 amp constant and 30 amp burst high load amp rates. That pack is not going to spring back up under such a light load when it's removed, and it should 10.2V as the pack voltage, meaning that's right about where the LVC (low battery alarm) of my GT is. Kered reported about 9.8V for one of his three Sovereigns. Well within the tolerance specs of a voltage regulator. No two are going to be identical, but they shouldn't vary by more than about half a volt or so. Hardly anything to have different conclusions in whether an 8AA nimh pack will work or not for long run times. As I said, it all comes down to the points I just now listed. One of those is the issue if somebody isn't getting long run times. Under such low amp draw if a pack is going to sag under that little of a load there is something wrong with the pack.

 

[Ron from Michigan]

Critter,I have used much higher rated batteries than 2500s with 8x AA batteries they just didn't give enough run time.I have had hits and misses with some home made packs and got advice or lectured from Kered, but from my experience 10AA or 10 AAA batteries are no brainers and work.At this point I have a stock alkaline pack for backup and a pack I made up of 10 AAA rechargeable that give me 10-12 hours before a recharge is needed.I have a Sovereign XS headed my way for a flip and may require a battery pack to be made.I'm going to carry a multimeter and check the battery before and after use to see how my pack is holding up.As stated earlier it would be interested to log the actual point on the pack that triggers the low battery alert for my Sovereign.Thanks Ron

 

[Rick(ND)]

Looks like Ron has seen this too with the 8 batteries over the 10 as he is experienced with the Sovereign and there in one of the post from Critter with all the info this was also posted from Kered it too was seen, just seem those that are experienced with the Sovereigns and been using them for a while agree you need the 10 cells if using rechargeable to make the Sovereign run correctly. Seems like those that are experienced Sovereign users see where 10 cells is needed.
Now for the Explorers they take the 9.6 volts to run as this is what comes from the factory in the rechargeable pack as there is only 8 cells in it, but the Sovereign uses 12 volts to run it correctly.
Quote
HawaiiMDer
Kered,

I bought 16 1.2 v energizer rechargeables from the store, the green color ones. They do not work like a 1.5 v cell does. They caused my Excalibur to be erratic and would all false every 20 seconds on the dot. Am i just imagining that? Now when i attached 10 of these cells together making it 12 v the detector worked fine. As soon as i replaced them with regular alkalines guess what, my detector worked absolutely fine.
Ken.

To the people that are new to the Sovereign or Excalibur's listen to those that are well experienced as they have seen the things you can do and those you should not.

Rick

 

[robby4570]

Rob that is low battery alert.Normal for a Sovereign with a low battery.Use a DC volt meter reading and post it.Thanks Ron

Now THAT'S what I'm talkin' about!!! OK, I was not told that by the guy I bought it from... he said the threshhold would go to a deep low tone that changing the threshhold knob won't change. He said that was my low battery warning.

Thanks for the education Ron. If someone else mentioned this tidbit earlier on, I guess I missed it. That's what I get from reading this thread on my phone instead of my laptop

 

[Ism]

I don't know if it was mentioned here in the depths of Critters posts but NiZn AA are 1.6v and they work very well for me in other devices.
They hold their charge for a long time on the shelf. Should be a great substitute for alkalines in the battery pack.
I don't have the battery pack for the Sovereign, but they are the rechargable I would use if I did.

 

[Critterhunter]

Ron, if you didn't get long run times from 8AA nimhs in the alkaline holder then it's one of the following issues I already pointed out...

1) You are not using 2500ma or higher nimhs (shoot for the highest you can as higher capacity will keep the voltage higher longer).

2) The cells you used were of poor quality, and so either not reaching full capacity or full potential voltage.

3) The cells were not excercised. When new nimhs or nicads need 4 or 5 charges and *complete* drainings before they will reach full capacity and voltage potential. Not just re-charged without draing completely, because that does NOT properly excercise a pack to increase it's voltage and capacity potential. You need to drain them in something like a flashlight or hooked up to a car tail light bulb (my favorite method...put all 8 in a 8 series battery holder from radio shack to generate the voltage needed to light the bulb up) in order to drain them completely. When the light goes out let the cells sit hooked up to it for another 10 minutes or so to insure all cells are at equal discharge to each other. My charger does drain cells to excercise them for you, but it takes much longer due to it's wattage limitations of my charger, so I just completely drain them on a car tail light bulb. Be careful when doing this to place the bulb on a cement surface, as tail light bulbs get hot. This only needs down 4 or 5 times when the cells are new, but a couple times a year I will charge/drain my cells this way about 3 times in a row to fully excercise them again. Makes for longer lifes and increased capacity/voltage. This is also a good way to recover bad packs or ones with very short run times.

4) The charger you used is not charging them to full voltage and capacity potential. Many cheap chargers falsely terminate too early or are basing the criteria of a full charge on reaching a target voltage of 1.2V and are not relying on the delta peak (meaning m/v threshold) to determine when fully charged. Even some cheap chargers that use this method to determine full charge have this internal setting set too low and so false terminate when the pack dips a little in voltage during the charging process, which is norma. There are little dips and rises in voltage during the charging process, but when really peaked that dip or "valley" in the voltage will be larger and more constant.

5) You were not using low-self discharge nimhs, and so when charged the cells sat on the shelf for days or weeks and drained in both voltage and capacity. If you aren't using low self-discharge nimhs then the pack needs re-peaked a day or so before the hunt. Some normal nimhs are better at holding their charge on the shelf than others, but just the same low self-discharge nimhs are becomming so common place these days that there is no reason not to just buy those and not have to worry about re-peaking before each hunt.

As Kered stated in those numerous quotes I posted, the manual for the GT was written years ago, and probably in fact for even older models of the Sovereign. Minelab used ancient Sub-A 1000ma cells in the GT. The primary reason why they used 10 cells was due to- very low capacity, & also due to the cells self discharging on the shelf. They put 10 in to boost the voltage so you didn't need to re-peak the pack for weeks between hunts. If you use low self-discharge cells this is a non-issue, as low self-discharge cells have only recently come along in technology. But even still, many "normal" nimhs hold their voltage on the shelf better than others do. I bought one brand of nimhs a few years back that would be near dead after sitting on the shelf for only a couple of days. Others I have that are not even rated as low self-discharge are good for many weeks after I charge them. Still, any future nimhs I buy will be low self-discharge, as they are getting very common and rather cheap these days, so no sense in not buying that type. Not all of these are as good as others, so one must research them on the net to see which hold up to their claims.

Rick, as you can see from the quotes I posted from Kered, he has used 8AA nimhs in this GT, Elite, XS2, and his Excalibur Alkaline pod as well with no issues with run time. That is for sure a ton of experience from which he drew from, so I'm pretty confident others can trust his opinion if they don't want to trust my experience with rechargeables over many years.

The Sovereign/Excal voltage regulator does indeed have a higher cut off point for low voltage than most detectors, but the Sovereign needing 12V to run on is simply not the case. Voltage regulators have specifications for the window of voltage they will operate at. For the Sovereign it appears the LVC point is around 9.8 to 10.2V, accounting for slight variability between regulators. No two are going to be identical, but the variances are going to be very close to each other to the point it's not an issue one would notice. I bet at the most about .4V or so is all you'd see in differences from one to another. So little it's not really a factor.

Back to the issue of 12V being needed for the Sovereign regulator...A regulator isn't designed for one specific voltage, but rather has a window in voltage range in which it needs to work properly. 8AA non-rechargeables are only going to show 12V for a very short period of time when used, because thier voltage drops faster than a high capacity nimh and will soon be as low or lower than the nimh during the discharge cycle. Regulators are not designed for one specific voltage. That's the whole reason why regulators are used in devices- to take in a wide window of voltage levels and ignore it, only putting out a static non-charging voltage to the circuit board (say 9V for example). If a regulator had a fixed narrow window of input voltage of say 12V, you'd get almost zero run time out of new non-rechargeables, because they only stay that voltage for a little while and quickly drop as they drain, much faster than high capacity nimhs do.

Yes, the Sovereign has a bit higher cutoff point for it's regulator than most other detectors. Off hand I would guess that the regulator used in the Sovereigns/Excals has a window that ranges from about 9.8 or 10.2V up to about 13 to perhaps 14.5 volts or so. Too high of an input voltage and the regulator can't expell the excess heat and will shut down on thermal overload. If your lucky it will work again once it cools down and resets. Linear regulators use a heat sink to waste off excessive voltage. If you are using 8AA non-rechargeable batteries in the alkaline holder, when new they are about 1.5V, but that excessive voltage above the 8 or 9V (or whatever) the Sovereign circuit board is only allowed to see is shunted off as heat to the heat sink on the regulator.

The reverse of that operating window is that too low of an input voltage and the low battery alarm begins to sound. But the truth is that the Sovereign's regulator doesn't "require" 12V, because if it did then your Sovereign wouldn't run long at all because non-rechargeables drop rather fast in voltage right away as they drain and will quickly be well below that 12V when new. And, nimhs hold their voltage constant and steady throughout the discharge, not dropping it nearly as fast as non-rechargeables. For that reason there comes a point very soon when fresh AA non-rechargeables are only putting out the same or less voltage than the nimhs are, because the nimhs will "flat line" their voltage during discharge. You can look up charts on this off the net. Nimhs keep the voltage held high until right near full discharge. Non-rechargeables drop in voltage much faster when draining.

 

[Critterhunter]

I don't know if it was mentioned here in the depths of Critters posts but NiZn AA are 1.6v and they work very well for me in other devices.
They hold their charge for a long time on the shelf. Should be a great substitute for alkalines in the battery pack.
I don't have the battery pack for the Sovereign, but they are the rechargable I would use if I did.

Yea, I'm not surprised you missed it, But I did mention if people refuse to believe Kered or me then to just buy zinc based rechargeables that have a higher per cell voltage count right at that of non-rechargeables. These zinc based rechargeables did have issues with reliability a few years ago but from what I hear it's no longer a problem. I never really read that heavy into them but I think they are designed for very fast high ramp charge rates. I think Raovac might be the leader in this type of battery technology and might have the best cells out. I know I've seen there cells that come with the charger at the major chain stores and I think they touted like 1 hour or less charge times for these cells.

But, beyond the reliability issue of cells going bad fast (which I think I hear has been fixed), I remember reading that they had not nearly as long of cycle lifespan as nimhs or nicads do. Whether that's been improved for the last few years I don't know, because I'm completely happy with nimh technology where I use it. I also don't know if those zinc based batteries hold their charge on the shelf better than non-low self discharge nimhs. You'd have to read about on them on the web to find out if they quickly self-discharge on the shelf, but if I had to guess I think I remember that they didn't do that and so that was also one of their major strengths, besides having around 1.5V per cell voltage for people that simply refuse to believe that the lower starting voltage of nimhs compared to regular batteries is not going to cost them detector performance or run time.

Besides zinc based rechargeables, there are also other chemistry types out there these days. Again, I've not read into it much so you'd have to do the research on your own to see what's new in that respect. I *think* there are now lithium based AA cells that have been adjusted in chemistry to lower their voltage within reason of regular AA cells. I would have to believe that is true because obviously Energizer has lithium based non-rechargeable AAs on the market that only have slightly higher voltage than regular AAs, so they should be fine in most devices. So I would suspect rechargeable versions of such chemistry are now out there on the market.

A big perk of the Energizer non-rechargeable Lithiums is they have much longer run times (2 to 3 times or so) than regular AAs, so they more than make up for the little extra cost. They are also super light. For those two reasons you might look into what might be out there in lithium based AA rechargeables. Just make sure they are designed with the lower 1.5V (roughly) voltage to work with devices using AAs, because there are AA lithium based cells out there that are like 3 to 4+ volts or so, and not meant for replacing your regular AAs cell for cell.

But, I think they now have "dummy" cells for using these. In other words, you put one of those cells in and then a dummy plug as every other cell, so though the voltage per cell is roughly double that of an AA, the dummy cell is just a circuit to pass the voltage to the next cell, so it's cutting the voltage in half. In other words, 4AA lithium rechargeables and 4 dummy cells in your holder should equal the proper voltage for an 8AA pack in series. I'm not sure about this though as I've only seen references to something about it, and off hand I don't know what the per cell voltage is of lithium ion based cells. I've just stumbled across small blurbs mentioning something like this.

I need to surf the web and catch up on the rechargeable technology I've missed over the last couple years because I haven't kept up to date on the latest and greatest stuff out there for consumer rechargeables.