Excal Problems

[Digging Fool]

I bought a nice used Excal 1000 a few years ago, and it's been a good machine. I noticed last fall that it was acting a little erratic, after being on for a couple hours. I had been using the Tiger Shark this season, but took the Excal out today, and the battery was showing fully charged on the battery tender. After using it for an hour and a half or so, it started making a "weird" tone, about every 30 seconds or so, like clockwork. Then, it started going crazy with high and low tones. Figuring it may be a bad battery, I checked it, and it had 12.4 volts. I don't know what the normal voltage is supposed to be, but would thing that 12+ would be good? This machine is the one with the blue headphones, and I don't know the exact age of it, but probably 7 years old or so. I've heard some not-so-good stories about Excals being sent in for repair, but would welcome an opinion on that. I mainly hunt freshwater, and the Excal goes deeper than the Tiger, so I prefer it at the end of summer/fall hunting. Any ideas or suggestions would be very much appreciated.

 

[Critterhunter]

Sure sounds like the low battery alarm. The threshold will go crazy (up/down/loud/etc) and you'll get that death squeel every 30 seconds or so.

If the pack is bad it can show a high surface voltage (called a surface charge sometimes) but once any kind of even small load is put on it the voltage sags. Usually a sign of a bad cell. You're going to need to feed it another pack and see if the problem goes away. If you've got the know how you can run it off your car battery (12V) and see if it works fine if you don't have another pack laying around. Car should NOT be running so as to avoid noise being generated by the alternator which will do strange things to electronics. Don't follow my advice or risk destroying your machine.

 

[Digging Fool]

Thanks, Critterhunter! I did buy a battery pack last year off e-bay, but I need to put it in the pod. Thanks for your advice!!

 

[Sandpiper]

Like Critter said voltage as good, but when a load is applied it drops tremendously. Sounds like your battery needs to be cycled, what I mean by cycle is to charge and discharge several times so it will hold maximum charge rate.
If you just charge till its full as your doing now it may not take for example 25-100 MAH and will not last anytime, but by cycling it should hold close to or not over 600 on the NICD or 900 on the NIMH.
This picture is an example of a charge NICD taken to a fully discharged rate 1 time and recharged.

 

[Critterhunter]

Yep, cycling might bring the pack back to life. Even though my charger has a discharge function, often they are limited by the watts they can handle and so take a long time to drain a pack. For that reason I prefer to just hook a car tail light bulb up to the pack to drain it fast(er). After the bulb goes out let it sit on it for another 20 minutes or so to insure all cells are at equal discharge, because an unevenly charged pack can cause bad run time issues where some cells are charged while others don't get the chance to catch up.

I prefer charging a pack at at least 1C (amp rate equal to capacity of the pack, for instance 1 amp for a 1000ma pack) if not higher to bust down any crystals that form resistance in the pack which a slow charge won't get rid of. Some guys even believe they need to zap it at like 2 to 5C or so to bust those crystals up. That can be dangerous on a pack not designed for such high charge rates, so if I don't know what a pack can handle I just do a high rate for say 2 to 5 minutes and then go back to a 1C or lower charge rate to finish it off. The zapping only needs done once, so further charging/draining can be 1C or less. I never try to push a pack beyond 1C when in a hurry, as that could shorten it's life. Some cells can handle that with no issues, but always feel the pack to see if it's getting hot while charging.

Even if you only have the stock slow charger, by draining/recharging the pack say 3 to 6 times you should still be able to recover it, unless the crystals are the problem and then it's going to require a higher charge rate. If you do, try 1C (another example, point 8 amps for a 800ma pack) first. Even then be cautious, watch your eyes when near it, and feel the pack for heat. If a pack is pushed beyond what it can handle (which usually means something higher than 1C to have that potential) there is risk of fire or explosion possibly, though I've never had that happen even when zapping a pack at say 2 to 5C for a few minutes to try to get it to come back to life.

A charger with a capacity display will let you know if you are making progress with the drain/charge cycling. Every time it's completely drained and then recharged you should see the capacity put back in climb at each completion of the charge. I usually know I've exercised my packs enough when after say 2 or three charges I no longer see the capacity making great gains.

The sign of good cells is they often hold more capacity than the label says. A 800ma pack for example, should hold maybe 1100ma or so if it's a healthy pack. That's why I never set the safety feature cutoff for the capacity limit on my charger which features that. If you set it to say 800ma for a 800ma pack then it will shut off then, even if the pack still hasn't told the charger that it's reached full charge yet.

The amp draw of the Excal/Sov is somewhere in the 50 to 69ma range depending on if it's sounding off to a target or not. That's so very little amp draw that it's virtually nothing. In fact, most nimhs and nicads can hold up under much higher amp draws than even store bought non-rechargeables. Meaning, if the pack is sagging it's voltage under low from such little amp load, then there for sure is an issue with the pack. It might just need exercised, but the load is so little that often that's a sign of a bad cell in the pack. Worth exercising it anyway to see what happens.

 

[John(Tx)]

on mine when it the battery needs charging, 12.38v and it just blares up, time to recharge. HH

 

[Digging Fool]

Thanks for the helpful posts! I just put the new pack in the pod, but saved the old one. Need to go out this weekend for a test-run.

 

[Critterhunter]

It shouldn't be sounding the low battery alarm at 12.38V. There are variances in what voltage exactly the low battery alarm on the Sovereign/Excalibur will sound off the low battery alarm. Kered said I believe around 9.8V on his Sovereign, where as mine sounds off at about 10.2V on my GT. Even though all these machines are using the same specifications for a regulator, there is going to be slight differences in manufacturing as to where that low battery alarm cut off point will be, but it's going to be right around the 10V range.

If you are getting a low battery alarm and then checking the voltage and finding 12.38V, then that's a sign of a weak pack as the voltage is sagging much lower when it's put under even the very light amp load of the Excal/Sov. I tested my LVC (low battery cutoff) on my GT by using a lipo battery, which can easily hold up under the super light amp draw of the GT and not sag it's voltage under load. This pack is meant for 15 amp continuous amp draws and even higher burst rates, and lipos are well known for holding their voltage high under heavy current loads. Even still, nimhs or nicads have the ability to hold up under higher amp draws than non-rechargeables without sagging in voltage, so if you are saying 12.38V was read after a low battery alarm and the pack was removed and checked, then that's a indicator that the pack might be bad or at the very least needs some exercising.

 

[Critterhunter]

Digging Fool, just be sure to top the pack off that morning or say the night before, because nimhs/nicads will self discharge on the shelf in as little as a few days (I've seen it happen) to a few weeks. That's the main reason why people report short run times with rechargeables. I also feel that's probably part of the reason why Minelab put 10 cells into the stock rechargeable pack, so that if it's sat for weeks after charging the voltage is still high enough to give you a day's hunt. That, and also because Minelab used ancient Sub-A cells with very little capacity (1000ma) which will drain faster and thus drop in voltage quicker then more modern higher capacity cells.

There are now low self-discharge nimhs on the market that claim to hold like 80% of their charge or more after sitting for roughly a year on the shelf. Some don't hold up to their claims, so anybody considering those should surf the net to see how they fared in tests by battery fanatics. There are entire websites set up by battery junkies who make it their life's work to test various rechargeables on the market. It's become a passion for them and a hobby.

 

[John(Tx)]

I have 2 battery packs, the original and my back up. The original is the one that makes the excal blare up when it reaches 12.38, I haven't had that problem with my back up, maybe because I don't leave it on the machine long enough, I just use it when the original depletes, which does it after about 6 hours of continuous use, maybe I need to replace the batts. My back up is an alkaline battery pod which I have filled with rechargables. I tried using alkalines but no go, even with fresh batteries, my excal would just blare and not run stable, hooked up the rechargables and ran like a top, that is why I don't use alkalines, will not work on my excal, wonder if anyone else has encountered this problem? HH

 

[Critterhunter]

Even if you suspect no issues with your pack, many feel it's a good idea to exercise the pack perhaps twice a year to insure it's at top capacity for longer run times. I do this with all my packs and it will both keep them in tip top shape and also increase the capacity. Some people think only Nicads suffered from memory problems. While that's true, and in fact isn't really an issue among Nicads these days as far as I know, Nimhs will still benefit from giving the chance to exercise their muscles and stretch their legs a few times a year, so to speak.

The first step in exercising a good pack for more capacity, or in trying to recover a bad pack, is to drain it completely dead. While my charger has a discharge function, it's limited by the watts it can handle (voltage of the pack X the amp rate of discharge). For that reason, I prefer to drain the pack on a car tail light bulb because it's much quicker. After the bulb has gone out let it sit for about 20 minutes to insure it's drained every cell to equal discharge. Also, be sure to place the bulb on a cement floor because they get very hot, which you should always do anyway with your packs when charging or discharging in case a fire should happen just to be safe.

Now you want to charge it the first time using a more "aggressive" charge rate for the reasons being discussed shortly here. You can exercise or try to recover a pack with the stock charger, but if you have an aftermarket charger then the first charge should be perhaps around 1C. For the stock GT pack which is 1000ma, that would be a 1 amp charge rate. This will bust down any crystals that form resistance and are not normally destroyed by a low amp rate to charge the pack. I have even done this 1C charge rate (roughly a 1 hour charge time) when in a hurry to get to the field when I still used the stock rechargeable pack, but I feel for the life of the cells it's always best to charge at a lower amp rate, like perhaps 1/2 to 1/3rd C. A 1C charge rate won't shorten the life of most modern nimhs or nicads, and probably won't with the GT pack either, but I would by all means not make it a habit in order to play it safe for maximum life/capacity of the pack. Being in a hurry to get to the field here and there probably isn't a problem though.

But for exercising the pack (even if it doesn't appear to be having issues or problems with short run times or just being a bad pack), I'll do 1C for that first cycle to break down any crystals that can form over time, but some will go as high as 2 to 5C to insure those crystals are broken down, at least in nimh or nicad packs for other applications such as in the RC plane/car world.

If I don't know what C charging rate a pack will handle, and yet I feel it's not working properly due to crystals, only then will I risk a say 2 to 5C charging rate for perhaps 2 to 5 minutes and that's it. Charging at such an excessive rate on a pack not designed to handle that can cause risk of explosion or fire, but if I feel it's needed as the only hope to recover a pack I'll risk it for that few minutes, using proper safety gear such as goggles and such of course, and then will return it to a 1C charge rate for the rest of the charge, but still will feel the pack during that charging process to insure it's not getting hot. If it's hot then you are pushing the pack and heat will slowly destroy the pack's useful life over time. Either way, if I don't suspect the pack has issues then 1C is what I'll charge it at for the first excises cycle, and even then it's a good idea to feel the pack while charging to see if it's getting hot.

So once the pack has been first drained, and then charged at that first "aggressive" rate to insure any crystals have been broken down, then it's time to drain the pack again via the car tail light bulb. IMPORTANT NOTE HERE: If you do use a car tail light bulb make sure you are not dead shorting the pack. Some car tail light bulbs have numerous contacts for various functions. If you have any doubt about this stuff then best to find a bulb with only two contacts, such as a side blinker signal or something. While some will drain nimhs/nicads via dead shorting them, I feel this is a very dangerous practice, or at least is very hard on the cells IMO. They have to have a load to drain them, such as a 12V light bulb of some type. You just want to be sure to use a light bulb that will drain the pack fast and won't have you waiting for hours. A typical drain time using a car tail light bulb might be perhaps anywhere from say 10 minutes to an hour or so, depending on the capacity of the pack and the wattage of the bulb. As said, once the bulb goes out let it sit for about 20 minutes at least to insure the cells are all at equal discharge. And again, make sure that bulb is on a fire proof surface because they get very hot.

Now it's time to charge it again. Now I prefer a more gentle rate. The stock wall transformer will work fine but it's going to take at least 10 hours or more to complete it due to it's super low trickle charge rate. Using an aftermarket charger, I will charge at say 300ma (about 3 to 5 hour charge time) to say about a 600ma charge rate (about 2 to 3 hour charge time). I don't feel either of these is really pushing the 1000ma GT pack.

Time to discharge again. Do this drain/charge exercise at least 3 times, but probably about 6 will yield maximum capacity and get the pack into it's best shape possible. It helps if you are using a charger that displays the capacity put back into the pack, because you can visually note if the capacity is still making substantial gains with each charge. When I don't see the capacity increasing all that much, I'll still do another charge or two to see if it in fact has hit the wall in terms of it's maximum capacity ability.

Remember too, that even if the pack seems fine, by exercising it you are going to increase it's run time. Also remember that a new pack also needs such exercising to get it into top shape. Expect very short run times from a pack until it's been charged a few times. Do the exercising (3 to 6 times or so) at least once a year or perhaps twice a year to keep your packs in top form.

There are some who believe a nimh or nicad should never be drained completely dead or you risk a cell reversing polarity, while others (like me) believe it's important to drain them completely to insure full exercise of the pack. From what I've read the reverse polarity risk is mainly when the pack has set on the shelf after it's been completely drained without re-charging it. Besides, even if you let the pack sit hooked up to a light bulb for 20 minutes or even an hour after the bulb has gone out, you'll find that when it's removed from the load (light bulb) the pack will immediately start springing back up in voltage. It would have to sit hooked up to a load for hours if not days before all charge is truly gone from the pack.

We aren't trying to reach that point with the light bulb, we're just trying to get all the cells at equal discharge to insure they all reach full charge at the same time on the charger. With cells out of charge balance with each other some might peak and cause the charger to believe the pack is fully charged, when in fact several cells might be while others are not there yet. That's one of the things that can cause a false "surface voltage" or "surface charge" of a pack, where it seems to show a high voltage when not under load but quickly drops when any kind of load is put on it.

Oh, by the way, if you are wondering how to hook up your battery to a car tail light bulb, head up to Radio Shack and get a pack of connection wires that feature alligator clips on them for about $3. Simply hook up one lead to one main battery lead on your battery, and it's other end to one of the SEPARATE connections on the light bulb. Then do the same for the other alligator connection wire. The positive lead from your battery should never be connected in such a way as to be directly passing current to the negative lead on the battery. That's a dead short. You always want a load in between them for draining, such as a car tail light bulb.

I think I've pretty much covered the exercising or trying to recover a bad pack thing as good as that's gong to get, and since this thread is now linked to the battery sticky in the future I'll just point people to that who have any questions on exercising a pack or trying to recover a bad one.

Once again the warming: Don't follow my advice or risk personal injury, death, burning your house down, destroying your detector, cooking your battery, or anything else bad you can think of. I make no claims to being right about all things. Only God can do that. And besides, opinions on the care and feeding of rechargeable batteries differs greatly among people. These debates have been going on for decades even about nicads, so do your own research and make up your own mind. I just am basing my opinion on my own research along with my own personal experience with rechargeable batteries for years in various applications, hobbies, and so on.

 

[Critterhunter]

Don't know why you'd be having problems with Alkalines. Are you sure you used the right type, because some store bought batteries are the wrong chemistry to run a detector. Refer to the manual on that. If you are using the right type and 8 cells, it should be roughly the same voltage as your 10 cell rechargeable pack.

 

[John(Tx)]

I was using Ray O Vac alkalines, maybe I should try Duracells? thanks

 

[John(Tx)]

I drain my batts about every 3 months using the car tail light bulb method but even then the batts still read around 11v but the tail light is not lit anymore. I will continue to let it drain about 2 more hours until the voltage gets down to about 6v then after the batts cool down I will recharge. I've heard not to let the batts drain down all the way that it's bad for them but I don't know if this is true. Is it ok to do this? thanks

 

[Rick(ND)]

Myself I never let a battery go completely dead as I have seen some that will start to leak or never able to hold a good charge. I was told to use a discharge charger so it take the battery to a safe level and recharges it to the correct level and go to a trickle charge. I have been using one since 1997 and never had a battery go bad yet. Some do use this method and run the completely dead, but I will not as I have seen what happens.

 

[Sandpiper]

I would never let them drain down all the way, The cutoff drain should be at 1.1 volts per cell there being ten cells that would mean that you should discharge to 11 volts.

 

[Critterhunter]

Yep, some believe you should never drain a nimh or nicad all the way dead. Others (like me) feel it's the only way to fully get a pack into top shape, so take your pick and decide for yourself.

The main issue with fully draining a pack is the risk of reversing polarity on a cell. But as said I've read that risk is only really a big one if you drain the pack dead and then sit it on the shelf for a long time without recharging it. If you drain the pack dead just be sure to charge it again right away.

Even if you let a pack sit on a car tail light bulb for an hour or two once the load is removed the voltage starts to spring back up again. Very hard to drain a pack truly dead unless it's sat on a load for many hours if not days. Besides, when the bulb goes out that's just because the voltage/current has dropped below what the bulb needs to light up. That's why I let it sit an hour or so on it once the light goes out. 20 minutes after it goes out should be enough to exercise it enough though and drain it darn near dead, but I'll give it an hour or two if I'm not in a rush.

Not only is this exercising the cells, but it's also insuring all cells are at equal discharge. Cells over time can get way out of balance and then when you throw it on the charger say 6 of the cells already were starting with much more of a starting charge while some other cells were near dead. Those 6 cells reach peak and then trigger the charger to think the pack is done charging, thus the other cells never caught up.

I've been draining packs dead like this in nimhs and nicads since the late 80's or so and never had a problem with doing that to exercise them, and as said I'll do this once if not twice a year or so and about 3 to 6 drains/chargings when I do exercise them like that. Used to be nicads needed this to resolve memory issues where they wouldn't drain or charge to full capacity, but even modern nicads or nimhs will greatly increase capacity/performance if you stretch their muscles like this.

Don't follow my advice or risk destroying you, your machine, your battery, your house, or all kinds of other bad luck.

 

[Critterhunter]

I would never let them drain down all the way, The cutoff drain should be at 1.1 volts per cell there being ten cells that would mean that you should discharge to 11 volts.

1.1 volts IMO is still a lot of charge left in the pack. Nimhs or nicads will hold their voltage on average at about 1.2V during most of the drain cycle. They might start at a lower voltage than a non-rechargeable but a high capacity nimh/nicad will flat line it's voltage as it drains and hover right around 1.2V for most of that discharge.

To each his own as these are all opinions based on our personal experience, beliefs, and research, but 11V on a 10 cell pack to me is still one heck of a lot of charge left in the pack. There's a full spectrum of cell chemistry storing that extra charge that is never getting exercised to try to get more out of it IMO.

I look at it this way, it's like continually topping off the gas in your snow blower every year without never letting it run dry once in a while to get rid of the old gas. If you keep topping it off the old/bad gas is just getting poured over by the new gas and sooner or later you've got performance issues with the carburetor. That's just my opinion anyway. Others I'm sure strongly differ...

 

[Digging Fool]

Some good and interesting advice here. My new battery pack is one I got off fee-bay at a good price a year or so ago. I hope it won't be some crappy junk. I still have my stock Excal charger, but after reading all the "hype" on another forum about the "battery tenders", I got a Tender Jr. It seems like it charges in too "little" time. Perhaps I need to go back to the stock charger? Anyway, I still have not taken the Excal out for a trial run. Took the Tiger Shark out today and had a little luck. Didn't have room in the truck for 2 machines.

 

[Critterhunter]

Look on that charger and see what it's output current is. Is it above the capacity of the pack (meaning higher than 1C, meaning less than an hour's charge time?)? For example, let's say the pack is 1600ma. It it charging at higher than 1.6 amps? If it is you may shorten the pack life. Some nimhs these days can hold up to higher than 1C charge times and still have a long life but I don't even like pushing a pack at 1C all the time. I only do that when I'm in a hurry. Far safer, or meaning easier on a pack, to charge at say 1/2 to 1/3rd C. Or, 800ma for a 1600ma pack (2 hour charge time roughly) is a 1/2C charge rate, or about 500ma would be roughly 1/3rd C for about a 3 hour charge time. These are times on a mostly dead pack of course. If the pack still has a lot of charge it'll take much less time to peak it. Sure, some guys will charge at say 2 or 3 amps on a pack that size and still get a long life out of it for years but over time it might lesson it's capacity (run time). Feel the pack when it's about half way through it's charge on the charger. Is it getting hot? Then you are slowly destroying the pack. Heat is a battery's enemy and is a sure sign it's being charged at too aggressive of a rate.

The stock GT charger is from memory I think 100ma output, which is so low that it's called a trickle charge. Pointless to charge that slow as it's not any healthier for the pack then say charging at 300 (1/3rd C roughly for about a 3 hour charge time to 4 or so), to say a 2/3rd C rate (about 600ma+ amp rate for about a bit less than 2 hour charge time). Either one of those is hardly even pushing any nimhs or nicads I'm aware of. 1C is borderline where most if not all packs shouldn't have issues with life span, but that's still a gray area, and beyond that rate you are for sure getting into the unknown zone unless you have the specs for the cells which say they've been built for higher than 1C charge rates without suffering life span problems.

Some guys will use chargers that charge a dead pack in about 15 minutes and still get long life, but unless the cells are designed for such an aggressive amp rate you're probably costing it some capacity over time. If it's hot then for sure you are.

Also, even doing the math the charge times often take longer than the math says. Two reasons why- charging is not very efficient so energy is wasted and it takes more time to get the cells charged. Second reason is that good cells often hold more capacity than the label says. A sure sign cells are healthy is if (when drained near dead) they will take more than the label says in capacity. Say 1300 or 1400ma for a 1000ma pack maybe.

The reverse of that is if the pack takes less capacity then the label it either means you need to for sure exercise the pack or the pack is going south on you. Also, these capacity readings are of no use unless the pack is dead or near dead when charged, because a half charged pack is only going to take enough more capacity to fill it back up again and that's all the charger will report has been put into it.

That's why I like a charger with a capacity display so I can keep tabs on how the pack is doing over time. If it's near dead and when charged isn't putting more capacity back in then the label says then time to exercise it 3 to 6 times or so and see if it's making any gains with each re-charge from doing that. When it flat lines or I don't see much more in gains after about 2 more cycles of drain/charge then I know it's as good as the exercising is going to get.

If the pack isn't drained near dead (like via a car tail light bulb) then you've got no way of knowing just how much capacity it's holding when you charge it either. It's always going to show a good bit less that way then what the label says.