Excal 800 coils

[Steve in PR]

I have been burning out coils, 4 in the past 4 months. Not doing anything wierd, as far as I know. In some cases, I am in 6" of water and burn it out after 10 minutes of searching. Battery checks out good and is charged. Electronics are new. What am I doing wrong? Any facts, thoughts or theories?

 

[John (west central FL)]

n/t

 

[JW]

make sure on the next coil it is finger tight, do not over tighten because that will pinch the cable and make it worse.

 

[Steve in PR]

What happens is that I get the machine back with a new coil and charge the battery normally with my MineLab charger. I go to the beach and start to hunt in 6 - 12" of water. After 15 or 20 minutes, while I am pulling coins and rings, the coil starts to howl. Just a continuous, loud howl that pitches slighlty up and down but does not cease. If I turn the unit off, it remains when I turn it back on. If I disconnect and reconnect the battery, it remains. If I let it dry out and turn it back on hours later, the howling remains. When they get it back for service, the howling is still there and they replace the coil, check the battery (ok) and test it and send it back to me and I charge the battery, go to the beach and my nightmare begins again.

Mind you, I think the techs have done everything correct and have been very concerned. They have replaced all wiring, the battery case and the PC board. It is an essentially new machine. I just can't figure out why this continues to happen.

I love the machine so I am determined to get it working right. I just hope someone has some experience, ideas or knowledge they could share.

 

[Steve in PR]

Thanks for the tip. I have thought that could be the culprit. Either that or the threads are damaged. Do they use RTV to seal or any sealant for that matter? I just don't understand how it could be happening time and time again. I am reluctant to touch anything done by the repair center. I have faith that they know what they are doing and I don't want to void the warranty on the repair. This last time, they left it submerged the entire weekend and it was fine on Monday, before they sent it to me. I am at a loss for any other explanation...

 

[Rick(ND)]

If you carry this Excallibur in the car and it is hot, or if the coil is sitting in the hot sun and you put it in the cold water it will draw in some water in the coil at the stain relief. If this is what is happening maybe it would be better to cool to coil down before you submerge it in the cold water. I would think by doing a little beach hunting where just the bottom of the coil is in water untill the coil cools down a little and then see what happens.
Just something to think about and try.

Rick

 

[Beachcomber]

That really can't happen on an Excalibur Coil as they are epoxy filled so there is no air inside to become heated or cooled. The Explorer is the one that does what you mention. It is a hollow coil. When it gets hot the air inside expands and if the strain relief isn't tight enough the hot air will expand and escape through the strain relief. THen when you go into cold water the air that is left inside contracts and creates a vacuum which sucks water right into the shell. It causes a lot of falsing. I know I have had 5 Explorer coils leak so far. The big problem with Excalibur Coils happens when people hipmount them. If they hipmount and hunt a lot usually the coil wire fails in about a year and you need to have the coil replaced.

HH

Beachcomber

 

[Beachcomber]

One thing you might try the next time you get it back from the repair center is to unscrew the strain relief cap and coat the wire and the threads with Marine Silicone then screw the cap back down snuggly and let it sit overnight before using it. I haven't had any problems with coils leaking since I have started doing this and I do it to every coil I buy before it goes to the beach for the first time!!! Also are you leaving enough slack wire at the bottom of the shaft to allow the coil to move without putting a lot of stress on the coil wire. Sometimes people wrap the wire to tight around the shaft right down to the coil which doesn't allow the flex and since the wire is the weakest link it breaks internally. Hope this helps....also check with Minelab to make sure applying the Silicone Sealeant won't void your warranty. It shouldn't but you never know unless you ask!

HH

Beachcomber

 

[CC2_IN_CA]

The Excalibur manual states you should not leave the coil
exposed to the sun for long periods. The black coil's temperature
could rise above 150 degrees damaging the coil.
That is straight out of the owners manual.

 

[Steve in PR]

I was desperate. 4 coils changes, new cables and control board replaced and the problem persisted. That left only one other possible suspect: the battery. The guys at Minelab had done everything humanly possible. All that remained was the battery. It had been tested at Minelab and passed. But, I noted that if I did not recharge it after every use, it put the detector out of commission with a constant,loud howling within 15 minutes, the next time I used the detector.

The manual states 10-12 hours on a charge. My outtings 3 - 4 hours max.

I don't know if this is memory effect or just a defective cell. Any opinions?

 

[Art (NWOH)]

If Minelab says the battery pack checked good then all cells must be working, otherwise the pack voltage would be obviously low.

Therefore, must be memory effect.................

Will charge to full voltage (won't happen with a dead cell) , but will go flat in a short period of time.

No matter how long you charge, it won't last any longer.

HH

 

[Rick(ND)]

If you are and you are charging them over nite and it still does it I would think you have a bad cell in it or A bad charger. Now if you are using a alkaline pod and putting rechargeable in it then that is your problem as it needs 10 cells not the 8 it will hold as they will only last a short time. One thing you could do is if you have a alkaline pack would be to put in 8 new alkaline and see how long it will last.

 

[Art (NWOH)]

When you have problems, the detector goes "EEEEAAAAA!!!!!!!" , then the threshold gets real loud ???

Do you know what the low battery indications are supposed to sound like ??

What kind of chargeing procedures do you use ?? Been rechargeing before or after every hunt by any chance ??

 

[Steve in PR]

I am using a factory rechargeable. It does charge overnight and that seems to be the key. I have to make sure that it is fully charged in order to have it work properly. Once it if fully charged, it is giving me 4 hours of dependable detecting.

 

[Steve in PR]

Threshold gets real loud. Don't know what a low battery indication sounds like. I was cocky and figured that I would not need to charge between hunts reading that battery should last 10 - 12 hours. :blush:

 

[Art (NWOH)]

The way it works.........

I was guessing at what is really going on..........

With Ni-Cd batteries, you always give them a full charge. Then you use them until the detector craps out. You never recharge before this if you don't want memory effect to set in.
If you don't think the pack will last for the next hunt, then turn it on and let it run until the detector starts squawking/ going nuts.

THEN you recharge for 14 hours.

With the Ni-Cd pack, my 2a will sqawk once just before the threshold starts to climb. After a bit, the audio will chatter like crazy. This is about what to expect when the pack is shot.

Minelab refers to a low battery condition as a "pip" every twenty seconds or so. BULL !!!
Imagine a velociraptor sitting down in the wrong place and getting his nads caught in a bear trap. What do you think you would hear ??

I was getting the impression that you had ruined your battery pack, and that you were sending your detector in for warranty work every time the pack went dead.

Don't know if this is the case, but sure sounds like it.

HH

 

[Art (NWOH)]

Do you have any way to rig a multimeter in line with the battery pack to measure current??

You said they replaced the board, but how about the power switch?? It's a long shot, but there may be a defective switch. The detector should draw zero current when turned off, and about 50 milliamps when turned on.

HH

 

[Steve in PR]

I suppose that I must plea guilty but with the lame explanation that I have only owned it since April.

I have done exactly what you had suggested. The unit went crazy after 15 minutes into the 2nd hunt without a recharge. I did a 24 hour recharge, went hunting for 4 hours with no problem but I have recharged the battery again before I go hunting again today. I expect it will work fine. I know that I am probably setting it up for a memory effect but if it works, I shoul dbe happy, right? I will let you know....

 

[Steve in PR]

I think I can. I'll get back to you.

 

[Art (NWOH)]

Just a thought......

My Ni-Cd has a little silver thing inside, the purpose of which is unknown.
A cell or two could be leaky, causing them to drain down over time.
This is about like leaving the dome light on in your car and slowly killing the battery.

If you can lay off hunting for a couple days, charge up the pack and measure the voltage. Should be at least 12V.
Let the pack sit around overnight before measuring again. Let sit overnight again and measure still again.

The voltage should still read above 12 volts.

Also, after measuring voltage, hook the pack up and run the detector for a minute, disconnect, then measure again.

With all this, and also the information about current drain with power off or on, should be able to determine if it really is a bad pack.


HH