Question about recharging NiMH pack for detector

[99watts]

Hi,

A few years back I inherited a Deepstar 3 by Surfscanners. It has sat on the shelf largely because I had no adapter to recharge it. Recently I got a new pack of batteries with the idea of recharging them externally. The battery pack is the same voltage 14.4 V but slightly more capacity than the original pack (3800 mAh). I got a charger also and tried as illustrated below. Ive charged and discharged the pack twice, and the charger will say full approx 4000 or more mAh after 12-14 hrs recharging. But once the pack is in the detector there seems no power, a tiny flicker on the detector power dial then nothing. I recall the detectors battery dial showing signs of life when I first got it so I am assuming I'm doing something wrong with recharging.So far as I can see I am charging at 14.4V and 0.3A for around the recommended time (although the charger shows it go above that at times for example 16-18v The photos of displays are 1. what the voltage and load of cell pack is to be to be charged at ( I set this as a custom setting) , and the other shows the start of charging at 0.3 A. from there it takes over 12 hours until says full and reads approx 4000 at bottom right. The batteries are noticeably warm in the last part of the charge.Love to get it going, it has never been outside. Any advice be most welcome , thanks.

 

[LE.JAG]

Hi,

must test the battery with a voltmeter
deepstar support the 16/17 volts, no problem

if the load is good, the needle of the dial should go all out on the green


otherwise, there is a problem .......

I must have an old charger deepstar, and I wanted to take a picture

 

[99watts]

Thanks LE.JAG,

I'm not good with these sorts of things as you can tell. New battery though and the detector has just been sitting for few years, cant help think I'm doing something incorrectly. The same story with the original battery when I tried charging. Although that had been flat for years. If you would consider selling your old charger please email me, if you don't use it of course. Kind of running out of options before having to send it away for repair somewhere. Thanks again!

 

[Reg]

I am not familiar with the deepstar but there might be something wrong with the detector and not the battery. Check the battery voltage where it connects to the pcb and then look closely for a fuse. It may not look like a fuse but more like a resistor. Check the voltage from the on/off switch to ground and see what you have. Maybe the switch is bad.

So, there are different possibilities as to what is going on.

Reg

 

[99watts]

Hi Reg, Thanks for your thoughts. I have carefully unscrewed the cover and taken a couple of photos. There is nothing that strikes me as unusual, no loose wires etc. I cant see a fuse. As you say, could be almost anything, I don't have a meter for testing voltage at this stage. What does PCb mean, can you please point that out it the photos? Thanks for your help. Ian.

 

[Reg]

I am sorry, PCB is short for Printed Circuit Board and it is the board all the components are mounted on.

Look carefully at the bottom left picture. Focus on the top left hand side of that pic and see if the yellowish rectangular object doesn't say fuse. It is the object right next to the tall standoff that is there to hold the top plate in place. In the pic, it appears to say fuse but it isn't that clear either, so I may be wrong.

You will need a digital voltmeter to make measurements. A cheap one is available at Harborfreight for about $6 on sale. They are a red rectangular digital meter. I have found them to be good enough for basic measurements. Read the instructions for the meter

To check a fuse, disconnect the battery and select ohms on the meter. This will be the section that displays the upside down horseshoe. Select the 200 ohm scale. Touch the two leads together on the meter and the reading should go close to 0 ohm. Usually, it will measure 1 to 2 ohms or so, though. Now, once you have the ohmmeter figured out, touch the two ends or leads of the fuse, one side with one meter probe and the other side with the second meter probe. If you can touch the leads properly, the meter should read about the same as when you touched the two meter leads together if the fuse is good. If the fuse is bad, it will have to be replaced. If you accidently got the leads of the battery reversed, the fuse is probably bad.

Taking basic voltage measurements is simple enough, but if you are uncertain, try to find someone very familiar with using a voltmeter to make them for you. You will have to connect the battery again for this measurement. Now, I like to tape the tips of the meter leads so just the very tip is bare. This minimizes the touching of a wrong component and causing damage. Once you are ready, you can touch one lead to the ground wire which is the black wire that connects to the ground connection (often indicated by GND). It is the black wire located in the bottom left pic at the top right hand of the pic that connects to the two screws.

The other meter lead will connect to the fuse first. Check both ends of the fuse where it is soldered on the PCB. You should read the battery voltage. If you read the battery voltage on both sides of the fuse, then keep one lead on the black wire mentioned earlier and the other meter lead to the on /off switch. The on/off switch leads are the two leads on the back end of the switch. If it is ok, you should read the battery voltage on both switch leads.

Now, I suspect the + side of the battery connects to the board and is the ground connection. The - side of the battery probably goes to the fuse and then to the switch.

Again, if you are uncertain of what you are doing, please try to find someone who is familiar with test equipment to help you. If you do find one of the two components I mentioned, the fuse and the switch, let us know. Sometimes you can get the switch to work using a trick I often use. If the fuse is bad, then you will have to replace it or have someone do that. I strongly recommend finding someone knowledgeable to do that.

You can email me if you need further instructions.

Reg

 

[99watts]

Thanks so much Reg!

That is the fuse. I went and got a multimeter this morning, the couple of places I asked did not want to touch the detector, guess it looks as complicated to them as to me. Anyway I did what you carefully explained, and I tested the battery itself also. Have to learn somewhere.

The battery seems fine for voltage after recharge.

at 200u ohm setting the electrodes show around 1.2 together and when I attach electrode to either side of fuse it says 1.5 I guess that means the fuse is still intact?

However when I did the voltage test with one electrode on earth the other either side of fuse I only get 16V on one side of the fuse.

I then connected earth and the wires at the back of the switch, there is absolutely nothing. Not on any of the leads.Can I conclude the switch has a problem?

Thanks!

p.s tested the fuse again more carefully as it seemed odd not to have voltage each side , it does so 16V each side of the fuse.

 

[LE.JAG]

Hi,

it becomes too complicated for me

may be just the oxidation on the connector ?
if it does not operate for a long time ........

+ I have a deepstar charger, it works and I do not use

mp

 

[Reg]

I sent this info via an email, but I will post it also so others who have a similar problem may find it helps.

Now, the type of fuse you have may check good with a simple ohm meter check but still be bad. So, check the voltage again across the fuse by placing one lead on the ground connection and the other on the fuse. Check one side first and then the other side. With the power switch off, there is a slim possibility the fuse may check good. However, when you turn the detector power switch on, the fuse may check bad. By bad, I mean you will have voltage on one side of the fuse but not on the other.

So, check for voltage on both sides of the fuse again, but make sure the detector power switch is on. If the fuse is good there will be voltage on both sides, but if bad, you will have power on only one side.

The reason for this test is I have seen this type of fuse fail under load but check good with an ohmmeter.

Logic says it is the fuse that is bad since there should be no other part between the fuse and the power switch except the pcb trace and they seldom fail.

Reg

 

[99watts]

Hi LEJAG,

Thanks very much for your reply We may be narrowing down the issue to something internal rather than the charging method. Ill send you a message regarding your charger. Kind regards, Ian.

 

[99watts]

Hi Reg, Thanks!

Yes, you are right there is voltage only on one side of the fuse when the power is on.

I disconnected the battery and tested the resistance between the fuse and the leads of the switch. It gave only 1.2 also.

Regards, Ian.

 

[Reg]

Hi Ian,

Hopefully, you can find someone to replace the fuse. Pulling the pc board out can be a real pain, so if it was mine, I would cut the leads on the fuse as close as possible to the fuse body, leaving as long of lead on each side as possible and simply solder the new fuse leads to the old leads.

The fuse should have some information on it, but I suspect it is a 1.35A fuse. My guess is the detector draws about 500 to 700 ma when operating. I think you can buy the fuses off ebay if you can't find one locally.

Hopefully, nothing else is wrong that caused the fuse to blow. If by chance the battery was connected backwards, there is a possibility one or more of the power supplies is bad also.

Reg

 

[99watts]

Thanks so much Reg, this has been a real help. The battery wire(s) has a Tamya clip so don't think the battery has gone in the wrong way, the charger also alerts you if you try to charge incorrectly in that regards. I think perhaps I will now send it off to an expert in electronics repairs, bit beyond me to attempt soldering something so delicate. Once I have it repaired I will report back here with the outcome. Regards, Ian.

 

[Reg]

Ian,

I have seen Tamaya connectors built and installed reversed to what I was using so anything is possible. One more thing to check is to be sure the voltage polarity is correct on the circuit board. To do this, you need to check the voltage at the fuse again but make sure to put the black lead on the ground connection and the red lead on the fuse. If done this way, the voltmeter should read a minus 14V. A horizontal bar will be before the voltage reading. We are not looking for an exact voltage but rather the right polarity.

Now, to verify the voltage, place the red lead on the ground connection and the black lead on the fuse and you should read a normal 14V or so with no black bar before the voltage reading.

Always make sure the connectors connect red to red and black to black. Several years ago, a friend purchased a Tamaya connector that was reversed and installed it. The reverse voltage caused damage to his detector The guy was mad a the person who sold him the connector, but the fact is they can come either way, so a person has to make sure of what they are doing.

Reg

PS: I caution anyone replacing a battery to make sure they have all connections and voltages correct. Double check everything and don't rely on everything being the same. Measure everything to assure voltages are correct before applying power to a detector. Getting something wrong even for an instant can let the smoke out of a part and when that happens, the part or parts damaged will have to be replaced also.

 

[99watts]

Hi Reg,

OK, I have checked both those as you explained..and the results are as you suggest, so seems o.k on that front.

I have found someone here who does electronic repairs and is happy to look at the repairs.( i pointed him here to read what you have told me)
I'm sending it off tomorrow.

Thanks Reg, for all this..I was lost for ideas,,

Ian.

 

[Reg]

Hi Ian,

There are lots of options when it comes to replacing the fuse. You can try to find an exact replacement and replace the defective one or simply install a fuse holder in the control box and wire it across the present fuse wiring. Another idea is to simply short the fuse in place and place an in line fuse in one of the leads coming from the battery. I recommend putting it in the black lead, but putting an in line fuse holder will work in either. A 2 to 3 amp fuse should work fine. You might try one as low as a 1.5A but if it is a fast blow, it might go out periodically.

The point is, it doesn't have to use an exact match.

If your friend needs help, feel free to contact me.

Reg

 

[Reg]

Hi Ian,

If you can't find anyone to work on your detector, I have a friend who will. He and I worked together for many years, and I can vouch for his abilities. Also, I would help him if needed.

If you need help and interested in my friend working on your detector, email me for details.

Reg

 

[99watts]

Hi Reg, Thank you for that kind offer. My detector arrived back today and fixed I sent it to a gentleman at Retronics in Auckland.(he has a webpage) It appears it was a capacitor Anyway it is 26 celcius and one of the lowest tides for the month so off to beach shortly Thanks!

 

[jetapneiste]

Hello,
99watts i missed you on mp, you can contact me on jfdjc@hotmail.fr