Jimma

Gumstick battery problem breakthrough.

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As I stated in a previous post,  for quite some time now I've been having problems with the NH-14WM gumstick batteries. 

In many of my portables,  they have become unusable, with some units saying that the batteries are flat even when they have just been charged. 

For example my first MD Walkman, a yellow MZ-R55 has not been usable on any of the gumstick batteries I own, both Sony and other brands, for quite some time.

It would just say "Low Battery" immediately the battery was inserted.  I tried different brands for battery of differing ages, all supposedly fully charged but to no avail.

I've cleaned contacts, tried adding small bits of foil, charged the batteries with different machines/chargers and other suggestions I've read in various places but all with no luck.

Many other units I have suffer from the same problem including 3 more MZ-R55s and an MZ-RH10 whereas my MZ-N1 and MZ-E45 and several others have no such issue.

It has been driving me mad!

Then a couple of days ago, for some unknown reason I thought I'd try scoring the positive end of an old Sony battery with a small, sharp screwdriver.  I then put it back into the MZ-R55 and to my surprise, for the first time in years, my first MD Walkman was happily playing on batteries without the AA sidecar and showing full battery level.

So I bought a small file and roughened up the surface of the + terminal on all my gumsticks and sure enough, all the previously problematic units were suddenly working as they should.

Why I should have to do this, especially on batteries that are new is beyond me but it has done the trick and made me very happy!! :imsohappy:

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Good trick, I will be this on my own gumstick batteries as they do the same.

Please feel free to find a similar trick for LIP-4WM...

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some kind of hi resitance you are over comming? maybe the coating on the battery to stop corrosion>

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So I bought a small file and roughened up the surface of the + terminal on all my gumsticks and sure enough, all the previously problematic units were suddenly working as they should.

To quote Winnie The Pooh, "Crustimony Proseedcake". Actually a piece of sandpaper does a great job provided you don't overdo it. You may need to work on the other (-ve) end of the battery too.

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Interesting, thanks for the tip. I will give this a try on a few that I've had troulbe with.

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Jimma, thank you so much for this tip! I've been struggling with this on my NH-900 for, oh I don't know, 5 years or so? Keep buying new batteries and have the same problem. I quadrupled the life of my original TWELVE YEAR old battery in seconds with a little sandpaper, and made a replacement battery work like the stock battery was new. I had tried (I thought) everything, even resoldering the positive connection on the battery door. It still never guesses how much charge is actually left accurately but it never did (it's been flashing for the last 2 hours of consecutive playback).

You will probably never see this but I hope others with this problem find your post. THANK YOU

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4 hours ago, hoodust said:

 It still never guesses how much charge is actually left accurately but it never did (it's been flashing for the last 2 hours of consecutive playback).

That might be a reason to adjust the charging/sensing circuits.

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Wait, you can do that??

Btw, my estimate of "quadrupling" the battery life was an understatement. It went from about 20 minutes of play to 6 hours (and this is an old, aftermarket battery that's been discharged and sat for a year several times) . I forgot just how long the battery on this thing lasts, especially playing LP non-Hi-MD recorded material.

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I have found a way to "restore" the gumstick batteries I had given up on and threw into a box one of my minidisk's came in.  I made a slot in a piece of wood and connected two wires with clips to the ends of the battery.  I then connected the clips to my LaCrosse BC900 battery charger and put the charger into renew mode.  The charger will charge then discharge the battery over and over improving the capacity until the maximum capacity is reached.  I had to cut a piece of a old ink pin to the size of a AA battery to attach the positive wire.  Some of these batteries now hold a charge almost like they when new (2+ hrs) and others less with the least lasting 40 minutes of play time.

NH-14WM Charger (2).JPG

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3 hours ago, mdenter said:

I have found a way to "restore" the gumstick batteries I had given up on and threw ...

 

Great stuff - and very environment-friendly.

And this is when "great minds meet" :-) - I came up with the exact same idea. For the gumstick "craddle" I used a Li-ion charger I bought on fleabay, (for $0.99 - incl. free shipping...). All electronics were removed, except for the spring loaded contacts. Cable and alligator clips were from an ex test lead (also cheapo Chinese thingies).

I have the Technoline BC700 (European version of the Lacoste), that is a great little charger. Besides my "dead" NiMH gumsticks, I actually revitalized more than 30 pieces of NiMH AA cells, that my cameras rejected with "low battery" message (and I kept buying new batteries, while only the improper chargers were the cause of frequent battery mortality...). Now, those old (some of them 14-15 years old) cells can keep about 60-80 % of their original nominal capacity.

 

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Yup works great. I did it slightly different, but same principle, hook up BC700 to terminals of defunct prismatic charger.

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i just sandpapered the contacts on my 2003 gumstick battery using sandpaper it is a gp 1400mah nimh and now it is running in my mz-nf810 and not going flat as soon as i turn on the player/recorder good trick will keep it in mind for the future when this happens

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