where can I buy a Panasonic MT920 battery

[jacisbck]

I've looked all over the place and just cannot find anyone selling this battery. I really like this watch and it's been in the box far too long now. Pls help anyone.

[retroleds]

http://www.smallbattery.company.org.uk/sbc_mt920.htm

[rewolf]

Here are two threads with lots of information about the MT920 and similar batteries:
http://dwf.nu/viewtopic.php?t=2583&highlight=mt920
http://dwf.nu/viewtopic.php?t=1649&highlight=mt920

[jacisbck]

I dont think they sell stuff over in our area just to those who live there. Unless im wrong and I've known to be wrong often.

[retroleds]

http://search.digikey.com/scripts/DkSea ... me=P296-ND

$2.25 USD plus shipping.

[rewolf]

http://search.digikey.com/scripts/DkSearch/dksus.dll?Detail&name=P296-ND

$2.25 USD plus shipping.

That's an ML-920, not MT-920.
They are different. ML-920 is 3V, MT-920 is 1.5V.
See here: http://dwf.nu/viewtopic.php?t=2583&highlight=mt920

[retroleds]

Good catch ReWolf.....I see from looking at the old thread you have the battery chemistry burned into your memory banks. And being an electrical engineer doesn't hurt either.

That MT 920 does seem a bit elusive. This is ironic, the whole battery quest, I had a Pulsar Solar(cells around the edge of dial), that is NOS but had no battery in it. So I pulled open another I had here - MT920, Panasonic. Guess I'll finally order some of those pricks.

Found some at www.batterybob.com - expensive little things! Anywhere from $16 USA to $27(12.5-21 EUR) Well, at least free shipping within USA.

A caveat to trying out a standard battery - at least in a Pulsar those install with the positive down, contrary to the standard of negative down. They have a screw down clip that is spot-welded to the negative side. Interesting stuff.

[clockace]

is that a capacitor type cell? i have an old swatch that is solar cell dial. it needs a capacitor that is 11mmx2.0mm. the designation for that cell is gc1120. that is a renata #. i found one at www.cousinsuk.com. they do not have the 920's either. i think the dimensions of the 920 is probably 9mmx2.0mm. the cell [1120] is 4.95eng pds + almost 10eng pds shipping! i google searched all over the usa and could not find one. peter

[rewolf]

is that a capacitor type cell?

No, it's not a capacitor, but a battery
Copied from the abovementioned thread:

Panasonic MT (Manganese Titanium Lithium)<clickme>
Excellent voltage and overdischarge withstanding characteristics
500 full discharge cycles (down to 1.0V)
Charging Voltage 1.6V to 2.6V
Average voltage 1.2V (1.5V to 1.0V), very similar to Alkaline
MT920 (D=9.5mm, H=2.1mm): 4.0mAh discharged to 1.0V

@jacisbck: If you simply want to get your watch running again, try a cheap 1.5V AG6 or LR69 Alkaline cell (not silver oxide). Alkalines are said to be "a bit" rechargeable, but I have never tried this.

@Ed: I don't have all this in my "memory banks" but I do know where to look and am trained to read data sheets VERY carefully (even between the lines)

[retroleds]

A few sites I visited indicated that ESA changed the designation to battery, even though some are actually capacitors. The two I bought off BatteryBob.com were both listed as capacitors, but that means very little. BB m,akes a big deal out of his "Free anti-static tweezers" with each purchase of those.

[azimuth_pl]

a similar quest.
I need a rare rechargeable/capacitor battery:
Leclanche 4106 with 1,1V
used for the mega-rare Bulova Thermatron from 1982.
http://www.hknebel.org/Uhren/Hersteller ... atron.html

[rewolf]

Ah, I see, you managed to open your Thermatron http://www.dwf.nu/viewtopic.php?t=2596

Have you already tried a capacitor like STW did?
I'm really curious about this watch, so feel free to bother us with anything you find out about the circuit

AFAIK the Leclanche battery is not produced any more - but other rechargeables in the low voltage range (<1.5V) will probably also work, some examples are here: http://dwf.nu/viewtopic.php?p=15237#15237

[azimuth_pl]

yes, opened indeed :)
you either have to create a screwdriver from scratch or risk damaging the nut or caseback.
my black NOS Thermatron bought as nonworking does work with a new battery
the capacitor solution by STW requires a new caseback because it utilizes a bigger diameter battery.
so I need a very small one and not all websites present dimensions of every accupack.

[rewolf]

Can you tell the dimensions of the battery?

[azimuth_pl]

well, the standard battery that fits perfect is a 392 = diameter 7,8mm x h3,5
8mm diameter would also fit, max height 4mm

other higher but still 8mm diameter batteries would also fit with some minor modification of the battery clamp.
323 - 5,4mm
393 - 5,28mm

[clockace]

the panasonic MT920 is used by seiko. they call it a capacitor. i just installed one in a junghans solar powered watch i have. it is working fine, exact cell that was in there. i got it from www.crtime.com. they are in texas. it cost $10.95+ shipping. the number is SK3023.24R. there is another # for it also. 7M42/V12. peter

[rewolf]

well, the standard battery that fits perfect is a 392 = diameter 7,8mm x h3,5
8mm diameter would also fit, max height 4mm...

That's a rather unusual size for such a battery. A Panasonic MT621 (d=6.8mm, h=2.1mm) could work, but probably need a spacer not to rattle.
http://www.abcde.de/mt621.html
http://www.uhrmacherwelt.de/uhrenbatterien/00000094a6150eebd.php

[azimuth_pl]

thanks!
the watch is even more unusual than the battery, however the Leclanche was not left inside so the movement is superclean but I also don't have any detailed reference.

STW wouldn't have to modify the caseback if a proper or smaller diameter accu would be available in the early 80's.
instead they made a semi-pro modification as pictured:


the battery clamp on the left (center) is fitted into the battery well, and the bigger rechargeable battery with plastic spacer is placed on top of the clamp and then covered with the caseback.

[azimuth_pl]

found an alternative to the MT621 which costs some 20$ on average.

Varta V6 HR is the same size (6,8x2,1) and sells for 7$ :)
check eBay - widely sold as back up battery for some PDA's.

these will fit the Thermatron - spacer suggested.