BHS Branded Metamec Battery Clock

[duncanlowe]

My parents still use a Metamec that the electronics are individual components. Uses a 'C' battery. Would have been bought early to mid seventies. There used to be a special type of 'C' cell presumably to allow for the low discharge.

[cheerfulcharlie]

Originally Posted by Mike Phelan

Yuck! Converting a clock worth money to a piece of worthless junk.

You're in the wrong business LOL, he removes the elaborate old mechanism, sticks in a £5 job, attaches it to the original heavyweight hands ...and then sells it on for prices approaching 4 figures or over.
I would suspect the original hands would grind the mech into powder after a short while, but maybe I don't give the cheap mech enough credit.

[Mike Phelan]

Principles above privileges, Charlie!

[Mike. Watterson]

Originally Posted by duncanlowe

There used to be a special type of 'C' cell presumably to allow for the low discharge.

UK Ever Ready sold ordinary Alkaline cells as Clock batteries. They didn't believe in Mallory's method of selling them as Duracell. There was never any other special kind of C cell.

Ever Ready tried to market Zinc Chloride as replacement for Zinc Carbon. Only any advantage at higher drain where Alkaline was better. Alkaline works out better than Zinc Carbon or Zinc Chloride for all cylindrical cells and eventually mercury buttons replaced by Alkaline, Silver Oxide or Zinc Air depending on application. Zinc Air seriously self discharges when seal is peeled so only used for always on like hearing aids (small) or cattle Fencers (Enormous!)

Later when US Eveready/NCC/UC started competing with Mallory's Duracell using Energiser the UK Ever Ready belatedly marketed Alkaline as Gold rather than specific batteries for specific equipment such as clocks and calculators.

[TonyDuell]

There was an Ever Ready C11 clock battery (C cell size). I am not sure it was an alkaline cell though, I remember having one in the mid 1970s that leaked, and I don't think it was like the typical alkaline battery leakage now.

A quick web search didn't provide any useful information.

Later one there was the PP3C and I think the HP7C. But here 'C' stood for 'calculator' not 'clock'. I have no idea what was special about those.

[Mike. Watterson]

Alkaline do leak from bottom seal failure. Zinc leak due to case being eaten.

The CII Clock batteries and any other regular size long shelf life genuinely high capacity domestic 1.5V cylinder cells only ever have been Alkaline.

I don't know what was in a PP3C, though regular layer or PP batteries are all sort of a Zinc Chloride Carbon Manganese biscuits without metal cases. They are quite high resistance but less leaky and better shelf life than cylindrical zinc cells. There are two kinds of alkaline PP3, one use rounded rectangle button cells (PP3C *MIGHT* have been this, I don't know). The other uses cells like AAAA except a little shorter. Some slightly longer PP3 actually use AAAA cells.

An HP7 is a Zinc Chloride AA cell which is IEC R6.
A U7 is a Zinc Carbon AA cell, also IEC R6
An HP7C can thus only have been an Alkaline AA = LR6, or MN1500, or else totally cynical branding.
http://www.blaukatz.com/tables/basic-round-cells/
Basically Ever Ready lost its way in the late 1970s. They tried to pretend Alkaline didn't exist. Their strategy was to buy competitors, but UK DOI blocked their takeover of Mallory (Duracell). Then Hanson bought them in early 1980s and sold off Superpilla & Diamon. Beginning of the end.


For N, AAA, AA, A, B, C, D, E, F, G 1.5V primary domestic cells there are only Zinc Carbon, Zinc Chloride and Alkaline. The Alkaline case connects to +, the others have the case as -, but some Zinc have a top disc and bottom disc to make them look like Alkaline and some early Alkaline had an insulating washer on the top to make them look like an LP cell (Leak Proof).
HP or HD (High Power or Heavy Duty) is misleading, they are Zinc Chloride. At low to medium current the capacity is the same as Zinc Carbon. They may have carbon power in some versions dispersed in the gel to additionally lower resistance. Only Alkaline really has more shelf life (up to 10x) and more capacity than Zinc Carbon or Chloride (3x at low current). Maybe x5 better than Zinc Carbon at HIGH current and then x3 better than carbon loaded Zinc Chloride.

Zinc Air is only used on very large cells or button.
Silver Oxide on button cells.

Lithium primary cells are 3.2V

[duncanlowe]

Originally Posted by TonyDuell

There was an Ever Ready C11 clock battery (C cell size). I am not sure it was an alkaline cell though, I remember having one in the mid 1970s that leaked, and I don't think it was like the typical alkaline battery leakage now.

That's the one. Here's a photo:

[Graham G3ZVT]

Originally Posted by Mike. Watterson

The CII Clock batteries and any other regular size long shelf life genuinely high capacity domestic 1.5V cylinder cells only ever have been Alkaline.

Now that's interesting Mike.
I activity avoided buying cells described as "clock batteries", believing they were unsuitable for high-draw applications.

Talk about keeping ones light under a bushel!

Excuse me if I'm being over-pedantic, but I noticed you typed CII as if it was a Roman 2, surely its a C11?

[Mike. Watterson]

Sorry, brain slipped into neutral. It's 11 not II, originally U11.
Though I've not dismembered a C11, so it could be anything. The only long life domestic primary cells that sort of size were Alkaline. Ever Ready made a massive investment in adapting from Zinc Carbon to Zinc Chloride (HP cell series) about the the time Mallory brought out Alkaline Duracell. They had no volume Alkaline production facility, so didn't want to sell Alkaline for general use. It was a bad decision.
The US Eveready (NCC/UC) I think developed the Alkaline cell in late 1950, maybe even 1956. They licensed it to Mallory as they decided not to market it.
Mallory (the Chemist that started the company) developed the mercury cell, and more importantly the button package system later used on alkaline, silver oxide and lithium coin cells in the 1930s. That made them a fortune in WWII as a power source for proximity fuzes. The original application as grid bias wasn't very successful. So the Alkaline cell, using the positive can and a disc seal on the bottom was a package related to the button cell. Naturally they were keen to market regular size cells as I don't think they had much Zinc Carbon production, though their Irish factory made Zinc cells for Ireland for Ever Ready UK with the regular Ever Ready labels. Ever Ready UK did buy a big lot of Mallory shares, but UK DOI blocked a takeover and forced them to divest.

Take label off an Alkaline cell and turn it -Ve to top. Note button & coin cells are all +ve case.

[Graham G3ZVT]

I'd like to hear views about the availability of Ni-Cad, and other rechargeable batteries. They must have been seen as a threat to the industry's profitability.

[Robsradio]

I was almost tempted to buy half a dozen or so 'old Ever Ready' batteries at the boot sale this evening, but managed to walk by. There was a cardboard covered transistor radio PP9, a 22v flash battery, a couple of early PP3s and an orange HP2, blue SP7 and a No8 3 v battery.
Some were a bit worse for wear.

[Mike. Watterson]

Originally Posted by rambo1152

I'd like to hear views about the availability of Ni-Cad, and other rechargeable batteries. They must have been seen as a threat to the industry's profitability.

No, they were not.
They existed I think even before WWII and certainly in regular sizes from late 1950s.
Issues from 1950s to 1980s:
1) You need a charger and two sets. That's expensive.
2) They were expensive
3) Capacity was about 1/3rd or less of NiMH today and about 1/3 of Zinc Carbon (in 1973, 450mA vs 1100mA for Zinc Carbon vs 2700mA Alkaline for AA)
4) Self discharge high, poor ready to go shelf life.
5) higher voltage packs can have short life due to one cell getting reverse charged on discharge.
6) Memory effect or even shorts if often only slightly discharged and recharged, especially at lower currents.
7) Ill suited to low current drain

The German/Dutch battery valve sets DID use NiCd (the square cross-section DEAC cells) for LT on Mains/Battery models.

Advantages of NiCd:
1) Very low cell resistance even compared to Alkaline which beats Zinc Chloride which beats Zinc Carbon which beats layer cells. Louder 6V & 9V sets thus used cells, not PP layer packs and that's why some UK models used 12V or 18V (half the current using 6V or 9V PP layer cells). Excellent for VFD calculators, two way radios and portable power tools.

2)Rechargeable.

So NiCd only used initially with docking two way radios and very high drain devices that could be charged each night. Many VFD desk calculators had NiCd as an option.

Even today most low drain applications use primary cells: Wireless doorbell systems, keyfobs, clocks, simple weather stations, portable radios with no DAB, remote control handsets, electret microphones, smoke alarms.
DAB radios often are rechargeable because the battery life is half a 1941 personal valve radio using a D cell for filaments.
Phones, tablets, cameras are very high current drain so are rechargeable.

[PsychMan]

Well in the end it did start running, and infact worked solidly since, so I left the job for another time. Unfortunately I get very little workshop time at the moment.

As luck would have it though when the clocks changed, the problem has returned and no amount of mucking about can restore the operation. So I will now have to delve into it

When its in this state it does tick, but the second hand only moves a little. I've noticed it does look like some of the minute hands do slip.

If I tap the clock it will get it running again until it inevitably stops. It takes a C battery and when the clock was in good order it would run for more than a year IIRC, so the battery is not that old.

I'll share any findings when I manage to crack it open. It seems when everything is in place mechanically it runs fine, I suspect something in the time adjustment changes this

[paulsherwin]

I've definitely seen these symptoms produced by a battery contact problem. The clock behaves in the same way when the battery is on the way out, but in that case fitting a new battery fixes things. The step motor controlling the second hand tries to advance by one second but fails and the hand just twitches.

[PsychMan]

Paul would this be the contacts to the battery itself or internal to the movement? The battery contacts look fine and untarnished, but then again, I have seen contacts before that looked fine but a imperceptible surface layer had formed adding some resistance.

Id definitely agree that the twitch of the second hand looks like a bad battery...

[paulsherwin]

Investigate the way the metal battery contacts are connected to the internal electronics. It's quite common for high resistances or intermittent contacts to develop there after many years. I can't give you detailed instructions without seeing the inside of the mech, and by that stage it will be obvious anyway.

I once fixed a clock with a similar fault by fitting an external AA battery holder and soldering the connections.

[PsychMan]

I cracked it open yesterday to have a look. I took some pictures, mainly for my own benefit but they might be of interest here. It was interesting to see the numbers and markings on the plastic plate beneath the aluminium (?) face.

A nice looking little movement, and quite refreshing to find such a thing that is entirely disassemble friendly!
I couldn't see anywhere that should be oiled, there didn't seem to be any evidence of that, and mechanically all looked ok to me. Perhaps it runs dry?

I took your advice paul and soldered some wire links onto the PCB tracks in case this turned out to be a battery contact problem. And actually upon reassembly it became clear it was.

The battery contacts weren't gripping the battery as solidy as they should. I had already bent them inwards before when I cleaned them, but seems they had relaxed back. When I "adjusted" them in again, the clock ran perfectly overnight on the same battery.

I've ordered a new C battery holder and will fit this underneath and attach to the wire links, hopefully the clock will run for some more years before I have to consider replacing the movement.

[PsychMan]

Last two pictures

[Julesomega]

I also had the failure of a similar clock with the German movement a few weeks ago, had to open it up - it is a quartz type with a minimal stepping motor with just two states. The armature is a cylindrical ferrite magnet set between two poles of an electromagnet that receives pulses from the 144F IC. My first thought was to replace the device but a) I can't find any data on them and b) while there are a few on ebay.de the cost would exceed that of a new movement. Find Dan's Clocks on eBay and you have many options mainly about the length of protrusion of the shafts for the hands. I asked for advice on which one to choose and got a quick reply.

[Paul Stenning]

The battery contacts just fixed with screws into plastic and pressing onto the PCB tracks does look like an area that could become loose and suffer with corrosion over the years. If you can bypass that with soldered connections to existing contacts or new battery holder they may well help.