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Hints, Tips and Solutions (Do NOT post requests for help here) If you have any useful general hints and tips for vintage technology repair and restoration, please share them here. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 13th Mar 2010, 9:02 pm   #1
David G4EBT
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Default DIY Number 8 Battery Adaptor

There was a recent thread entitled 'Remember These?' , which seems to have run its distance, about the 'No 8' 3 Volt battery. I didnt contribute to that thread, but coincidentally, a little signal injector Ive had for more than 20 years, which uses a No 8 battery, died on me last week. I took the injector lid off, and found a little note Id put inside stating that the battery was installed in May 1997, and cost of 85p!

These once popular batteries, evocative of a bygone age, were used in small torches and in test equipment, but are now not stocked by high street shops, Maplin, Halfords etc.

They are however, still available via internet the lowest price I can find being 3.45.

They've been known by a host of different numbers and are now known as 2R10, so anyone looking for a No 8 battery will have as much luck as asking for a U2 a title which went out in the 1970s. (D Cells AKA MN1300).

The 2R10 (or if you prefer, 'No 8') only has a capacity of 1000mAh, whereas a smaller lithium battery the CR123A has a capacity of 1.6Ah, so I decided to make an adaptor to use a CR123A in preference to a 2R10/No 8.

Luckily, 20mm plastic conduit has an internal diameter exactly the same size as a CR123A. All that was needed was a spacer, which I made from a piece of wood, drilled through the centre, with a brass cheese-head bolt, so that when assembled, it's the same length as a 2R10/No 8 - namely, 74.6mm.

The 2R10/No 8 battery is 21.8mm diameter 1.8mm larger than 20mm plastic conduit, so for my requirements, 20mm diam was near enough Im only interested in functionality not making an exact replica.

However, I know that there are those who do enjoy making replica batteries of the exact size, and there are two ways of doing this:

1) 20mm plastic conduit is an exact fit inside 22mm copper plumbing pipe, which is just 0.2mm (8 thou) diam larger than the 2R10/No 8, so a copper sleeve could be made from that pipe and slipped over the plastic conduit and glued in place, then a label affixed.

2) Thin card could be rolled around the conduit to bring the diameter up to 21.8mm and glued in place, then a battery label affixed.

I claim no originality for this idea an easier option can be found here:

Make a replica size 8 3Volt battery:

Or you can buy a 2R10/No8 from here at 3.45 each:

I bought two CR123A 1.6Ah lithium batteries for 4.75 (buy one/get one free) inc VAT and P&P from here:

A useful website for reference purposes it illustrates a whole range of batteries and cells, and their dimensions and specifications.

I dont have any connections with any of the above, or indeed any commercial organisations except as a satisfied customer.

Ive attached some pics which illustrate the adaptor I made, it its new home!

There are other (cheaper) options - A card of two Type N (LR1) 1.5V alkaline batteries, (though not as high a capacity as the lithium 1.6Ah CR123), typically cost less than a pound.

LR1s are 10mm diam and 30mm long each, so that's 60mm the pair. All that would be needed would be a 14.6mm spacer to make up the length, and a wooden rod 20mm diam, drilled through 10mm to insert the batteries into a piece of 20mm plastic conduit.

The first pic shows the component parts, the second shows the battery, wooden spacer with with the bolt in place, the final pic shows the battery in situ.

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Old 22nd Mar 2010, 2:18 pm   #2
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Default Re: DIY Number 8 Battery Adaptor

Hi David from another David.I remember the no8 myself from years ago,as you say mainly used in torches.I mainly used the u2 myself and I remember my mother would buy a u2 for me while she was out shopping.Then there was the lp2 which was the leakproof version.I remember reviving these batteries by warming them by the side of the fire.Another battery which seems to have dissapeared is the pp6.we had a radio which used that one.
Cheers fom David
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Old 24th Mar 2010, 12:09 pm   #3
David G4EBT
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Default Re: DIY Number 8 Battery Adaptor

Hi David,

Thanks for reading my posting and for your comments.

Re the PP6, I think that may have been discussed on the forum before. You can get them, (just as you can the No 8) but at a price. EG, here:

Like many who grew up in the 1940s, I have fond memories of the No 8 battery. Small torches which used the No 8 seemed to be popular back then - maybe being smaller even than U11 batteries, they were cheap to buy in the war years, (when you could get batteries that is!). The downside is that they didn't last long.

My bedroom was on the top floor of a three story house and wasn't wired for electricity, so my little torch was a constant companion to extend reading hours beyond bedtime beneath the blanket!

I also had a penlight torch - I think it was made by Lucas. It had a metal case and clipped into the top pocket. When you wanted to use it, you pressed the clip against the barrel of the case which acted as a switch. It took a couple of what are now called AA cells.

I've made another No 8 battery adapator a bit simpler than the one I mentioned in my first post, this time using two LR1 cells, which can be had for under a pound the pair, but are 1 A/Hr compared to a 3V lithium battery, which is 1.6A/Hr. For occasional use as in my little signal injector, 1A/Hr would be fine.

This 'Mk2' adaptor consists of a spacer to fit between the two LR1 cells to make up the length of 74mm (the length of a No 8), a tube made from rolled up card, rolled around a ballpoint pen case of the right diam for the batteries to be a sliding fit, and a length of 20mm plastic conduit as before.

The paper tube is pushed inside the plastic conduit with a dab of glue to keep it in place.

If desired, more card and a replica label could be glued to the outside of the conduit to make it up to the diameter of a No 8- 22mm. Or a length of 22mm copper pumbling pipe could be slid over the conduit to make up the diameter, but I'm not personally concered about making an exact replica - only about functionlity.

I cut the spacer from a piece of aluminium rod, about 11mm diam, (same as the cells), but a piece of metal cut from a bolt or whatever is to hand would do just as well.

The pic is self explanatory.

Hope it's of interest.

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Old 24th Mar 2010, 12:48 pm   #4
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Default Re: DIY Number 8 Battery Adaptor

Very clever, and some good links.Thanks.

Batterycity looks a good site but look at the price of their PP9's!!
"Nothing is as dangerous as being too modern;one is apt to grow old fashioned quite suddenly."
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Old 25th Mar 2010, 1:12 pm   #5
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Default Re: DIY Number 8 Battery Adaptor

Great adaptor!
Just playing with high voltage....
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Old 6th May 2010, 5:52 pm   #6
michael cumming
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Default Re: DIY Number 8 Battery Adaptor

Great minds think alike, I use the same type N cells or LR1s in series. I did a quick mock up using two of these cells taped together with 1P pieces to make the length up. I did this to test my lamps and it worked. Originaly these batterys were made up of two U8 cells at 1.5V each in series.
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