Using AAA cells to build a HT battery?

[Martin G7MRV]

I have access to many, many AAA cells, for nowt (my favourite price). I'm wondering whether a HT battery built from a large number of these would provide sufficient current for a simple one valve regenerative set? (See my other post in this forum!)

I currently (no pun intended) have enough cells to raise 90V. I believe the circuit I'm building should operate comfortably at considerably lower supply voltage than that.

Of course, the heater supply will be derived from a much higher capacity battery (probably a 12V SLAB)

[paulsherwin]

Yes, the HT current would be adequate for a 1 valve headphone set, which will only use a few mA. Connecting 60 batteries in series will be a bit of an ordeal though.

Many (all?) modern PP3s have 6 AAAs inside rather than containing a layer battery.

[Martin G7MRV]

Originally Posted by paulsherwin

Connecting 60 batteries in series will be a bit of an ordeal though.

Many (all?) modern PP3s have 6 AAAs inside rather than containing a layer battery.

I might delegate the job to my 8year old apprentice!

I don't have ready access to PP3s these days, though years ago when I worked on community alarm call systems I had hundreds, and did used to make big HT packs from them, for 'fun' purposes! (usually involving wire wool, carbon rods and other inflamables!)

The AAAs comes free due to certain medical usage rules!

I did this https://www.vintage-radio.net/forum/...ghlight=killer

[michael cumming]

I agree with Paul on this one as it does seem alot of work, Older HT batteries did use 60 U10s but the PP3 is better to use and Alkaline ones do use six AAAs inside. If you have all them batteries to use then go for it but it will be fiddly work.

[Martin G7MRV]

I think the fiddly part will be forming them into a block and getting them secured (hot melt glue?) I'll knock up a timber frame to hold them while i do that, then construct a cardboard case around them.

The soldering although quite considerable i dont think will be as fiddly as the SMT stuff i have to deal with these days

[ppppenguin]

Especially when you can get 10 Duracell alkaline PP3 for £7.45

http://www.amazon.co.uk/gp/product/B000SHVGXA

Why bother with cheap and possibly nasty pound shop PP3s when you can get good ones at that price.

If you're going to use AAA or AA cells remember that you'll be doing the whole tedious assembly job again one day unless you use rechargeables.

[Sean Williams]

How about a couple of suitable sheets of PCB material - you could "etch" the pads out to link the cells as required - one top and bottom with some plywood backing problem solved - and it can be disassembled for cell replacement.

[Martin G7MRV]

Originally Posted by ppppenguin

Especially when you can get 10 Duracell alkaline PP3 for £7.45

http://www.amazon.co.uk/gp/product/B000SHVGXA

Why bother with cheap and possibly nasty pound shop PP3s when you can get good ones at that price.

If you're going to use AAA or AA cells remember that you'll be doing the whole tedious assembly job again one day unless you use rechargeables.

Or, £0.00 when theres a box of hundreds of AAAs sat behind me

[Steve_P]

Well I don't see why it won't work, as the HT on battery sets is a mere smidgin. If the batteries are OK, go for it and see. 60 x 1.5 = 90, etc.

For 1.5v, or 7,5v, put 2 or 3 in parallel for every 1.5 Volts.

Cheers,

Steve P.

[ParcGwyn]

6 AAAs wont fit in a PP3 footprint, I think they maybe AAAAs. The capacity of alkaline AAAs is about 1100mAh so they should last for very long time. I used cheap zinc carbon PP3s from a market store to run a BEREC battery receiver together with 5 cells from a torch battery (the type with springs on top can't remember the number) for the lt (7.5v) and the batteries lasted for a couple of years with occasional use, mainly at weekends.


Dave
GW7ONS

[Martin G7MRV]

Originally Posted by ParcGwyn

6 AAAs wont fit in a PP3 footprint, I think they maybe AAAAs. The capacity of alkaline AAAs is about 1100mAh so they should last for very long time. I used cheap zinc carbon PP3s from a market store to run a BEREC battery receiver together with 5 cells from a torch battery (the type with springs on top can't remember the number) for the lt (7.5v) and the batteries lasted for a couple of years with occasional use, mainly at weekends.


Dave
GW7ONS

Your right Dave, its AAAA inside a PP3,

These are Procell AAAs. There as near to brand new as you can get without actually being brand new. Theyve been used in medical devices with very, very stringent usage limits. I think its cardiac monitoring, and they can be used for no more than 24h before being disposed of!

Im going to start putting the pack together tomorrow. I might do them staggered (close packed in crystallography terms ) so as to make sticking them together easier!

[Martin G7MRV]

Actually, just reread the schematic for the receiver were building, and it calls for ~28v HT! So, thats a much simpler battery to build. 20 cells will do it for that one.

[GMB]

Anyone doing this might want to be careful about the power of such an HT battery.

Modern batteries have quite low impedance. An HT stack of AAA cells has about 5 to 10 times the power delivery capability to that made from PP3's (or even a typical valve-rectified HT supply).

So a short circuit could do a bit of damage!

In my thread https://www.vintage-radio.net/forum/...9&postcount=26 I did some measurments/guesses, it is quite impressive what comes out of a modern alkaline celled HT pack!

[ITAM805]

Hi Martin, how about using some 15mm plastic conduit, say 2m lengths, stacked vertically and fill them with your AAA's - you then only have to solder the top and bottom cells to next the stack (Gravity Stack ™). Barmy yes, but easy to refill when necessary

[Martin G7MRV]

Oddly, I did have this very same idea!

I had to abandon it, because my son will want to demonstrate this radio at school, so a rectangular box will be much more convenient.