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Alkaline batteries are really very good

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Alkaline batteries are really very good

Post by Radiomobile » Thu Dec 06, 2012 10:16 pm

I've just been looking at some Energizer and Duracell data sheets and they seem to confirm what I've found in practice - that modern alkaline batteries really are very good.

Taking a radio with xx96 series valves the total LT current would typically be 150ma. Equating to a 10 ohm load.

Looking at the manufacturer's data sheets for the same load a D size (LR20) will give 80 hours service when used 4 hours per day to a 1.2 volt end point. Somehow I can't imagine an AD35 with it's two Zinc Chloride cells would do better than this.

The smaller C size (LR14) is also good for about 32 hours on the same basis.

With the older xx91 series valves and a total current of 250ma the D size (LR20) is still good for over 30 hours.

I know I'm pushing my luck, but the single C size (LR14) in my Marconi P20B is lasting well in spite of the 250ma load, though I have to admit I don't use the set for more than 30 mins at a time.

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Re: Alkaline batteries are really very good

Post by Michael Watterson » Thu Dec 06, 2012 10:43 pm

The Alkaline D cells are better than the F cells, which are Zinc Carbon. But recently the PJ996 has been selling very cheap, so these work out cheaper.

Unfortunately while the Alkaline D cells are x2 to x3 better than Zinc Carbon for valve filaments, the price is more than x5 for Duracell / Energiser. The Tesco ones are better value and I recently got some "Kodak" badged Chinese ones cheaper still.

On the Marconi that uses 5 x D cells I just use the cheap Zinc Carbon ones. I use Alkaline for the B141 and B114 packs. For the larger packs I'm using F cells while they are cheap. 3 x Alkaline D cells in parallel is maybe a little better than 4 x F cells in Parallel. There are a few packs that used 8 x F cells in parallel!

On the small 7.5V packs that used 5 x B Zinc Carbon cells, the smaller AA Alkaline are about the same or slightly better run time. For a PP9, the 6 x Alkaline AA is about 1/2 the run time, but a lot cheaper. Alkaline 6 x AAA work well as a PP7 innards though with only slightly shorter life.

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Re: Alkaline batteries are really very good

Post by Michael Watterson » Thu Dec 06, 2012 11:27 pm

1V you do get operation. Though not great. 1.1V is a more realistic end point than the Makers often rated end point of 0.9V which is unrealistic except for torches and motors.

Some Russian and East European B7G battery valves are 60mA and 30mA filaments and also designed for NiCd not Dry Cell. I guess with 1.2 vs 1.4V they had to up the filament current.

Series current is usually more than 50mA or 25mA due to balancing resistors and o/p tube Anode + Screen current particularly. Rule of thumb is to add HT current to LT filament current. But it depends too on the Battery architecture. The Pye PE94MBQ/LW and RCA 8BX6 both use 6 x 1.4 @ 50mA, but the RCA has HT- to LT- and the Pye has HT- to LT+, presumably because it does SW and wants higher EOL HT to ensure the DK92 oscillates at up to nearly 20MHz. The RCA being MW only. Pye takes 71mA on LT! My B135 battery pack is 60 x AA for HT and 6 x D cells for LT for 9V and a 7.5V tap (though I have not yet found any set that uses the 7.5V on a B135).

On the RCA, the RCA VS019 pack (all Zinc Carbon, Layer for 90V, cells for 9V, same as B135), was supposed to last over 125 hrs. 6 x Zinc Carbon D cells at 53mA might last more than 125hrs. But at over 70mA you'd need 6 x F Cells to get more than 125 Hours. F cells are 50% more capacity roughly in the past, but now cheap D cells are not filled as much as F cells in a PJ996 are, they put two hollow plastic bungs at top.

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Re: Alkaline batteries are really very good

Post by Michael Watterson » Fri Dec 07, 2012 10:11 am

I have got 3.2V coin cells at 11c each from HK. Works out similar initial price but fits better and gives longer life. You don't need 90V as the discharge is flatter.

AAA are better value
AA are best value, so I use them for largest packs. The B137 can take two sets of AA in parallel, but I have it 1/2 filled with LT & HT.

12V Alkaline cells about same size as a 1.5V N or "lady" cell allow smaller pack than PP3s, but the lifetime is poor and cost is very high. Only useful for a "custom" miniature HT pack.

I only use Alkaline PP3 in the B114 or other small packs that are 67 to 70V, for these I use 8. Using 8 x Alkaline might do instead of 9 Zinc Carbon PP3 for the smaller 85V.

Approx costs in Euro for cheap batteries (mAH at 9mA HT) Bold is Zinc Carbon, Italics is Alkaline
60 x AA ( 1000 2500) = 7.50 24.00
60 x AAA ( 500 1100) = 7.50 24.00
10 x PP3 ( 460 590) = 7.50 15.00

(IEC tests are at higher currents, so losses higher and mAH worse on data sheets)

Considerations for a HT pack
Initial batteries cost
Cost per hour
Difficulty of connecting batteries or cells (PP3 easy, AA/AAA only easy if a holder fits. 12V & coin cells hard)
Standby time when intermittently used (Lithium coins best, Alkaline, ZnCl, ZnC, NiMH worst)

For a B126 the PP3 is actually not bad, but Kodak and some others slightly too fat to "daisy chain". Width of 3 x PP3 side by side is the most critical dimension for the B126 box. Even if the 12V batteries were cheap they are too small and too short life at 9mA, probably only 1/3 volume of a B126 box, so you'd want to parallel 2 sets using a pair of 1N4148. That would be 14 or 16 packs (84V or 96V nominal, or 6 x 2 = 72V for a B114), so the 12V Alkaline need to be less than 50c each, not a likely scenario.

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Re: Alkaline batteries are really very good

Post by Terrykc » Fri Dec 07, 2012 11:55 am

Looking at Michael prices for AA alkaline, they seem rather pricey by UK standards - €24 ~= £19.40

These are post free in the UK: ... ue-40-pack

£8.49 for 40 = 21.2p ea. = £12.735 for 60

10+ £6.49 for 40 (400) = 16.225p ea = £9.735 for 60

However, you don't have to buy 400 at a time to get the price down!

These tests ...

... show that even the cheapest batteries have such a good performance that they far outperform any slightly superior types, such as the exceedingly expensive Duracell varieties.

So, 6 for £1 (16.66p ea.) from Poundland (£10 for 60) or 6 for 99p (16.5p ea.) from 99p Stores (£9.90 for 60) will do an excellent job and at a significantly lower cost than the best zinc carbon types ...

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Re: Alkaline batteries are really very good

Post by Michael Watterson » Fri Dec 07, 2012 6:06 pm

Not Post free to Ireland... Also possibly we have higher VAT (23%). Poundland is called Dealz here and £1 = €1.49! Somewhat inflated? Dealz and other "bargain" stores only erratically have Alkaline. My Alkaline prices are Aldi / Lidl.
Duracell and Energizer are crazy price. Also for low current drain the Energiser 1.5V disposable "Lithium" at 50% more than Duracell Alkaline, but no longer life than generic Alkaline.

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Re: Alkaline batteries are really very good

Post by Michael Watterson » Fri Dec 07, 2012 6:57 pm

This is good, but 200mA is still high for an AA!
but at 9mA HT or 25mA to 30mA series (5 in 7.5V pack or 6 in a PP9) the Alkaline and Zinc Carbon (or Chloride) mAH capacity is dramatically better, esp the basic Zinc, but "lithium" and NiMH no improvement as they are low resistance.

Here is estimation of 65mA and 200mA. At 9mA (larger 67V, 85V 90V or 120V HT packs) the Alkaline moves closer to Lithium and Zinc Carbon / Zinc Chloride near identical and about 1/2 life of Alkaline.

compareAA.jpg (10.24 KiB) Viewed 1498 times

The "higher" performance types of Zinc Chloride is no better than Zinc Carbon at very low drain (progressively more so less than 70, totally true at 10mA).
The "higher" performance types of Alkaline or "lithium" 1.5V are no advantage either over ordinary Alkaline at all as you go less than 50mA, certainly very much at 20mA for AA or 10mA for AAA

Energiser, ordinary Panasonic, Duracell Alkaline are no advantage over "generic Alkaline. Special Panasonic or Energiser "Lithium" only give significantly better life where current drain is so high that NiMH Rechargeable cells are better choice. (Tesco DAB Radios, Digital Cameras etc).

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