AA cell to D cell Battery Converters...... any good?

[RoverJim]

I have a number of radios which use D cells but rechargeables are expensive so I was thinking of using the AA to D cell converters widely available on eBay, some taking 1 AA and some 2, anyone used these and any disadvantages you can think of?

[paulsherwin]

The main disadvantage is greatly reduced capacity. If you use them in something power hungry like a DAB radio or a CD ghettoblaster they won't last long, even if you use alkalines.

[RoverJim]

I take your point, but I have seen a lot of reports on D cells (particularly Duracell), quoting that they are little more than AA's as regards capacity in a D shell.

[vidjoman]

Most battery makers offer a range of qualities within a size. Check the spec of each battery. A cheaper type is unlikely to have the same power as an expensive one. Cheap D cells possibly could be almost the same as a better AA type. Think I would stick with D cells. Why not use rechargeable ones.

[paulsherwin]

Originally Posted by RoverJim

I take your point, but I have seen a lot of reports on D cells (particularly Duracell), quoting that they are little more than AA's as regards capacity in a D shell.

This is true of some rechargeables, but not usually alkalines. It's always advisable to check the capacity of any cell before buying it as there is a lot of variation.

[wireful3]

Jim, I have also come across these reports, I have several radios that use D cells but have no experience to show that they don't have more capacity than AA cells. I only use my sets infrequently but can rely on several months operation with cells I buy frm the Supermarket. This is usually better than other sets that use AA cells.

There is a potential problem if the adapter uses cells in parallel. If they are not reasonably matched they can self discharge even when switched off.

Perhaps some member has made discharge measurements to confirm these reports. I have no recent experience but years ago I did some tests on layer batteries and found them very tedious. Varying loads complicated things and I have never been inclined to do the same for my radio batteries.

[RoverJim]

Originally Posted by vidjoman

Most battery makers offer a range of qualities within a size. Check the spec of each battery. A cheaper type is unlikely to have the same power as an expensive one. Cheap D cells possibly could be almost the same as a better AA type. I think I would stick with D cells. Why not use rechargeable ones.

I think you're right, I have found a bulk buy of Duracell Procell at 69p each & these have a capacity of 18000mAh, which seems pretty handy.
High capacity rechargeables are expensive and I'd need about 30 of them!

Originally Posted by paulsherwin

This is true of some rechargeables, but not usually alkalines. It's always advisable to check the capacity of any cell before buying it as there is a lot of variation.

Not many manufacturers or sellers indicate capacity, but see my reply above for what seems good value.

[60 oldjohn]

I was lucky at a Radio Rally I found "used D cells" 8 for £1 When I asked the vendor said they were back up power for medical equipment, and had to be changed every year whether or not they had been used. They were all Duracell Procell. I bought £5 worth at a further discount, there was only one that tested below new. So there are bargains to be had out there.
John.

[GRID LEAK]

I don't know if you are aware of the possibility of recharging alkaline cells. A quick look here http://rechargingalkalinenonrecharga...logspot.co.uk/ will give you a few ideas.
John.

[pmmunro]

As these data sheets show, the energy which can be extracted from a cell depends very much on the rate of discharge. Comparing cells of the same quality from the same manufacturer, it seems highly unlikely that an 'AA' cell would last more than about one eight of the time of a 'D' in a broadcast radio application. The difference between the best quality 'AA' cell and the poorest 'D' might be much closer.

If the receiver designer has selected the battery cells carefully, he/she will have taken the cell characteristics into account in choosing a particular type. This suggests that 'AA' cells could be overloaded to the detriment of their service life.

http://ww2.duracell.com/media/en-US/...1500_US_PC.pdf

http://ww2.duracell.com/media/en-US/...1300_US_PC.pdf

Whatever primary cell type is used, the price of portability is high when cell costs are compared to the price of running a receiver from the mains.

It would probably be fair to assume that cell manufacturers who do not publish data sheets will not be able to match the quality of those who do. However, the number of battery cell manufacturers is far fewer than the labels under which they are sold.

PMM.

[paulsherwin]

Originally Posted by pmmunro

If the receiver designer has selected the battery cells carefully, he/she will have taken the cell characteristics into account in choosing a particular type.

A lot of domestic radios do use the biggest cells that will physically fit in the case, so you may find essentially the same circuit being run by 4AAs or 6Ds or anything in between. In this case using smaller batteries will just mean that you have to change them more often, which may or not be a problem depending on the pattern of usage.

[saxmaniac]

I run a Hacker RP 75 on 10 AA rechargeables of 2300 ma/h capacity to give the 12v needed and these last long enough for it to be a very practical way of doing it. "Industrial" rechargeable D cells are available at around 5000ma/h. The domestic types are no better than AA cells for capacity.

I am interested if anyone has experience of all the "no name" rechargeable D cells on ebay with 10000 or 11000 ma/h capacity. Is there something very wrong with these that the branded manufacturers wont touch them? They are quite cheap for what they are

[RoverJim]

I have opted for Duracell Procell D cells from an on-line seller at 0.69p each with an advertised capacity of 18000mAh, which seems pretty good value to me, only time will tell.

[Herald1360]

Originally Posted by saxmaniac

I am interested if anyone has experience of all the "no name" rechargeable D cells on ebay with 10000 or 11000 ma/h capacity. Is there something very wrong with these that the branded manufacturers wont touch them? They are quite cheap for what they are

No experience, but even an early NiCd D-cell ran to 4000mAH in industrial (full of actual innards, rather than filler) form, so I would think that 10000mAH should be easily enough fitted inside for a NiMH cell.

Yuasa do 9000mAH and they're pretty respectable.

http://uk.rs-online.com/web/p/d-rech...eries/6755670/

[paulsherwin]

The best you can get out of a NiMH AA seems to be about 3000 mAH so at least they're real D cells.

There seems to be a tradeoff between capacity and low discharge characteristics, at least at reasonable prices. You can buy 800mAH low discharge AAs in packs of 2 from Poundland, while low discharge Ds are difficult to find anywhere in the retail market. Low discharge rechargeables are much more versatile.

[Mikebay]

Have you looked at Lithium cells? Have been using both AA and AAA cells from China for over a 18 mths now with excellent results. In my camera, tripling the no. of shots, in test gear similar results. Oh yes, and in radios too(!). They have a pretty much constant voltage output right thru their life and are capable of very high discharge rates. Bit dearer, but if compared of length they are cheaper.

[mark pirate]

I run my Bush TR82C from seven AA Nicad batteries, I get around five weeks use before recharging, so quite economical for a set in daily use.
I also use a couple of PP9 batterys that I made up from eight 800Ma AA cells, this gives a decent life in my Hacker sets.

Mark

[Nicklyons2]

I've found most of these adaptors to be of apalling quality - the additional contact surfaces only serve to give more chance of intermittent contact and the ones I've tried were a very poor fit to the AAs; IMHO a waste of time & money. Not wishing to appear as a salesman for Poundland et al but the cost of quite good 'D's from them shouldn't break the bank.

[RoverJim]

Thanks for all the replies, I'm giving them a wide berth and going with my decision as noted in post #13.

[paulsherwin]

Poundland sell reasonable quality Sony branded zinc chloride Ds in packs of two, but they don't stock any alkalines in this size. 69p for a Procell is a good price.