Difference between battery sizes

[JimM]

Hi all

Apart from the obvious physical dimensions what is the difference between an AA and a D cell battery. They both are 1.5V but does the larger one have more power, last longer etc

Reason I ask, is that I have a 4 x D Cell LED Maglite torch, but no spare batteries in the house. D cells are going to cost over £10, but for the same money I can get a load of AAs and a 4 pack of AA-D converters (or I have a few spare AA rechargeables I could use)  However if the AAs aren't going to last very long then I'd probably be better off going with the 'proper' size

Cheers

Jim

[andyf]

Putting it at its simplest, Jim, the bigger the battery, the more electricity there is within it. D cells are the same voltage as AAs, but that voltage will last much longer. Overall, D cells may be cheaper.

As to rechargeables, a rechargable D cell doesn't hold as much as a "disposable" one. Same with AAs. And rechargeables of any size only put out 1.2 volts each - 80% less than their disposable equivalents. That means that if your torch really wants 6 volts from 4 x 1.5V batteries, it will only get 4.8V from 4 rechargeables. The beam won't be anything like as bright. Of course, if your converter will take five 1.2V rechargeables, they will add up to 6V.

If you fancy your chances  at simple electronics, "disposable" batteries can be recharged ten times or so - see
http://madmodder.net/index.php?topic=2583.0

Andy

[Darren]

You could change the bulb to a lower voltage and use rechargeables ...?

Do they make a 4.8V bulb, or something close?

[Andrew_D]

You said you are using an LED light...they don't use very much current, so the AA's will probably last plenty long enough. Sure, they won't last as long as the D's, but you probably won't notice the difference with LED bulbs.

Andrew

[Bluechip]

You could change the bulb to a lower voltage and use rechargeables ...?

Do they make a 4.8V bulb, or something close?

Not LED's, but they do make incandescent lamps Darren, but usually in the 'flanged' sort.

CPC have the 2x, 3x, 4x 'ni-cad level' @ 2.8V, 3.6V,4.8V.

http://cpc.farnell.com/_/2-4prkm700/lamp-p13-5s-700ma-2-4v/dp/LP02588

Must admit, never seen other types, ie, LES, MES etc. with these voltages.

Just had to remember to change the lamp if ni-cads replaced by zinc oxide, otherwise torch lit up magnificently, but not for long  

Dave BC

[75Plus]

You might check this out for "D" size batteries.

http://cgi.ebay.co.uk/DURACELL-PLUS-D-BATTERIES-PACK-OF-4-DATE-2015-CHEAP_W0QQitemZ150407274460QQcmdZViewItemQQptZUK_ConsumerElectronics_Batteries_SM?hash=item2304f8dfdc

Under 4 quid shipped!

Joe

[JimM]

Cheers Joe, that's a great spot, got some on the way to me

[Russel]

Rechargables should work just fine with a Maglite LED flashlight. I have both a 2d and a 2C cell Maglite [LED] flashlights that are very bright with Nimh rechargable batteries. The LED module uses a relatively low voltage, there is a circuit board in the led "bulb" that regulates the current to the LED.

Here is a link to a little 2C Maglite project: (Scroll down aways to see the machined part.)

http://www.candlepowerforums.com/vb/showthread.php?t=228376

Flashlights with incandesent bulbs will suffer from lower light output with rechargable batteries due to the lower voltage of Nimh cells. But they are direct drive with no voltage or current regulation other than the resistance of the bulb.

The catch with Nimh rechargable D cells is the inital cost. I paid about $30 for a pair of good low self discharge D cell batteries for my LED maglite, but I get about 10 hours of very bright light between charges. With a good charger (more $$) and reasonable care, you should be able to get hundreds of charges out of the batteries.

[Darren]

I've got a small LED torch I got from the market for a quid ....

I'd forgive you for thinking that it must be rubbish costing just £1, but you'd be wrong .... it beats my three times the size Maglite hands down in size, light output and battery life.
In fact the batteries seem to go on forever !!

They are nothing like the old filament bulbs at all