Connecting 100 AA batteries parallel to have bigger capacity

why not to connect batteries parallel

Hi, all,
Is it advisable to connect 100 pieces of non-rechargeable AA batteries in parallel to provide bigger capacity?
Any comment?

regards
wanchope

battery + in parallel

With this arrangements, you can only have better current output but the output voltage will be same as the batteries are in parallel. And the batteries are assumed to be equally charged.

batteries in parallel aa

Interesting question? Well the small constant current aveiloble from the bateris is a consequence of the need for smaller dimensions, if you conect 100 bateries what wuld you get? noting realy only a vaiste of space, as there are a lot better ways to produce DC power.

Re: AA battery in parallel

Not exactly a waste of space!

Parallel - as well noticed by hamdard - will give you standard say 1.5V ( same voltage as one battery) but 100 times more power. You can drive bigger load for more time than one of them, as now you have all the power driving capacity multiplied by 100.

Of course this is if you want to use this arrangement for this purpose. But then again you need extrmely lot of space. I guess the question is hypothetical in order to serve a two to five AA in parallel in wanchope design.

Better results you will have with a bigger voltage output battery and a step down circuit. If you use a car battery with a voltage divider in the output, you will have higher capacity, less space.

What is your application?
D.

Re: AA battery in parallel

wanchope,
This will work, but there are some practical problems. You will get some circulating currents if the cell voltages are not exactly equal. This results in current drain, even with no load. Eventually, the cell voltages will equalize, as the cells with the highest voltage become partially discharged. The cells will not share current equally because of unequal effective series resistances. The cells with the lowest series resistance will provide more current. The bottom line is that you will get more current capacity with n cells in parallel, but you won't get n times the current capacity of a single cell.
.
As Dkace pointed out, there are better ways to obtain higher current capacity.
Regards,
Kral

AA battery in parallel

Ok... this is interesting. Consider I have two rows of five 6F22 9V dry cells (i.e, two cells in series, and five such pairs in parallel).

What is the expectations regards :

1. Peak current capacity
2. Voltage and current capacity
3. Discharge rate and efficiency

I think answering these questions will be enough to satsify the OP.

Re: AA battery in parallel

vsmGuy,
1) Approximately 5/2 times the capacity of a single cell, due to the internal series resistance being twice that of a single cell
2) Twice the voltage of a single cell 2X9=18. Current capacity = capacity of a single cell, assuming load resistance >> internal resistance.
3) Discharge rate = 5X the discharge rate of a single cell. I'm not sure what you mean by efficiency.
Regards,
Kral

Re: AA battery in parallel

Hi, You can't connect batteries in Parallel since they will discharge each other since not all batteries have the same voltage rating !. If you need more current, take a bigger battery D type or put them in series and use a step-down switching converter to lower the voltage again but increase the current !.

Re: AA battery in parallel

to get the sum you will need to connect all of them batteries in series,

I always wondered if a hundred batteries would be good enough to shock someone to death

Re: AA battery in parallel

To my suprise, this thread becomes so hot! Thanks for all your comments. Actually I am looking for a power source of 400A.h @ 4.5volt. I am thinking of putting 3 AA batteries in series as a pair. And then parallel these pairs to achieve this requirement. I have checked some D cell batteries. But it seems like the space needed is larger than using AA. I am aware of the potential problem of the inequality of voltage of each battery. And the AA battery I am going to use is e2 lithium battery that can handle high surge current (3A). Any more comments?

regards
Wanchope

Re: AA battery in parallel

two parallel 2R resistors, make R ohms.

Re: AA battery in parallel

You cannot use 100 AA cells in parallel, everyone here says right.

I do not agree with you that D cell needs more room than AA cell with the same purpose and features, since the bigger cell the much higher cell capacity/volume ratio, you should check the battery handbook or datasheets for this idea.

I agree with PaulHolland that you should connect 100 AA cells in series and use a DC-DC converter, that is the best solution here in my opinion, you can use most of them until they are dead.

nguyennam

Re: AA battery in parallel

if you connect so, total charge will increase 100 times. Q=it. but voltage sthe same as a AA battery.

Re: AA battery in parallel

Anyone else has better option for high power battery source? Saft's LSH-20 (13A.h @ 3.6Vvolts, high current) is the best I could find at the moment. But I still need to parallel quite a lot of them to achieve 400A.h @ 4volts. Any help?

Thanks.
Wanchope

Re: AA battery in parallel

Please wanchope: I tell you for the last time YOU CAN'T PUT BATTERIES PARALLEL !!!. If you need lots of current you should go for NiCd (Nickel Cadmium) batteries they have the highes current rating for size !. If you need the highest capacity Ah (not current Amps) then go for Lithium batteries !.

regards,

Paul.

Re: AA battery in parallel

Hi, Paul,
I need combination of both, high current (2A pulse) and high power 400A.h.

Wanchope

Re: AA battery in parallel

Use a CAR battery not a normal one since its only about 36Ah but the one used in trucks they can do what you need but do not forget they will get empty if you do not use them. About 1% a day is lost !, so after 30 days 30% is gone. No normal single battery can deliver 400Ah only BIG 12V truck batteries. sorry.

One D battery has about 20W energy if you remove it slowly in >100 Hours. So since you need 4 V * 2A = 8W. So D cells are possible. One battery is by 0.1 A about 16 - 18Ah. If you want you can put 40 D cells in serie and use a DC step down converter very easy. You will have about 500Ah left after the loss of the DC converter ... 40 D cells is less than the maximum 75 V (1.66 * 40 max) you can put in a standard step down chip from National, two Amps is nothing for these chips and you will use all batteries until they are completely empty. This is the most efficient way, believe me. This due to the fact that you drain the batteries in constant power discarge mode which is the best mode for batteries to be in. Your battery pack will be heavy though: 139gr * 40 = 5.6 Kg !!. So if you do not need more than 400Ah use 32 D Cells the weigth will be about 4.5 Kg !!.

AA battery in parallel

The earliest known artifacts that may have served as batteries are the Baghdad Batteries, from some time between 250 BC and 640 AD. However, it is not known what electrical function they may have served, and if they were in fact batteries at all.

The story of the modern battery begins with the 1786 discovery by Luigi Galvani of what he thought was animal electricity. It involved what we now recognize as an electric circuit consisting of metal A, in contact with a frog's leg and Metal B in contact with the leg AND Metal A, thus closing the circuit. In modern terms the frog's leg served as both electrolyte and detector, and the metals served as electrodes. By 1791 Alessandro Volta realized that the frog could be replaced by cardboard soaked in salt water, and another form of detection could be employed. Having already studied the electrostatic phenomenon of capacitance, Volta was able to quantitatively measure the "voltage", or electromotive force (emf) associated with each electrode-electrolyte interface, finding the emf to always be on the order of a volt. Such a device is called a voltaic cell, or cell for short. In 1799 Volta invented the modern battery. He did this by placing many galvanic cells in series, literally piling them one above the other. This Voltaic Pile gave a greatly enhanced net emf for the combination. (In many parts of Europe, batteries are called piles.) Later researchers placed galvanic cells in parallel. Such banks of cells are called batteries, presumably after the earlier use by Benjamin Franklin to describe Leyden jars (capacitors) in series and in parallel.

Although early batteries were of great value for experimental purposes, their limitations made them impractical for large current drain. Later batteries, starting with the Daniell cell in 1836, provided more reliable currents and were adopted by industry for use in stationary devices, particularly in telegraph networks where, in the days before electrical distribution networks, they were the only practical source of electricity. These wet cells used liquid electrolytes, which were prone to leaks and spillage if not handled correctly. Some, like the gravity cell, could only function in a certain orientation. Many used glass jars to hold their components, which made them fragile. These characteristics made wet cells unsuitable for portable appliances. Near the end of the 19th century, the invention of dry cell batteries, which replaced liquid electrolyte with a paste made portable electrical devices practical.

Re: AA battery in parallel

Thanks, Paul,
Because of the higher self discharge rate of the rechargeable batteries, that is why i want to use the primary cells. And my equipment is supposed to work outdoors. The higher temperature will make it even worse.
I could only found one D cell that is 13A.h @ 3.6 volt. (pulse current 3A)

Which way is more efficient:
1. In series, then step down.
2. In parallel with protection diodes

Wanchope

Re: AA battery in parallel

Hi, In series since if yo use the in parallel you have a huge loss (0.3V minimum) for a 1.5 V battery this is (0.3/1.5) * 100% = 20% loss. with a 3.6 V battery: 0.3/3.6 * 100% = 8%. A good stepdown you can make 95% efficient with about 5% loss !. You should also use normal D cells Alkaline, they are 1.5V can buy them in normal stores. They are relatively cheap and have a huge enery density. Temperature performance is very very good also -20C .. +55C !! Use 32 in serie as I told you and your done !.