Batteries

**devomiddel** · Nov15-09, 12:44 PM

How are the cells (say 2V) of a typical lead acid battery connected in series to increase voltage to 12V when all the neg. plates are connected together and all the positive plates are connected together which as I understand is the principle of connecting two batteries in parallel (pos. terminal to pos. terminal and neg. terminal to neg. terminal) which does NOT increase voltage, only capacity ?? For sure I'm missing a basic concept.

**mgb_phys** · Nov15-09, 12:53 PM

Think of voltage as electrical pressure - with all the 2v cells in a row the pressures ad up to give a lot more pressure but only the strength of a single cell. With the cells in parallel it's just like one big cell so they only have one lot of pressure but much more strength.

A good way to think of cells in parallel is to just think of joining the plates of the cell together. If you made the plate twice as big, or made two plates the same size and welded them together, or made two plates the same size and connected them with a wire = the same thing

**Pythagorean** · Nov15-09, 04:43 PM

mbg, this sound a lot like a capacitor. Am I taking their similarities too far? I'm realizing we never studied cells in either EE or physics.

**mgb_phys** · Nov15-09, 04:47 PM

No, it's also a good way of picturing capacitors in series and parallel

**vk6kro** · Nov15-09, 08:09 PM

How are the cells (say 2V) of a typical lead acid battery connected in series to increase voltage to 12V when all the neg. plates are connected together and all the positive plates are connected together

The car battery has 6 separate cells in it and they are internally connected in series.
They then bring the two end connections out for you to use.

They are NOT connected in parallel.

**MacLaddy** · Nov17-09, 02:07 PM

Originally Posted by devomiddel

How are the cells (say 2V) of a typical lead acid battery connected in series to increase voltage to 12V

With the explanations above I still don't understand how wiring in parallel would increase the voltage to 12v? I thought you could only raise the voltage if you wired in series?

For vk6kro's car battery example all six cells would be supplying 12 volts in parallel, not 2, correct?

**mgb_phys** · Nov17-09, 02:10 PM

Originally Posted by MacLaddy

With the explanations above I still don't understand how wiring in parallel would increase the voltage to 12v?

It doesn't - all the examples are describing how to connect them in series.
I was explaining that if you conected them in parallel it was no different to a single cell and so no change in voltage

**MacLaddy** · Nov17-09, 02:22 PM

Oh, I think there must be some miscommunication from the op's original question, because it sounded like they were describing a system in parallel.

It's all new to me.

**mgb_phys** · Nov17-09, 02:43 PM

The OP is wrong in thinking that all the plates are connected in parallel in a car battery they are connected in series to increase the voltage.