Do I run batteries in series or parrallel?

[thewise1]

I plan to buy 2 batteries for my n64p, I want to double check which way I want to run them before actually wiring them up.
I was thinking this way would be best and acceptable. I plan to use the pdv 0700 (2 of them if this works)

Run the charging jack to one battery, then the output of that battery to the charging port of the second battery, and hook up the second battery to the console, kind of like this:



I don't think it will work because the first one might overcharge the second one, unless the protection circuit just turns off the flow to stop charging.

[nevermind1534]

My knowledge is that each battery hooked up in series adds to the voltage, each one hooked up in parallel adds to the capacity (Mah)

[thewise1]

Yeah, I think that's it, kirchoffs law I believe, I have to check my notes.

[Kurt_]

Just did Kirchoffs law in Physics class in Engineering in university.

Man was that a joke.

Taken from the lecture notes, word for word.

Junction Rule: total current in = total current out
at each junction (from conservation of charge).

Loop Rule: Sum of potential differences around any closed loop is zero (from conservation of energy).
Charge q moves through circuit changing its potential
energy qV but eventually there is no overall change.

But yeah.

For batteries, series = add voltages. parallel = add currents (or amp hours)

[thewise1]

Yeah it is really stupid how hard they make it to understand the deffinitions. Just list the rules, like for series, voltage is additive, current is constant, etc, etc

Thanks kurt_ I'll just hook up a couple junctions and be fine. Thanks.

(NOW I'LL HAVE 8400 mA

[thewise1]

Wait now how do I charge them with one power jack?

[Kurt_]

Power in is connected to the power out (to console, i assume) on the protection circuit in most cases.

[rikitheshadow]

Bump

Maybe ya'll can help me with a question I have about batteries running a portable.
PLEASE take it easy on me I have not studied anything like this!

If i purchase 2x Li-polys, each one 3.7v, I run them in a series to get 7.4v, but each one has 3800mAh.
Does that mean my portable's power supply will only have 3800mAh or do they stack in a series?
This may sound stupid, but I got lost in the previous posts in this thread.

[Life of Brian]

They will only have the 3800mAh capacity, but total voltage will be 7.4v.

[thewise1]

Yeah, it's a ratio, You may actually double the amps but you also double the voltage so it's powering out twice as much as before, so you're back down to 3800.

[Kurt_]

Something like that, but no.

In both situations, you double the power of your battery system. Power is measured in watts.

Power = Voltage x Current
...and the units...
Watts = Volts X Amperes

You're not doubling the voltage and current, then you'd be quadrupling the power.

Depending on how the batteries are hooked up alters their behaviour with each other. Kind of like if you have a frictionless moving object. If you have another object bump it from behind, it accelerates and gets faster (Like hooking batteries up in series). If you have two objects running beside each other, they don't bump into each other, so they don't get faster, but now you have two objects. If these were to hit another object (or do work on an object), it would do twice as much work as if you had only one object performing work. So then you still have one object rolling around that can do the same amount of work later (Like batteries in parallel).

Or something like that. It's hard to explain stuff in high school terms or earlier.

[bicostp]

The easiest way to remember:

Series adds volts
Parallel adds amps



You can get a 10v, 2000mAh battery pack out of these theoretical batteries by connecting two pairs in series in parallel.

[thewise1]

All I'm wondering now is how to charge them with only one power jack

[Rekarp]

connect the positive lead on the jack to the positive on the battery. Vise visa for the negative.

[thewise1]

connect the positive lead on the jack to the positive on the battery. Vise visa for the negative.

For both batteries? like have 2 cables coming from the one positive to each battery, and two negatives coming from the one prong on the power jack?