Battery life Questions

[ricky_wcy]

Loading current = 500mA
4 serial D-cell battery = battery life is 12hrs

The Question is how to double or triple battery life by

Option A
(Diode + 4 serial D-cell) // (Diode + 4 serial D-cell)
Is it possible to double battery life ?

Option B
(Diode + 4 serial D-cell) // (Diode + 4 serial D-cell) // (Diode + 4 serial D-cell)
Is it possible to triple battery life ?

 

[wizpic]

All you need to do to double the capicity of the batteries is parallel them no need for diodes,
If you put them in series you double the voltage and not the capacity.

So to get 6V 1000ma or 1500Ma you will need 4 1.5V in series to give you 6V do the same for the other battery pack then just join up the positive to positive and neg to neg and you will have 6V 1000ma battery pack

hope that helps you
wizpic

 

[ricky_wcy]

Yes, series 1.5V batteries will lead to increase voltage not capacity
I use 6V because I need to drive motor

Let me explain in more details for my circuit
-----------------------------------------------------
1. Motor (operating voltage = 4.5V - 6V)
2. MCU (operating voltage = 2.7V - 3.3V)

Also, parallel all battery pack without diodes, the current will flow into others due to different intenal resistance. BIG PROBLEM

 

[wizpic]

Ricky trust me you do not need diodes just connect them up you will be ok

I should know I've worked with batteries for 10years and never had a problem

We use 4 x 6v 225AH batteries to give 24V times 2 to give us 24V 550AH and not use diodes

and where is THE BIG PROBLEM

 

[ricky_wcy]

Each battery has different internal resistance and voltage
Current may flow from 1 battery to other while //

Are you HK guy or China guy, wizpic.
Let's share the knowledge if you don't mind

My msn is ricky.wcy@gmail.com

 

[wizpic]

Trust me the internal resistance will not casue the current or voltage to flow from 1 battery to the ohter battery, I onced used 8 x 1500MA nicad to give me 4.8V 3000Ma just buy joining them together and it did not do anyting

The only thing you will need to be careful with it that use new batteries same age, you can use any age battery safely but the only draw back is that the better ones to soon drop down to the lower leves

I'm UK

wizpic

 

[Bukitoo]

I will have to consider parallel batteries solution for my project.
I thought that I should use 2 diodes for avoid batteries differences. However I think that If the batteries are new I won't need the diodes (my system do now charge the batteries because it will neve will be connected to power line)

I've found this related links:
**broken link removed**
**broken link removed**

 

[johnyaya]

I too have been designing battery operated devices for many years, parallel batteries are not my first choice. Operators can (and do) insert batteries backwards causing major problems, especially when using Lithium. Maximum life is achived when all batteries are same type (ie. Duracell) and age (ie. same box) even for serial configurations. I'm assuming that the motor will draw much more current than the MCU circuit, therefor I would optimize power for the motor (4 X 1.5v = 6V if using Alkaline). I would select larger cells (ie "D" instead of "AA") to get the required runtime. If Alkaline batteries won't do it, try Lithium.

 

[ricky_wcy]

Thank for all guys share your design knowledge on battery life.

I am using 4 x 1.5V D-cell Energizer Alkaline in my project.
The battery life is not enough. What we expect is to double or trible the battery life. So, besides D-cell alkaline, what kind of batteries I can use to make this achievement

 

[wizpic]

if you have got the room why not use a 6V 10AH sealed lead acid battery, it would take the same amount of room has the tripple battery would, you could make a charger then and just rechaege it rather than throw them away

now there's a food for thought

have a look here
**broken link removed**

you can get these all over the world