×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Alkaline cold temp performance

Alkaline cold temp performance

Alkaline cold temp performance

(OP)
I have been experimenting with AA's and C cell alkalines. I have 6 AA's in parallel (3+3) that produce 4.5 volts.  I have another setup of 4 C cells in series with 6 volts.  I have been freezing them below -4 and immediately powering my circuit.  The AA's power up and the C cells don't.  Any thoughts on why this is occuring?
 

RE: Alkaline cold temp performance

Interesting.  Have you measured the voltages of both setups just before powering the circuit and immediately during the power up?  That would provide more info to reach a conclusion.

Also what is it you're trying to power up?

Keith Cress
kcress - http://www.flaminsystems.com

RE: Alkaline cold temp performance

Your C cell configuration has about 5 times the internal resistance of the AA configuration.  

This would allow the AA configuration to have a surge capacity of something like 37 A, compared with 10 A for the C cell configuration.

If your load sinks 5A, your C cell configuration would only deliver about 3 V, while your AA cell configuration would deliver almost 4 V.

These are all RT values.  Below 0°C, the internal resistance values are roughly double the RT values.

TTFN

FAQ731-376: Eng-Tips.com Forum Policies

RE: Alkaline cold temp performance

Your question is pretty vague.
What type of battery are you using?
Are they rechargeable?
What are the Ah ratings?
What load are you using?
Batteries are all different. Some batteries perform better at low current discharges and others at high current.
There are so many parameters to be considered.

UPS engineer http://www.powerups.co.uk

RE: Alkaline cold temp performance

(OP)
Thanks for your responses.  Apparently the higher ESR of the C cell's is too much for the circuit.  I will do more testing and report.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login



News


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close