Alkaline cold temp performance

[blackfin]

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?

 

[IRstuff]

Chemical capacity decreases
Internal resistance increases

TTFN

FAQ731-376

 

[itsmoked]

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

 

[IRstuff]

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

 

[raithrovers1]

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

 

[blackfin]

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.