Battery Characteristic

[faridfauzi]

Hi,im a fresh bachelor electrical graduate (5 month graduated to be exact).
My company required me to design a power supply system for a microwave system. I done searching for rectifiers & inverters module.

Right now i stucked at choosing battery for the system. I do know Peukert's formula.
But i just need one explanation/clarification from experienced engineers about batteries.

Battery Discharge Constant Current Characteristics Amperes <---- what this means? I got one table from batteries manufacturer:
F.V/TIME 5min 10min 15min 30min 60min 3h 5h 10h 20h
1.60V

775 525 415 265 163 63.9 45.7 25.4 13.4
1.70V

736 499 398 254 156 63.0 45.0 25.2 13.3
1.75V

692 469 378 242 149 61.7 44.1 25.0 13.2

Does it mean if my system drawing 12Vdc 13A - the battery can support the system for 20hours?

I got the table from here:

http://www.polluxbattery.com.my/250ah-12v-battery.html

 

[IRstuff]

Does the data fit Peukert's formula?

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[faridfauzi]

I did calculate the data using peukert`s, im using 1.2 as the peukert`s constant (since the manufacturer didnt give me the exact constant).

What i found the data table and my calculation is way off. Almost 20% - 30% off.

How accurate is peukert`s formula?

 

[IRstuff]

Peukert's formula is not particularly accurate, particularly at high current draws, since additional non-idealities rear their ugly heads.

TTFN
faq731-376

Need help writing a question or understanding a reply? forum1529

 

[itsmoked]

Just means testing with a constant current source. Something that varies its resistance as the battery voltage declines to keep a constant current.

Something being run by a linear voltage regulator would work this way. The load would always draw its regulated current and as the battery voltage drops the linear regulator would just be shaving less and less voltage off - current would not change.

Conversely, something more modern, would possibly have a switching supply that pulls a fixed POWER from the battery. As the battery voltage falls the the current draw would steadily increase to compensate.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[faridfauzi]

Thank you guys for the informations