battery weight and volume

[tevad]

Hi,

I am in the process of trying to gain a much greater knowledge into the technical aspect of batteries. I am currently writing a report on electrical automotive batteries. I have one question which I hope someone could help me with:

If I know an average power that the battery needs to deliver, how can I calculate the weight and volume of the battery required?

Thanks,

Tevad

 

[itsmoked]

You can't really unless you know more details like the duty requirements of the battery.

For a rough estimate find the usual charts of 'Specific Weight' and Specific Volume" for the various battery chemistries.

Once you have those you need the amps your load will demand and the drain time between charges. Multiply those two together for the amp-hours. That's the number you use for the size and volume.

If this is for a real application you also have to take into account the allowable depth of discharge to prevent battery damage. This would increase the resulting volumes or weights by something like %50.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[DanEE]

"If I know an average power that the battery needs to deliver, how can I calculate the weight and volume of the battery required?"

Well how about using the battery manufacturers spec sheets for a given technology battery to first identify a battery that meets your power requirements, then see what the weight and dimensions of the battery are.. All the info is there, if you are looking at commercial/industrial batteries.

If you look up a range of battery capacities, and weight and dimensions, you can develop a formula that approximates the data.

 

[IRstuff]

Battery capacity and type are not necessarily driven by average load. Ostensibly, automotive battery capacity is dictated by a variety of competing demands on the battery system:
> cold cranking capacity
> parasitic load capacity
> unintended load capacity
> compatibility with existing batteries

The car design team must then determine what they need to do to meet their internal requirements. Only then can a size and type be determined.

Obviously, in some cases, the ability to use a commonly available battery might outweigh all other considerations, resulting in a battery system that might be grossly overdesigned for its intended application.

TTFN

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