Calculation of Battery CCA based on Peak Current and Average Current
Calculation of Battery CCA based on Peak Current and Average Current
(OP)
Something I have never done before as our vendors usually specify how many and of what type to use.
I have a 24 volt system (heavy truck) Using an MTU 16V 4000 Engine. The manufacturer specifies that the peak starting current is 1900 Amperes. Then once the Engine reaches 150 RPM the current is 850 Amperes.
I know that this this is basically an inductive load and has wave form on a time scale that peaks on a time constant, then falls off to the average current. Ignoring the rise and fall in current related to each compression stroke. How would I calculate the CCA Rating of the battery? There must be a rule of thumb for this right? Also this would be two or more 12V batteries in series parallel to get the 24V. Anyone have a way to do this?
Your help would be greatly appreciated.
I have a 24 volt system (heavy truck) Using an MTU 16V 4000 Engine. The manufacturer specifies that the peak starting current is 1900 Amperes. Then once the Engine reaches 150 RPM the current is 850 Amperes.
I know that this this is basically an inductive load and has wave form on a time scale that peaks on a time constant, then falls off to the average current. Ignoring the rise and fall in current related to each compression stroke. How would I calculate the CCA Rating of the battery? There must be a rule of thumb for this right? Also this would be two or more 12V batteries in series parallel to get the 24V. Anyone have a way to do this?
Your help would be greatly appreciated.
Regards,
Jon





RE: Calculation of Battery CCA based on Peak Current and Average Current
Bill
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"Why not the best?"
Jimmy Carter
RE: Calculation of Battery CCA based on Peak Current and Average Current
There are many variables in vehicle battery selection other than the draw of the starter. How cold does it get? What are the parasitic draws? How long does it have to sit between uses? What happens when the batteries start to lose capacity with age?
A 14 liter truck engine typically requires two 8D batteries, although one will sometimes do. If we used a straight ratio of number of batteries to displacement, a 65 liter engine would require 9 of them. (Of course, connected in series, they would need to be in multiples of two.)
My gut tells me that 6 or 8 would be the right number, but I would look around and see if you can find a similar engine in a similar truck and see if what they have been doing for batteries is satisfactory.
There are sizes larger than 8D available but I am not familiar with them in real life.
RE: Calculation of Battery CCA based on Peak Current and Average Current
Keith Cress
kcress - http://www.flaminsystems.com
RE: Calculation of Battery CCA based on Peak Current and Average Current