Does parallel connecting batteries double the CCA?

Yes it does.

Only if they are identical batteries in identical state of charge , and at the same temperature.

The current delivered depends on the internal resistance of the batteries and this is affected by the above parameters.

Now now boys everyone likes to think they know about batteries !so I think he has got the correct answer to get himself out of trouble.

My Patrol has had parallel batteries for its 11 year life, on my third set of batteries now. Ive never had any charging problems and always change both batteries at the same time. I have a power thirsty 90 litre fridge, hence the parallel configuration. No solenoids to fail and less wiring this way! Michael

Hi bungarra and I ASSUME you are looking at improving you starting ability.

While adding another battery in parallel will increase the CCA by the amount the new battery is rated at, just as adding another battery will increase the total Ah by the amount of AH the new battery has.

But please note, the Ah of a battery has no connection to the CCA and you can’t use one to calculate the other.

The CCA rating of a battery is based on the amount of current that battery can supply at 0f ( -18C ) and the battery’s voltage does not drop below 7.2v.

Next, if a vehicle manufacturer requires a minimum CCA of say 800, this does not mean the vehicle will draw 800 amps while starting.

The vehicle might only draw 350 amps while starting but needs to have a minimum voltage of no less than 10 volts to be able to start, so the manufacturer will have established that a battery with a CCA rating of 800 amps, will not drop below 10v while supplying 350 amp needed to start the motor.

Back to your question, if you have a battery rated at 700 CCA and you add another battery, rated at 500 CCA, you will now have a total CCA of 1200 amps.

If your motor needs an 800 CCA rating to start, it will still only draw 800 amps while starting BUT, it will now be supplied that 800 amps at a higher voltage.

This has a number of advantages. The first is that a motor is easier to start when a higher voltage is applied to the starting motor.

Plus, because the batteries are not discharged to as low a voltage while starting, they will be recharged in a shorter drive time and spreading the starter motor current over a larger CCA means the batteries will probably have a longer operating life.

Last but not least, you do not need the same size, type, age, shape or colour of batteries to increase your CCA.

Don't forget that the length and sizing of the cables used to link the batteries in parallel will affect the total amount of current drawdown ability, too.

Cheers, Ron.

..


A one-sentence question, a one-word answer, and then.................!!!!!

I'm never, ever, ever going to answer another battery question!

Sorry chaps.

HI
I may as well add my 2bobs worth to Allan's & Driveafe's post
Both are totally correct
[[a] if you parallel connect batterries the CCA &/or the Ahrs are the sum of the individual ACTUAL capacities
This takes into account
[a] different manufacturing tolerances.
[b]Different RATED capacities
[c]Different actual capacitites due to aging'

There may be slight difference in SOC during charging & recharging due to different internal impedance. but these will balance out over time

It would be impossible for one to be flat & the other to be at say 20%SOC

BUT both batterries should have the same charging requirements regarding Max charge voltage , float voltage & depth of recommended discharge.

Where high current demands are possible, the connection configuration is important.
The battery interconnections should be the same length & the SAME sized cable
The load Pos & charge Pos should be taken from one battery & the load neg /charge neg connected to the other battery.

PeterQ