How do I calculate the CCA for my engine?

[Chubb]

I have a Volvo 2001 and I want to calculate the CCA so I can buy the smallest stater battery I can (space is at a premium). I've asked Volvo and they don't know?

So is there a simple calculation to work it out?

 

[pvb]

There isn't a simple calculation. However, it's worth remembering that the 2001 is only about 0.4litres, so even the smallest car battery will start it. The starter motor is 800W, so the current is less than 100A.

If you want the very smallest battery, look at the Red Flash and Red Top ranges - but be warned they're expensive.

 

[VicS]

Basically I dont think you can "work it out" It would be nice to think that the starter motor power (Probably 0.7kw as that what it is for the 2010) divded by 12 would give a realistic figure but I dont think it does. Even dividing by 9 (because the volts will drop down almost that low) gives only 77 amps.

If its not in the workshop or owners manual and Volvo cant tell you, God knows (probably).

 

[Piers]

Agreed with all the above, with one addition. A cold engine always seems to require more power to trun the starter. Maybe because the oil's thicker, etc. I'd suggest installing the max CCA (Cold Cranking Amps) battery you can fit. if that's not enough, make a biiger fitting!

 

[Col]

Could use an optima gel battery- You can mount those upside down. Gives you a better choice of where to fit it.

 

[pvb]

[ QUOTE ]
Could use an optima gel battery- You can mount those upside down. Gives you a better choice of where to fit it.

[/ QUOTE ]Wouldn't it be the same shape upside down as right way up? /forums/images/graemlins/tongue.gif

 

[halcyon]

[ QUOTE ]
Basically I dont think you can "work it out" It would be nice to think that the starter motor power (Probably 0.7kw as that what it is for the 2010) divded by 12 would give a realistic figure but I dont think it does.

[/ QUOTE ]

The kw rating is the output, not the input, hense yes your right Vic.

A lot depends on the starter motor type and manufacture,, but 250 or 500 amp starter motor cranking currents are about the norm.

Volvo spec sheet normally give the required battery size and required CCA, but not in every case.

Brian

 

[wotayottie]

[ QUOTE ]
[ QUOTE ]
Basically I dont think you can "work it out" It would be nice to think that the starter motor power (Probably 0.7kw as that what it is for the 2010) divded by 12 would give a realistic figure but I dont think it does.

[/ QUOTE ]

The kw rating is the output, not the input, hense yes your right Vic.

A lot depends on the starter motor type and manufacture,, but 250 or 500 amp starter motor cranking currents are about the norm.

Volvo spec sheet normally give the required battery size and required CCA, but not in every case.

Brian

[/ QUOTE ]

250 amps into an 0.7kw starter would imply a maximum voltage of around 3v - 500 amps would give 1.5v . Well I suppose he could assemble a battery back out of AA rechargeables from Aldi. /forums/images/graemlins/grin.gif

In the real world I guess that a decent motorcycle battery will do the job - there are bikes now with 1 litre V twin engines that take some turning over, and have starter motors of this sort of power. Only thing you need to be wary of is that smaller batteries usually have smaller capacity. They might turn the engine oiver to start, but they wont do that trick as often if your engine is a poor starter.

 

[KenMcCulloch]

The YanmarHelp.com website usefully provides recommended CCA for starter batteries for various sizes of engines. That indicated a 200cca battery for my 1GM10; I have a starter battery specified as 330cca which seems to do the job more than adequately on a similar sized engine to the Volvo 2001.

 

[halcyon]

[ QUOTE ]
250 amps into an 0.7kw starter would imply a maximum voltage of around 3v - 500 amps would give 1.5v .

[/ QUOTE ]

Please read, 0.7kw is the output of the starter motor, not what the input is.
It is not a electrical kw.

Brian

 

[pampas]

Just a thought. I seam to remember reading somewhere, its the max power rating with a 15 second cranking time + 5 attempts. totalled in amperes and deducted from the max,capacity of the cell under test. May be wrong but along those lines.

 

[wotayottie]

[ QUOTE ]
[ QUOTE ]
250 amps into an 0.7kw starter would imply a maximum voltage of around 3v - 500 amps would give 1.5v .

[/ QUOTE ]

Please read, 0.7kw is the output of the starter motor, not what the input is.
It is not a electrical kw.

Brian

[/ QUOTE ]

Meant to write "minimum" not "maximum" /forums/images/graemlins/blush.gif but the efficiency of a decent motor should be somewhere round the 70% mark so even assuming a full 700 watt output thats 1000w in and 2 volts at 500 amps. On a more realistic 9v, its 100 amps or so. Depends on battery location and cable run amongst other things.

I still reckon that a decent sized bike battery (maybe something like the ones the use on Harleys) would do the job.

And a kw is a kw is a kw independent of whether the motor is petrol or leccy or even water wheel.

P.S. Apparently the CCA is the amperage the battery can deliver for 30 sec at 0 deg and with a min of 7.2 v. If my logic is right then a CCA of 1000/7.2 would be the min required = 140.

 

[halcyon]

[quoteAnd a kw is a kw is a kw independent of whether the motor is petrol or leccy or even water wheel.

[/ QUOTE ]

The amperage loading was taken from the manufactures performance graphs for the starter motors used by marine engine builders.

The output power is quoted as hp or kW, input amperage varies with torque, speed, voltage etc. Some quite smalll engines ( 12 - 30 hp ) these days can have a stall current of 600 amp and a running current of 250 amp, in normal running conditions.

Brian