Battery power

pheran

pheran

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How can I find out the size of starter battery required for an engine, in this case a Perkins M135? Six cylinder/6 litre normally aspirated diesel. I understand the power requirement is expressed as Cold Cranking Amps (CCA). Is this correct please? The official engine handbook I have, rather oddly, doesn't mention it at all and Mr Google hasn't been able to help. TIA.
 
24v installations in new yachts typically seem to use a couple of 70Ah AGM batteries, which probably have about 800CCA. If yours is 12v, you'd presumably need something a bit meatier. Why not ring Perkins and ask?
 
pheran said:
How can I find out the size of starter battery required for an engine, in this case a Perkins M135? Six cylinder/6 litre normally aspirated diesel. I understand the power requirement is expressed as Cold Cranking Amps (CCA). Is this correct please? The official engine handbook I have, rather oddly, doesn't mention it at all and Mr Google hasn't been able to help. TIA.
Click to expand...

It does mention it in the installation handbook, maybe not in the user handbook. I have one of those engines as well.
They have different specs dependent on the minimum temperature the motor will be used in.
You need 2 x 12v batteries in parallel for 12v or in series for 24v.
Each 100amps and 800 cold cranking amps is about right I seem to remember.

I have 2 x 140amp batteries that are each around 800 cca....but these are probably a bit bigger than needed.

You can start it on one but if you ever have a problem you will be stuck. I always start mine on 2 and they last at least 5 years. I can easily load test them by changing the switch to 1 battery and seeing how well it cranks. Its never good on one battery.
 
fuss said:
It does mention it in the installation handbook, maybe not in the user handbook. I have one of those engines as well.
They have different specs dependent on the minimum temperature the motor will be used in.
You need 2 x 12v batteries in parallel for 12v or in series for 24v.
Each 100amps and 800 cold cranking amps is about right I seem to remember.

I have 2 x 140amp batteries that are each around 800 cca....but these are probably a bit bigger than needed.

You can start it on one but if you ever have a problem you will be stuck. I always start mine on 2 and they last at least 5 years. I can easily load test them by changing the switch to 1 battery and seeing how well it cranks. Its never good on one battery.
Click to expand...

Thanks for that. Since there are now individual batteries that will deliver more than 800 CCA, I was hoping to get away with just one starter and use the space to accommodate an extra domestic battery. But you don't reckon thats a good idea.....??
 
pheran said:
Thanks for that. Since there are now individual batteries that will deliver more than 800 CCA, I was hoping to get away with just one starter and use the space to accommodate an extra domestic battery. But you don't reckon thats a good idea.....??
Click to expand...

No, one battery doesnt work. My boat was setup with 1 start battery and 1 battery for small 12v systems like instruments and VHF. It all could be combined with a vetus 1or2or both switch.

I always had starting problems as there is just not enough reserve in 1 battery... The slightest start problem and the battery becomes tired.

I changed the design to 2 dedicated start batteries as is in the handbook and all works fine.

Also, as I have a 3 meter cable run to the starter, I changed the cables to 90mm2
 
Last edited:
It says
Batteries ....................................Two 12 volt 510 amperes (BS3911) or two 12 volt 790 amperes (SAE J537)
It doesn't say whether it means CCA or MCA.
CCA under J537 means -18degC, 30 seconds to 7.2V (for a 12V) i.e. 1.2volts per cell. MCA would be 0degC.
CCA under BS3911 is more conservative, I think from memory it's to 9.6V i.e. 1.6Vpc.
You're more likely to see a J537 rating quoted.
790A CCA J537 is typically around 90Ah capacity, they vary depending on construction.
You might find a single 180/200Ah battery to give around 1600CCA but it will be very unwieldy!
 
Troubadour said:
It says
Batteries ....................................Two 12 volt 510 amperes (BS3911) or two 12 volt 790 amperes (SAE J537)
790A CCA J537 is typically around 90Ah capacity, they vary depending on construction.
!
Click to expand...

yep, dont go under 90ah for each
 
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