OMC 3.8 V6 Starting Amps

The two engines will be installed shortly; time to buy batteries. The boat came without any.
The manual does not state an Amp draw for the starters - but of course there is also a large resistance from the intermediate, top and lower gearboxes.

Any one got a definitive figure for the Cold Cranking Amps from a battery?
Its easy to say 'buy the biggest you can afford', but they suddenly leap up in price and weight after a certain point.
If the deep cycle/ domestic battery is joined to the starter battery just for starting - would this not raise the starting amps sufficiently?

Thanks gents, I have had no information from any battery supplier . . .

 

Cranking current will be between 220 and 300 Amps, depending mainly on temperature.

Unless you plan to make trips in subzero conditions, a 75 or 80 Ah battery can easily cope with that.

 

CCA is the current at -18 deg C that will reduce the terminal volts to 6v in 150 sec.......very usefull ......get the idea out of your head that a starter motor draws 400A when cranking 120/150 A is more like the figure..( spent years testing the things ) ...Most V6 of your capacity would have an N70 battery which I think is 100ah....as used on a diesel Land rover discovery mk1 or 2 .....a better guide when comparing batteries is the reserve capacity ...time taken for 25A to discharge the battery ...typical for your situation about 120 min...this figure is not so easy to fiddle as the AH which can be at 5 ..10 or 20 hours ..
The bigger the battery you buy the longer it will last as they all deteriorate from new and when a small percentage remains working you get staring problems .the more you start with the longer it takes to reach that small amount.....more important for battery life is to ensure the alternator is getting them up to 14.4 v and avoid sealed batteries..

Buy the cheapest battery you can for a given RC (I buy from K mart..exide ) keep the receipt and if it goes tit **** buy another identical and take the old one back for a refund on the new receipt ... all batteries are created equal ..only the case and the warantee changes with price ...the makers are charging you an insurance premium in case it fails .....not all the jews are in Israel.....now where did that pistnbroke go ....ahhh Manifold me thinks ....