I'm looking to install a separate start battery for my swanson It currently has just one battery bank .
the engine Is a Lister stw3m 30hp with a 3.2kw starter motor max current draw of 280amps on the clamp meter.
many CCA do think Ill need?

I suggest minimum 660 CCA.

If your sticking to one battery then I would suggest the largest deep cycle battery that fits in your battery box.

I replaced my old starter batt. with an SSB 105ah AGM from Batteryworld last year thinking of my home batt bank (2x105's) carking, I would still have something to fall back on to run nav.equipment, lights etc. for safety's sake. Not a place saving few quids. Methinks.

How you going to charge it kurt?
regards,
allan

Hi thanks for every ones input freeradical that battery table is excellent cheers
I think ill go for a 500-650cca Its tight on space and I was worried it might be to small but seems more than enough
I was thinking one with caps to top up water but a agm battery does look like a good option it will be trickle charged by a 20w panel/reg
I've just installed a combination battery switch a make before brake type to split charging from the 75amp alternator with soon to be install sterling alternator regulator.
I'm looking at 2x 335ah 6v fullriver agms for house as the will fit where the old battery's are again concerned it might be a little small for cruising and around 400w of solar for charging once installed

I would still stick to a lead acid battery with removable caps and check the levels regularly. 400w is a lot and will boil that battery dry quickly when that expensive regulator plays up!

The size of your house battery and its charge system is directly related to how much power you use ie, I have a 130 ah battery and 300w panels and don't require extra input, that being said I've lived of the grid most of my life so I guess I've been trained to tread lightly, LED lights and a fridge with a danfoss compressor a small inverter for charging battery tools a car stereo and Internet via iPad (12v charge ). If you want to run a TV, air conditioner, ice cream maker etc you are gunna need moor input and storage, every situation is a bit different so you tailor make it, I looks to me tho you've got a fine and dandy system in mind

hopefully the victron mppt will be up to the job .
I've calculated 400ah battery bank would be ideal with refrigeration auto pilot chart plotter lights small fan I pad ect radar when needed but no ice makers/ aircon or big inverters .
I could fit 2 big trojen L16 435ah 6v wet battery's but they would have to be moved forward and vent in to the cabin they would also have a long 5m cable length to battery switch

I am not sure where you are in Sydney. I am on the boat so don't have the details but I purchased a 135ah AGM dual use battery so it is deep cycle as well as high cranking. From memory it was about $250.
They are in Peakhurst.

I wouldn't be too concerned about 400w charging that would only happen in a goldie locks moment, maybe ! It's impossible to maintain any sort of PV directional discipline onboard

I'm thinking this one for the start battery www.centurybatteries.com.au/resources/battery-finder/product/ns70m
620cca should be plenty its the biggest start battery I can fit if install full river agm house battery's

I recon it will spin your 30hp like a top. I use a battery not as big as that to start a 50hp ingersol rand in a bobcat

Select to expand quote

kurt88 said..
I'm thinking this one for the start battery www.centurybatteries.com.au/resources/battery-finder/product/ns70m
620cca should be plenty its the biggest start battery I can fit if install full river agm house battery's

That battery will start an 8 litre Gardner diesel very easily. Your engine alternator would then have that battery recharged in a few minutes. If your only going to have one battery on this yacht with solar panels, victron charger, fridge, radar and autopilot etc and not going to motor sail everywhere then you should be thinking deep cycle battery. Deep cycle batteries will start small diesels like yours easily.
The ideal set up would be a deep cycle battery as the ships battery and a separate small starter battery for the main engine. The starter battery doing nothing but starting the engine and the alternator recharging that battery. Use a rotary switch to jump start if ever needed or jumper leads or even a charge pack.

Hi Kurt
My Swanson 38 starter battery is MS600 (600 CCA 130 RC) which kicks over a 50 hp Yanmar
Cheers JB

wish my swanson had a gardner 6lx maybe a bit heavy
The plans is to have 2 separate battery's one for start and a house bank 20w of solar for the start and 400w for the house bank hopefully sorted out by spring I've got most of the wiring done just need the battery's and solar panels

j bear how big is your house battery bank and where is it located? , mine is under the aft berth in front of the steering quadrant

Hi Kurt
my house battery is a deep cycle 40 amp/h(Jaycar) and is under the chart table seat .The starter battery is on the same side ,but under the 1/4 berth on the concussion run ! The starter battery was originally in the back of the engine room center which sounds like in the same position just the bulkhead is further back? . Next time I.m on her I'll take a happy snap and post it .
My 38 has basic electronics,BG sounder / depth ,radios autohelm and TV
She did have an 30 hp Lister that was rebuilt and freshwater cooled,( it's in the Doyles seafood launch now) but we replaced it because ,at higher revs she sank her bum a little and made a big stern wave .

Cheers JB

cheers jbear ill get some pics up when I'm done to
yeah the lister is a heavy lump around 330kg wish mine was freshwater cooled

Super crap auto stock those Century marine batteries. They regularly have them on 30% off sale. I have the slightly smaller one on my boat. I did a lot of reading about AGM vs this that and the other and decided lead acid was the best way to go. They are not fussy about charging etc. Also can take abuse of sitting on a swing. Just orientate them the right way (bow to stern) and keep them topped up.