battery info pls

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smitch6

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28 Jun 2017
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Hi
i have a 20ft cruiser
thinking about batteries.......
I will be running
coolbox 40w
led lights everywhere prob about 1w i'd of thought as they are very low power.
bilge pump (occasionly hopefully)
radio/cd

they are the only electrics i'll have apart from the outboard which will be a new
tohatsu 15hp 4 stroke e/s etc

the spec says 70ah 650cca battery for the outboard

I was going to get 2 x 75ah dual leisure/starting batteries and then a cross over switch

so when engine is charging it'll be on both.
once moored switched over to leisure battery and keep 1 specifically for the engine.

however i got told the 75ah batts have a tendancy to be faulty and have been offered a new 110ah Leisure batt at a good price.
so was thinking get 1 leisure 110ah and 1 normal 70ah for starting

is this ok? or should i get 2 dual

Not sure how much power i'll actually use as i suppose we will moor up for an eve and have the coolbox going for a few hours but turn it off overnight just to be safe.

any input or ideas pls?
as i'm a bit funny and don't like having 2 batts dif sizes lol a bit of OCD i think
 
LED lights will be at least 1W each, maybe 2W. 40W coolbox is going to draw lots, around 3.5A when running. What output do you get from the outboard to charge the batteries?
 
CLB said:
LED lights will be at least 1W each, maybe 2W. 40W coolbox is going to draw lots, around 3.5A when running. What output do you get from the outboard to charge the batteries?
Click to expand...

And I suspect the coolbox will run all the time it is switched on, ie no thermostat so at 3-4 amps the 75ah battery will be down to 50% in 10 hours. 50% is about the limit you should go down to and I think an outboard would struggle to get it back up to 100% without a very long run.
 
I think you will find most batteries, even those sold as leisure batteries , have a good CCA rating so can act as engine starter batteries.

I used to have a 25ft boat with one compressor fridge. The fridge is the biggest electrical demand on most boats.
Stops of 24 hours were possible without battery issues . However at least three hours on the move would then be required to significantly recharge the battery from the engine alternator.
 
Get a solar panel may not be enough for cool box but will keep the batteries charged whilst away from boat .
 
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