Is mine big enough to satisfy her needs?

[byron]

My boat's domestics are powered by three 110 Amphour deep discharge leisure batteries. Bearing in mind she is totally electric and dripping with electronics plus two fridges, is this enough power?
On the pro side I do have a 9.7KVA gennie with it's own starter bank and two seperate batteries for the engines.
The reason for my question is because it appears one battery is phut on the domestics, so I am replacing all three, so now would be the time to add another battery even if it would mean re-modelling the battery box to take another one.

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[Piers]

I believe the calculation is 3 x the daily consumption for required battery amphours. Then the question becomes the charging and the 50/85 rule (discharge to 50% and recharge to 85% of the capacity). Are your gennie / alternators able to cope with this?

There's an excellent article in the last issue of Passage Maker on this - do you take the mag?

Piers du Pré
www.playdeau.com

 

[tr7v8]

To add to what Piers said, the rule of charging is that the battery capacity should be approx 3 x the maximum charge o/p. EG 40 amp alternator 120 amp hour battery.

Jim
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[byron]

Being a bit of a dimwiddy I guess I will just replace like with like to be on the safe side. Better safe than sorry by trying to be too clever.
Thanks guys for the replies.... hey! I'm a Rapper /forums/images/icons/crazy.gif

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[Spacewaist]

Obsessed with the size of your equipment.....?

Trouble is, like all men, you seem obsessed with the size of your equipment and oblivious to the womans desires..... what is her daily consumption?

With two fridges and an autopilot, Ill guess, she consumes 200AHrs daily; 250+ if sailing through the night. Id have said you need north of 500 Ahrs capacity for that sort of consumption (and a 100/120 amp charger).

IN summary you need as big a capacity batteries as you can fit in the space available

 

[airbubble]

Re: size does not matter its how long you can use

see paulineb -s Q on the MBY forum of a last weekend, on what do you think about to make it last longer.........

on a more serious note: 440 Ah should work out ok even with two fridges, but backed up by genny. However, do not change ONE battery out of a bank of four, unfortunately, that does not work. They have to be equal and equally new otherwise you'll get stray currents from the better ones trying to patch up the older ones, again like the younger ones amongst us chasing our partners, in the end leaving us all without.......