Thursday, 24 January 2013

Less is more - batteries ?

I am trying to get my head around batteries.... we have two 110a/h on Percy and Waterlily has three x x110a/h, both plus starters.

Now I know with three you will get longer power supply, simple really, but you would then have to charge up three batteries instead of two. So whilst my smartgauge will drop to say 90% on Waterlily after an evening aboard maybe Percy's Smartgauge will drop to 80%. it used to take an hour to put 10% back into Waterlily's battery bank so it will be interesting to see what it takes to put the same 10% back into the two on Percy.

Now as I understand it batteries die based on their discharge/recharge cycles. So is it the case that taking a battery to 80% then recharging is worse that 90 % and recharging? If it is marginal then surely it is better to have less batteries as they will be cheaper to replace when the time comes.

Also I suppose there is less risk with fewer batteries of one dropping a cell and causing the others to work so much harder without the owner knowing?

I have been following a post on Canal World about smartgauges... normal pin balling around with a few insults in there but in the main an interesting thread. I think the Smartgauge is a little smoke and mirrors device, simple at what it does but reliable and users like me get drawn to its % comfort. There are other ways, many will just use instinct/experience to know how much to run the engine, others use multimeter's to alert them to 12.2 volts (is that the magic figure for the time a battery bank needs recharging?) Anyhow I like the reassurance, having been without power is not a good experience and the thought of destroying a battery bank because you are not aware of its low voltage state or a dead cell within the bank is not comforting.

I'd be very interested in what you use to monitor your power?



Jim said...

I'm ashamed to say that I just run the engine for an hour or so on days when I haven't moved. I have no idea how much my batteries are charged at any time! Like Percy, I only have 2 x 110a/h batteries but I have been advised recently that I'd be better off increasing that to three although my current set have lasted 4 years and my starter battery is the one that was fitted when I bought Starcross eight years ago.

Captain Ahab said...

I sit in Jim's camp. I dont have a clue about the state of my battery charge. I run two 110 a/h batteries which were replaced at 5 years last time and my rule of thumb is that if they cant keep the fridge going all night they are knackered. I have converted to LED lighting and only run the fridge / laptop and I have never run out of power. That said, I cruise a lot so they must be fully charged each day and when we stay put I run the engine for an hour or so for water and a bit of a recharge. Sometimes I think ignorance is bliss.

Nev Wells said...


Go to the smartgauge alter and say three hail gibbo's .... Each to their own. I am sure I could get by without, but I am a whittler and like to know what is happening to the various part of the boat. The price I have paid for the Smart gauge is about the cost of a set of replacment batteries, but I was sure I was running the engine more than I needed so burning fuel as well as more servicing. I know my neighbour uses a natty £20 maplins device that displays the voltage via plugging into a cigarette socket, as well as telling what current draw is happening via said device - it feeds out 12v I recall. It works for her. My other neighbout uses his expereince of living afloat to know how long to run his engine. Those like you who cruise more than moor will get a decent charge into your batteries anyhow. All good fun in the end and a reason to fettle....!