Batteries

[pkb]

What is the life expectancy of a well looked after battery - ie is there a period of regular usage after which they begin to lose their ability to retain a charge and should be replaced? I've had my current boat from new for five years and most years have had the two domestic and one engine batteries - "serviced" - by the yard during the winter lay up. When we're on the boat and plugged into a shore supply and using the fridge etc I also switch on the charger so I suppose they have been reasonably well maintained.

Advice would be appreciated.

Peter

 

[Steve101]

Funnily enough I was having this conversation down the pub the other night (Honest!) It's three years according to someone who actually works in the industry. I've had the one on my Lancruiser now for five and not had a problem, aparently it's down to the depth of the "drip tray" at the bottom of the battery. Incidently he explained the only difference between a "normal" gel battery and a "marine" gel battery is....wait for it.....fifty quid!

 

[tyger]

If you have had the batteries for five years that is pretty good going! General advice seems to be to replace a battery when its capacity has fallen by 40% of the original capacity (e.g. if you are only getting 60 amp hours from a 100 amp hour battery). When you replace one battery you should replace them all.

To the best of my knowledge age is not a direct influence on the condition of a battery. The most significan factors are:, the number of discharge / charge cycles and the average depth of discharge (e.g. 100 cycles to 50% of capacity will "age" the battery more than 200 cycles to 25% of capacity). It sounds as if you are looking after your batteries pretty well - the most important thing is not to leave your batteries in a discharged state.

Measuring the actual capacity of your battery is a relatively simple (but tedious) process. In practice you can probably form a rough idea of battery condition from how frequently you have to recharge by running the engine at sea compared to when the batteries were new.

As always all above IMHO.

Terence

 

[tyger]

Re: Batteries PS and correction?

This url gives a test procedure for determining the capacity of a battery.

www.windsun.com/Batteries/Concorde.htm

Note that they recommend replacement at 20% below rated capacity and not 40% as I stated.

Terence

 

[pkb]

Re: Batteries PS and correction?

Thanks for the input - very helpful.

Peter

 

[billmacfarlane]

On my last boat I had originally a couple of Lucas batteries which lasted 3 years. I changed them for a couple of Italian deep cycle jobs and and installed a TWC charger to replace the alternator regulator. They were still taking a good charge 8 years later when I sold the boat. I'd be interested to know what your boat yard does and how much they charge to "service" your batteries. Apart from topping the cells up if possible , putting a smear of Vaseline round the studs and applying a top up charge where necessary , I can't think of anything else a boatyard can do .

 

[Twister_Ken]

In my case they put the batteries on trickle charge for the winter (or at least they claim to).

 

[pkb]

The term "serviced" was used loosely as I couldn't come with a proper technical term. They do all of what you say as well as put it on a trcikle charge. I've never been sure if that is better than me keeping them on board with the charger on but it seemed like the right thing to do! Maybe its just another case of a yachtsmen and his money being easily parted.
Peter