Advice please - batteries

[Guest]

Two duff engine starting batteries on my single-engined boat. Were 75Ah "leisure" type. What should I get for replacements? Is leisure type better because used relatively infrequently with possibly long lay up over winter? Is cheaper better? I've been offered 65Ah leisure type at £35 each + VAT. Is that good enough or do I need educating?

 

[Guest]

what size and type of engine are you starting and what is the alternator output

 

[Guest]

Re: Battery question

Volvo diesel TAMD41P 200hp. I'm afraid I have no idea of the alternator output. Can you advise without?

 

[Guest]

Wrong Batteries

Lesure batterys are for things like Lights,
fridges and things that need low power for a long periods of time.

Engine starting batterys are for things that need
high power for short times ie engine starting.
See your local stockist.

I've got twin 200's in mine but cant remember the size off hand.

 

[Guest]

Re: Wrong Batteries

I've got the earlier version of your engine - TAMD41a's. What sort of battery you need depends on whether you have separate batteries for domestics and engine starting. If you have separate batteries for starting, something for a large diesel car or van will probably do but rated around 100ah. If not you need a dual purpose battery of similar capacity - 100ah but preferably more - say 130ah. My boat has five such beasts - four wired in parallel doing both engine starting and domestic 12v supply plus a completely separate battery (with separate charger) for generator starting. The battery must be able to supply around 500amps cold start power for the engines and if you get pure leisure batteries, the heat that generates can distort the plates and cause it to fail.

If you go for traditional lead acid batteries, expect to pay about £55-65 each. Gel batteries are better and will last longer but cost 2 to 3 times more and it is debateable whether the extra cost is justifiable, especially if you have a good shorepower charging system. My batteries are Varta lead acid and are as old as the boat (12 years) and still going strong.

Nick

 

[Guest]

Re: Wrong Batteries

But, But Nicks an Accountant From Scotland so what do you expect.

It's all a load of twadle.

Speak to Bob The Builder, To Get the Job Done.

 

[Guest]

Re: Wrong Batteries

Hi Nick,

Thanks for your input. hlb (is that Bob the Builder?) may not think much of your advice but I find practical experience is at least as helpful as theoretical prescriptive directions without explanation.

I have four small leisure batteries (75ah) - two dedicated to engine starting and two to domestics. We had a changeover switch added so we could (by throwing the switch) start the engine from the domestics pair. The marine electrician who fitted our shorepower and battery charger assures me that all four batteries are charged both from the alternator and from the charger (when hooked up).

I don't have the option to go for larger individual batteries without changing the battery box layout, which I could do but since it's all worked OK for 4 years I don't see the point.

Bear in mind I have only one engine so presumably only need half the power of a twin engine installation. I have now purchased two relatively cheap 65ah leisure batteries to replace the duff engine starting batteries. This presumably gives me 130ah total?

I may have made a mistake but at least it won't be too expensive. Best way to learn - as ever.

All the best.

 

[Guest]

Batteries

For one engine two 65 AH will probably be OK as long as they are able to handle the cold starting load which will be about 500amps. The capacity of the battery is determined by things like the size of the plates inside it and you can get various ratings out of the same external measurement. My batteries, for example are 13.5inches long, 6.5 across and 8.5 deep. I bet thats roughly the same as yours.

The acid test is if it all works and if so then great, although I would be disappointed with only four years from a set of batteries if your shorepower is permanently connected when at your berth.

Nick