Advice please - batteries

[Guest]

Two duff engine starting batteries on my single-engined boat (Volvo diesel TAMD41P 200hp). 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 because don't last too long anyway? I can get 65Ah leisure type at £35 each + VAT. Is that good enough or do I need educating?

 

[Guest]

Think you need help here Tim!!

We have a 105ah 'deep cycle' battery for starting the 28hp Beta diesel on our Cobra 850, and have a 120ah automobile battery as back up/domestic. This seems to be adequate for our needs - however - I think that the size battery you are using would be a bit "gutless" for the size lump you are trying to start! I, as you have probably already guessed don't know an awful lot about marine electrics, but a piece of advice I received from a marine electrician was "avoid cheap leisure batteries for starting, go for heavy duty, ideally truck type batteries. For the domestics use whatever you feel comfortable with for the number of instruments you will be running from it". Well, I suppose that it makes sense! Hope this helps!!

 

[Guest]

Agreed

More money= much better batteries

Spend £100 on a good engine battery, it will be worth it.

Most people go for the standard flooded batteries, but they are "Marinised" in that they are more heavy duty and the Ah is suited for starting engines.

There are newer technologies in the form of Gel and AGM (cant remember what this is, Glass Mat or summink) which are much more expensive to start with but hold more cycles, last longer etc.

 

[Guest]

Two options for you.

A. Buy a good quality auto battery with a cold cranking capacity to meet the engine spec. for starting (Battery 1 say), and a deep cycle battery with the capacity you need for the domestics (Battery 2).

Advantages - each battery is right for it's purpose, and this is the cheapest way to a proper installation.

Disadvantages - neither battery is suited to the others job, unless the domestics battery is a dual purpose design which also meets the engine starting requirement.

B. Particulaly valid if you have manual battery switch(es) and no fancy charge controller. Buy two identical dual purpose marine batteries. They all do them at around ninety quid for 110 amper/hours(each).

Why?

The ones I refer to can deliver plenty of current for starting your motor without buckling the plates, and can withstand reasonable deep cycle without suphation problems associated with auto (short cycle) batteries.

Advantages

You can happily start up on either (or both) if needed, and switch to 'both' whilst underway and forget them. If the batteries are identical (size, brand age), the charge will balance across both and they will get a full charge each. Swap them round each season and they will last you as long as you don't run them completely flat, or leave them in anything other than a fully charged state.

Disadvantages

Costs a bit more, but at least you know you have redundancy built into the system if Batt. 1 fails completely.

And that is A GOOD THING at sea.

 

[Guest]

Re: Think you need help here Tim!!

Well, now I'm really confused. The bloke in my local car battery place (who may or may not be expert, I admit) suggested I'd do as well with leisure batteries because "heavy duty" batteries like to be used often (as in a car). The boat engine batteries would be used (say) four time a week on average during the season and then not at all for (well, if other winters are like this last one) six months (I know I should take them off and store them in the garage and charge them once a week and all that but reality is I probably won't). As I said, the batteries I took off are 75Ah "leisure" type and they've lasted four years (probably would have lasted longer if I'd ever topped them up - which I'm somewhat ashamed to say I didn't).

Also, my domestics batteries are also 75Ah leisure type and they're still going strong - started the engine no problem when I had to use the crossover switch because of the duff engne batteries (must remeber to top them up now!).

I'd prefer to spend £80 every 4 years on a pair of downmarket batteries - at least if I do neglect them the mistake isn't too expensive.

Does that make any sense or is it wishful thinking?

Thanks for the last advice anyway.

 

[Guest]

Re: Think you need help here Tim!!

Everyone has said it all, but where to buy - I found Halfords the best bet recently for range of choice, price and especially as they give a 2 year replacement guarantee (No I don't work for them!)

Good luck

 

[Guest]

My own personal preference is for a deep cycle marine battery exclusively for the engine but not too great a capacity as a deep cycle battery needs a fair measure of discharge before it will function properly.Without it the battery will fur up. For domestic I prefer a bank of at least 2 75-100 ah batteries. The whole bank is charged by a microprocessor controlled charger controlling the output of the alternator regulator for more efficient charging.