Should the no1 battery also be a deep cycle battery?

[Guest]

I'm about to change the two batteries. The previous owner tells me they are both leisure (deep cycle).

My logic says perhaps the No.1 (engine battery)should be a "normal" heavy start car type battery.

What does the panel think? Thanks for any comments/advice, Paul

 

[Guest]

A car battery is fine if its sole use will be cranking. The most important thing is the engine battery should have a CCA (cold cranking amps) rating sufficient for your engine, if this requirement is met then its ok.

Buying batteries is a black art, many 'leisure batteries' are little more than car ones with a picture of a boat/caravan on the side and a nice plastic carry handle.

 

[Guest]

beg to differ! no.1 should be normal car/lorry type for starting designed to give it's all quickly into a starter to swing a seldom used diesel. no2 should be a deep cycle designed to deliver a lower amperage over a much longer time between charge cycles. using the wrong type of battery in either bank will work but will shorten the usefull life of either battery and would be false economy.

 

[Guest]

err.... we don't differ, we agree the engine battery should be a cranking type!

 

[Guest]

Engine start battery can be an ordinary car battery...

The engine start battery only needs to be an ordinary car battery. Don't be confused by the "heavy truck" image of diesel engines - most 25-30hp boat diesels are only about 1.0 litre engines. Think of the tiny batteries which are fitted in small diesel cars, which have much more powerful engines!

 

[Guest]

Re: Engine start battery can be an ordinary car battery...

I am about to replace 2 batteries also.They are both 102Ah Acdelco maintenance free batteries that are at least 6years old and have given good service for engine starting,domestics,autopilot,instrumentation etc.I am looking at alternatives also.Has anyone any guidance on "dual purpose batteries"?

 

[Guest]

You use oversize marine spec batteries not because car batteries won't do the job but because car batteries won't survive long under charged and marine charging systems - unless you have a motor boat/motor sailor - never return the batteries to a full state of charge. If you keep the boat on a marina with power available to charge and if you aren't concerned about the boat vibrating your battery to bits, I agree, why not just use a car one.

 

[Guest]

As explained to me by a battery expert

Sorry if I'm repeating whats been said but to recap with the advice given to me by a battery expert - car batteries are designed to provide lots of power for a short time but don't like being discharged or standing for periods below fully-charged. Leisure type batteries are OK for this but don't like the sort of heavy load a starter motor demands. Apparently the difference is in the number and thickness of the plates in the battery. You can get "compromise" batteries which I have done. If I were starting from scratch I think I'd go for a small car battery for starting and a bigger, deep-cycle type for domestic supply and emergency starting. The guy I spoke to was from CPC batteries in Twickenham - they were very helpful and have good quality batteries at competitive prices, when I was there they had a few in a sale at below half-price (tel no is 0208 898 6972) - hope that of interest!

 

[Guest]

Thanks for the comments, it\'s obviously not totally clear cut. But sounds as though my "logic" wasn\'t a million miles off! nm

nm

 

[Guest]

I know that this may sound a bit 'thick' but what is a deep cycle battery....I always understood that a battery had a certain number of 'charge cycle'lifes built into it by the way that the plates were constucted(essentialy thick or thin), and that the battery would perform reasonably well untill it had 'consumed' these life cycles...your average car battery has in general about 200 such cycles going upto your average traction battery that has about 2000 such cycles... and a cycle was more or less taken to be from upwards of 80% of charge via a discharge that took you to below 20% of charge...that been 1 cycle or other things been equal.....hence there is nothing wrong with taking a car battery to a reasonably low point of discharge...you just don't get many bites at the cherry....there longevity comes from the fact that to start the average engine takes only a small percentage of a full cycle...a traction battery on the other hand will always be taken from +80% to at or below 20% hence it will use most of one 'cycle' each day in its normal designed environment . A batteries max current draw is also a matter of design in that higher draw needs beefier seperators and post connectors...all a matter of choice...you can get an excellent 50ah unit from Lucas with a four year warranty for £40 or you can get an equally excellent 120AH traction unit from Chloride at about £90 per cell (yes 6 needed to make 12v) but wow what a battery....if you had the room......for my part I would go for a couple of 120ah heavy duty Truck units from a reputable maker like Lucas, rotate them during the season and never ever let them stand idle in winter

 

[Guest]

Setting apart the cranking battery question (we use a car battery to start the engines, whether it is the right thing to do or not) I'm surprised there appears to have been no mention of golfcart batteries, unless I missed something. These 6 volt batteries are small enough to make lifting and stowing a doddle and you can team them up to make a 12 or 24 volt supply. In the USA it is generally accepted by a lot of cruisers that you get the best value for money out of them, as service batteries and we are certainly happy as larry with ours. It figures that if they will put up with the golf cart business they must be pretty sturdy and they are certainly less expensive on that side of the Atlantic than their counterparts in the marine world. Maybe they are more expensive in Europe? I wouldn't know but, if they are not, I would certainly recommend taking them into consideration. Cheers!

 

[Guest]

Its the way you use them. After employing differentiated batteries i'm now going to install two identical leisure batteries, why? It goes like this, leave the moorings on engine, after ten minutes switch off, but leave battery selector on No1 since I want to recharge it. Sail all day, pick a nice anchorage for the night, sail out the following morning switch on the engine back in the moorings (another 10 minute charge). Outcome the starter battery has been insuffiently recharged an the aux battery not at all. Now with twin leisure batteries start the engine on "both" , down in the anchorage switch to either one or two (not both) to maintain emergency back-up.

Hope we get the kind of Summer we can do that sor t of thing

Best wishes.