light weight engine battery

[timevans2000]

Does anybody know of a small light weight engine starting battery for a 30 hp engine. I would like to use the existing 110 amp engine battery on the domestic bank and fit a small light starter battery.

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[Talbot]

lots of them in makro at cheap prices (i.e. just buy the cheapest battery for a car that they have. If this is too large and money is no object, but weight and size are, then buy a 1000cc motorbike battery.

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[Robin]

Try your local battery supplier (Yellow Pages) since what you need is very much a car thing rather than a boat thing. You should be spoiled for choice as almost any battery for say a diesel Fiesta upwards would do the job and not be expensive. If you go for a sealed one it will be easier to find somewhere to fit it.

Do think about how you are going to charge it though. If you use a split charge diode system you may need to upgrade to a smart regulator to overcome the voltage drop, if you opt for a changeover switch arrangement you need to have a good memory to remember to switch back to charging the service battery. Not difficult problems but need some thought.

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[pentland]

Red Flash batteries

There has been a thread on these

www.dmstech.co.uk

Paul

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[ChrisE]

If it is light, rather than cheap, look up carbon batteries. They use some carbon fibre rather than lead. They cost about 30% more than lead acid but apart from being lighter they can be run flat and recharged, unlike their lead equivalent.

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[Guest]

We are the main distributor for DMS and sell both cheaper lead/acid cells, carbon fibre and Red Flash engine starters.

A motorcycle battery will soon die turning over a diesel engine and isn't built well enough to resist huge vibration. A red flash is the best option for you. These units are pure lead AGM technology and fully sealed. They are maintenence free and can be orientated in any direction.

Depending on whether you have a diesel or petrol, you'll need the RF1000 or 700.

RF700

AH Cap: 17AH Dimensions (lxwxh) 170x99x175 mm price is £71.18 inc

RF1000

AH Cap: 26AH Dimensions (lxwxh) 250x97x152 mm price is £82 inc

We supply these with a full 5 year warranty.

Details on the DMS site: www.dmstech.co.uk or www.merlinequipment.com

Hope this helps - James

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[PeterGibbs]

Why small? Why lightweight? Isn't starting your engine easily and smoothly one of your priorities?

If it is, may I recommend you get a real starter battery - suggest 70 amp for a 30 HP engine, and rejoice if it feels just a little heavy - that way you will know that there are just a few lead plates within that might just work for several seasons, and most importantly, when you most need it!

PWG

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[pvb]

At last ... common sense rules! (nm)

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[MainlySteam]

Re: At last ... common sense rules! (nm)

Took awhile.

Should add that if the old battery used for engine starting was a cranking battery it will not last many discharge cycles in a domestic bank.

John

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[BrendanS]

Re: or look at it another way

If the old battery is not knackered (and hence due for disposal anyway) keep it for engine starting duties, and buy a proper deep discharge battery to add to the domestic bank?

<hr width=100% size=1> I asked an economist for her phone number....and she gave me an estimate

 

[Jools_of_Top_Cat]

I have Two 125AH starter / domestic carbon batteries. Built by Elecsol in Flintshire North Wales, so helping the local economy me thinks.

Have a look at the site, might solve having too much wieght on board a cat, which is why you are asking for a lightwieght solution. Not everyone can just keep throwing wieght into their boats!

Hope this helps.

<A target="_blank" HREF=http://www.elecsol.com/index.html>http://www.elecsol.com/index.html</A>

<hr width=100% size=1>Julian

<A target="_blank" HREF=http://www.topcatsail.co.uk/movies.html>Dolphin Movie From Top Cat</A>

 

[BrendanS]

Take your point about weight on a sailing cat, but the points on the thread still apply (and are read by many that will not know that a Prout is a Cat)

I sometimes think that people should give more detail when they ask questions, that would aid in giving accurate answers. However, the wealth of detail that comes out of general questions makes them well worthwhile

<hr width=100% size=1> I asked an economist for her phone number....and she gave me an estimate

 

[timevans2000]

I already have two 110 amp hour service batteries. I have solar and wind/towed charging of these batteries. I also use them to start the 30 hp diesel engine. I have a 110 amp hour standby battery for starting the engine should the service battery bank ever be too flat to start the engine. This has never happened. The existing standby battery has a 5 watt solar panel permanently connected so it always shows about 13.2 volts on the meter.

I would like to use the existing standby battery as another service battery giving me 330 amp hours on this bank. I havent got much space left in my battery box for a 4th battery. Also my boat is a catamaran and I am always conscious of adding more weight, with the consequential lose of performance.

I think I need a small reliable light battery that will start my engine in the unlikely event that the service bank goes flat. This is highly unlikely as there is an alarm on the battery management system set to activate at 50% capacity left in the batteries.



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[timevans2000]

Hi James,
My engine is a Yanmar 30 hp diesel. Is a 26 amp hour battery sufficient for starting this engine?

Also, what weight is the RF1000 battery?

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[Guest]

RF1000 battery weighs 9Kg... Yes it's okay for a 30HP Yanmar

In response the Elecsol Carbon Fibre batteries, we supply these also. General experiences have been OK - but not great. Perhaps the most difficult issue is getting the manufacturers to honour their 5 year warranty.

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[MainlySteam]

James

I assume that the 26 Ah is a C10 rating which I think is standard in UK - most of the rest of us use C20, of course, and should be careful if reading the thread and thinking of a new battery too.

Regards

John

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[Guest]

John,

it's a C20 rating I believe... Will check for you

James

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[Guest]

Very true ....

But if like many people who don't actually discharge their domestic's that low ...... it doesn't really make a difference. It is true that a Domestic Leisure battery is designed to go lower in discharge than a cranker ......

I have used cranking batterys for years - having screwed up too many leisure jobs when needed that emergency engine start. That I decided to keep all as topped up as possible and use crankers in both slots.

I know many other boaters who use similar ---- wouldn't adnmit it at the bar of course - as they don't want to be targets for comment !!!!

C'mon then own up - how many out there use Crankers in both domestic and starting role ...... I knew it - too scared to own-up !!!!


<hr width=100% size=1>Nigel ...
Bilge Keelers get up further ! I came - cos they said was FREE Guinness !
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[MainlySteam]

Re: Very true ....

<<<C'mon then own up>>> Not me. I have a bank of nice Trojan batteries for the domestic load.

If by cranking batteries you are talking about batteries designed for use on service vehicles with heavy electrical loads then I have some sympathy with your claim. If you are giving everyone the idea that your common old starting battery of the size one would normally use for cranking a small marine diesel then you are doing a disservice. They will die, unless you have very low electrical loads (like in a car the only things to be supported when not under charge are a radio, sometimes, and a clock!) and keep them continually topped up at a high level of charge. Hardly appropriate to any boat with any comforts at all.

Deep cycle batteries will crank an engine as long as the bank is of sufficient size, but I certainly would not make a habit of it with a single small capacity battery. For the same reason, and the load case is far worse, I always suggest that the engine cranking battery should be used to power a windlass, but generally many forumites climb all over one claiming that the domestic bank, or heaven forbid, another battery in the bow, is the best option.

John

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[MainlySteam]

Thanks James.

However, from your background, I know you will be recommending the battery from sound experience of them doing the job. In which case I would quite safely assume that it is a C10 rating as a C20 battery of the same amp hours would not be appropriate.

Regards

John

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