Car Batteries

Hi,

I'm designing a large scale radio control submarine (13ft) and am currently working out battery space.

I'm going to use 3 car batteries (need 36V) and was wondering if there is a 'standard' size battery?

I don't want to design it so it only fits one size, only to find out when I change batteries nothing will fit. Is there like a catch-all size that will fit just about any car battery?

Cheers,

Michael

Reply to
Michael
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"Michael" wrote in news:tFPnh.26458$ snipped-for-privacy@text.news.blueyonder.co.uk:

Blimey.....you'll need plenty of space for the ballast tanks if you want to be able to float 3 car batteries! Couldn't you use a smaller deep cycle version or would the Ah rating be insufficient?

To answer your question, AFAIK, vehicle batteries are all 12v, because on larger vehicles & generators I have always found that a combination of 6 or

12v units have been used to provide the required voltage.

Stu

Reply to
Stu

"Michael" wrote in message news:tFPnh.26458$ snipped-for-privacy@text.news.blueyonder.co.uk...

I would say to go for a very common size as they will be available for a very long time and be generally cheaper to buy. Such as a Ford Fiesta battery, base size : 8 and a quarter by 7 inch (210 x

180) Height minimum is 7 and a quarter but 8 would be more sensible. Main danger though is fumes which are explosive in a confined space like a sub !! so really you should go for a specialised gel battery or suchlike. A fiesta bosch battery is about thirty quid, a gel battery would probably be triple that.

Mrcheerful

Reply to
mrcheerful

Reply to
Michael

Thanks Mrcheerful, I'm most likely going to be using them in a sealed (ventable for charging etc) container though, with just batteries in so there should be any sparks (hopefully :-) )

Michael

Reply to
Michael

dont use car batteries they are not suitable , you need to use deep cycle batteries that can take constant charging cycles

Reply to
Steve Robinson

"Michael" wrote in news:ajQnh.26482$ snipped-for-privacy@text.news.blueyonder.co.uk:

Will you be fitting a sealed bulkhead at the propulsion section? Your motors will produce a lot of sparking from the commutator.

Sealed batteries would be a smaller and safer option but these are much more expensive in terms of cost per Ah. The cost of 36v and 60Ah would run into hundreds! One other advantage would be the flexibility regarding weight distribution but if your total weight is 2t I guess this won't matter.

Stu

Reply to
Stu

"Michael" wrote in news:AhQnh.26480$ snipped-for-privacy@text.news.blueyonder.co.uk:

Reply to
Stu

Batteries give off fumes when discharging as well as charging (all be it far less) , you also need to cool the batteries , and protect them from condensation within your sub far better to use leisure batteries or sealed gel batteries designed for marine use , car batteries are designed to be used in short bursts in a ventilated area , you need also to allow for pressure differentials , even if your sub only goes down 30 feet the presure differntial is quite large , could be enough to crack the battery or push out the fluid , might pay to contact yusa (lucas) they are one of the leading manufacturers of batteries and will be in a far better position to offer advice on the type of battery you need

Reply to
Steve Robinson

I really wouldn't use car batteries - unless you are only going to use

1/10th of the capacity or so, and replace often.

They are not designed for deep cycle use, and may fail with little warning, due to physical failures of the very thin plates.

Unless the model will never be at risk if the batteries fail.

Reply to
Ian Stirling

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Reply to
Duncan Wood

"Duncan Wood" wrote in news:op.tlqvtrytyuobwl@lucy:

Understood. I was thinking how small the surface area would be, without realising that it doesn't matter due to the principle of buoyancy that you outline above.

Stu

Reply to
Stu

The only battery manufacturer in the UK, I believe, is Tayna in Colwyn Bay. Why not talk to the technical team directly.

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Reply to
Lin Chung

You really don't want to use car batteries as these aren't suitable for deep discharge and will have a short service life. Get the correct type.

Reply to
Dave Plowman (News)

True but a standard car battery will be cheaper to replace...if you want a very common size I'd look at the 063 car battery that's extremely common in small engined petrol models.

Reply to
Vim Fuego

It will only be cheaper in the long run if you restrict greatly the amount it's discharged by. Which would be silly in a model as you're adding weight (and cost) for no reason. Of course you might get one replaced free under warranty, but the dealer might get suspicious with three...

Reply to
Dave Plowman (News)

deep cycle batteries are about 2 / 3 times the price , life expectancy of a car battery deep cycled will be less than 6 months , life cycle of a deep cycle battery about 3 years

Reply to
Steve Robinson

Ok thanks guys,

Michael

Reply to
Michael

Seconded - you should use leisure batteries, not car batteries. They look about the same, but the leisure ones will withstand cycled discharging far better than any car battery.

I've bought a total of 5x 85ah leisure batteries from County Battery over the last few years, and they have been fine each time. £34.03 each + VAT:

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Regards,

Alan.

Reply to
Alan

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