Engine starter battery - distance from engine?

[Danny1234]

Hello

Am in the final stages of refining my design for my would be widebeam boat, .....

Minor question, ... I'm considering having the starter battery for the main engine somewhere else than in the actual engine compartment

(haven't decided where yet and I do realise this may need some ventilation, ...) ..

2 reasons ...

I might be able to locate it somewhere reasonably warm (not to warm), .... but mainly to stop the battery getting very cold in winter, thus reducing the charge and making it harder to re-charge

Also, could be of some benefit with regards to security, one could easily just disconnect the starter motor battery without having to lift up the engine bay covers, .... if the battery was actually somewhere in the main cabin, then someone would actually have to break into the main cabin (which should be a lot more secure than the engine compartment), ... then actually know where the battery was.

 

Question then, what is the longest distance one would reasonably be able to have the starter battery from the engine? I'm thinking 4-5 metres should be sufficient. My understanding is that in theory one could overcome any voltage drop issues by just having a much thicker cable. Is there some potential issue I'm missing here?

 

Regards

Danny

[nigeljan]

indeed with very thick battery cables could be achieved,but I would be more concerned about explosive gasses from your battery discharging into the main cabin

[Danny1234]

indeed with very thick battery cables could be achieved,but I would be more concerned about explosive gasses from your battery discharging into the main cabin

 

Yes, ..... that is a concern. Haven't fully decided to do this yet, .... locating a safe place would be a min requirement

 

Thanks for the confirmation

 

Regards

 

Danny

[bottle]

I know it is a new build but check theBSS site

 

batteries are not allowed in any 'living area', if I remember correctly.

[nicknorman]

You would have a long unfused large +ve cable running through bulkheads etc which, if damaged / worn through could cause a fire either in the cable or battery. Starter batteries take very little charging and will last months or years between uses if in good condition. Therefore I think you are trying to tackle a non-problem, and creating other issues in the process. I would keep the starter battery near the engine.

[Timleech]

I know it is a new build but check theBSS site

 

batteries are not allowed in any 'living area', if I remember correctly.

 

My reading is that they are, but there must be adequate fixed high level ventilation.

 

Tim

[Biggles]

I think you are making a wrong move here. Keep it close to the engine. Your fears regarding charge are unlikely to materialise. However I can see a shed load of other problems if you put it inside the cabin just to keep,it warm.

 

Na. Bad idea!

[jelunga]

I agree. No need to go to the expense of thick cables. Battery will be chrged by the engine mostly and therefore heat from the engine will raise surrounding temperatures. Charging separately will be only to replace internal self discharge and as such at a low current.

Unless you have the same system fitted as the Army Coventry Climax Generator set where an Austin 7 engine driove a mains generator but the wood cased starter batteries had no charging system.

[steve hayes]

I agree, keep it simple. You will introduce more problems than you hope to solve.

 

Steve

[dor]

but mainly to stop the battery getting very cold in winter,

Think of all the cars that start without problems every morning, even in very cold weather. The battery on the boat won't get as cold as a car battery either.

 

It takes less than one amp hour to start an engine which will be replenished in minutes, so I don't think you need to worry about the battery. The starter battery on most boats last for years even if the domestic batteries get shot.

[system 4-50]

You would have a long unfused large +ve cable running through bulkheads etc which, if damaged / worn through could cause a fire either in the cable or battery. Starter batteries take very little charging and will last months or years between uses if in good condition. Therefore I think you are trying to tackle a non-problem, and creating other issues in the process. I would keep the starter battery near the engine.

One of the fun things about doing your own design is that you can attempt to find a better way to do things. In my fit-out I have put in underfloor heating to avoid cold floors for example. But I am quite realistic in expecting that even if it works I will probably not use it, for one reason or another. Anything that really, really works would be in widespread use. The golden rules of boat design (some of) are :

Is the problem you are addressing really the problem that you think it is? On the day, will the inconvenience be so small you won't bother with the solution?

Does the solution that you have come up with solve the problem? Does it create more problems of its own?

Hundreds of highly skilled boat builders have confronted the problem you are looking at, why have they not adopted your solution?

 

 

I don't mean to be discouraging, just pointing out the pitfalls I encountered in the fantasy world of the design stage of my fit-out.

[Teadaemon]

I know it is a new build but check theBSS site

 

batteries are not allowed in any 'living area', if I remember correctly.

 

As Tim has already mentioned, there's no problem per se with having batteries in a living area, indeed it may be one of the places in a boat that already has fixed high level ventilation (which prevents a build up of hydrogen gas). The relevant section of the BSS is 3.1, specifically check 3.1.1 Are all unsealed or open-vented batteries ventilated to prevent risk of explosion through hydrogen accumulation?

Edited January 27, 2013 by Teadaemon

[dmr]

Not sure about security, taking and driving away of boats is very rare.

Theft of the battery itself is marginally more likely but still very rare.

However any battery thief will lift the engine lid and spot those huge thick copper cables that you plan to use and will think it is Christmas

(actually it probably will be as I have observed an increase in scrap metal theft just before Christmas)

 

A battery will loose some capacity and cranking amps at low temperature but should be specified such that it can still start an engine when its very cold!

 

........Dave

[Guest]

I feel that you may be trying to cure a problem that doesn't exist. Our start battery has sat on the swim plate for over nine years, and has easily started the engine in all weathers. It was fine even in the two extreme winters a few years back (-20 once). If you are really worried about theft, it would be a doddle to put a locking bar over it. If anybody wants to nick your boat, they would bring a battery with them, or nick one off another boat.

[John Holden]

I feel that you may be trying to cure a problem that doesn't exist. Our start battery has sat on the swim plate for over nine years, and has easily started the engine in all weathers. It was fine even in the two extreme winters a few years back (-20 once). If you are really worried about theft, it would be a doddle to put a locking bar over it. If anybody wants to nick your boat, they would bring a battery with them, or nick one off another boat.

 

Or even bump start it