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#1 Steve

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Posted 14 May 2019 - 08:24 PM

Someone smarter than me will have the answer. Let’s say you wanted to save some weight. Starter battery is around 20 kilos I suppose. A little jump starter about 1. Why not just swap one for the other? Charge it with a USB connection like you do with a phone and as long as the motor generally starts easily then what’s the problem?
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#2 w44vi

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Posted 14 May 2019 - 08:46 PM

If your after weight reduction with your battery go lithium ion. Depending on how big your motor is you maybe able to use a motor cycle battery 


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#3 wheels

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Posted 15 May 2019 - 05:48 AM

Jump starters are just baby Gel batteries and are not capable of giving any log term cranking ability. If it doesn't start first try, you are stuffed. Diesels, especially when Cold and a little worn, need a good turn over period to build compression high enough to fire. So a decent Start Batt is needed.


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#4 Steve

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Posted 15 May 2019 - 06:55 AM

But if your motor always starts first click?

If not I guess you could link the house batteries.

I suppose there's one more fly in the ointment.  The bloody anchor winch.

But if you were getting all anal about a particular regatta then one small house battery and a jump starter would suffice?

Hell of a lot easier than taking off the toilet seat, the cupboard doors, the squabs and the speakers.  We did all that (and more) for the RNI one year and it was amazing how much of a pile of gear we ended up having to store. Hundreds of kilos but really only compensated for all the extra palaver required for cat 2.


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#5 Sudden5869

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Posted 15 May 2019 - 01:11 PM

Yeah I thought about Lithium ion for starter battery last year.
I think Lithium ion batteries require a complete Battery Management System. Without that you may not comply to regs, insurance coverage etc....
Happy to be corrected.
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#6 Knot Me... maybe

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Posted 15 May 2019 - 01:30 PM

I think Lithium ion batteries require a complete Battery Management System. Without that you may not comply to regs, insurance coverage etc....

Yes they do require management gear std flooded lead don't. But that gear is not for YNZ or insurance as such, it's more to stop you blowing your boat up or even worse blowing your own arse up.

 

As Boeing and a few others have found if these lithium's go bad and dump all they energy out that can happen inside a millisecond with massive and disastrous results. I was told if that happened with mine all my wiring could literally vaporise. No idea if that is true or just a wise person trying to scare me away from playing in there.

 

My battery has 13 wires coming off it that go to many assorted black boxes that go click and thunk.


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#7 harrytom

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Posted 15 May 2019 - 03:41 PM

Hand crank??


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#8 mcp

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Posted 15 May 2019 - 07:33 PM

Jump starters are just baby Gel batteries and are not capable of giving any log term cranking ability.

 

They are usually Lithium Polymer, also commonly known as LiPo.  Of the mainstream lithium ion chemistry batteries,  these are the highest energy density and also the most likely to fail and go into thermal runaway.  They are very sensitive to being balance charged correctly.   

They will deliver amazing amount on Amperage instantaneously at C ratings of up to 95C or more, which make them perfect for the jumpstart application.  They are also the reason for the recalls of a number of smart devices that spontaneously combust. 

 

I would not keep one of these on a boat.  Go have a lookie around youtube and google for Lipo fires.  

 

 

Also someone above mentioned Lithium Ion.   Just to be clear,  this is a line of multiple different types of battery chemistry and not one type.

For automotive or marine, you want to use a lithium Iron Phosphate or LiFePo4. This is because it is one of the safer chemistries [safer in my opinion than flooded lead acid] and also because its nominal voltage and full charge voltage more closely matches the lead acid type equipment found on most boats and vehicles.  So fully charged at 3.65v per cell = 14.6v at 4s and a nominal voltage of 12.8 - 13.2.  The cobalt & manganese types are 4.2 volt fully charged, so 12.6 at full at 3s and 3.6 nominal, so 10.8 at 50%. So they don't work easily with normal 12v systems. 

 

On my boat,  I am going to install Lead Carbon [not to be confuse with lead crystal] from a reputable company [There is good and bad lead carbon] or maybe LiFePo4.  But probably Lead Carbon.


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#9 Island Time

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Posted 15 May 2019 - 07:40 PM

Agreed. Lead carbon looks pretty interesting.
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#10 Dtwo

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Posted 15 May 2019 - 08:02 PM

Yes they do require management gear std flooded lead don't. But that gear is not for YNZ or insurance as such, it's more to stop you blowing your boat up or even worse blowing your own arse up.

 

As Boeing and a few others have found if these lithium's go bad and dump all they energy out that can happen inside a millisecond with massive and disastrous results. I was told if that happened with mine all my wiring could literally vaporise. No idea if that is true or just a wise person trying to scare me away from playing in there.

 

My battery has 13 wires coming off it that go to many assorted black boxes that go click and thunk.

 

LifePO4 isn't going to blow anyone up, exciting as it may sound.  Using it in a boat vs a car environment means that the rates of current draw and the size of the bank itself is hardly scratching the surface of what they can provide - which means an inherent safety margin of some magnitude.  You really don't want to drop a spanner across the bank though.

 

The battery management systems exist more to safeguard the batteries from low or high voltages, which will quickly kill your bank.  Basically a wallet protection system.

 

As for Boeing, which knob told them that putting batteries in a fuel tank was a good idea?


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