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Old 27 April 2003, 06:56   #1
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Country: UK - Channel Islands
Boat name: Spud
Make: BWM
Length: 5.75
Engine: Mariner 125
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Batterys, who does know?

Yet again after many hours of reading through the forum on batterys I have found many pro's and con's but no definiative answers.
  • It has been said that we RIB users do not need Deep cycle batterys due to the fact that our boats are not running lights pumps etc for extended periods without re-charging like our fenderless friends.
  • Also that it is better to have a acid free / sealed battery on a RIB so that during rough sea's the acid does not spill out.
  • But also it was said that a sealed / maintance free battery will not be able to cope with the output from a outboard. Apparently a car regulator will put out 11/12 volts continuiosly. Where a outboard will a times pump out up tp 18 volts!
  • Then it was said that all we needed is a regular cheap car battery!

Now this is what I read on the forum last night. So you can see where I am non the wiser due to many conflicting opinions.

Also how do I calculate what battery power i need to run SPUD, all she has is a fishfinder, gps, vhf and the outboard. With bilge pump and nav lights run very infrequently?

Thank You again,
Lee
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Old 27 April 2003, 11:39   #2
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Country: UK - England
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Hi lee

See comments below, inserted onto your post


It has been said that we RIB users do not need Deep cycle batterys due to the fact that our boats are not running lights pumps etc for extended periods without re-charging like our fenderless friends.

Agree, however be aware that if you leave it long periods between using your RIB you may be better of with a deep cycle battery.


Also that it is better to have a acid free / sealed battery on a RIB so that during rough sea's the acid does not spill out.

Most batteries you find will be lead acid, belive me you dont want to pay for anything else. However you will find that the "Fredom" type from AC Delco use a different construntion and is sealled.
I would say that most sealed or semi sealed lead acids wont have many problems, unless you use you self righting frame a lot . You can go for gel cells but they dont come cheap. Also the, I think "Red Start" being sold for marine starting are aemi sealed or sealed.


But also it was said that a sealed / maintance free battery will not be able to cope with the output from a outboard. Apparently a car regulator will put out 11/12 volts continuiosly. Where a outboard will a times pump out up tp 18 volts!

Rubbish, car put out about 13.8 to 14.4 volts, 11/12 wont even charge a 12 volt cell. As for 18 volts, maybe the very small unregulated outboards, i.e. 4hp but for bigger outboards they should be fully regulated and similar to the 13.8 to 14.4 voltages. However some fancy charging regulators may go higher to put current back fast but I have never heard of the going upto 18V, maybe 15.6V but I think that it.


Then it was said that all we needed

If i was fitting a battery to a RIB, i would go for the Leasure type cell which still have lots of current to start, have good self discharge and are cheap, but a normal car battery in my option would do fine.

Hope this helps

Regards Gary
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Old 27 April 2003, 15:15   #3
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Country: Ireland
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Battery capacity

Just make sure the battery on board Spud has enough cranking power eg 550 cranking to turn the starter this is your biggest load.The other thing your battery supplies is amps per hour add your total wattage,ie 60 w lights 40 w pump 20w sounder this eg is 120 w divide by 12 the voltage this gives you 10 amps.If this equip ran for 1 hour you would need a 10amphour battery, in reality nav gear sounders etc use mili amps very little and batteries in boats for example could churn out 50 60 70 amps for hour
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Old 27 April 2003, 19:24   #4
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Garrygee's info is good. Here's a bit extra though. Many of the semi sealed modern car batteries breath through a vent hole in the end of the gallery from the cells. This hole is designed to take a vent tube. This can be fed out through a small hole in the consol. It will ensure the hydrogen, formed whilst charging, does not accumulate in your locker and cause an explosion next time one of your switches sparks it's contacts! Blowing up a battery - personal experience here.

18v - My little Mariner 30 gives 18v from its unregulated charge coil but only on an open circuit. Once connected to a load it's fine. It can even be used directly for 12v. nav lights.

JW.
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Old 28 April 2003, 07:22   #5
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Hi

I had some problems with my "old" engine a Yamaha 115 2 stroke. The problem was actually not the engine but my kill switch which separates the battery from everything else. I was out sailing when the switch was accidentally turned off, while the engine was running. This produces over 18 Volts on the rest of the system where my VHF was connected, this blew the power part of the VHF costing 130 to fix. Not a DIY project.
My Sounder and Radar survived, but they are rated 12 - 34 Volts


I tried the same thing with my new engine a yamaha Vmax, with everything turned of, and VHF cable disconnected. Started the engine put some revs on it, switched off the kill switch, and looked at the voltage meter, nothing 13.5 Volts.

I guess there might be something different in the voltage regulater different engines.

So try to test it before you burn something.

Regards
Rene
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