What rating for a service battery?

C

cngarrod

Well-Known Member
Joined
29 Nov 2002
Messages
281
Location
Ipswich, UK
Visit site
Hi guys,

Have got to replace the service battery on the boat.. have no idea what rating to get...?

Nothing major running on the vessel, lights, radio (occasionally) and don't leave the fridge on anyway.. and never leave anythign on when not at the boat...

so is it best to go for the biggest that will fit o a middle of the range one???

Cheers,

Craig.
 
The trouble with electrics on boats is that no matter how little powwer you think you will need before long you'll decide you want a little bit more.......
I would use a couple of 110AH leisure batteries - about £50-60 each which would give you around 75AH of useable capacity without running them down too far.
This would let you overnight with fridge running no problem. I say two cos if you only put one in now its not a good idea to parallel another one in later - better to have a matched pair. Also, whts your domestic charging arrangement like?

TonyR
boatone@boatsontheweb.com
www.boatsonthethames.co.uk<P ID="edit"><FONT SIZE=-1>Edited by boatone on Wed May 1 08:47:34 2002 (server time).</FONT></P>
 
Thanks Tony,

I have 2 batteries, one for engine starting and one for domestic. I am told that they charge from the engine when it is running, but haven't checked how it is regulated or similar as yet... truth is not toally sure how to check!

Ideally i just wanted to dispose of the domestic as it is dead, and replace with the same.... Good idea about putting 2 in though, how would i wire this in?

Thanks,

Craig.
 
Just connect the two batteries in parallel, pos to pos and neg to neg. This will keep voltage at 12v but AmpHour capacities add together to give double capacity of one battery.

Basically only around one third of a batteries capacity is really 'useable' so the idea is to get enough capacity to make sure all your demands can be supplied by one third of total capacity. I have 3 x 110AH on my boat so reckon I can rely on around 100AH of really useable power without recharging which gives me a couple of nights in one place without needing to run the engine, even with the fridge running all the time!

TonyR
boatone@boatsontheweb.com
www.boatsonthethames.co.uk
 
As previously stated, you can never have too much battery capacity. Get the largest you can fit/afford. On my 44 footer I have 2 x 200amp as the primary bank. Currently these run all systems and do for starting the engine. I also have a pair of 110 amp batteries. The plan is to dedicate them to engine starting and use the two big ones as domestics.

For charging them consider fitting a solar panel to trickle charge the batteries. I am looking to fit a couple of cells and after having spoken to various people, they swear by themj.
 
Fit the biggest battries your alternator can handle and you have room for, extras grow on boats like the hair on SWMBO legs!
 
You must log in or register to reply here.

Share this page

Top