Quick question about dual batteries

[Vulkyn]

Well was looking to fit another battery to my father inlaw's speed boat, however i ran into battery isolators and switches.

The guy at the shop was trying to convince me battery isolators sort out charge, trickle charge the battery and insure that battery consumption is alternated.
In other words the ultimate batter solution ... sounded too good to be true so i did what any sane man would do .... run for expert advice

[Grt Lks Seadog]

The glib answer is yes, a battery isolator is a really good idea. Do a web search on them and you find units that will keep your batteries equally charged and don't do bad things if one of them will no longer hold a charge.

A more detailed answer requires more information about the boat.

1) Does it utilize an inverter on-board to provide AC power?
2) Does it ever connect to shore power?

If both of these are true, then there are inverters with charge controllers that take care of these things for you, but you'd still need a battery A/B switch just to be safe.

3) If 2 is yes and the boat is of metal construction, then the isolator is insufficient. In that case you also would want an isolation transformer, which is a whole different animal. This is non-trivial situation that requires care to be taken so that the boat's batteries and inverter don't end up supplying the marina with power instead of the other way around or that you don't introduce a serious cathode depletion situation, i.e., watching your zinc's evaporate before your eyes when you connect everything up.

[Vulkyn]

1 = no
2 = no
Boat is fiber glass

Its a 6 meter speed boat with an outboard engine so we are mostly running things like radio, fish finder, lights etc....
The idea is redundancy and safety more than anything, also we have 2 bilge pumps 1500 gph so the extra battery to give some more operation time should both pumps need to work . ...

[CDK]

Just install a standard 4 way battery switch (Port-Both-Stbd-None) in a convenient place. Put it in Both during cruising, switch to one battery when anchoring so there will always be a fully charged battery to start the engine.

[Vulkyn]

Thx for your posts folks !

So when engine is switched of i will manually select which battery to use? And would that mean i need draw power from both batteries to run lets say bilge by duplicating the wiring ?

Just trying to wrap my head around it and learn a bit more in the process

[CDK]

No need to duplicate wiring. Just buy the switch from Vetus and follow the instructions that come with it.

[Vulkyn]

Ahh you got a link for them? They do not exist in Egypt ....

[CDK]

Vetus is the brand name, sold worldwide. I would buy it from any German or Italian boat shop because they are the nearest for my location.

Google for Plastimo or Vetus. Are there no marine suppliers or marinas in Egypt?

[Vulkyn]

There is but not conventional shops or they are very little of them.
Its either some one buys in bulk randomly looking for a good price or a very few ones that import brand names.

That's reason i ask for these details is my posts, i find it very difficult to get reliable information and i dont like to rely on others in delicate things like electricity as 70% of the time they do a bang up job ....

Ill go back to the person i talked to and see what brands he has ...

http://www.vetus.nl/

and listen to CDK, he knows what he is talking.

[Vulkyn]

Thx CDK and apex !
They have a dealer in Alex

And yah CDK's posts are most informative thx !

[Vulkyn]

Well the agent was very helpful, he sent me their catalog to my office by mail.
So will have a look at what they have

[Vulkyn]

Ok just received Vetus, Jabasco and Rule trade catalog from the Egyptian agent

I am one happy Egyptian awesome information

Originally Posted by Vulkyn

I am one happy Egyptian awesome information

Thats because your old gods are still on power Amun, Osiris and the whole pack.

Where the newer ones rule, no one is happy.

[Vulkyn]

ROFL ....

nice one .... i guess one looks now at the small things to bring a smile and for me its boats