Battery switch

[Picks]

Hello all,

I've just graduated to a colvic ufo 31 from sailing dinghies for a few years hence i have little knowledge of battery set up or electrics. I have an isolater switch to select between both batteries, 1 battery or off. They are 85 amp/h batteries. My question is which position should the switch be in for different activities e.g. first starting engine, motor sailing, and cruising with sails up? I have just basic equipment on board ( gps, vhf radio, etc ) and no equipment with a big drain on battery bank such as fridge.
Thank you for help.

 

[the_branflake]

It really depends on your setup but if its as simple as you suggest i would start on 1 and then get myself ready to leave the mooring whilst the engine warms a little then before setting off switch to both.

This way you give the start battery a boost first then start charging battery 2 aswell. When on board I would be on battery 2, most likely the same when sailing.

Hope this helps.

 

[VicS]

Pretty much as above

I would:

Decide which battery to use as starter battery.

Select that one

Start the engine

When that battery is recharged switch to the other battery ..... BUT VIA THE BOTH POSITION



DO NOT ever switch to OFF while the engine is running. You will most likely blow the alternator diodes if you do!

 

[Picks]

Thanks for your replies. Been very helpful.

Cheers.

 

[wooslehunter]

Normally the switch sequences: off, 1, both, 2.

So switch to 1 to start, both when the engine is running & 2 for domestic. It makes the sequence easier to remember.

Check your batteries though. You may have two types fitted. A starter battery may be in position 1 & a leisure battery in position 2.

Starter batteries are designed for supplying a large current for a short time & then charging back. The total amount of capacity used in starting is small. They are not designed to be deep discharged on a regular basis. They can of course be deep discharged & charged again but doing this repeatedly will reduce life capacity. Once in a while is fine.

The reverse is true for leisure type batteries. They are designed to supply a much smaller current for a long time & deep discharge. They can be deep discharged repeatedly. They can be used for starting but repeated use for starting can reduce their life.

Therefore, it's common for boats to have both types fitted. You may very well find though that you have starter batteries in both positions.

 

[Stu Jackson]

Basic Battery Wiring Diagrams

and this:

1/BOTH/2/OFF Switches Thoughts & Musings - SailboatOwners.com