Dual Battery Switches Question?

[Lundy]

I am in the process of connecting my Deep Cylce battery
and main cranking battery via a dual switch.
My question is, Can you select either battery while the engine
is running or do you need to start on the one you want charged?
I have been told if you change over while running you will blow a relay
and charge nothing??
Can anyone clarify this??
Hopes this makes sence.
Steve

[Heath]

Safe to swtich batteries while the donk is running as long as your switch is make before break. Never turn switch to off, while donk is running.

[Barrymundi]

Whilst on the subject......

If I have my switch on "BOTH" and connect by battery charger up to top the battery up because my bloody $%%#$ sh^t of a boat has been sitting in the shed for 6 weeks waiting for some good weather, will I be charging both batteries ?

Al

[noluck]

i m with Heath just swich to both and to 1 or from 2 to both and to 1 dont go to off position

[Heath]

Yes.
In theory both batteries will be charged at the same time so it will take twice as long.

But in real life what will happen is that the batteries will equalise. So if one is flatter than the other, the flat battery will draw straight from the charged one so that the voltages become equal, then they will start charging. Since there will be less resistance to the battery that you have the charger connected to, I would think that battery would become charged first, the process of equalisation which will continue to happen until both batteries become charged.

[Black_Rat]

What happens when the switch is turned to off when motor is running :-/
Damo

[peterbo3]

I believe that a lead acid crank battery & a calcium deep cycle are not compatable on the same circuit - switch at ALL or both charging together from the motor.
Engine running with switch to OFF will cause major elec damage.

[Mad_Barry]

boat has been sitting in the shed for 6 weeks waiting for some good weather,
Al

Don't worry about it, by the time the weather comes good the batteries will need replacing anyway ;D

Will be a lot of bumpy rides for the predators comp this weekend by the look of it.

[Spaniard_King]

You should never charge both batteries at the same time, one will get charged and the other will get a bit of a charge. It may work but it is not good practice for if you leave the switch on both and have a crook battery it will drain the good one if you forget about it :o, then it's VMR time 8)

Garry

[Lundy]

Ok Heath, How do you tell if your switch is "make before break"?
Steve

[Robbo_Townsville]

When I charge the deep cycle I have the switch on off (Off that is). I was told by the dealer never to turn the isolator switch while the motor is running.

[Heath]

Ok Heath, How do you tell if your switch is "make before break"?
Steve
Most packets the switches come in will state it, if you just have the switch it's easy to test with a multimeter. Basically most switches have Batt 1 - Both - Batt 2 - Off, using the Ohms setting on your multimeter you will see a physical connection at all times between the feed terminal and one of the battery terminals on the switch. This ensures that there is a load at all times when switching batteries. Except when the switch is in the off position of course.