12/24V battery switch on neg.?

[CaptainJS]

Hi all,

I have two 12v batteries connected to create 24 V, thats fine. I also have some accessories that only uses 12 V. I dont need to use them all at the same time. I also only need 12 V from one of the batteries (not both), which is why the 12c acc. is connected to the neg of one of the batteries.

So my question is; can I have a simple on/off switch on the cable connecting the two batteries, to simply cut the serial connection to have them give 12 v each?

If yes, then can you suggest a good switch for a boat (corossion free etc)?

Thanks

 

[Creekwood]

Sounds like a bad idea and a good way to fry the 12v side when you forget. Just go old school and get another battery for the 12v side and separate the 24 and 12.

 

[Coz]

What is the purpose of the switch?

 

[CaptainJS]

The purpose is to switch the batteries output between 12v and 24v (just one of them will then be connected to 12v).

 

[Thornton69]

Does your main engine charge at 24? Why wouldn't you just pull your 12 from the first battery to ground?

 

[CaptainJS]

No this is totally isolated from the engine. No charging (except from at home). I use the 24v for trolling motor and 12v for for stereo. Dont have to use both at the same time.. now i am taking the plug off the terminal and on when i switch, just want a switch to push/turn in stead.. is that possible?

 

[Coz]

The purpose is to switch the batteries output between 12v and 24v (just one of them will then be connected to 12v).

still not sure why you want to do this. There’s nothing wrong with your diagram without the switch. You can pull 12v off either battery or 24v across the 2. Most bass boats are wired that way. You should have 4 wires total. Bat 1+ & bat 2- to trolling motor. Bat 1+ & bat 1- or bat 2+ & bat 2- for 12v stuff

if you really want to disconnect the 24v, you can use any switch that has an amp rating higher than your trolling motor.

 

[bobeast]

still not sure why you want to do this. There’s nothing wrong with your diagram without the switch. You can pull 12v off either battery or 24v across the 2. Most bass boats are wired that way. You should have 4 wires total. Bat 1+ & bat 2- to trolling motor. Bat 1+ & bat 1- or bat 2+ & bat 2- for 12v stuff

if you really want to disconnect the 24v, you can use any switch that has an amp rating higher than your trolling motor.

^^ this ^^ no need to overcomplicate it. If you do want to get fancy-shmancy you could put a SPDT switch and wire it such that you can draw from battery 1 in one position, or battery 2 in the other.

 

[ttmott]

The only issue is the battery life will suffer greatly as batteries in series will not equalize. The pre 2006 SR 550DB's are 24 volt boats in which the 12 volt systems operate from one of the batteries which are in series to get the 24 volts; similar to what you want to do. They have a singular 24 volt battery charger. You need an 12/24 Equalizer to both obtain the 12 volts and ensure the battery bank remains balanced.
Vanner and Eaton among others make them.
https://www.invertersupply.com/index.php?main_page=product_info&products_id=29563

https://www.eaton.com/Eaton/Product...alizers/Series21030BatteryEqualizer/index.htm