300A electronic battery switch?

To switch between two 12V batteries I need a 300A switch that can be controlled by the Arduino.

Does anyone know an electrically controllable battery switch without mechanical parts?

Thanks in advance.

A MOSFET? An extremely beefy MOSFET...

Do you need to switch 300A or carry 300A? Most mechanical battery switches are only rated to carry high current, not to switch on or off with that current flowing.

Maybe a bank of parallel MOSFETs.


This thread is a continuation of anther thread:


It has been opened here because it is no longer related to motors.

The switch needs to carry up to 300A, but the electronic control should just be 5V, 9V or 12V small scale.

Something like this, just as a switch(SPDT) instead of a contactor(SPST):

20A-350A Gigavac Contactor w/ 12V DC Coil

I take it that is a YES to the question :

Do you need to SWITCH 300A UNDER POWER (as opposed to switch a battery that when that powers a 300A load that is NOT powered up at the time it is switched)

Case A: LOAD (300A) OFF B: LOAD (300A) ON

Which are you inquiring about ?

Yes, connected (under power) when switching.

I think we're moving into IGBT territory here...

...How much money do you have to spend?

Even IGBTs are not usually switched with the maximum load. What you are asking is going to be expensive.

Can 4 @ 130 Amp Mosfets in Parallel ( $12.00 ) be balanced so that no one Mosfet handles too much?


Highly Inductive Load ?

If purely resistive load then polarity does not matter? Wire Batteries in series and switch the load via H-bridge and common between batteries?

200 Amp, 400 Amp & 600 Amp H-Bridge from PowerX

PowerX .

and a HEATSINK (AIR COOLED , lower left corner, maybe fans too)

Well, two 300A remote GIGAVAC contactors would make 2*89,30 USD. That is acceptable.

I was just hoping to find a remote battery switch to do the job in one single piece...

Thanks for your input.

cr0sh: I think we're moving into IGBT territory here...

...How much money do you have to spend?

Not IGBT, that would be very bad indeed. IGBT's have a fixed, large, voltage drop (1.6 to 2.5V is typical), they are designed for high voltage high power. MOSFETs completely rule low voltage high power. You would not consider IGBTs till about 50 to 100V and up. Most IGBTs have one of two voltage ratings, 600V or 1200V. That's a clue.

Lets see, 1.6V drop at 300A is 480W dissipation, quite mind-blowingly poor for a contactor!