Battery Isolater Question

[That One Guy]

This is taken from Sure Power's website.

4. Start Signal input
This is the input for engine start signal override. When power is applied to this input, the relay will close if the Aux. Battery is no less than 0.85 Volts below the Main battery.

The manual says to use a momentary switch, but it seems smarter to use a continuous switch(or whatever the normal ones are called). Maybe I'm missing the point of what this feature is for. Can anyone explain?

 

[97discosd]

Despite obvious reasons why you should use a momentary switch the best answer I have for you is if you want what ever this switch controls to work get a momentary normally open switch like the manual says

 

[That One Guy]

Well obviously those reasons aren't obvious to me. Care to share a little more of what I am ignorant to?

 

[97discosd]

Assume battery voltage is 12 volts. 12v is sent to switch. Once you push the momentary switch it allows 12v to pass completing the circuit, once you let go circuit is open. If you had a normal toggle switch when the 12v will constantly complete the circuit. Your home pc power button is an example of an mom switch. Press once pc turns on/off, hold it and it will turn on and off untill you let go.

 

[dwh]

TOG,

Since I have no idea what unit you are talking about, I need more information...

What is the link to the Sure Power manual?

 

[MakersTeleMark]

Can't you just wire it to the start wire coming from your column?

 

[That One Guy]

97disco, thank you, but that is a similar answer to the one I got from my step dad. I understand the difference between the two types of switches, but don't know why you would only want to connect the circuit momentarily. That's what I meant by "Maybe I'm missing the point of what this feature is for." The way I see it, you would only want to connect the circuit to use the main battery if the aux batteries are too low to supply power(assuming the engine isnt running, so the batts aren't charging).


Here you are, dwh.
http://www.fourwheelcampers.com/batteryseparator1315.pdf


Makers; yes, that is one of the options the manual includes, but I always like having options if need be.

 

[dwh]

The momentary is in case you run the engine battery too low to start the truck and need to momentarily connect the two for a quick jump-start off the aux battery.

You probably wouldn't ever want to tie them for a long period of time if one is significantly lower than the other (unless there is some charging going on), so a normal switch wouldn't be appropriate.

Seems to me there was a post here within the last week or two about a recall on those units. Something about starting fires.


EDIT: Hrmmm...

I think I see what might be throwing you off. Yes, you could use a normal switch instead of wiring it to the ignition or using a momentary. Theoretically.

The flaw in the theory is that the electromagnet in the solenoid itself draws some power (around an amp). So if you used a normal switch and just left it on, it would be drawing power (for the electromagnet) whenever the battery's voltages are high enough for it to energize the solenoid and tie them together. That would eventually drain them both to the point where it would disconnect them (de-energize the solenoid), leaving both batteries in a somewhat discharged state.

Repeatedly doing that wouldn't be healthy for the batteries over the long term.

 

[That One Guy]

Oh! Now I understand! I was seeing it backwards, thinking it was for using the main battery to supplement the aux batts. Yes, I saw that recall too, but am not concerned. It was only a part recall and not every one of them, so I'll try it and see how it goes. Thanks a lot for clearing that up!