Surepower smart solenoid

Yep,

They rely on the power from the main battery to switch the relay.

You'd be unlikely to get it down to 3 volts?

You could always whack a manual battery switch and addition cabling to connect them. There's probably some good reason why you shouldn't do that though. I reckon someone will tell us before the nights out.

*any* solenoid will need volts to close the contacts. if the main doesn't have it, get it off the the aux, i.e., wire switch to the aux instead.

Hi Footloose,

The 3 volts has nothing to do with your main battery. That terminal is for the "Optional Auxiliary Start Connection", and it can get the 3V from anywhere you like. Supplying 3V to that terminal will only force it to parallel so that you can get additional starting power by having both batteries paralleled. My opinion is that you should only force it to parallel is if your aux battery is in good condition and is a good cranking battery because if your main is down on power (which is the whole reason you are using the start assist feature), then forcing them to parallel will equalise the batteries as soon as you parallel them.

It does not anywhere say "there must be 3V in the start kitty for it to work". It only says "the start signal must be able to produce atleast 3V". The 'start signal' can come from anywhere - it's only to force it to parallel.

In my car, I have only ever once forced it to parallel by supplying atleast 3V to that terminal and that was when I went on holidays (leaving my car to sit for 2 months) and the main battery went a little low because it sat idle and the immobiliser would have drained it a little. Paralleling with my aux (which is an idential batt) gave me enough to start the car.

Now, having it permanently wired to the ignitition means that the start signal terminal will receive 12V from the start signal when you turn the key (at the position of when the starter turns over). This means that every time you start the car you are supplying the Smart Solenoid 12V and it will parallel the batteries. Each time you start the car. You mention you have a switch, which means that unless you flick the switch, you will not be forcing it to parallel. (Obviously depending on which way you flick it!)

Remember that it doesn't care where it gets the 'optional' 3V...that can be via a switch, a start signal. It can even come from a 9V battery, I imagine. Fact is, it only needs atleast 3 volts. Can come from Aux or main - up to you.

It does NOT need 3V in the main kitty. If there was only 3V in the main kitty, then the batteries would be seperated (as they seperate at 12.4 volts or something) and your aux and main would drain independantly. And if there was only 3V in the main, you should find out why it only has 3V!!!!! That would be strange. Leaving your lights on would drain it, but like I said - you aux would not drain in this situation.

The unit works very well - and if you mean by "dumb" solenoid a "normal" solenoid, then I'd doubt you'd be better off with it. I'm not an expert in automotive electronics, but I know how the Smart Solenoid works...I think that with modern EFI cars with computers, a normal solenoid will not protect against voltage spikes.

What pavo said. :-)