Where to install split charge solenoid

[Brett]

Finally, I'm getting round to fitting my third battery & split charge system.

Whereabouts would you recommend installing the solenoid (Cole Hersee type) I know it's got to go as close as possible to the main battery, just looking for ideas as there isn't a lot of room around there for installation.

 

[Chris]

Mine is in the boot where the subwoofer thing was - you can see it through the speaker grille. The instructions say that it should be as close to battery as possible - but mine is wired with 50mm cable and trust me it couldn't work any better if I tried. It's absolutely brilliant. I have the Victron Cyrix 400 amp unit with 2 mega fuses in line

Chris

 

[Paul]

Where is your 3rd battery?

 

[Chris]

Sorry Paul - was that a question for me or OP?

Mine is in the boot.

Chris

 

[Paul]

For Brett, i put mine in the boot too.

 

[Chris]

OK, cheers Paul. Gotcha

My decision, for reference was driven by the fact that not all of these chargers are waterproof. Almost no drop over that cable so where's the problem? Bit tricky putting it in the bonnet. Stuck it in the boot.

Chris

 

[Paul]

i did mine like this, would just substitute isolator for relay

 

[Brett]

3rd battery will live in the boot, I haven't got one of those fancy cyrix chargers like you fellas though! Just a simple allbright style solenoid.

 

[Chris]

Mine is other side.

So Brett, how will you control the on and offness of the relay? There needs to be either a switch or a voltage sensing gizmo somewhere. If it's just a relay controlled by some other wizardry then it doesn't matter where you put it. It's usually the sensitivity of the voltage gizmo that dictates that it's near to the battery so that it gets a true reading of the alternator output. But the relay set up that you describe is just a switch. You can put that anywhere.

Without voltage sensing, say by using a manual switch, when you crank the engine (if you forget to flick the switch) you will be pulling from the third battery. Probably fine it it starts first flick, but if you need to crank, then you could be pulling major amps up the cable to the starter. Fine if its Armageddon cable like mine, but if you used thin stuff, you could easily fry it. So, best not rely on memory and have some auto switching in there. Which is much easier to fit nearer the main battery of course.

Chris

 

[Brett]

Chris, it is some other dark wizardry, the relay is a 250 amp continuous rated (intelligent ) type, under normal operation the relay links the batteries for charging & isolates them when discharging.

There is also a battery monitor which you install in the cab, which obviously indicates the state of the batteries & also allows you to link them all together in an emergency, e.g. flat main battery.

It's the T-max system which is basically a rip off of the IBS or National Luna system.

 

[Jon Wildsmith]

If the voltage sensing is done at the solenoid then you need to either have it as close to the main battery as possible, use very thick cables or accept that it won't behave quite as it should. If the voltage sensing is done via another wire on the control unit like an IBS then the solenoid position doesn't matter for the voltage sensing.

 

[Brett]

That's where I was intending to install it Jon, I was just looking for ideas from anyone eles who's done this as to where to fix it, to the battery tray, inner wing etc?