Redarc "Start assist"

[ova50]

I am doing my dual battery setup, and are using a Redarc SB1112.
I have most of the wiring in place and are wondering about the start assist.
Being a momentary switch I am assuming that it would not be wise to use this for an extended period as it may burn out the solarnoid.
Would my assumption be correct ??
Thanks

[Winnie]

The switch is just an override, it connects the batteries together regardless of voltage. Considering that when you are driving the solenoid is connected for hours at a time I would not worry about it. I did not put the switch in mine, if I ever have to start off the 2nd battery I have got jumper leads in the car. If you are using that switch you need to use much thicker cable and bigger fuses.

[Cuppa]

It’s just a means of jump starting off your aux battery. You can either use a momentary switch or touching the wire to earth when wanting to jump start will achieve the same thing. Having the switch saves needing very long arms or someone to assist.

Cuppa

[ova50]

The cable I am using is 4 gauge and 100amp circuit breakers.
I think I may leave the start assist inactive.
Will post the pics when I get it finished.
Thanks Guys, appreciated.

[BigRAWesty]

The switch is just an override, it connects the batteries together regardless of voltage. Considering that when you are driving the solenoid is connected for hours at a time I would not worry about it. I did not put the switch in mine, if I ever have to start off the 2nd battery I have got jumper leads in the car. If you are using that switch you need to use much thicker cable and bigger fuses.

You gotta remember change is usually 90-110A, depending on size of alternator. Cranking a diesel can reach 4 times that.
So most electrical stuff like these have a Max burst for X seconds. The red arc isolator is 200A I think, but can handle 500 for 5 seconds (from memory)

The biggest thing is wire size. If you intend On using the second battery as a back up starter the normal 6mm twin core ain't going to cut the mustard. You need to atleast match the size that goes to your starter motor..
I've used 26mm2 welding cable.. Over kill?? sure, but cheap and it's one thing I know will work, and work safely..

[Yendor]

The switch is just an override, it connects the batteries together regardless of voltage. Considering that when you are driving the solenoid is connected for hours at a time I would not worry about it. I did not put the switch in mine, if I ever have to start off the 2nd battery I have got jumper leads in the car. If you are using that switch you need to use much thicker cable and bigger fuses.

Very good post mate.

[Yendor]

You gotta remember change is usually 90-110A, depending on size of alternator. Cranking a diesel can reach 4 times that.
So most electrical stuff like these have a Max burst for X seconds. The red arc isolator is 200A I think, but can handle 500 for 5 seconds (from memory)

The biggest thing is wire size. If you intend On using the second battery as a back up starter the normal 6mm twin core ain't going to cut the mustard. You need to atleast match the size that goes to your starter motor..
I've used 26mm2 welding cable.. Over kill?? sure, but cheap and it's one thing I know will work, and work safely..

There is no way on earth you would have 90-110A running through the dual battery isolator when charging from the alternator.

The override function is just a sales pitch. If you need to use it once that's an error, if you need to use it more often there's something wrong with your setup.

You would be better off investing the money is a good set of jumper leads then battery cables linking your isolator to your second battery.

[BigRAWesty]

There is no way on earth you would have 90-110A running through the dual battery isolator when charging from the alternator.

Why wouldn't there be close to that if charging a flat battery on an older car with no fancy gizmos, just an isolator??

The override function is just a sales pitch. If you need to use it once that's an error, if you need to use it more often there's something wrong with your setup.

You would be better off investing the money is a good set of jumper leads then battery cables linking your isolator to your second battery.

Why is it a sales pitch?? The units can handle it so why not have to option?
My battery currently is shot, so starting of my second. I'll be changing it when I gets back on the road, but when our out Bush, and your battery is shot, and your leads are right at the bottom of the draws, Its a good option. And it's usually free..

Not being disrespectfull, your a knowledgeable bloke, just asking why

[Cuppa]

re. welding cable.
I have used welding cable to carry the output from roof mounted solar panels on our bus. It is a relatively cost effective solution & having fine strands of copper it is also relatively flexible. However for a long term installation attention needs to be paid to sealing the ends of the cable, as the finer strands can tend to ‘wick’ moisture along the cable, eventually resulting in oxidation & resistance within the cable. more of an issue with solar where every volt counts, but good practice for any set up.

Yendor’s post got me thinking, & I think he’s right about good jumper leads being a more economic & flexible investment than heavy cables between the batteries. That said Westy’s comment about having a heavy gauge cable between starter & aux is also reasonable, especially if the aux is not convenient to get at with jumper cables & essential if there is the possibility of using the override for jump starts. I guess the point is to avoid the need for jump starts in the first place. The dual battery setup I removed from my vehicle to Telstra standards used 35mm2. A similar but 24v setup in my bus also has 35mm2 (but this utilises a SBI24D (two way) & the heavier gauge helps minimise voltage drop for the solar input.
Only time I have ever joined the batteries together using the manual override of the SBI in the bus was when we had a flat starter resulting from the alternator karking it, but I was glad I had the heavy cable on that occasion. Given the positioning of the battery banks relative to each other a set of jumper leads would have been a real pain & carried higher risk of shorting against the vehicle body.
Using 70mm2 between the pod batteries & the under bonnet cranker in the Patrol allowed for winching or jump starting at the flick of a switch without needing to access the pod bank which would be a hassle.

[Yendor]

Why wouldn't there be close to that if charging a flat battery on an older car with no fancy gizmos, just an isolator??



Why is it a sales pitch?? The units can handle it so why not have to option?
My battery currently is shot, so starting of my second. I'll be changing it when I gets back on the road, but when our out Bush, and your battery is shot, and your leads are right at the bottom of the draws, Its a good option. And it's usually free..

Not being disrespectfull, your a knowledgeable bloke, just asking why

Are you for real?? You are posting like you know.

An older vehicle would be lucky to have a 60A alternator.

A GU has a 100-110 amp maximum output alternator fitted. So assuming the alternator ignores the electrical demands of the vehicle and trying to charge the cranking battery.

You are saying it will pump 90 amps into the second battery?. Wouldn't this demand drop the voltage to below threshold of the VSR anyway? Have you tried pumping 90 amps into a battery?

Why would you go out bush with a shot main battery?????? I would recommend you have your jumper leads sitting on the passengers front floor then.

BTW......It's a sales pitch because it's not really needed......you are better off haveing a good set of jumper leads that you can jump start from another vehicle if needed.