Redarc dual battery set-up ... anyone have one ?

[rumy1]

I have just set up my dual batteries using Redarc smart solenoid. When the power is off, the red light stays on ... it says in the instructions that this may happen but how many people does this happen to ?
If you have a Redarc setup does your red light stay on after your power is off ?
I have double checked the wiring and all appears fine.
I have run my negative from my aux battery back to the start battery negative .... this should be fine ? This is the only doubt I have but pretty sure it would be ok.

[EDNA]

I have the Redarc system in my car and the light stays on for a while. From memory it is quite normal.

[goddy100]

I have one in my car as well. From memory, what happens is the unit looks at the primary battery voltage, and if it drops below a certain level (about 12.5V) then it will turn off the relay, making the little red light go out. The idea is that you would need to start the motor and run the alternator to get the battery back up to the correct voltage, enabling the relay to close again. To test this, just put a load on the primary battery (such as a spotlight) and you should see it go out as even a small load can give enough of a voltage drop. Need to have the motor off though to see this. The negative wires are fine, they should be linked together at some point, or the system would not charge at all. In a car they are done through earthing on the chassis, not a good idea in a tinny, impossible in fibreglass

goddy

[Jru29]

I have a Redarc in my car too. Yep the red light stays on after the vehicle is turned off. It's not uncommon for me to hear the solenoid come in after starting the vehicle and have it running for 15-30 seconds or so. It's quite a solid "thunk". As already stated the microprocessor tests the system voltage on the main battery side and will open the circuit if it sees the voltage going low. If it sees the voltage is high enough (indicating the main battery is nearly fully charged) then it will close the solenoid allowing the secondary battery to then be charged up. (I cant remember the exact voltages but it will be on the website/instructions)

As a side note I've heard that when using a system that parallels up batteries (Like the redarc) its good practice to have identical batteries from the same manufacturer. The reason for this is that batteries from different manufacturers or of different plates sizes/numbers may have differing internal resistances. Basic ohms law says that current will always take the easiest path, so most of the current will go through the battery that has the lowest internal resistance, the battery that has the higher resistance will still get charged but at a slower rate.

Hope this makes sense...

Jru

[driveon]

Hi jru29, this is one of many myths about 12 volt systems, you can use any type of battery with any other type of battery.

Once the alternator is running, it will charge anything that is connected to the electrical system and it won’t know what it’s charge.

Point is if you have two identical batteries and one is only used for cranking and is left at near full charged state and the other battery is used to power all your accessories while the motor is off, after a few hours these two identical batteries are going to have much different states of charge so it’s no deferent between this scenario and having two different types of batteries.

Cheers.

[rumy1]

At the moment I have all the positive leads to my cranking battery because that how it was till I put my second battery in. I have been told that all the accessories wires that run to the main battery should now run to the aux battery ... is this correct ?

[driveon]

Hi rumy1, there’s a simple rule of thumb, any thing you need to use while the motor is running, connect to the cranking battery and anything you need to use while the motor is off, connect to the Auxiliary battery.

Cheers.

[rumy1]

Hi rumy1, there’s a simple rule of thumb, any thing you need to use while the motor is running, connect to the cranking battery and anything you need to use while the motor is off, connect to the Auxiliary battery.

How simple is it to follow these instructions .... when you think of it like that then I can't go wrong !!!!

Thanks driveon !

[fairpractice]

can't see the logic in driveon's rule of thumb..The point of isolating the cranking battery is to heve it fully charged for starting. run all accessories of the "house" battery preferably a deep cycle..or you've wasted your $$ on the redarc.

[rumy1]

That's what I have done --- ran all the accessories to the 2nd battery. All I have on the main battrery now is the main power in and the positive joining to the Redarc and the trim & tilt.

Thanks fellas for all the replies !!!

[driveon]

can't see the logic in driveon's rule of thumb..The point of isolating the cranking battery is to heve it fully charged for starting. run all accessories of the "house" battery preferably a deep cycle..or you've wasted your $$ on the redarc.

Hi fairpractice, the importance of this type of set up is to have anything that is going to be using power after the motor is off, like the CB, fridge and so on, should be on the auxiliary battery so these devices won’t flatten the cranking battery.

As for anything you only use while the motor is running, there is no reason to move them from the cranking battery to the auxiliary battery because they don’t use any power while the motor is off and as such won’t flatten the battery so why make work for yourself if you don’t need to.

Cheers.

[rumy1]

Hi fairpractice, the importance of this type of set up is to have anything that is going to be using power after the motor is off, like the CB, fridge and so on, should be on the auxiliary battery so these devices won’t flatten the cranking battery.

As for anything you only use while the motor is running, there is no reason to move them from the cranking battery to the auxiliary battery because they don’t use any power while the motor is off and as such won’t flatten the battery so why make work for yourself if you don’t need to.

Cheers.

Makes sense to me !!

[JimHovo]

What about sounder and live bait pump? I use them in both situations(with motor on and off)

[driveon]

Hi JimHovo, the sounder and live bait pump are just like the CB and fridge, if they need power once the motor is turned off then they should be connected to the auxiliary battery.

Cheers.