2nd battery on/off

[NJV6]

Does anyone run a relay or anything with the ability to turn off the 2nd battery so there is no drain? I have USB outlets which have a blue glow on them all the time and the volt meter.

I am considering putting a 50amp relay or solinoid on a switch that I can turn the system off without having to disconnect the battery. Anyone see issues with that?

[Greg Grey Grumbly]

2nd Battery On Off

I just installed a dual battery in my PS

To isolate the rear I installed a 70 amp Narva relay near the start battery.

The relay can be energised from any ignition ‘on’ source, power from the main battery is fed in and the aux battery power out. So whenever ignition is off, no power to the rear battery or for that matter,rear towbar mounted Anderson plug. Repco run the relays for about $25.00.

Greg

[NJV6]

Thanks, That to me sounds like you are using a relay as an isolator where some use a VSR and some use dc/dc chargers.

I have all that but want to know how do others turn the second battery system off after the battery or just leave it always on.

[old Jack]

I have all that but want to know how do others turn the second battery system off after the battery or just leave it always on.

If you isolate the aux battery at the charge input end then you are not getting a recharge voltage to top up the battery every time you drive it. Even with the fridge turned off there will still be drain on your battery from the power consumed by electronic controllers and natural discharge of the battery, this will only be milliamperes but over an extended period will drain the battery.

OJ.

[Merts]

I just installed a dual battery in my PS

To isolate the rear I installed a 70 amp Narva relay near the start battery.

The relay can be energised from any ignition ‘on’ source, power from the main battery is fed in and the aux battery power out. So whenever ignition is off, no power to the rear battery or for that matter,rear towbar mounted Anderson plug. Repco run the relays for about $25.00.

Greg

An isolator between the main battery and the aux won't isolate any devices which are connected to the aux battery. It won't do what the OP is asking about.

[Dicko1]

My 2 aux batteries in the rear tub have a dc/dc charger, engel fridge connected all the time, several USB sockets with the blue lights and a 12 volt display. Never had an issue with battery drain as it is minimal and as soon as you start your car your battery is charging anyway.. Keep it simple...no need for the relay...just something else to fail at an inopportune time.

[Kingbrown]

To help you decide whether you need to isolate the parasitic loads from your auxillary battery, you should establish what the load is and for how long the battery will be sitting idle (without being charged).

For instance, if your're going overseas for a month and you have three connected devices that draw 15mA each, then:

3 x 0.015A x 24hrs/day x 30 days = 32Ah.

As mentioned previously, an extra relay and associated wiring would add another level of complexity and a point of potential failure to your system.

[NJV6]

Thank you Dicko and Kingbrown, you have answered my question exactly, the system stays on and the very small draw downs are not going to affect anything. At most my vehicle is parked for 2 weeks and any longer I could pull the fuse at the battery.


Cheers.