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UBS on battery


liamstears

Question

Decided to go the UBS route for 2 door contact sensors and a temperature sensor as it's much cheaper this way but 1 problem I see in the future is that if I want to use the door contact sensors in my alarm and I have a powercut (everything else is either battery or on a battery backup)

 

What I'm wondering is if it's possible to run the UBS on battery?

 

I would think maximum usage would be 3-4 hours at any 1 time worse case scenario. If I run a 12v power supply could I use a 12v relay and just switch over to a 9v battery?

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On 8/8/2020 at 5:07 AM, liamstears said:

If I run a 12v power supply could I use a 12v relay and just switch over to a 9v battery?

 

So you want to make a UBS UPS?? ;-)

 

Yes, The UBS will work on 9v. And yes, you could easily make a device to switchover the power using a SPDT  relay. Run the 12v power to the relay coil. Connect the normally open contact to +12v power, and the normally closed contact to +9v battery. The common relay leg connects to the + power in of the UBS. The - power out on UBS connects to ground of the power supply and ground of the battery.

 

Personally,  I have separated alarm and automation functions, leaving security to a dedicated security controller. 

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  • On 8/9/2020 at 6:44 AM, Tim__ said:

     

    So you want to make a UBS UPS?? ;-)

     

    Yes, The UBS will work on 9v. And yes, you could easily make a device to switchover the power using a SPDT  relay. Run the 12v power to the relay coil. Connect the normally open contact to +12v power, and the normally closed contact to +9v battery. The common relay leg connects to the + power in of the UBS. The - power out on UBS connects to ground of the power supply and ground of the battery.

     

    Personally,  I have separated alarm and automation functions, leaving security to a dedicated security controller. 

     

    Thank you Tim

     

    I decided to just go ahead and do it and so far it seems to function perfectly

     

    Not too sure how long the battery will last and also the 2 relays for the sensors are 12v relays so not sure how long they will stay active/working on a 9v battery but for now it's functional

     

    Long term I think I will look into an alternative battery, maybe something that can deliver 12-14 volts

     

    Decided to use a standard UK electrical back box for mounting and have the temp sensor mounted externally to get an accurate temperature reading too

     

    EDIT: Just bought an 8x AAA battery holder, that will give me 12v, and should still fit inside the enclosure, it's overkill for a battery backup for when mains fails but i'd much rather have too much than not enough which I think will be the case for the 9v battery, plus I can put them in and forget about it, those batteries should easily just last the shelf life of AAA's so around 5 years

     

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    Edited by liamstears
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  • So made some slight modifications

     

    Swapped over to 8x AAA batteries now, these are not secured so they can easily be removed and replaced. Added a protection diode to each of the relays and added inline diodes to both battery and mains power inputs to protect them from any surges or reverse voltages from eachother.

     

    This should now run smooth with plenty of battery life for any power cuts, I am very happy with the result

     

     

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