AC battery backup without ups possible?

  • Thread starter zefram12
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In summary, the conversation discusses a quote given by a local alarm company for connecting power to an alarm system. The setup includes a 30VA 16VAC transformer connected to a 7ah 12V battery. The alarm can run on AC power but also has a backup battery for when the mains are off. The concern is that there is no charger for the battery, potentially causing it to overcharge and become a fire hazard. The participants also mention the need for a rectifier to convert AC to DC for charging and the possibility that the alarm actually runs on 12V DC.
  • #1
zefram12
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Hi,

A local alarm company has given me a quote, and they want to connect the power to the alarm as follows:

The 30VA 16VAC transformer is connected to a 7ah 12V battery.

The battery apparently can run in AC mode, this was news for me.

The alarm requires AC power, and is connected in parallel with the battery.

They claim the alarm will run from the mains power if mains is on, but the battery will provide backup power when the mains are off.

What concerns me is there is no charger for the battery in the setup. I don't know about AC charging, but wouldn't this setup cause the battery to permanently overcharge? Potentially be a fire hazard?
 
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  • #2
The battery could have something to prevent overcharging, or have a sufficient voltage rating to stop charging at some point.
Just a guess, I don't know the devices.
 
  • #3
Ok, thanks for the response, I guessed that may be the case. The way I understand it the AC needs to be converted to DC for the battery to charge anyway.

I unfortunately only have the description of the items, not actual skus or model numbers.

Also, one would hope that their standard setup isn't something that could explode :-)
 
  • #4
I think they are oversimplifying things for you.
 
  • #5
Averagesupernova said:
I think they are oversimplifying things for you.

Agreed.
there has to be at minimum a rectifier on the output of the transformer to convert to DC
Then if its a standard 12V 7Ah sealed LA or gel battery, there's also likely to be overcharging prevention circuitry

cheers
Dave
 
Last edited:
  • #6
Willing to bet the alarm REALLY runs on 12V DC...but needs AC (via the transformer) for continuous operation - there is a small rectifier in there somewhere.
 
  • #7
I won't take that bet!
 

1. Is it possible to have an AC battery backup without using a UPS?

Yes, it is possible to have an AC battery backup without using a UPS. This can be achieved by using a DC-to-AC inverter and a battery. The inverter converts the DC power from the battery into AC power, providing the backup power supply.

2. How does an AC battery backup without a UPS work?

An AC battery backup without a UPS works by using a DC-to-AC inverter to convert the DC power from a battery into AC power. The AC power is then used to power devices during a power outage or when the main power source is unavailable.

3. What are the advantages of using an AC battery backup without a UPS?

There are several advantages to using an AC battery backup without a UPS. One advantage is cost savings, as a DC-to-AC inverter is typically less expensive than a UPS. Additionally, an AC battery backup without a UPS can provide longer backup power duration as the size of the battery can be customized.

4. Are there any disadvantages to using an AC battery backup without a UPS?

One potential disadvantage of using an AC battery backup without a UPS is that the inverter may not provide the same level of protection against power surges and spikes as a UPS. However, surge protectors can be used to mitigate this risk.

5. What type of devices can be powered by an AC battery backup without a UPS?

An AC battery backup without a UPS can power a wide range of devices, including household appliances, electronics, and medical equipment. However, it is important to properly size the battery and inverter to ensure they can handle the power requirements of the devices being powered.

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