question

christoff83 avatar image
christoff83 asked

Does a small battery backup require an ATS?

Hi all,

In my livingroom at home, I’m running a small battery backup for the TV, wifi and occasional laptop or other small device. The setup is: Phoenix Ve.Direct 12|375 standalone inverter, Blue Smart 12/15(3) AC charger and a 105 ah, semi-deep cycle lead acid battery.

Does this setup need an ATS (Automatic Transfer Switch) or can I permanently leave the charger in the wall socket connected to the battery, the inverter connected to the battery and the wifi + TV connected to the inverter?

Thanks

Phoenix Inverterbluesmart ip22transfer switch
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3 Answers
Alexandra avatar image
Alexandra answered ·

@christoff83

I had a similar setup but with a lithium. I left the charger plugged in permanently. It sorted itself out.

Just recently added a 75/15 with a 300W panel. Happy days. Wall charger doesn't really do anything now.

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christoff83 avatar image christoff83 commented ·

Thanks, appreciate it.

So, that means the load AND the battery will both draw power from the charger at the same time. If the charger is strong enough, it will power the load and charge the battery. If the battery is full, the charger will power the load. If the charger is switched off; or mains supply drops, then the load immediately draws power from the battery via the inverter.

Now that's all good and I'm happy with that. Here's my problem (or rather point of confusion): most modern chargers are "smart chargers" right? Like the Blue Smart. They have these special algorhythms with special charging stages, each stage with a very specific voltage and current - all designed to best manage the battery. Now, how does the smart charger get these special charge parameters to the battery with an active load? Does the load not interfere and basically void all these smart charge stages?

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Alexandra avatar image Alexandra ♦ christoff83 commented ·

@christoff83

The charger stays in bulk if plenty current is being drawn. Absorption is a charging stage where less amps are being used after the bulk stage is done. It will go to float after that. Shouldnhappen at least once a day when you go to sleep ;).

If you are using more than the 15A the charger can supply then you will draw your battery down. If the charger exceeds load, it will charge up the battery.

375VA is 30A draw from the battery. I assume you aren't running it full beans like that continuously. Mine has a fairly steady load of 100 to 120w. Laptop tv internet basically so a draw of about 8 or 9 amps continuously.

You set the battery chemistry and charged voltaged on the charger itself so it will handle the battery accordingly.

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marekp avatar image
marekp answered ·

@christoff83

If your system cannot feed power back to the grid, ATS is not necessary.

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Kevin Windrem avatar image
Kevin Windrem answered ·

Placing a lead-acid battery inside is not a good idea. During charging, the battery will expel hydrogen and oxygen and could be explosive. Also, sulfuric acid can be expelled which is corrosive to most things metal.

AGM is much safer as it does not outgas significant amounts. Lithium Iron Phosphate is even better.

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