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Can a battery charger keep a battery charged while that battery is powering an inverter?

Written By: Generator Man - Jan• 31•13

Question by Jon: Can a battery charger keep a battery charged while that battery is powering an inverter?
I am using a 6 amp battery charger to charge a 70 aH marine deep cycle battery which is connected to a 750 watt inverter powering a 700 watt (6 amp) vacuum. Would the battery stay charged while it’s in use?

BTW- The battery has 2 positive terminals and 2 negative terminals. The charger is connected to the larger set and the inverter is connected to the smaller.

Best answer:

Answer by classicsat
In that case no.

The 6A charger is 6A on the output. 700W at 12V is nearly 60 amps. It would just discharge the battery 10% slower.

Also, a 750W inverter may not run a 700W vacuum. and a 70Ah battery thin for a 60A load.

You might get less than an hour practical power, if it works. If you have real AC power, run the vacuum from that. For practically portable, get a petrol powered generator.

For a true standby supply ( not needed for a vacuum), get at least a 120A or more power supply/charger, 200Ah or more batteries, and a 1KW or more inverter,o or just the batteries and a standby inverter with a modest sized charger.

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  1. Desert Dust says:

    I have to ask why not just plug the vacuum into the outlet the charger is plugged into and totally skip the charger/ inverter thing? You are going around your elbow to get to your big toe.

  2. lare says:

    the answer is no. the terminal voltage on the charger has to be about 15 to 16 volts to induce a charge in the battery. the battery in operation drops down to about 12.5 volts or less. in order for a charger to get the terminal voltage up to 15 volts, it would have to be at least a 65 amp charger so it could pull the entire load of the inverter and battery. also the inverter, designed to operate at 12 volts, might fail if fed 16 volts from a charging battery.

  3. Sella says:

    Don’t do that,it can damage your battery or laptop.

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