# Load resistor for 12V battery

#### rajansn24

Oct 9, 2016
10
Hi,

I am having Sealed Lead-Acid Rechargeable battery with capacity of 12V / 7.5Ah.

I want to connect a load resistor across the battery for discharging.

The load resistor should be designed in such a way that it should take maximum of 1 Amp current from the battery.

So what is the exact load resistor value and how many watts required for 1 Amp current consumption?

Pls tell me the suggestion.

Oct 5, 2014
6,341
12w light bulb

#### Audioguru

Sep 24, 2016
3,653
Use Ohm's Law to calculate the value and power rating of the resistor.
But the battery voltage runs down as it is discharging so pick an average voltage of about 13V. 13V/1A= 13 ohms which is not a standard value, use 12 ohms and the average current will be 13V/12 ohms= 1.0833A. When the battery is fully charged at about 14V then the heating power in the resistor will be 14V squared/12 ohms= 16.3W so use a resistor rated for 20W or 25W and keep it in free air, not enclosed. It will get very hot.

Why do you want to discharge the battery?

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