# Higher current output from transformer?

I just received a battery charger in the mail, but I forgot to purchase the power supply. I was wondering if it was possible to use a transformer from an old lamp to supply the charger instead:

The charger takes 11-17 volts as input, 50 W as max charge and charge current of 0.1A to 6A [Link]

The transformer specification are:

My textbook says that the current in the primary circuit is related to the current in the secondary by:

$$I_{1rms} = \frac{N_2}{N_1} I_{2rms}$$

So N2/N1 must be: $$V_{2rms} = \frac{N2}{N1} V_{1rms} => \frac{N_2}{N_1} = \frac{V_{2rms}}{V_{1rms}} = \frac{12V}{230V} = \frac{6}{115}$$

Is it possible to increase the load resistance so that I can draw 6A (the maximum of the charger) through the transformer?

$$I_{1rms} = \frac{6}{115} 6A = 0.31 A$$