#153717  by Andrew and Debbie
 Sun Aug 04, 2019 11:02 am
How do I work out how many watts of generator capacity I will need to power my 40 amp 12 volt mains powered battery charger? Just wondering if the 900 watt inverter generator on special at Supercheap Auto will do the job.

https://www.supercheapauto.co.nz/p/tool ... 53026.html

 #153718  by Paul
 Sun Aug 04, 2019 11:07 am
Hi , Watts = Volts x Current. Ie 12volts x 40 amps = 480 watts. So the 900 watt inverter generator will be fine. Make sure it is a pure sine wave one.Paul
 #153719  by Nut17
 Sun Aug 04, 2019 11:27 am
The Charger will be producing at least 14.00 volts and there will also be a percentage of loss - So I estimate that you will be around 600 - 650 watts, so still within the capacity of your inverter generator. For a couple of years I powered a 50 Amp battery charger in the caravan using a 1200 watt PSW inverter powered by the tow wagon. The inverter was drawing just on 80 amps at 13 volts !! - Close to the maximum of the inverter. I now use a 2000 w inverter to do the same job.
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