# DC Bus for Solar Charge Controller Battery

I am just learning the set up for a back up power. I am just wondering whether the DC output from the charge controller or the battery can be used for multiple loads.

For example, I want to power my modem which has a rating of 0.5A, 12V and my laptop which is 19V, 3.4A. How am I suppose to get the power from the battery if there is only 1 line coming from the battery or the controller. I am also planning to make an LED panel light.

I am just confused on how to go about this. I hope you could help me with diagram or if ever I will be needing a circuit for a bus.

• Follow the link given in this answer. May 19, 2016 at 16:10

This is how to calculate how much power you need. You have two devices: a modem and a laptop. (0.5A)(12V) + (19V)(3.4A) = 70.6 W. So you will need to provide at least 71 W of power.

I'm wondering why you want to run the laptop from an external battery. Does the laptop not already have a battery?

Are you using a UPC that outputs AC 120V? It sounds like you want to power your devices directly from the charging circuit.

I would advise against this since the UPC is designed to output the standard 120 VAC. If you bypass it you will not have any current limiting fuse or circuit breaker in case of a short or overload.

• Thank you for the response. My laptop has a battery, but its not on prestine condition. It only last for an hour instead of 6hrs (what it used to be). I am thinking of using a UPS. But I don't know the rating for the UPS. I wanted to run these things from a back up battery set up since we are having intermitent supply of electricity.
– Dale
May 20, 2016 at 9:32