## Two power supplies in parallel - what would the resultant power, voltage & current be

I am working with RTGs right now. I want to hook two of them up in parallel to charge a battery. Basically, the setup I had planned is like this:

I am trying to determine the power, current and voltage that would be given to the battery.
I have been trying to research and know about Kirkhoff's laws. However, do they work in this situation when the RTGs have their own voltage and current?

For reference, the RTGs both have a current of 0.248A and a voltage of 13.89V.

How do I calculate what is given to the battery?

Thanks!

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 Recognitions: Homework Help Yeah - kirkoffs laws work for this situation ... one loop has two PSUs in it and the battery is a load ... you'd normally model the real components as an ideal source with a series load. A totally dead battery starts out as a load and gradually becomes a source as it charges.
 Recognitions: Gold Member Learned about RTGs for the first time. Wow,they are amazing. In your case, they produce roughly 13.89*0.248 = 3.44 watts each, supposedly for decades. Just curious, would you mind telling how much does those thing cost? As for your question, If everything is straight forward, the current given to the battery would be twice. What is the AH rating of your battery?

## Two power supplies in parallel - what would the resultant power, voltage & current be

I assume the current is short circuit current which implies an internal resistance of 56 ohms. This means that as the battery becomes charged, it will continue to charge slower and slower. If the internal resistance is a constant the formula would look like this.

charging current = (Vrtg - Vbatt) / 56

For 2 RTGs the current would be approximately double.

 Considering the nature of the sources you should not use your simple parallel connection, without proper control and sharing circuitry.
 Check the charge capacity of your battery. Like how much Ampere-hour it can hold. The battery will probably behave like a capacitor being charged, with some internal resistance.