Switching batteries in paraller/series

Hi all!

I decided to request help from you experts with this project: https://www.circuitlab.com/circuit/gkbp36/paraller_series-circuit-14_4_28_8v/

IDEA:

  • "OUTPUT1" should be either 14.4V (when only BAT1 connected / BAT1 & BAT2 in paraller) OR 28.8V when BAT1 and BAT2 are in series.

  • OUTPUT1's voltage should be switchable from 14.4V (one or two batteries connected) to 28.8V (two batteries connected)

  • "OUTPUT2" should always provide 14.4V

Questions:

a) How to wire the two batteries to get the values listed above?

b) Are my schottky rectifier diodes correctly located?

c) There's a 15A circuit breaker that is enough for the load but should there be an additional breaker for OUTPUT1?

by Nopsa
May 29, 2013

"a) How to wire the two batteries to get the values listed above?"

Your circuit looks to be wired to do what you want. Though the function of SW1 is unclear and your V(BAT2) = 0 is possibly an error (as drawn 130601)

If you learn to drive CL, you can simulate it and see for yourself.

:)

"b) Are my schottky rectifier diodes correctly located?"

Depends what you want them to do doesn't it? You haven't specified.

"c) There's a 15A circuit breaker that is enough for the load but should there be an additional breaker for OUTPUT1?"

That depends on the battery capacity and what maximum load current you need to be able to supply and/or fault current you need to protect against. Again, you haven't specified.

About simulating with switches:

How to simulate opening or closing a switch so that you don’t have to go back and forth between build and simulate modes to see the circuit operation in both states.

How do you model or display a power jack of the sort that when plugging into this jack switches or reroutes a voltage?

There are at least 3 ways to do this.

i) You can do sims with swept parameters where the swept parameter is the switch state.

ii) Or use the time controlled switch.

iii) Or use the voltage controlled switch (driven by a suitable pulse source).

This thread gives some more information about these techniques:

https://www.circuitlab.com/forums/modeling-and-simulation/topic/v476bfdj/is-there-a-model-for-a-male-power-jack/

A simple 'ON if the power is plugged in or OFF if it is not' jack can be represented by a normally open (SPST no) switch.

It could equally be represented by a normally closed (SPST nc) switch if the power is normally plugged in.

The sort of jack that physically reconnects between say an internal battery and an external supply can be represented by a changeover switch (SPDT).

i) You can use any of the CL switches and draw a box round it with some text to explain what it represents;

ii) if you use the 'static' switches as shown in:

https://www.circuitlab.com/circuit/2xpye8/

then in one run, you can simulate the circuit once with the switch open and once with the switch closed.

However, note that if you use the static changeover switches like the SPDT shown in:

https://www.circuitlab.com/circuit/954hs2/

then you cannot see the results of the A switch closed (B open) and then the B switch closed (A open) in one simulation run because you cannot select the switch state as a sweepable parameter. You have to do two simulation runs which is a bit naff.

iii) if you use the time controlled SPDT switch then you can simulate how the circuit behaves with the switch in the before the changeover state and then in the after the changeover state;

iv) you can use two voltage controlled switches driven by a PWS() or PWSREPEAT() source to make an SPDT switch which you can switch any time you like:

https://www.circuitlab.com/circuit/d66f6n/

(see:

https://www.circuitlab.com/docs/expressions/

and

https://www.circuitlab.com/docs/circuit-elements/#behavioralsources

for more about the PWS() source)

by signality
June 01, 2013

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