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Is it possible to connect 3 sealed lead acid batteries in both parallel and series at the same time like in the diagram below?

enter image description here

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    \$\begingroup\$ Note that your 12v and 36v wires are shorted together. Obviously, this cannot work. \$\endgroup\$ – Barry Nov 14 '16 at 0:09
  • \$\begingroup\$ @Optionparty the answer editor on this website does have a schematic editor \$\endgroup\$ – Marcus Müller Nov 14 '16 at 0:43
  • \$\begingroup\$ Click on the schematic editor button above the answer field. \$\endgroup\$ – Marcus Müller Nov 14 '16 at 0:56
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    \$\begingroup\$ @MarcusMüller Thank you so very much. I think I will be able to contribute more often. \$\endgroup\$ – Optionparty Nov 14 '16 at 2:36
  • \$\begingroup\$ Yes it is possible. However, you might not like the results. \$\endgroup\$ – David Jan 11 '19 at 4:31
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A 4P2T could switch the 3 batteries from (series 36v) to (parallel 12v).

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ thank you so much! out of curiosity, is it possible to use dip-switch instead of 4P2T switch? \$\endgroup\$ – harayz Nov 14 '16 at 12:46
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    \$\begingroup\$ @harayz the thing about the 4P2T switch is that they switch simultaneously, so that there's no chance you accidentally short something. And no, dip switches are for milliamperes, so you certainly won't charge batteries through them. \$\endgroup\$ – Marcus Müller Nov 14 '16 at 13:08
  • \$\begingroup\$ A diode in series with a 12v charger, in parallel with the output, would provide automatic charging when the 4P2T is in the 12v position and become a blocking diode when the 4P2T is in the 36v position. \$\endgroup\$ – Optionparty Nov 14 '16 at 14:03
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NO. If you look closely at your diagram, you will see that your green links form a DEAD SHORT from GND to 12V. Clearly not viable at all. Don't even think about it.

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To achieve this you would to wire all the connections back to a couple of relays and just switch between them as needed. You'd need to be careful to prevent energising both relays simultaneously, achieving a dead short as pointed out in a previous answer. To do this you could wire the signal to Coil 1 through a NC (Normally Closed) contact on the opposing relay. When you energise Coil 2, the NC contact will open, preventing current travelling to Coil 1.

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