Setting up charging station for mobile battery use

[SunEagle]

I just realized the switch I ordered is 12V and the panel is 30V, 9A. How about this? I can trip when I remove battery #2 out and reset after Battery #1 is connected I am good with a 30Amp breaker since my CC is rated for 30A and I have 10AWG wire. The battery fuse of course will be smaller 10amp

Breaker.JPG

That device should be able to "break" a DC circuit and not fry or arc. I use one on my small solar/battery system. Just make sure your wires are rated for that switch.

[cbird02]

while the amps may be low it is the voltage level that will determine the length of the arc. That switch may handle a few changes but the contacts will pit and deform each time there is an arc.

I just realized the switch I ordered is 12V and the panel is 30V, 9A. How about this? I can trip when I remove battery #2 out and reset after Battery #1 is connected I am good with a 30Amp breaker since my CC is rated for 30A and I have 10AWG wire. The battery fuse of course will be smaller 10amp

Breaker.JPG

[cbird02]

How long does it take to fry a charge controller ? Half a second ? 3 minutes ? Your switch is likely a "break before make" so there's going to be a fraction of a second with no battery attached to the controller ? Will it reboot? Fry ? Shut down and hang ?

The order will always be Panel to CC OFF, hook up battery, CC comes on, Panel to CC ON. When removing battery, Panel to CC OFF, Remove Battery, Switch to Battery #1, CC comes on, Panel to CC ON

[Mike90250]

How long does it take to fry a charge controller ? Half a second ? 3 minutes ? Your switch is likely a "break before make" so there's going to be a fraction of a second with no battery attached to the controller ? Will it reboot? Fry ? Shut down and hang ?

[SunEagle]

Couple items came up from same post in FB group. # Is there an issue with detaching the panel (via a continuously connected switch) while sun is on the panel. Keep in mind it is one 9amp panel, not a huge array. I have only read about arcing potential, but in this case the connection is within the ON OFF switch

while the amps may be low it is the voltage level that will determine the length of the arc. That switch may handle a few changes but the contacts will pit and deform each time there is an arc.

[cbird02]

Couple items came up from same post in FB group. # Is there an issue with detaching the panel (via a continuously connected switch) while sun is on the panel. Keep in mind it is one 9amp panel, not a huge array. I have only read about arcing potential, but in this case the connection is within the ON OFF switch

[cbird02]

I would look into a fuse rated less then the switch rating. While this should protect you it may cause the fuse to blow if you exceed it's amp rating.

Sounds good, I was thinking that I would do a 15 amp fuse. I only have a 9 amp solar panel and don't have any room on my roof for any more panels so no expansion concerns. Thanks

[SunEagle]

Both switches are rated for 20a and I am using 10awg wire. What do you suggest for fuse sizes in that case?

I would look into a fuse rated less then the switch rating. While this should protect you it may cause the fuse to blow if you exceed it's amp rating.

[cbird02]

Both switches are rated for 20a and I am using 10awg wire. What do you suggest for fuse sizes in that case?

[SunEagle]

Cool that is how I drew it up first, glad to have confirmation



Yes, this was my intention



My design takes care if this. When the two position switch is on Battery #2, it disconnects from Battery #1. String #1 CC only sends power to Battery #2 and the wires from Battery #1 dead end at switch. This is an either/OR design, String #1 is either sending power to Batt #1 or Batt #2, the switch has no "1&2" option. In pic below the battery would be the charge controller and the bulbs are Batt #1/#2

DPDT wiring.JPG

My only concern is that the contacts on that "switch" are rated with enough amps to handle the loads and can be switch under load if the need arises. Remember DC voltage creates Arches when a circuit is opened under load.

[cbird02]

you don't need to switch the battery minus leads

Cool that is how I drew it up first, glad to have confirmation

Battery 1 will always be charging from Charge Controller (CC)

Yes, this was my intention

When low battery #2 is connected, battery #1 will dump all possible amps into battery #2, in an attempt to equalize the voltages. The high amps could damage both batteries & the wires

My design takes care if this. When the two position switch is on Battery #2, it disconnects from Battery #1. String #1 CC only sends power to Battery #2 and the wires from Battery #1 dead end at switch. This is an either/OR design, String #1 is either sending power to Batt #1 or Batt #2, the switch has no "1&2" option. In pic below the battery would be the charge controller and the bulbs are Batt #1/#2

DPDT wiring.JPG

[Mike90250]

you don't need to switch the battery minus leads

Battery 1 will always be charging from Charge Controller (CC)

When low battery #2 is connected, battery #1 will dump all possible amps into battery #2, in an attempt to equalize the voltages. The high amps could damage both batteries & the wires

[cbird02]

Like this PV2.PNG

[cbird02]

Excellent this is exactly what I was thinking. Does this look good? I realized after making the diagram that I would wire the negatives to the two position switch also.
PV.png

[Mike90250]

Charge Controllers can easily be damaged, if connected to solar panels and no battery.

You can use a switch or circuit breaker on the PV input to the Controller to easily disconnect the PV before changing batteries,