Solar charge controller choice?

[PaulRainbow]

This is even more critical with MPPT controllers that the input voltage is well above the battery voltage, so with both types of controllers less than 36 cells is not ideal.

However, it is quite rare to find a 80w solar panel with anything other than 36 cells, so you should not have any problems. The number of cells should be listed in the specifications or you can just count the number of squares visible on the front surface.
If you select one of the Victron MPPT controllers with a single panel it is sensible to avoid selecting a panel with a low voltage.

With no Bluetooth devices to monitor the controller, change setting or update the firmware i would definitely not fit a Victron controller.

I can manually connect all 3 batteries together in an emergency using a toggle switch (if engine fails to start). Cannot work out what I VSR is?

Mike

Voltage Sensing Relay, typically used for split charging. You may, or may not, have one.

 

[MINESAPINT2]

Multi battery isolator Sure Power model 702.

 

[PaulRainbow]

That's a split charge diode, if it's more convenient to connect your solar controller to this, it's ok to do so, connect to the same terminals as the mains charger. Do not connect a single output solar controller to the central terminal of the diode to charge both batteries.

 

[MINESAPINT2]

Thanks, I was thinking I would connect the charge controller outputs to the outer posts on the split charge diode.

I bought the dual solar charge controller in post 2.

As well as fitting a solar panel I am also replacing the Cavalier Electronic charger as it is broken. My new 240v charger is a Victron Blue Smart ip22 12v 30a 3 outlet. I note although I will be fitting fuses on the live from the solar panel to the controller and from the controller to the batteries there is no fuse between the 240v charger and the diode or the batteries. Should there be?.

Thanks

Mike

 

[PaulRainbow]

Thanks, I was thinking I would connect the charge controller outputs to the outer posts on the split charge diode.

I bought the dual solar charge controller in post 2.

As well as fitting a solar panel I am also replacing the Cavalier Electronic charger as it is broken. My new 240v charger is a Victron Blue Smart ip22 12v 30a 3 outlet. I note although I will be fitting fuses on the live from the solar panel to the controller and from the controller to the batteries there is no fuse between the 240v charger and the diode or the batteries. Should there be?.

Thanks

Mike

You can connect to the outer terminals.

No need for a fuse between the panel and the controller.

You need to fuse the cables that go from the diode to the batteries, at the battery end. The Victron charger is fused, so just connect that to the diode. If the solar controller has it's own fuses, do the same, else fuse that close to the controller too.

 

[MINESAPINT2]

Thank you Paul,

Now you have got me wondering about fuse size?.

We are now planning to connect 1 x 55 amp alternator (to the central terminal) and a 30 amp Victron battery charger and a +/- 8 amp solar panel to the outer terminals.

Mike

 

[PaulRainbow]

Thank you Paul,

Now you have got me wondering about fuse size?.

We are now planning to connect 1 x 55 amp alternator (to the central terminal) and a 30 amp Victron battery charger and a +/- 8 amp solar panel to the outer terminals.

Mike

If you fuse the two red cables at the batteries (post #36) with 60a midi fuses they will protect the cables and be sufficient for all sources, with some to spare.

I'm assuming the cables are 10mm, so check that i'm right.

 

[MINESAPINT2]

Will check cable is 10mm (8 AWG). I have some Oceanflex 6 AWG ordered to wire the Victron.

The battery box has a lid and I am now wondering whether to fit the 60a midi fuses inside the battery box or external?

Thanks again

Mike

 

[PaulRainbow]

Will check cable is 10mm (8 AWG). I have some Oceanflex 6 AWG ordered to wire the Victron.

The battery box has a lid and I am now wondering whether to fit the 60a midi fuses inside the battery box or external?

Thanks again

Mike

The fuses are only there to protect the wiring between the batteries and the diode/charger, so they should be fitted as close to the batteries as sensibly practical. If that means close to, but outside of the box, that's fine if the cable inside the box cannot short.

As you will be using thinner cable from the diode to the solar controller you should fit fuses to those cables, close to the diode. These need to be rated lower than the cable and at least the max current of the controller output. I would mount the controller close to the diode, use 2.5mm cables and 10a blade fuses.