One set of solar panels charging two battery banks

[LadyG]

8 hours ago, Richard10002 said:

I hadnt even thought of that  

 

Is there such a thing as a 1/2/off switch without the "Both"?

 

I must admit to consciously going from one to the other via Off on mine and, as both are 12V, I dont think it would matter if I went via both.

But not when the alternator is working, I assume?

I must be totally confuse again: if it is essential to have solar energy going to batteries via controller, and never having no batteries connected when solar feeding the controller, or when engine is running, [in both cases energy generated has no where to go], what is the difference when "OFF"is selected?

I assumed OFF is only used when everything is shut down for some reason,  and solar covered over or disconnected in some way 

Edited May 15, 2020 by LadyG

[Jen-in-Wellies]

8 hours ago, The Gravy Boater said:

This interests me.  I had thought about having two battery banks... the lithiums for quick charging and the various other benefits... the LA for dumping excess charge when your lithiums are full.  So when drawing power the system would take from the lithiums until they hit 50%, then switch to the LA until they hit 50%, then switch back to the lithiums to use their remainder.  In charging it would get the lithiums to 100% first then dump any excess into the LA (which would never be below 50%).  Sounds like you are using an analogue solution with a manual switch but can it not be done automatically with some battery management system?  In all probability I'm just going to go for a larger lithium bank but if there is a way to have a cheaper battery reserve, why not.

A suitably sized changeover relay, driven from a switched output from a battery management system could potentially do this. Most relays are changeover ones anyway. Double pole to switch both positive and negative rails. Rated to switch the max voltage and current from the solar panels. You would need a back up of some sort to cope with the relay sticking so it fails to safe from the Lithium batts point of view.

Jen

 

 

[peterboat]

1 hour ago, LadyG said:

But not when the alternator is working, I assume?

I must be totally confuse again: if it is essential to have solar energy going to batteries via controller, and never having no batteries connected when solar feeding the controller, or when engine is running, [in both cases energy generated has no where to go], what is the difference when "OFF"is selected?

I assumed OFF is only used when everything is shut down for some reason,  and solar covered over or disconnected in some way 

The alternator and solar together aren't an issue,  I did it for years with no problems 

[Jen-in-Wellies]

1 hour ago, LadyG said:

But not when the alternator is working, I assume?

I must be totally confuse again: if it is essential to have solar energy going to batteries via controller, and never having no batteries connected when solar feeding the controller, or when engine is running, [in both cases energy generated has no where to go], what is the difference when "OFF"is selected?

I assumed OFF is only used when everything is shut down for some reason,  and solar covered over or disconnected in some way 

You would want an OFF setting for the solar to disconnect the panels from the solar controller(s). It is important to have this as if you disconnect the controller from the batteries with the panels still connected it can destroy some models of controller. Having the panels disconnected is not a problem even in sunshine. There will be voltage across the ends of the wire, but no current flowing. There doesn't need to be anywhere for it to go. A bit like an AA battery in its packaging from the supermarket. As @peterboat says, having the solar panels connected while the alternator is turning isn't a problem. Most boats with solar are set up like that.

Jen

[LadyG]

1 hour ago, peterboat said:

The alternator and solar together aren't an issue,  I did it for years with no problems 

Wrong end of stick Peter.

 Not together, either of them or both puting energy in to the batteries, both have to be puting enegy in to the batteres, and be connected. If the swtch s OFF oes ths not mean.

1] the alternator wll blow if engne is runnng.energy, 

2] the solar connector would blow if the solar power sends energy, but the batteries do not get that energy.

PS I am not clear how the batteres get the energy from the controller, ths brings me back to why can one controller not send energy to all battery banks.

Edited May 15, 2020 by LadyG

[ditchcrawler]

10 hours ago, Richard10002 said:

Yes... I was just throwing something into the mix that seems to have worked for me and, with some modification, might work for the OP. It seems it wont  

I made the same mistake for someone wanting to install two inverters on a boat as a method of change over and never considered the both position

10 hours ago, Richard10002 said:

Yes... I was just throwing something into the mix that seems to have worked for me and, with some modification, might work for the OP. It seems it wont  

I made the same mistake for someone wanting to install two inverters on a boat as a method of change over and never considered the both position

[Detling]

11 hours ago, ditchcrawler said:

What happens when you switch to "Both" when one battery is 12 volts and the other 24 volts?

Melting wires and magic smoke from 12 volt appliances and lights etc.

[Richard10002]

13 hours ago, ditchcrawler said:

What happens when you switch to "Both" when one battery is 12 volts and the other 24 volts?

This switch looks like it doesn't have the option for "both".

 

https://boatelectricals.co.uk/blue-sea-battery-switch-9001e-3-way-350a/

 

The fact that you have to go from one bank to the other via "Off", means that you ought to turn off the power from panels to controller while switching. I have a breaker between panels and controller which works as a switch, so can easily turn off the panels.

 

Clearly there is the possibility of human error where you don't switch the panels off when switching from one bank to the other. I suppose a relay could be inserted as well as my breaker, or instead of, in order to automate the turning off of the power from the panels.

[Richard10002]

5 hours ago, LadyG said:

But not when the alternator is working, I assume?

I must be totally confuse again: if it is essential to have solar energy going to batteries via controller, and never having no batteries connected when solar feeding the controller, or when engine is running, [in both cases energy generated has no where to go], what is the difference when "OFF"is selected?

I assumed OFF is only used when everything is shut down for some reason,  and solar covered over or disconnected in some way 

The switch I have is in the solar and 240V charger feed into the circuit. If it is turned off, it only stops any charging from solar and/or the 240V charger. The alternator only charges the LA bank and, if it is running, it continues to charge the LA bank. The switch I am talking about has no effect on the connection between alternator and LA battery bank. I can see how it would be confusing  

 

The only danger I can see is if I were to select "OFF", (thus turning off the feed from solar controller to batteries), without turning off the feed from panels to controller. I think this can damage some controllers, and I'm not sure whether my EpEver Tracer is one of them. Bear in mind, because both my banks are 12V, (+/-), it doesnt matter if I go via "Both"

[ditchcrawler]

4 hours ago, Richard10002 said:

This switch looks like it doesn't have the option for "both".

 

https://boatelectricals.co.uk/blue-sea-battery-switch-9001e-3-way-350a/

 

The fact that you have to go from one bank to the other via "Off", means that you ought to turn off the power from panels to controller while switching. I have a breaker between panels and controller which works as a switch, so can easily turn off the panels.

 

Clearly there is the possibility of human error where you don't switch the panels off when switching from one bank to the other. I suppose a relay could be inserted as well as my breaker, or instead of, in order to automate the turning off of the power from the panels.

Thanks for that, I can go back to my thread of 2 inverters now