Changing Batteries- disconnect Solar Panels?

[CJ13]

I’m going to replace my service batteries. They’re charged from various sources including Solar Panels via a Victron MPPT controller.
Do I need to disconnect the solar panels from the controller or can I leave them connected?

 

[PaulRainbow]

I’m going to replace my service batteries. They’re charged from various sources including Solar Panels via a Victron MPPT controller.
Do I need to disconnect the solar panels from the controller or can I leave them connected?

You need to disconnect them from the controller. Just pull out the negative from the panels.

 

[Boater Sam]

Yes or cover them completely.
Removing the battery from the controller by either the isolator or physically disconnecting the batteries with the panels still in the sun can destroy the controller. Instantly!

 

[Irish Rover]

Yes or cover them completely.
Removing the battery from the controller by either the isolator or physically disconnecting the batteries with the panels still in the sun can destroy the controller. Instantly!

That's interesting. I didn't know that when I replaced all my batteries 3 years ago in July in the full glare of the Turkish sun. Luckily everything seems to be working fine.

 

[neil_s]

The manual for my solar controller specifies connection to be made to the battery before connection to the solar panel - and disconnection of the panel before removing the battery supply. I have always managed to obey, so far!

 

[Gary Fox]

I didn't know this requirement, but when I moved my panels I accidentally obeyed it anyway

 

[CJ13]

Thanks- that confirms my thought.

 

[lustyd]

In theory could a relay be used to automatically isolate the panels if the battery connection went down?

 

[TernVI]

So what happens if the controller > battery fuse blows?
Presumably this puts the controller in the same 'no battery' situation which it's not designed to cope with?

 

[lustyd]

Yes, but the cable between it and the battery will be fine so all good

 

[wingcommander]

My impression, based on Victron instructions IIRC ,battery is connected first so controller can establish 12 or 24 volt bank automatically. Then solar panels. Although granted this may only be a one off initial requirement.

 

[andsarkit]

If it is excessive voltage that damages the controller then it depends on the controller. If it is designed to take a series string of panels and maybe up to 100V then it is unlikely to be damaged by an open circuit 12v panel which may go to 20v.

 

[LadyInBed]

I put an on/off switch between the panels and controller. It just seemed a sensible thing to do!

 

[[3889]]

I blew up my controller by not disconnecting from panels first so it does matter, sometimes at least.

 

[[3889]]

I put an on/off switch between the panels and controller. It just seemed a sensible thing to do!

Me too, now.

 

[thinwater]

Yes or cover them completely.
Removing the battery from the controller by either the isolator or physically disconnecting the batteries with the panels still in the sun can destroy the controller. Instantly!

This. Cover them. You can add a switch, but a couple of dark towels is simpler. A gauge will confirm that output is zero.

 

[lustyd]

How is that simpler? The switch will be next to the battery you're disconnecting. The towels will need to be found, carried up on deck, placed, held down with something, later collected and cleaned.

Or just flip a switch

 

[thinwater]

Finding towel on a boat is not hard, since you use them every day. If they need cleaned you have some dirty panels that need cleaning. Probably due for laundry anyway, at that rate. Turning off a switch dos not denergize the panels (just like you can't turn off a battery), which is needed for other things. Folks can forget that.

But yeah, you can add another switch. You will need this switch about once every 5-8 years IME (your expereince could be different). You may also have a breaker you can turn off. About the only times I have used this was changing batteries (three boats).

 

[iantomlinson]

Surely you had put an inline fuse. Just pull it out while you replace the panels. When everything is done, bang the fuse back in???????????

 

[lustyd]

Turning off a switch dos not denergize the panels

They don't need to be de-energised, panels aren't like that the electrons just sort of wiggle about unless they have a purpose. If you turn off the switch the panel will be quite happy in the sunshine on its own. It'll get warm, but only as warm as when your battery is charged.