Is this charger behaviour normal?

[Sapphal]

I have 700w of solar connected to a 550Ah domestic battery bank through an Outback MPPT controller. I am currently in the marina with the mains hooked up. During the daylight hours I switch the Victron Centaur 12/20 charger off - even though it seems to do nothing when the solar kicks in. As dusk approaches I switch the charger back on. However, If I switch the charger on before the Outback has gone into Snooze mode the charger does not kick in when the Outback goes to snooze - I then have switch the charger off and on again to start the charger which the goes into its bulk/absorb/float sequence and holds the batteries at 13.7 volts. In the morning as dawn breaks and the Outback wakes me with its clicking it takes over the charging and, as previously mentioned, the charger appears to do nothing.  

 

Is this his behaviour Normal?  If I am not at the boat overnight then it appears that the batteries would not be kept topped up overnight. Admittedly, there would only be a minor drain on the batteries.

 

just hoping one or more of the experts on here may have thoughts on this. 

 

TIA

[Alan de Enfield]

It depends on the output voltage of the controller and the battery charger.

 

If (for example) your charger is set at 14.0 volts and the solar at 14.4 volts, then the battery charger will look at the voltage (14.4 volts) and say "I'm not needed' and stay asleep until the voltage drops below the battery charger setting.

 

If your batteries are charged by the solar why are you bothering to charge overnight with the (to be paid for) electricity to power the battery charger ?

[Sapphal]

Yes that’s what I thought. But in winter I would need the charger. So I can assume that when the battery voltage drops low enough then the charger will kick in. In effect, when on shore power I can just leave the charger on and it will only kick in when needed by the batteries.

[Alan de Enfield]

51 minutes ago, Sapphal said:

Yes that’s what I thought. But in winter I would need the charger. So I can assume that when the battery voltage drops low enough then the charger will kick in. In effect, when on shore power I can just leave the charger on and it will only kick in when needed by the batteries.

Yes.

[mrsmelly]

Solar or not I would leave the charger on all the time whilst pluggen in. The cost is less than peanuts ( literaly )

[Alan de Enfield]

7 minutes ago, mrsmelly said:

Solar or not I would leave the charger on all the time whilst pluggen in. The cost is less than peanuts ( literaly )

But - the other side of the coin :

 

It will not operate during the day when solar is working (and overproducing)

As 'leccy is used overnight the battery charger will kick-in and start to re-charge the batteries (using up X pennies of main leccy) doing so.

The batteries will be fully charged again by morning when the solar comes back on stream.

 

Had you not left the battery charger on, the solar would quickly have topped the batteries back up to full (probably by lunch time)

 

You have wasted the 'pennies' used every night for 6 months (10p per night = £18.00  which will pay for Oil and filters to do an engine service)

 

My battery charger is switched on October/November and switched off April.

Solar charges the batteries during the day, usage reduces the SoC during the night, solar tops it back up the next day.

Edited April 17, 2019 by Alan de Enfield

[Sapphal]

Thank Alan de. I agree with the October to March charger routine. I will leave the charger off and see how long it takes for the batteries to come back on the solar. I will do it for a few days including dull days. 

 

Thanks to all

[Sea Dog]

The probable reason it appears to only work if you switch it off and on again is because the batteries are full enough for the chargers to be in float mode. Switching a charger off and back iusually n forces it into bulk mode.

 

I leave my shore powered charger on when I use it and let it and the solar charger sort themselves out.

[BruceinSanity]

When not living on the boat here in Mercia, I leave the shore power off and my 135W panel connected through the Tracer to keep the batteries topped up. I’ve never found the batteries below 100% charge on visiting during the day, even in December. I turn the shoreline on if I’ve got work to do on the boat or when staying overnight to chill the fridge down.

 

I sleep sound when away from the boat knowing that there’s no risk of a battery failure/overcharge/boom-boom situation developing and not much risk of an electrical fire with no mains on.