2 x MPPT controllers, 4 solar panels and wiring to one battery bank

[lw395]

Yes, maybe, but he view seems to be if you switch on the Victron first and will not effect the second because it will have already determined the alogrithm to follow......

That's not always going to happen. It's an automatic system. If there is any wind in the period before the panels connected to the Victron see their first sun, the wind charger will up the voltage.
One could have a system of programmable switching, so the wind charger was charging the engine battery instead in the period before dawn. Likewise if the solar panels connected to that charger see sun before those connected to the Victron.

 

[lw395]

....
Yes, but it would seem almost all controllers are no where near as intelligent as we think and nearly all a lot less intelligent than Victrons.
...e.

It's a matter of opinion whether one thinks the Victron model of charging control is more or less intelligent than any other.
It depends what information one is prepared to provide to the controller.
Mostly the controller is having to operate with no knowledge of loads on the batteries, no knowledge of the actual capacity and usually only the voltage from which to infer state of charge.
Some solar chargers at least get to measure battery current separated from load current.
Which model is best will depend on how you use the system. A completely different charge regime might be best for a boat laid up than one in use 24/7.

Most of the Victron solar controllers were never designed for yachts, but do a good enough job if you understand how they work and don't go around making life hard for them.

 

[ip485]

That's not always going to happen. It's an automatic system. If there is any wind in the period before the panels connected to the Victron see their first sun, the wind charger will up the voltage.

OK but if that is a concern why not turn off the wind charge at some point in the morning so the Victron can start its alogrithm based on the SOC at that point, then turn the wind back on.

Of course this is in relation to cruising and not in a marina somewhere or on a bouy berth. With SP I dont think any of this especially relevant.

no knowledge of the actual capacity

All of my controllers require to have the capacity and battery type set, the MPPT is a lot more sophisticated beyond that. I was very firmly told off because I left the setup to a marine electrical engineer only to find that none of the chargers had been correctly set. The consequence can be very serious because the batteries may never be charged to their capacity - a sure recipe for disaster.

 

[PaulRainbow]

OK but if that is a concern why not turn off the wind charge at some point in the morning so the Victron can start its alogrithm based on the SOC at that point, then turn the wind back on.

Did you not read the figures i posted earlier ?

 

[ip485]

Post 24?

but wasnt that with a fully charged bank?

 

[PaulRainbow]

Post 24?

but wasnt that with a fully charged bank?

Never mind, you're never going to accept anything that's posted here, unless it agrees with your misinformed thinking.

 

[ip485]

Fair enough, I am sorry to have annoyed you.

I would have been interested to know if you had read the other thread and your thoughts.

I have no doubt my thinking may be misinformed, hence my interest in this topic. I am just trying to make sense of all the contributions on the other thread that seem to point to the conclusion I have reached (which may well be misinformed).

I hope I am definitely not one to want anyone to agree because I am totally happy to change my thinking and I am still struggling to make sense of a subject which seems so unclear and the subject of so much debate.

 

[ip485]

There is one particular post that seems to me to make sense;

"Now, throw in a second charger.


If the target voltage hasn't been reached, which means the first charger is outputting max current trying it's darnedest, but not yet succeeding (aka Bulk mode), the second charger will also start outputting current attempting to raise the battery voltage. Now you have the full output of both chargers trying to raise the battery voltage. The battery will charge faster, the voltage will rise faster, and the target voltage will be reached sooner. But both chargers will operate at max capacity with no conflict, and unaware of the other chargers presence.


Once the target voltage is reached, but chargers will now regulate their current output to maintain the voltage. It is very unlikely that both will contribute equally or proportionally to the task, but it doesn't matter. As long at the battery voltage is being maintained, both chargers and the battery will be happy.


As the battery reaches full charge, each charger will independently decide when it thinks the battery is full, and will stop charging. This will almost never be at the same time, but again, it doesn't really matter. You basically will get the longest charge time of your different chargers. And lead batteries are very tolerant of longer absorb times, and often benefit from it, so certainly no harm is likely."

 

[lw395]

Fair enough, I am sorry to have annoyed you.

I would have been interested to know if you had read the other thread and your thoughts.

I have no doubt my thinking may be misinformed, hence my interest in this topic. I am just trying to make sense of all the contributions on the other thread that seem to point to the conclusion I have reached (which may well be misinformed).

I hope I am definitely not one to want anyone to agree because I am totally happy to change my thinking and I am still struggling to make sense of a subject which seems so unclear and the subject of so much debate.

The OP started this thread to consider a fairly well defined scenario.
Paul and I have given our thoughts based on the parameters of the OP.
You seem to be off on various tangents, talking about completely different chargers where the thresholds between charging stages are different or even unknown.
That's neither relevant nor helpful.

Your central point seems to be that when charging is current limiting, then adding more chargers can only be a good thing. That may be true up to a point, but there are limits to how much charge current is actually desirable, and the current limited phase is often fairly short anyway.

 

[ip485]

Well, thank you to both of you. It really has been an interesting discussion and a lot to learn. Sorry if it has meandered a bit. Sorry if I also find it such an intriguing subject. I read Chemistry and Biology at Uni - but not physics (as you can tell) although there is some chemistry involved in this! I still find that there isnt a huge amount of clarrity and potentially so many different ways chargers appear to work without many of them saying exactly how in the material available on the web. I would love to see one of these alogrithms written out.

Anyway thanks very much and hopefully others may find some of the links useful.