Alternator and Solar living in perfect harmony!

[PaulRainbow]

That's interesting Paul. My combination of simple alternators (one 80A alternator on each engine) and 400W of solar through the Victron MPPT do not behave like that.

With mine, if I'm on solar alone and the solar has reached float voltage on it's own and I start the engines, then the engine alternators will put out just 5 amps or so.

If the solar panels alone have not reached float voltage but are still on the bulk stage they will be showing perhaps 10A going into the batteries at say 12V or 12.5V. If I then start the engines, the alternators totally take over the charging regime and both alternators will start putting 40A to 70A into the batteries which will be 80A - 140A if I'm running both engines. The alternators will then run the whole show until the battery voltages rise to over 14V and the Victron kicks into float.

Once I start the engine/s I can leave the solar panels connected or not .... it doesn't make any difference because the panels just throw in the towel as soon as the "big boys" join the party.

Richard

I'm finding that happens when i turn my mains charger on Richard, the solar controller just shuts down. It's all about where the various charger set points are. Your alternators are obviously set to a higher voltage than mine, so they "over rule" the solar controller. Mine is lower than the solar controller, so the solar controller is King.

Mine works fine for me. If i needed to make more use of the alternator output i'd make some changes there, but for me it'd be a waste of time and money.

The OP has a big alternator, a small solar panel and motors enough for the lack of alternator output to concern him. So, it's important for him to get as much from the alternator as he can.

 

[PaulRainbow]

So we can safely say it works! I keep contemplating fitting 2x 250w rigids on the flybridge which can be de-rigged when I go out as i have a mooring on the other side of the river to move onto in the next few weeks.

Might be worth considering a flybridge bimini with flexible panels on the top ?

 

[matthewriches]

Nope! It's already been coined the Gin palace of Southwold.

Rather have solid also as if I get a shed, I can put the panels on top. Also more wattage for your money.

Might be worth considering a flybridge bimini with flexible panels on the top ?

 

[noelex]

That's the whole point of my original post. If the solar controller voltage exceed the setpoint of the alternator regulator it will stop the alternator output.Therefore, if the current from the solar controller is significantly less than the current the alternator is capable of producing you're better off turning the solar controller off..

If the solar controllers voltage set point is higher than the alternator set pont (which is common when a simple inbuilt alternator regulator is used), once the battery voltage is above the alternator set point the current from the alternator will indeed drop to zero. This is correct.

If the output from solar regulator can raise the battery voltage to a higher level, and this voltage is appropriate and safe for the battery type, in my opinion the solar controller should not be turned off.

I think on this point we should agree to disagree.

 

[PaulRainbow]

Of course we all know what amps are - why keep barking? Can't you post nicely? :tranquillity:

So now current being used = 9A, 16A alternator output so 7A into the batteries.
Close to what the solar was putting in with a different 3.5A being used, 9.5A solar out > 6A going into batteries.

What's the alternator regulator set point voltage & voltage @ the batteries alternator only?

Given the limited data it sounds like the domestic draw could have been 5.5A more with the alternator only than with solar, solar/alternator.

Device output doesn't mean a great deal, amps into the batteries is where the action is

Solar only was 9.5a at the controller, 6a into the batteries
Starting the engine added about 0.5a at the batteries.
Alternator alone, solar controller off was 25a, reduced to 16a, at the batteries

So if device output means nothing (which is nonsense) the amps actually going into the batteries were :

Solar 6a
Solar and alternator 6.5a
Alternator alone 25a, reducing to 16a after a while.

 

[GHA]

Solar only was 9.5a at the controller, 6a into the batteries
Starting the engine added about 0.5a at the batteries.
Alternator alone, solar controller off was 25a, reduced to 16a, at the batteries

So if device output means nothing (which is nonsense) the amps actually going into the batteries were :

Solar 6a
Solar and alternator 6.5a
Alternator alone 25a, reducing to 16a after a while.

What voltages?

If your alternator is putting more amps into the batteries than the solar at a lower battery voltage than the solar then physics is very wrong..

 

[ip485]

What charge state were the batteries at when you performed the test?

 

[PaulRainbow]

What voltages?

If your alternator is putting more amps into the batteries than the solar at a lower battery voltage than the solar then physics is very wrong..

I've taken some readings from my own boat, because it's handy, i happen to be onboard. I could take readings from any of the boats i work on, they won't all be the same, some will be like Richards findings.

But, I'm not here to justify my every post to you. The OP asked a question, i answered it. He can choose to take my suggestion, or leave it.

 

[PaulRainbow]

What charge state were the batteries at when you performed the test?

Not 100% charged. All the tests were taken at the same SOC.

 

[GHA]

I've taken some readings from my own boat, because it's handy, i happen to be onboard. I could take readings from any of the boats i work on, they won't all be the same, some will be like Richards findings.

But, I'm not here to justify my every post to you. The OP asked a question, i answered it. He can choose to take my suggestion, or leave it.

So you won't say what voltage the batteries were at when your alternator was putting in more amps than the solar? It's fundamental to your argument.

If , as you say, somehow an alternator can push more amps into a battery at a lower voltage than solar pushing less amps then either a big branch of physics is wrong. Or you are wrong.

 

[PaulRainbow]

So you won't say what voltage the batteries were at when your alternator was putting in more amps than the solar? It's fundamental to your argument.

If , as you say, somehow an alternator can push more amps into a battery at a lower voltage than solar pushing less amps then either a big branch of physics is wrong. Or you are wrong.

The figure i posted are what they are. Like i said, i don't need to justify myself to you. Get lost.

 

[GHA]

The figure i posted are what they are. Like i said, i don't need to justify myself to you. Get lost.

Unable to back up your statements? Unwilling or just don't know the voltages?

So in Paul's world physics is wrong and a battery can somehow tell that current is coming from an alternator and let more in without increasing the voltage.

Righto.

Another never wrong solent grumpy goes on ignore, no great loss. Must be like Victor Mildrews birthday party in there

 

[ip485]

Not 100% charged. All the tests were taken at the same SOC.

OK, it would be worth running some tests.

If you recall earlier in laymans terms I mentioned that all most chargers are concerned with is the resistance they "see" to the charge.

One of the things I did when I mapped my system was to run the batteries down to 50% charge, and then monitor the rate at which the batteries absorbed charge using different sources and graph the results. I have built up a reasonable picture in that way that models how they recover.

At a low state of charge, not surprisngly the batteries will absorb an enourmous amount at a signifcant rate for the first 15 minutes or so, and then the charge backs off very appreciably, but is still good. Of course as the batteries recover to 75% or more the rate of absorption reduces still further. One of my mains chargers (because of the settings) backs off much earlier so by 80% charge whereas the two might have been producing over 60A one of the chargers has fallen away to almost nothing, rather similiar to what you are seeing.

Of course as the bank temperature rises and if the period of charged is prolonged the resistance will increase even more and the chargers back off more quickly. A short period of rest, "tricks" the chargers back into bulk and this can be a very good way of truly recharging the batteries to close to 100% each cylce (obviously even though the monitor is indicating 100% if it isnt recalibrated the actual AH capacity is gradually falling away over the life of the bank, even though if you do nothing to your monitor you will be kidding yourself that the bank is still recovering to 100%.)

It is therefore possible that your setup is doing a much better job than you imagine BUT allow the bank to drain to 50% or so and then see what charge each source is contributing combined or separately.

You might be pleasantly surprised.