Charge Controlling for Wind and Solar

[Bash]

Originally Posted by Zakimimula

Ok, I worried about the same issue; what happened if two regulators are connected to the same battery bank, won't they conflict?.

that will not happen. Each regulator keys into the bank's voltage.

I have four regulators/charge controllers aboard. They independently control the shore-power charger, the alternator, the solar bank, and the wind generator. Each system is rigged to either dial back or discontinue charging once the battery bank reaches a certain voltage.

They work together nicely.

[Zakimimula]

Aha! (light bulb over head goes on) so regulators reduce the power supplied to what the battery can take. If the batteries are discharged, they can take lots, so all regulators attached will supply whatever they can.

If the batteries are being charged by a massive source, like an engine driven alternator, they also butt out, because the alternator is supplying all the battery can take.

But if the battery is being trickle charged by wind and solar sources via a regulator, then they combine their charge because the battery can take everything they can supply.

Do I have the right of it?

Cheers, and thanks very much for your patience explaining something that must seem very obvious to you.

[goboatingnow]

Originally Posted by Zakimimula

Aha! (light bulb over head goes on) so regulators reduce the power supplied to what the battery can take. If the batteries are discharged, they can take lots, so all regulators attached will supply whatever they can.

If the batteries are being charged by a massive source, like an engine driven alternator, they also butt out, because the alternator is supplying all the battery can take.

But if the battery is being trickle charged by wind and solar sources via a regulator, then they combine their charge because the battery can take everything they can supply.

Do I have the right of it?

Cheers, and thanks very much for your patience explaining something that must seem very obvious to you.

No not really. When the battery is discharged all available charging sources will contribute current unto the charge acceptance level. As the terminal voltage rises then certain charging sources will dominate over others due to differences in the regulator settings, but it doesn't really matter what source is providing the current source once something is.

Dave

[colemj]

Originally Posted by Zakimimula

Aha! (light bulb over head goes on) so regulators reduce the power supplied to what the battery can take. If the batteries are discharged, they can take lots, so all regulators attached will supply whatever they can.

If the batteries are being charged by a massive source, like an engine driven alternator, they also butt out, because the alternator is supplying all the battery can take.

But if the battery is being trickle charged by wind and solar sources via a regulator, then they combine their charge because the battery can take everything they can supply.

Do I have the right of it?

Cheers, and thanks very much for your patience explaining something that must seem very obvious to you.

That is very close to correct with minor technical and semantic quibbles - but definitely correct enough to allow you to go ahead with confidence.

The thing that trips up most people when first thinking about this stuff is the term "voltage regulator". There really isn't such a thing. A better term would be "amperage regulator" because that is the actual mechanism by which they do their jobs. I don't know how it came to be called voltage regulation.

If any part of the system regulates voltage, it is the battery. The regulator simply supplies all the current it can until the battery tells it through voltage sensing to back off the current supply. This is ohm's law relating battery voltage and internal resistance to current.

So all of your charging sources will supply all the current they can until your battery voltage rises enough to hit their charging set points. At this point they will start to fold back their current output to try to keep the battery at this set point. It is also at this time that your regulators will start to "fight" for control because each is not precisely calibrated to one another and some charging sources are more variable (solar with occasional clouds passing by). So one will probably predominate.

The good thing is that it doesn't matter at this point. Any single source can provide all the current the battery requires, so it doesn't matter whether that current provision is supplied equally from all or just by one. And, for example, if solar is predominating when it starts raining, wind will jump in and take up the slack.

Mark

[cwyckham]

Great explanation, Mark.

[Zakimimula]

Thank you all, I think I have it now.

Incidentally, we ran the engine again yesterday to charge the batteries up.

Murphy's Law came into play... With the barometer nose diving in accordance with the forecast, I was hoping to avoid starting up as we are expecting 30kts today. The wind gennie would give the batteries a nice bit of charge and save me the diesel. It wasn't to be; the batteries needed the charge sooner rather than later. Having said that, the batteries are currently at 89.8% charge, and it'll be interesting to see how much we get today.

Anyway, I checked the voltage on the batteries as they charged. They started at 13.25v and I watched as it came up over time to 14.1v. All nicely congruent with the explanations given here.

Thanks again.