Solar charging with A/C charging

[CapnCrunch]

I am running a Xantrex 2500 inverter with charger that automatically comes on when the boat is connected to shore power or my honda 2000i generator. I also have one solar panel with a victron 100/30 controller. The boat is in a covered slip so the solar is not producing any output in the slip and the batteries are being charged by the Xantrex charger.

My question is: is it safe to leave the solar charge controller connected when the shore-powered xantrex charger is running?

TIA

[a64pilot]

I leave mine connected, but have set it so that absorption voltage is set at float voltage limits. I don’t want my bank being taken to absorption voltage every day sun comes up.

[sailorboy1]

I leave mine connected, just like I leave it connected when motoring.

[CapnCrunch]

Thanx, guys. I figured it was OK but wanted to make sure.

[SV Bacchus]

We are still new enough to sailing that I never even thought about it, duhhhh! Thanks for asking that question.

Like SB1, are on the hook a lot so the issue is when motoring. I never disconnect anything, fire em up and go. Never experienced a problem, thankfully!

[hellosailor]

Arguably safe--but pointless. And electronics can be funny that way. If they're turned OFF when they aren't going to be used, they can't get in trouble.

[rgleason]

I saw a wiring diagram with two relays too isolate the chargers from the solar panels. I believe this was a Genasun diagram and I was wondering why, because I don't have any relays for my little 14w solar panel. Sorry, don't know anything more than that. Found it, see attached.


Would like to know more.

[ramblinrod]

Originally Posted by CapnCrunch

I am running a Xantrex 2500 inverter with charger that automatically comes on when the boat is connected to shore power or my honda 2000i generator. I also have one solar panel with a victron 100/30 controller. The boat is in a covered slip so the solar is not producing any output in the slip and the batteries are being charged by the Xantrex charger.

My question is: is it safe to leave the solar charge controller connected when the shore-powered xantrex charger is running?

TIA

Is it safe?

Well, safety is a matter of perception and comes in various degrees.

Almost anything can kill you under the wrong circumstances.


In general, leaving solar panels and shore charger connected at all times is not a problem.

However, when away from the boat, leaving a large bank connected to ships loads and charging systems is a lower degree of safety than shutting everything down and isolating it.

The degree of safety depends on vessel electrical system condition, loads, and charging capacity.

The most unsafe factor I see, is horrendous DIY wiring.

It is so common that I estimate 90% of boats have several unsafe electrical system issues. In some cases, the degree of unsafe is horrific. (I have refused to work on boats until all propane and flammables are removed by the owner.)

Beyond poor wiring, the degree of unsafe diminishes rapidly.

With refrigeration left running to preserve food, one needs some form of charging system connected to keep the batteries from being exhausted.

To be as safe as possible, I recommend scaling the charging system to the load when away from the boat.

E.g. If the maximum load is bilge pumps (e.g. 10 A-hrs) and fridge (e.g. 2 A-hrs), limit the charging system to 15 A-hrs.

This way, if something goes wrong, a battery is less likely to boil dry and go into thermal run-away (which is rare, but could burn down the boat and everything around it).

In my opinion, leaving the boat with the water cooled refrigeration running is pretty unsafe, but folks still do it (and most don't sink ;-).

[hellosailor]

rg-
That diagram appears to confusingly show the Genasun MPPT controller twice. Once on the left column as a power source, and again, in the big picture of it at the bottom/right.

Additionally it shows an optional Genasun controller, which appears to be able to toggle two control lines that can drive relays on other charging sources or load sources, so that using the optional controller, you can then turn on/off any two other devices that can be relay controlled.

In some cases this function is built into an MPPT controller panel, i.e. they will have a relay-driver or relay built in, so that you can automatically turn the anchor light on when the sun isn't shining, and off when it has come back up. There are all sorts of hookups that different people might want. That's when you begin to cross over from "dumb charging" to feedback loops, AI, and control systems. For instance, if you are on metered shore power, you might choose to turn off the shore power entirely when you were getting good solar power, and just use the shore power at night, when it was the cheapest available source.

[Cpt Pat]

Originally Posted by a64pilot

I leave mine connected, but have set it so that absorption voltage is set at float voltage limits. I don’t want my bank being taken to absorption voltage every day sun comes up.

I have the same concerns about daily inappropriate solar charging to the absorption voltage (14.4 volts) when on shore power. So I installed a relay that's powered by shore power that disconnects the PVs from the solar charge controller. It's the simplest solution, and it doesn't require futzing with the solar charge controller configuration. If shore power fails, or I disconnect shore power to leave the dock, the relay de-energizes and the solar panels automatically come back on line. A good relay cost me $40.

[OceanPlanet]

Originally Posted by rgleason

I saw a wiring diagram with two relays too isolate the chargers from the solar panels. I believe this was a Genasun diagram and I was wondering why, because I don't have any relays for my little 14w solar panel. Sorry, don't know anything more than that. Found it, see attached.


Would like to know more.

Those controllers connected to the batteries in those diagrams are NOT solar charge controllers. They are the Genasun lithium battery BMS modules that control the charge & load relays.

The Genasun solar controllers that are shown, are connected only to the charge bus.

[rgleason]

Bruce, thank you for the explanation. I should have looked more carefully. Lithium batts are not very familiar to me.

[rgleason]

So the lithium controller relay opens when there is no charging and the other one closes when the inverter has a load?

Dumb learning question, why are they needed?

[OceanPlanet]

Originally Posted by rgleason

So the lithium controller relay opens when there is no charging and the other one closes when the inverter has a load?

Dumb learning question, why are they needed?

See attached on how our dual-channel BMS system works...this is for the Lithionics systems, as Genasun no longer mfgs Li batteries. However the operation is similar.

Basically, the BMS opens it's internal charge "charge" bus connection in the case of possible overcharge. The "load" bus connection is opened to prevent over-discharge. The "FCC" charge control is used to turn off charge sources before the charge contactors are opened, to prevent damage to sources (for instance, alternators).

[rgleason]

Some good diagrams here, explaining how the Li batterys are isolated by the BMS and dual bus from becoming overcharged (activating the relay)



There is a PMS (Power Management System) too from Phippi

and the Manual


This is too sophisticated for our little boat, but perhaps some of it will be useful.(someday?)