Solar Panel Wiring

[LMRanger]

I have a new to me 2015 R25SC, HIN FMLR2514J415. It has a solar panel on top. What I don't have is a wiring diagram of where the solar controller and any on/off switches are located.

Also in the battery compartment there are two (2) Blue Seas ACR's that I would like to have identified. Where do they get the power from and what batteries they are charging.

Any help from the factory on these would be greatly appreciated.

Ralph Masters
Puffin

 

[ShortCut]

An ACR is a 'magical' 3-terminal devices that simply has one wire to ground and one wire to each of two batteries. It gets its power from the connected batteries and there are no other inputs or outputs. The ACR simply monitors the voltage at each connected battery and keeps its relay open if neither battery is 13.0 volts or higher. If it detects higher than 13.0 volts for 90 seconds or higher than 13.6 volts for 30 seconds, it connects the two batteries together (in parallel) through a relay. If paralleled batteries drop below 12.75 volts for 30 seconds or below 12.35 volts for 10 seconds, the relay opens.

This means that if a charging source (any charging source) is connected to one of the batteries, the other battery will connect to the charging source when the voltage criteria is met. With two ACR's, all three battery banks can be charged from the single charging source (such as solar).

I can't help with the specific wiring details of your solar power system because I put together my own system. I would look for the controller and monitor devices to be either in the cave by the circuit breakers or near one of the batteries. I would not expect to find an on/off switch for the solar panels, although fuses could be removed to serve that purpose.

Marshall

 

[knotflying]

You may also find it in the cockpit lazerette on the port side usually the one that holds the generator.

 

[JohnL]

Very useful discussion of ACRs. If you have two ACR units in your charging system sharing solar panel output among three battery banks (house, engine and thrusters) then is there any need to also have the factory issued duo PWM solar panel controller in the mix that shares solar panel output between the house and engine banks? Wouldn’t one more efficient MPPT controller be a better choice feeding the house battery bank be a better choice, leaving the sharing among the other two banks to the ACR relays?

 

[knotflying]

The MPPT is more efficient in hot temperature and will perform the same in cooler temperatures. IMO, your assumption is correct, why charge the engine battery when it is really the house that will need the charge. Sooner or later though all the batteries get the charge when the relays kick in. I have had my boat going on 9 years now and I tend to stick with the adage, "If it works, don't fix it."

 

[Red Raven]

I’m with Knot on this. A MPPT controller is larger and more expensive and the currently installed PWM controller meets our needs (even though clearly less efficient) so no strong motive to change. However, if I were installing a system from scratch I would install higher voltage panels (or put our existing panels in series) and use an MPPT controller. I agree there is not a strong motivation to have a dual controller with the ACRs in the system. The only condition where this is advantageous is if the panel is putting out less than 13volts (and thus no ACR relay closure) then you will still get some charge to the engine battery with a dual controller. Even then, I don’t think it is very important as the engine battery is fine with no charge for far longer than you would be on the hook. Perhaps if you were to keep the boat moored on a ball full time with no power in a cloudy area (such that the ACR doesn’t regularly close) then it may be warranted.

One minor correction. The MPPT controller is less advantageous over PWM in hot temperatures not more efficient. This is due to lower solar panel voltages with warmer temperatures. In general, however, an MPPT controller is typically more efficient than a PWM controller due to the typical mismatch in panel voltage vs battery charge voltage. All additional power from higher panel voltage over battery charge voltage is lost with a PWM controller.

Curt

 

[knotflying]

Curt, my bad, about the efficiency of the MPPT V PWM. I inadvertently reversed it. 😀