mppt controller with 3 outputs?

[sharpey]

Hi all,

Am replacing my burntout sterling charger, and am thinking Solar is the best bet for me (swinging mooring).

I'm pretty certain that I've 3 batteries each isolated from the other, so that's 1 for engine start with its own on/off switch and then 2 for the house connected with a 1,2,both plastimo round switch. The old charger had three outputs.

Is there an mppt controller out there that has 3 outputs? I'm only planning on having 1 80w panel.

Any help/hints most appreciated.
Cheers,

James

[familycruisers]

Midnite Solar has two primaries and two sets of auxillary contacts but not sure you want that much controller for an 80w panel.

[Sumner]

You would be better to tie the two house bank batteries together and run the charge controller to them along with the output from the alternator if you have one. Then use...

Blue Sea Systems Automatic Charging Relay (Starting Isolation)

....a combiner between them and the start battery to keep it charged.

Here is a good post on the whole deal...

Battery bank design recommendations - SailNet Community

...and I think there are other ones on this site also by Maine Sail. Hopefully you can add more solar also in the future. Here are links to the solar installs on our boats...

Macgregor 26S Outside Mods page 33

Endeavour 37 Electrical Mods Index

Good luck,

Sum

[noelex 77]

Originally Posted by sharpey

Hi all,

Am replacing my burntout sterling charger, and am thinking Solar is the best bet for me (swinging mooring).

I'm pretty certain that I've 3 batteries each isolated from the other, so that's 1 for engine start with its own on/off switch and then 2 for the house connected with a 1,2,both plastimo round switch. The old charger had three outputs.

Is there an mppt controller out there that has 3 outputs? I'm only planning on having 1 80w panel.

Any help/hints most appreciated.
Cheers,

James

Normally solar only charges the house battery and for charging I would link both house banks.
The start battery gets very little drain.

It's helpful to be able to comine the house and start batteries.this can be used to charge the start battery via solar occasionally.

The Gensun controllers are a good match for this sized panel. Consider the Rogue if you are planning to add more panels in the future.

[thinwater]

Please correct me if I am wrong, but the following is how my charger functions:

The main output is for charging batteries. Generally, as others have posted, the batteries are combined for this purpose.

The auxiliary output is for things that can be powered dirrectly from the panel. One reason to do this is to allow something (12v dehumidifier or a fan) to be powered on sunny days will not be powered when the sun is down or obstructed by clouds. This prevents the fan from flattening the batteries if there are a few cloudy days in a row.

The auxiliary outputs are NOT for battery charging and are NOT regulated for that purpose.

---

Of course, a different charger could be different, but I find the above logic rational and practical.

[sabray]

My vote tie the house Batts together. Use cheap blue sea combiner to hook up the start batt. I am year 7 I think with lifeline batts.160 watts of solar. Still seem fine cheap easy and works. Could get very complicated as more reply. I can only tell what has worked

[Sumner]

Originally Posted by thinwater

Please correct me if I am wrong, but the following is how my charger functions:.......

.....The auxiliary outputs are NOT for battery charging and are NOT regulated for that purpose......

.....Of course, a different charger could be different, but I find the above logic rational and practical.

It is going to depend on the controller. We have Blue Sky controllers and they have a second 2 amp auxiliary battery charging output. You can use the output as a load controller also, but not both ....

AUXILIARY OUTPUT
The auxiliary output can serve one of three functions; a 2A auxiliary battery charger, a 20A load controller with Low Voltage Disconnect (LVD), or a 20A variable Dusk-to-Dawn lighting load controller. The Charge/Load function is selected by DIP switch #4 shown in Figure 3. The IPN-ProRemote is required to adjust LVD thresholds or enable Dusk-to-Dawn lighting control. Auxiliary outputs in a multi-controller system will function normally, but only the auxiliary output in the master can be configured or monitored using the IPN-ProRemote. The auxiliary output “Load” LED will illuminate whenever the auxiliary output is ON.

I probably wouldn't try with our controllers to use the 2 amp output on any load other than a battery.

Originally Posted by sabray

My vote tie the house Batts together. Use cheap blue sea combiner to hook up the start batt. I am year 7 I think with lifeline batts.160 watts of solar. Still seem fine cheap easy and works. Could get very complicated as more reply. I can only tell what has worked

I agree, run all charging sources to the house bank batteries that stay tied together. The batteries will last longer and will charge better.

Use the combiner between the house bank and the start battery (which can just be a reserve battery) to keep it topped off.

Wire the switch as Maine Sail suggested in the link in my other post...

#1 Assign house bank to batt switch position #1
#2 Install reserve battery to position #2
#3 Wire alternator output directly to the house bank with sufficient size cable & fuse.
#4 Install ACR (combiner) or Echo Charger between banks.
#5 Use boat in position #1 for starting AND house loads. Switch to OFF when you leave it's that simple.

Put fuses withing 6-8 inches of your batteries and you have simple efficient wiring that will work and keep both sets of batteries charged.

The combiner that I recommended has a safety feature that won't let the starting amperage go through it if wired to the starter switch. If you need to use the reserve battery for starting put the switch in position #2.

The nice thing about the system above is that if you have to you can disconnect the batteries from all loads with the flip of a switch yet they will still be charged by the solar,

Sum

[thinwater]

Originally Posted by thinwater

Please correct me if I am wrong, but the following is how my charger functions:

The main output is for charging batteries. Generally, as others have posted, the batteries are combined for this purpose.

The auxiliary output is for things that can be powered dirrectly from the panel. One reason to do this is to allow something (12v dehumidifier or a fan) to be powered on sunny days will not be powered when the sun is down or obstructed by clouds. This prevents the fan from flattening the batteries if there are a few cloudy days in a row.

The auxiliary outputs are NOT for battery charging and are NOT regulated for that purpose.

---

Of course, a different charger could be different, but I find the above logic rational and practical.

Yup, this is going to require reading the manual; I just did. On my last boat the above was true, but on my current boat it is not; the load begins to draw from the batteries if the sun is down. Dumb.

I should not have posted until I did my reading.

[goboatingnow]

Why not use a simple diode splitter


Dave

[noelex 77]

The load or auxiliary terminals of a solar controller can do may different things. On the good controlers the parameters are adjustable, sometimes to a very high degree.
They could be programmed, for example to turn something on for 5mins every 100 mins from 10am to nightfall. Such versatility is amazing, but generally not a great deal of use on a yacht. Adhering to the KISS principle I usually elect to control things manually myself.

The cheaper solar regulators usually have a fixed function. The most common is to turn on 12v power when light levels are low, for example an anchor light.
The second most common is to apply power, or turn it off when the battery voltage drops below a certain level, for example to turn the fridge off if the battery is low.
Be careful of the maximum current permitted. It is often quite low, so a relay is needed.

[familycruisers]

The Midnite is a very smart piece of work. The auxiliarys are fully programmable. MPPT really comes into its advantages with higher voltage grid tie pv's being so cheap it makes springing for the more expensive MPPT a no brainer. Plus this controller will take better care of your batteries. Wet acid then becomes a better/ cheaper option because you're not consistently gasing your batts.

[noelex 77]

Originally Posted by familycruisers

The Midnite is a very smart piece of work.
.

The Midnite is a great controller, but overkill for the OP 1x80w.

The self consumption is also a bit high for such a small amount of solar.

[Maine Sail]

Originally Posted by goboatingnow

Why not use a simple diode splitter


Dave

Many of the diode splitters sold have no way to "excite" or turn on a solar controller or modern battery charger so you'd need to do a work around...

Lots of controllers and battery chargers will not turn on unless they sense a safe "turn on" voltage. The Center post of most diode splitters has no voltage unless another source is creating it.

There are many ways to skin the cat.. Sterling even makes a combining relay that is "latching" style which has very, very, very low standby draw, they claim 0.0005A or .5mA, for use with small solar arrays..

ProLatch R

The Echo Charger or Duo Charge would also fit the bill with the Echo or simple combining relay being fairly inexpensive..

[familycruisers]

Originally Posted by noelex 77

The Midnite is a great controller, but overkill for the OP 1x80w.

The self consumption is also a bit high for such a small amount of solar.

Precisely what I said in my first post. The subsequent post was to answer the second question posed.

[hellosailor]

"Why not use a simple diode splitter"
Because an MPPT controller typically does not use a dedicated battery sense lead, so you'll be reducing the voltage to each battery by about 0.3 volts, or 25% of charge depth.
Combining the two house batteries will allow for load cycling them to a lesser depth, which translates into much longer life and lower costs. (Assuming rashly they are similar batteries that can be combined.) And then an echo charger or other isolator to dump excess charge to the starting battery becomes a simple and effective way to integrate that into the system.
But even two outputs from an 80W MPPT controller? I know I've seen one on the RV market but suspect that's going to really limit the choices. Might as well save the money on the MPPT charger at that point and just buy twin 50W panels running raw.