Which solar regulator for duel battery system?

[Silverback]

We plan to have two 125W Sharp solar panels installed which, coupled with the 2 x 60W vinyl stick-down panels already on the cockpit top will provide a total of 370W - if my sum is correct.

Question is which regulator for a duel battery system?
Eg: One 12V cranking battery and one 12V 'house' battery with a switch over.

We have reference for a 2430MPPT regulator to suit the above - can anyone shed light on what MPPT stands for and what advantages a MPPT regulator offers if any?

I imagine our power draw will come from use of the fridge, freezer, auto pilot, computer and lights mostly, with the HF radio, phone charger and other accessories added on ocasion.

Also any information the use of a brass or stainless Earth-block bolted to the hull under the waterline.

Any feedback would be appreciated.

[Minggat]

Try
Blue Sky Energy Inc.
Sounds like a lot of solar energy and not much space to put it in. I know that I have overkill in my system with 6 golf cart batterys. (I used to have 8). I'm guessing that you don't have mch room for more batterys, but only one house battery isn't much for what you plan to load on it. The fridge/freezer alone will really take a toll. Batterys live longer when they share the load with their friends. That also includes shareing charging cycles.

There's tons of info on the subject in these threads.

[hellosailor]

MPPT regulators are "smarter" and more expensive than conventional ones. Very much the way to use with solar, if you can afford it. If you've got an engine alternator, note that running the solar power into the batteries probably will confuse the alternator regulator, disconnect the panels when you want efficient bulk charging from the alternator.

Brass and stainless have no place underwater on a boat. You'd want bronze if you have to install a grounding block of some kind, but you may want to pick up one of the more popular books on 12-volt systems (Calder, etc.) to get an overview of all these things before you start attacking them piecemeal. A Dynaplate (sintered bronze) is fine for a radio/electric grounding plate, but should not be used as a lightning ground.

[starfish62]

The MPPT means Maximum Power Point Tracking. Supposed to optimize the output. All of your panels sound like they are 12 volt? You wouldn't need an MPPT for 12 volt panels. They are used with the higher voltage panels, generally. They are WAY more expensive than the straight voltage regulators, and I've had salesmen say they were overkill for a small system. I've also had salesmen say they were essential, so it's caveat emptor like everything else: research and make an informed decision. I could not recommend Northern Arizona Wind and Sun more highly. Great folks, and have been in the buisiness a long time. Here's their site. I notice you're in Mooloolaba. Do you know "Little Coconut?"
Solar Panels - 1 to 200+ Watts

[Silverback]

Thank you 'Minggot', 'Hello Sailor' and 'Starfish 62' for your feedback.
I now understand what MPPT stands for and the information on the Dynaplate is usefull. Checked 'Northen Arizona' and 'Solar pannels' very helpfull thank you. No I havn't yet come across "Little Coconut" Starfish62, is Little Coconut the name of a boat or a 'user name?
Thanks again foiks.

[scotte]

One nice thing about MPPT controllers is you can wire your panels in series, thus reducing wire size needed to carry the same amount of watts, however you have to be careful that series panels are shaded equally. You also still have to stay within input spec of the controller, but this can be done by connecting things in series/parallel (similarly to the way 6V batteries are used in a 12V system).

[starfish62]

No I havn't yet come across "Little Coconut" Starfish62, is Little Coconut the name of a boat or a 'user name?
Thanks again foiks.[/quote]

Little Coconut was a small, steel sloop that I was stuck in Vuda with for a couple of months in late 2006. I heard they made it to Mooloolaba (that was their hailing port) and sold the boat there. Piet, I believe, was the captain's name and the crew was Ben and Andy.

[over40pirate]

I wouldn't worry about hooking thepanels to both batteries. I'm sure you have a battery selector switch to choose which battery to charge. Just hook the controller output to the switch.

On my boat, I do it this way, and only charge the starting battery now and then.

There is no problem having the engine charging while the solar panels are. If the regulator for the alternator senses high voltage from the batteries and solar, it will just not charge. You don't want it to if the system is already charging at max voltage.

With a good solar controller, you can use it to charge at high voltage for battery conditioning. The one I have does that. I have only used it on the barn lights, as we are not reasdy to splash the boat yet, so I can't give an opinion on it. It does have fancy led lights!

[hellosailor]

"and only charge the starting battery now and then."
not a good idea. Starting (SLI) batteries have very thin plates, to provide a high impulse charge for starting. That also means they lose plate material relatively quickly, and it does not reform very well. They are designed to be used and then RECHARGED IMMEDIATELY. Any substantial amount of discharge, for any length of time, will do permanent damage to them fairly quickly. (Less for AGM types than wet.) SLI batteries don't like being deep cycled at all, they are generally expected to be cycled something like 10% or less in normal use. So, maybe 2 or 3 fast starts, or one week, between charges--but anything more and I suspect you'd be killing the battery way faster than needed.

[over40pirate]

Not sure what SLI means, but my starting battery ($59 car battery) lasted me 3 years while cruising full time. Maybe I charged it more than I thought. At the time my solar panels didn't have enough watts for ultimate charging, and sometimes I had to start the diesel just for charging. I figured I could sacrifice a little starting battery life, for less running time and assosiated diesel engine fuel, maintinance costs, and noise.

[starfish62]

I hooked my two panels up like over40 said. I had two house banks and one start battery and charged all (if I desired) through a switch. Just put the hot from your voltage regulator out to the common on a typical 1-2-both switch. I took the neutral to a shunt on a Xantrex monitor. If you have a shunt system and hook it up that way the battery monitor will show what you're making from the panels. It's nice to feel like you're doing something productive just because the sun is shining!

[Ex-Calif]

I agree that an 11+ meter boat should be able to fit more than one house battery. Especially with all those goodies.

I squeezed another house battery in my little boat. People laugh when I tell them there are three batteries under the cockpit sole.

My plan is to add solar and continuously charge the house. I reckon the starter battery will get it's recharge from the alternator after the engine starts.

[hellosailor]

Putting the shunt in the negative is a good & common idea. Just make Real Damn Sure that it is bolted in firmly. If it should loosen up (two more connections that can fail) you can get a ground fault back through other equipment, like expensive electronics and radios, that blows them instead of fuses since the fuses are inevitably in the HOT side only.

If you've ever seen radio installation instructions that say to fuse BOTH power leads to the radio--this is what they are trying to avoid. (And they'll usually say to wire it directly to the battery, partly for the same reason.)

[Therapy]

Originally Posted by hellosailor

If you've ever seen radio installation instructions that say to fuse BOTH power leads to the radio--this is what they are trying to avoid. (And they'll usually say to wire it directly to the battery, partly for the same reason.)

I have never heard of anyone that did/does that.

Should it be on my (long) list?

[Reality Check]

It is the technically correct thing to do.... just sometimes harder to accomplish than some are willing to undertake... All In all it is far better protection as HelloSailor has indicated... IMHO he is also probably one of the most informed on the subject of solar, wind and battery power on the forum... just check out some of his other very detailed responses... he is dead on....