Which charge controller for Yacht PV installation

[la7qz]

Hi

I have been asked to make recommendations for an installation on a sailing catamaran. The boat has 2 main battery banks (in addition to engine cranking batteries which we will ignore for now). One bank is approximately 400 Ah, the other is 500Ah. The banks provide power to different systems on the boat which is an unusal setup. A more normal design with the house banks would be to use one or the other to power everything. The yacht already has a Kiss 400W wind turbine with no regulator (or fuse...) connected direct to the starboard battery bank.

The store that are selling him the panels recommended wiring two panels to each battery bank with two independent 30A charge controllers. This would certainly be simple, but would have the disadvantage that you could often have a situation where the panels on one side of the boat are shaded by sails and/or rigging and then only one battery bank would get charged. On a long ocean passage with a constant wind direction, you might see a situation where the panels on one side of the boat see very little sunlight so the corresponding battery bank would suffer.

My suggestion would be to find a charge controller built for two battery banks so that the output from all panels would benefit both battery banks. The Morningstar Sunsaver Duo comes to mind, but is not capable of handling the output from 600W of panels. Another possibility would be to join the output of all four panels and still use one charge controller for each battery bank. Is there any reason this wouldn't work?

The boat also has a Kiss 400W turbine and they are considering adding one more. The Kiss has no regulator at all. So, another possibility would be to combine all the PV panels, split to the two batter banks via diodes and then install one Morningstar Tristar with dump loads (possibly in the water heater) for each battery bank to take care of the output from all RE charging sources.

Owen

[DamonHD]

I'd be inclined to go for the last of those options as it is nice and simple.

But you might do SOME of the panels via the MS Duo since that is likely to be more efficient in a low-voltage system when you're short of sun than the diodes.

Rgds

Damon

[tecker]

I like two battery banks in all installations .This requires switching disconnects etc for both banks and bringing all wiring to a central control with A bank and B bank charging and load control . This allows one bank in standby with a full charge . In your case the third set from the power plant might be brought in to the main control with main motor charging as backup . The four 150 watt panels in parallel with be ok with the blocking from each panel . As for charge control use an inverter and Dump to the set in use running lights can come on with a a dump situation . Run all the wind through the water heater and switch around with the temp controls . Wind gensets will always be in a state of flux while the solar will be more steady ( far as charge voltage ) . Install a controller for each  wind gen with a small battery set that matches the the charge voltage of the solar panels .This allows the inverter to go about control using all sources on the same buss .Power plant as emergency backup . I'm assuming the water heater is low voltage . The water heater make a good series load for wind .

[la7qz]

OK, here is what we ended up doing:

Four 150 Watt panels, two each side of the boom.

The boat has two house banks, one feeding lighting etc, the other feeding navigation instruments etc. There are no dedicated engine cranking batteries. A most unusual configuration, but then the boat was built in France... The genset does have it's own starting battery though.

We have connected two panels to each of two Blue Sea MPPT controllers, one for each of the two battery banks. The Kiss wind turbine and a Tristar 60 with a 600W 12V heating element in the water heater is connected to the starboard battery bank. A blue sea battery combiner capable of passing a maximum of 60 Amps parallels the two banks when the battery voltage on either bank is above 13V.

In addition, there is a two bank charger running from the diesel genset and a factory installed battery combiner that operates from the main engines, switching on when either engine is running. (Connected to the engine ignition and charging lamp.)

We got the panels up and online today. The Tristar and dumpload and the battery combiner will be installed tomorrow.

I decided against just using two Tristars in dumpload configuration to control everything because a malfunction while the boat was unattended for more than a day or two could lead to cooking the batteries. In the current configuration, a malfunction of a charge controller will simply lead to a reduction of charging current.

A malfunction of the Tristar in a windy period could still cook the batteries, but it's unlikely the boat would be left unattended for any length of time without shutting down the wind turbine.

PS. Wish I had room for those four beautiful 150W panels on my ketch...

Owen

[DamonHD]

Thanks for the update!

Why doesn't the battery combiner melt in a huge surge at the moment that it parallels the batteries I wonder?  And I'm guessing that the two battery sets must be well-matched too.

Rgds

Damon

[la7qz]

The battery combiner is designed to limit the throughput to 60 A max. It will not pass more than 60A however much is available.

And... the battery banks are well matched.

Owen

[DamonHD]

Yes, though it looked like some sort of resistive thing which might get rather warm!

Do you know if they do current limits as low as ~10A on these things, to protect my rather small (40Ah gel) battery?

Rgds

Damon

[la7qz]

Hi

The device I used is this one.

http://bluesea.com/products/7600

I have installed quite a few of them on yachts an not heard of any problems. The cutin point is adjustable and there is also an adjustable overvoltage protection. The unit has terminals for two batteries. In the default configuration it will combine when the voltage on battery A rises above the set cutin point. It can also be configured so that it combines if the voltage on battery A or B goes above the set point.

However, for as small a battery as you are talking about, maybe something like this would be more appropriate:

http://www.xantrex.com/web/id/103/p/1/pt/8/product.asp

On my boat, all charging sources including PV, wind, charger/inverter and the engine alternator are connected to the house battery bank (four Trojan T-105). A Digital Echo charge keeps the engine cranking battery topped up. I also have an 8D gel battery which is going to serve as a dedicated communications battery (ham and marine radios) and I will charge this one with the Blue Sea charging relay in the first link.

Of course, if you have the time to play around with stuff yourself and do not have to rely on these things for your safety out on the big blue ocean, you could use a Ghurd controller to control a big contactor capable of carrying the maximum expected current (and then some).

Owen

[DamonHD]

Yes, that looks like the sort of thing I might well use, thank you.

A whole little technology niche that I was ignorant of!

Rgds

Damon