My multisource battery charger project for small boat

[emayd]

More explanation here

[smac999]

The solar panels, engine, and wind gen. Are all going to output different voltages. You can’t just tie them together like that. Each needs it’s own regulation.

[emayd]

Originally Posted by smac999

The solar panels, engine, and wind gen. Are all going to output different voltages. You can’t just tie them together like that. Each needs it’s own regulation.

It was first variant of controller with 3 separate DC-DC modules. But unfortunately there is a problem to synchronize them. It needs external 2 KHz impulses source.


After that I've tested variant when all 3 sources connected to one input of DC-DC.



If high voltage source can't deliver enough power voltage dropped down till next source, etc. If all sources can't deliver enough - voltage drops till 6.3V and DC-DC switched on CC mode and utilize all power that available.


Maybe it doesn't perfect solution related with different internal sources resistance. But it simple and works.

[SVHarmonie]

Even if it does work it is a crappy battery charger. Holding 13.6 volts at the battery terminals will not charge them completely because it is too low, and it is too high to hold them as a float voltage, they will gas and boil away.

What problem are you trying to solve-exactly? A lack of funds? A burning need for a creative outlet?

There is nothing about this solution that is better than a standard setup with proper multi step chargers.

[emayd]

Originally Posted by SVHarmonie

...
There is nothing about this solution that is better than a standard setup with proper multi step chargers.

Please point me on charger that gives possibility to reduce current, brakes wind generator, charging battery when source voltage is low. I didn't found any ...


This DC-DC controller reduce current asymptotically to zero when battery going to preset voltage. This is very smart controller and, if I right understand information printed on battery, 13.6 is between 13.5 and 13.8 V

[noelex 77]

Originally Posted by emayd

This DC-DC controller reduce current asymptotically to zero when battery going to preset voltage. This is very smart controller and, if I right understand information printed on battery, 13.6 is between 13.5 and 13.8 V

The recommendation to charge at 13.5-13.8v is for standby use. This is where the battery is normally kept at 100% SOC.

You need a charge profile that is suitable for cyclic use. Typically this may involve charging at 14.5v, keeping this voltage for couple of hours and then dropping down to 13.8v.

Keeping the battery at 13.6v for cyclic operation will significantly reduce the battery life and also reduce the energy the battery can absorb in a short period of time, for example, while the solar panels are functioning.

Having said the above, these small sealed batteries are not expensive so the short life is perhaps not a great issue, although the slow charge rate is likely to be frustrating.

There are many commercial battery chargers and solar regulators that I think would be a better solution. The difficulty is the wind generator. I would concentrate your obvious considerable electronic skills on developing this aspect of your design. This would be useful to many users.

[emayd]

There is no problem to set charging voltage to 14.8 and add an extra guard module that will separate charger from the battery till voltage drops below specified level.
For example 13.0 or 12.5 V. But I'm not sure that in current situation battery is in cyclic mode. If input sources deliver enough current, battery will not be used at all. In this case it is like standby mode. It's happened because both DC-DC preset for same output voltage, but between battery and load is a diode that drops voltage on 0.3 - 0.5 V.

[Lake-Effect]

Originally Posted by emayd

More explanation here

Interesting. Obviously it's for a small system; it would help people understand your choices if you could describe your DC loads and powering requirements.

We have a small boat. I put in a single flooded group-24 deep cycle battery. It's overkill for the all-LED lighting loads, VHF, GPS, depth sounder, but will be handy if we add a tiller pilot.

Currently, we are able to keep the battery topped up with just a 20" x 20" portable solar panel. When necessary, we have a small 4A smart charger we can use. We have a charging output from our outboard, but haven't needed it yet. With such a light load, the battery has seldom been deeply discharged and it's going on 13 years old.

So - all our charging sources connect to the battery(with overcurrent protection for wiring) , and all DC loads are fed from the battery (through a breaker panel) . It's simple but works.

[noelex 77]

Originally Posted by emayd

For example 13.0 or 12.5 V. But I'm not sure that in current situation battery is in cyclic mode. If input sources deliver enough current, battery will not be used at all. In this case it is like standby mode.

Small boat “camping” is great, but perhaps I am not understanding your usage pattern. I would have expected some occasions with no charge input and a net discharge to the batteries. For example, at night (no solar), calm conditions (no output from the wind generator) and not running the outboard.

[emayd]

Originally Posted by noelex 77

Small boat “camping” is great, but perhaps I am not understanding your usage pattern. I would have expected some occasions with no charge input and a net discharge to the batteries. For example, at night (no solar), calm conditions (no output from the wind generator) and not running the outboard.

We are small team







and for sailing we use usually two Ducky-19 inflatable catamarans.





Maximum is four person per boat. Every one has at least one professional or semiprofessional camera. I have two. One video camera per boat. Last year was added quadro copter. This is additionally for two handheld marine radio, navigation chart-plotters, etc.




We sail mostly in remote locations. You can find from pictures our travel in Canada, Greenland, Cape Horn, etc. Sometime we use mini container, or boxes to send equipment to start point. Sometime we take our boats with us in plain as sport luggage.


We all times limited with weight and size of our equipment. We can't take with us big car battery. This why we have to use lightweight solution without restriction to take it on plain.

[Lake-Effect]

Originally Posted by emayd

We are small team ...


and for sailing we use usually two Ducky-19 inflatable catamarans....


We all times limited with weight and size of our equipment. We can't take with us big car battery. This why we have to use lightweight solution without restriction to take it on [airplane].

...wow. How interesting! Thanks for explaining. That's some serious cruising!

[emayd]

I can implement next variant.
Does it make sense to add hysteresis in charging procedure?
Disconnect charger when buttery is full and connect it again when battery voltage drops on some level? Or all time keep charger connected.
Charger quite smart, it reduce current to zero if battery near preset voltage.

[Lake-Effect]

From doing a bit of reading from your link on the Marlec wind generator:

• apparently, the generator should always be connected to a battery; I'm guessing that without a battery connected, there is the danger of wind generator overspeeding and generating excessive output voltage, which could blow up your regulator and loads.
• Marlec makes a suitable charge regulator which will manage the generator, the charging cycle, AND it also accepts and manages the current from a solar panel. You might still need current limiting if the max charge current is too high for your chosen batteries.

If you were to use the above Marlec charge regulator, then the engine generator output would be connected directly to the battery. You might need some means of interrupting the current from the engine generator if the battery voltage was going above 14.5V.


Please consider these ideas. The Marlec HRSi regulator is meant to work with the wind generator, it has the proper charge profile, and it is probably more robust than the imported modules you're considering. I also think that the batteries are key components and must be the "center" of the system: all current sources and all loads must connect to the batteries.


There should should also be a resettable breaker in series with the batteries to protect wiring in case of a short circuit.

[emayd]

I use Marlec charger about nine years - https://www.marlec.co.uk/product/hrsi-regulator-1224v/


And I'm not satisfied with it. It can't limited current to battery, it can't utilize electricity if output voltage below charging voltage. It's pity to see that your wind generator rotates with some good speed full day, but controller say that it doesn't enough. There is no possibility to insert current limited module in between, because the controller needs to be connected direct to battery , and I didn't found right way to include a motor alternator in this circuit.


Solution from Marlec probably good if you sailing on weekends and need to keep your battery in between.



This a reason why I started this project.


I've attached picture from my previous solution.


Instead of reset fuse I prefer simple from cars.

[smac999]

why are you trying to limit current? put 14.4v to the battery. it will limit itself.

chargers control voltage, not current. batteries control current.