Kunfoosed is me

Re: Kunfoosed is me

OK they/are and will be all connected to the batteries by wires from their controllers

This is on a boat :-)

The 80A alternator is as per manufacturers wiring 100W of solar ATM going to be around 500W with a Rutland 913 wind generator

http://www.marlec.co.uk/products/windchargers/rutland-913-windcharger/

Yes i know Gel cells dont like masses of AMPS which is why i have not changed to a 220A alternator.

However IF or when the Gel cells die i am thinking of changing to LifePo batteries :-) which dont have all the problems and issues with Lead Acid batteries

BUT if the controllers all are set to 13.8 V which is i believe the recommended voltage for Gel Cells - what happens then?

my understanding of this is a bit flaky

Ever so slightly kunfoosed.

The controllers wind/solar and of course my engine alternator put out something like 13.8 volts (Gel Cell batteries)

The Batteries being at rest and at say 12.5 V are needing charged - when the (all or any of these charging sources) are charging the batteries are/is the battery voltage not sitting at (the chargers output voltage of) 13.8V with the batteries 'accepting a charge'? Fully charged and at rest voltage being somewhere around 12.5V? So until the batteries have physically reached that voltage they keep 'accepting' the charge?

So IF one of the three possible charging sources are/is charging the batteries how do the other (one or two) charging controllers know that the batteries are indeed needing charged?

I understand battery voltage and charge states - i think - the voltage thing that is - and i do regularly use a DVM to check on my battery charge state

BUT surely taking my engine driven alternator our of this equation for the moment IF it is windy and sunny with both the wind and solar charging the batteries wont the batteries actually be at this 13.8 Volts level (and i believe being Gel Cells the charging voltage is held down at 13.8 V so as not to create holes in the Gel Electrolyte) so how do the wind and solar controllers know that they can charge the batteries - is it the current flow they measure....since 'surely' with either or both charging the batteries the batteries will be sitting at 13.8 V?

Surely with solar connected and charging there will be no resting state until the batteries are fully charged................so how will the wind generator controller understand what is going on (either the alternator or the solar charging the batteries) and ADD to the battery charging. Obviously this state off affairs also relates to all charging sources and controllers - how do they know that another charging source is active and the measured battery voltage is not an at rest voltage - so the batteries (are being charged) need charging from them as well to shorten the time to fully charged?

this is where i am very confused


What am i missing here or what have i not understood?

thanks again

kindest regards

David

Re: Kunfoosed is me

Re: Kunfoosed is me

Quote:
Originally Posted by Highland_Fling
BUT if the controllers all are set to 13.8 V which is i believe the recommended voltage for Gel Cells - what happens then?

The controller set to 13.81 volts will "win" and the other controller set to 13.79 volts will "lose". If both are set to 13.80 volts, then they will share the current (based on their available current--alternator and solar panels, etc.).

I dont know how to reply to keep the format

But here goes with my thoughts and understanding

Well that sounds clear and understandable - so which system charges the batteries will depend on their various settings (if they are all set to 13.8V it will depend on how accurately they measure that) as well as how efficient they are in monitoring the batteries voltage.

Quote:
The Batteries being at rest and at say 12.5 V are needing charged - when the (all or any of these charging sources) are charging the batteries are/is the battery voltage not sitting at (the chargers output voltage of) 13.8V with the batteries 'accepting a charge'? Fully charged and at rest voltage being somewhere around 12.5V? So until the batteries have physically reached that voltage they keep 'accepting' the charge?

Charging at 13.80 volts for days/weeks on end will probably "over charge" the battery bank. So, that is why there is a "float" charge (around 13.2-13.6 volts). This is just enough voltage for the "optimum" chemistry/long life of the battery bank.

If you "floated" the battery at 12.7 or 12.5 volts, it would not last as long and may tend to self discharge a bit (you need a "voltage gradient" to move current from the high voltage source to the low voltage destination).

Surely the three controllers will ‘properly’ manage the batteries voltage and charging Plus we will be running quite a few 12V loads Refrigeration, Inverter, Lights, (LED’s) Three PC’s plus charging of phones and the PC’s and of course the Autopilot and Instruments.

Quote:
So IF one of the three possible charging sources are/is charging the batteries how do the other (one or two) charging controllers know that the batteries are indeed needing charged?

Technically, it can be a problem. Some controllers have one voltage only settings and others have absorb and float settings, along with a timer (i.e., sit at 3 hours of Absorb voltage, then fall back to float voltage until battery falls below 12.7 volts for > 10 minutes).

Since the alternator is generally assumed to only run at limited times, it probably only has the Absorb setting (no float).

Typically the alternator will start charging at 20/30 Amps and within 30 or so minutes drop back to under 10 Amps……..this is I believe with the batteries at a 80% or so charged state and running the engine for hours and hours to get to a totally fully charged state ( the float part of the charge curve) is just silly for so many reasons………this is where I see the solar and wind coming in to play as once they are on the boat they can charge the batteries at no additional cost notwithstanding silently

The solar charge controller assumed to run for years, can have Absorb and Float voltage settings, plus some way to figure out the transition between the various charging stages.

If your boat ran the diesel 24x7 for weeks at a time (motoring across the Pacific), it is possible that a high absorb only charge setting could damage the battery bank (I don't know for sure).

SEE ABOVE

http://www.marlec.co.uk/products/windchargers/windcharger-controllers/

http://www.google.co.uk/url?sa=t&rct=j&q=hrdi%20controller%20installation%20manual&source=web&cd=1&sqi=2&ved=0CB0QFjAA&url=http%3A%2F%2Fwww.jgtech.com%2Fpdf%2FHRDi%2520Manual.pdf&ei=58y6Tqe6KZT68QOynLW2Bw&usg=AFQjCNH-wyJcpawQKADakT2zWxI9LN8YuQ&sig2=Z97lguRV_K0nullZUXfdvw&cad=rja

From elsewhere

http://www.qsl.net/wb3gck/gel-cell.htm



Quote:
BUT surely taking my engine driven alternator our of this equation for the moment IF it is windy and sunny with both the wind and solar charging the batteries wont the batteries actually be at this 13.8 Volts level (and i believe being Gel Cells the charging voltage is held down at 13.8 V so as not to create holes in the Gel Electrolyte) so how do the wind and solar controllers know that they can charge the batteries - is it the current flow they measure....since 'surely' with either or both charging the batteries the batteries will be sitting at 13.8 V?
More than likely, if your motor/alternator is running, it will be supplying the majority of the charging current (if all are set at 13.8 volts).

Only when the motor is shut down, will the other charging sources start to supply more charging current (again, this depends on battery charge, your boat loads, and the settings of the charge controllers--such as 13.5 vs 13.9 volts due to wiring voltage drop and variation in calibration of the various controllers).

From reading your replies I had come to this conclusion

Will it hurt anything--probably not unless one of your controllers is programmed incorrectly or is not functioning correctly (or you have too much voltage drop in the charger to battery bank wiring, or other issues).
NO wiring problems and issues

Quote:
Surely with solar connected and charging there will be no resting state until the batteries are fully charged................so how will the wind generator controller understand what is going on (either the alternator or the solar charging the batteries) and ADD to the battery charging. Obviously this state off affairs also relates to all charging sources and controllers - how do they know that another charging source is active and the measured battery voltage is not an at rest voltage - so the batteries (are being charged) need charging from them as well to shorten the time to fully charged?

In the end, you monitor the state of charge of your battery bank (very difficult to do with sealed batteries and no battery monitor). You cannot even monitor electrolyte levels to know if you are over/undercharging.

We have a Merlin Battery monitor AND our Gel Cells are 11 Years old and just refuse to die :roll:

To a degree, people will reprogram, for example, the Absorb timer. During summer it may be set to 2 hours, and during winter to 4 hours or more (for controllers with that feature). Because, in summer, there is more than enough sun, and in winter, there is never enough.

Don’t think I can re program that

I hope it helps... It is confusing and, in the end, you have to monitor the state of charge of your battery bank--and adjust what you can (voltage set points, charge timers, running alternator when the battery is low and there is no sun, etc.).

YES that was a great help as we sail in the Caribbean the days when there is no sun are quite rare - the solar is always producing something even on cloudy days.

WE have a Morningstar 15A MPPT Controller for the two solar panels we have at the moment We might upgrade to the 45/60A MPPT Charger once we have put a lot more solar on board.

It is actually surprising (at times) that everything works as well as it does.

YES 11 year old Gel Cells wooo hooooo

But if you stop your battery state of charge vigil--At some point it will come back to bite you. It always does.

-Bill
__________________
20x BP 4175B panels (replacement) + Xantrex GT 3.3 inverter for 3kW Grid Tied system + Honda eu2000i Inverter/Generator for emergency backup.

many many thanks

kindest regards

David