Solar settings for float and discharge

[rwoodnz]

Hi All

Checking with folks whether I can rely on the default settings for my new solar controller. I'm new to solar and have purchased two 100W flexible solar panels with a 20amp controller:https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1

These will charge two new 110Ah 12V DC31 Lead Acid Calcium batteries in parallel. I intend to leave the panels up permanently, only removing for racing. There are controller settings to switch them off after a set amount of time each day also.

Specs:
Each Solar Panel
Cell material: Monocrystalline silicon
Pmax(Power at Maximum under STC) ：100W
Imp(Current at Max Power, A)：5.55A
Vmp(Voltage at Max Power, V)：18V
Voc(Voltage at Open Circuit, V)：21.6V
Isc(Current at Short Circuit,A)：6.11A

20A Solar Controller
Voltage: DC 12V / 24V
Rated load current: 20A
Overload protection: 14.4V / 28.8V
Overload floating charge: 13.7V / 27.4V
Charge recover voltage: 12.6V / 25.2V
Protection against discharges: 10.7V / 21.4V

I've heard it is critical to get the charging voltage settings right to avoid overcharging, and not to rely on default settings.

When I look at manual what it has as adjustable are:
float or CV voltage (default 13.7V)
discharge reconnect voltage (default 10.7V)
discarge stop voltage (default 12.6V)

Are these defaults suitable?

[Pete7]

You are also going to need the charging specifications from the battery manufacturer to avoid guessing. Can you post these too?

Pete

[thomm225]

It looks like you have a PWM controller.

They work fine, but an MPPT is more efficient (and better for charging expensive battery banks) and you can adjust your absorpion and equalization voltage as well as your float. My settings are still on default. Float 13.8 volts; Absorption: 14.4

I have both but I don't have an expensive battery bank.

Most folks seem to like the Victron MPPT controllers. Mine is a 75/15 and cost about $90.00 whereas my PWMs cost between $14.00 - $35.00

You can also monitor all voltages on the Victron from your Lap top with a cable or from your phone

https://www.victronenergy.com/upload...WM-or-MPPT.pdf

https://www.victronenergy.com/upload...verview-EN.pdf

SmartSolar charge controller MPPT 75/10 MPPT 75/15
Battery voltage 12/24V Auto Select
Maximum battery current 10A 15A
Nominal PV power, 12V 1a,b) 145W 220W
Nominal PV power, 24V 1a,b) 290W 440W
Max. PV short circuit current 2) 13A 15A
Automatic load disconnect Yes, maximum load 15A
Maximum PV open circuit voltage 75V
Peak efficiency 98%
Self consumption 12V: 25 mA 24V: 15 mA
Charge voltage 'absorption' 14,4V / 28,8V (adjustable)
Charge voltage 'equalization' 16,2V / 32,4V (adjustable)
Charge voltage 'float' 13,8V / 27,6V (adjustable)
Charge algorithm multi-stage adaptive or user defined algrithm
Temperature compensation -16mV / °C resp. -32mV / °C
Continuous load current 15A
Low voltage load disconnect 11,1V / 22,2V or 11,8V / 23,6V
or BatteryLife algorithm
Low voltage load reconnect 13,1V / 26,2V or 14V / 28V
or BatteryLife algorithm
Protection Battery reverse polarity (fuse)
Output short circuit / Over temperature
Operating temperature -30 to +60°C (full rated output up to 40°C)
Humidity 100%, non-condensing
Maximum altitude 5000m (full rated output up to 2000m)

[rwoodnz]

Thanks Pete

I don't have charging information for the batteries, only that they are Maintenance Free Calcium. I'm not sure the supplier has it, although i have asked. I had calcium batteries previously so am assuming no problem charging from the existing shore power controller and the alternator.

Looking around online it seems there is a universal problem getting charging information for calcium batteries. There is plenty of talk however on needing a higher voltage to get to full charge. One figure touted is 14.8V, others say over 15V.

Now I see thomm225 response and that is what I was starting to think, that I need a better charger, which I have no problem going for, that will deliver a higher settable voltage. This controller I have has an overload protection of 14.4V that doesn't appear to be adjustable, so I guess it is never going to fully charge these batteries.

[admiralslater]

I agree get a Victron controller and set it up to match your batteries. They do lots of cool things like allowing you to change the frequency of equalization etc

[thomm225]

Originally Posted by rwoodnz

Thanks Pete

I don't have charging information for the batteries, only that they are Maintenance Free Calcium. I'm not sure the supplier has it, although i have asked. I had calcium batteries previously so am assuming no problem charging from the existing shore power controller and the alternator.

Looking around online it seems there is a universal problem getting charging information for calcium batteries. There is plenty of talk however on needing a higher voltage to get to full charge. One figure touted is 14.8V, others say over 15V.

Now I see thomm225 response and that is what I was starting to think, that I need a better charger, which I have no problem going for, that will deliver a higher settable voltage. This controller I have has an overload protection of 14.4V that doesn't appear to be adjustable, so I guess it is never going to fully charge these batteries.

I think the PWM controller will charge your batteries fully but maybe not as efficiently as the MPPT. I still have my pwm hooked up to the 50 watt panel that is only used when I'm going out on the boat. I have the float set to 14.0 volts on this one so it will still charge after the Victron has stopped at 13.8 volts. It's float setting

I used a $12.00 Chinese PWM controller for about 5 years but it charged the batteries right to 14.4 volts and it stayed there so I would disconnect after a couple days

We have several battery experts on here that will give you all the details (sometimes so many it's confusing) that you need. They will be along soon I'm betting

PS. The Victron is fun to play with and you can monitor everything from your phone. I use my laptop and a cable

https://www.youtube.com/watch?v=UPJbtmNhVOk

[rwoodnz]

Yep. I'm thinking this is good advice and looking at the Victron 100/30. If I am calculating correctly this will also mean I can double the number of panels at a later date if I need to.

Still not clear about what I need this to do to work best with these Lead Calcium batteries. Is it the 'absorbtion' charge that needs to be adjustable?

Anyone with a Victron 100/30 who an tell me what the voltages are adjustable up to?

[Pete7]

Ok, what make and model are these batteries and are they sealed or can you top the electrolite up by removing caps?

Pete

[ramblinrod]

PWM controllers are fine, and the default settings are for flooded lead acid. They will serve well. I have used them for years. If you produce all the energy you need with this system, it will be just fine. If you need about 15% more, you could swap the controller for an MPPT. EPever Tracers controllers are pretty good and the remote meter, Bluetooth or wifi options are cool and relatively inexpensive. But if all you want/ need is the energy your current system can produce all the bells and whistles of other higher featured components are no real benefit. Can’t speak to the needs of your batteries without knowing more about them. Another unknown that is important is how you intend to use them. How deep discharge, how frequently?

[newhaul]

Originally Posted by rwoodnz

Hi All

Checking with folks whether I can rely on the default settings for my new solar controller. I'm new to solar and have purchased two 100W flexible solar panels with a 20amp controller:https://www.amazon.co.uk/gp/product/...?ie=UTF8&psc=1

These will charge two new 110Ah 12V DC31 Lead Acid Calcium batteries in parallel. I intend to leave the panels up permanently, only removing for racing. There are controller settings to switch them off after a set amount of time each day also.

Specs:
Each Solar Panel
Cell material: Monocrystalline silicon
Pmax(Power at Maximum under STC) ：100W
Imp(Current at Max Power, A)：5.55A
Vmp(Voltage at Max Power, V)：18V
Voc(Voltage at Open Circuit, V)：21.6V
Isc(Current at Short Circuit,A)：6.11A

20A Solar Controller
Voltage: DC 12V / 24V
Rated load current: 20A
Overload protection: 14.4V / 28.8V
Overload floating charge: 13.7V / 27.4V
Charge recover voltage: 12.6V / 25.2V
Protection against discharges: 10.7V / 21.4V

I've heard it is critical to get the charging voltage settings right to avoid overcharging, and not to rely on default settings.

When I look at manual what it has as adjustable are:
float or CV voltage (default 13.7V)
discharge reconnect voltage (default 10.7V)
discarge stop voltage (default 12.6V)

Are these defaults suitable?

you need a better solar charge controller the one you have in the picture is just about the worst thing you can use next to direct hookup to your batteries .

Here is the cheap one I would recomend to my customers that can't afford a good mppt for initial installs.
https://www.ebay.com/itm/WindyNation...edirect=mobile

[thomm225]

Originally Posted by newhaul

you need a better solar charge controller the one you have in the picture is just about the worst thing you can use next to direct hookup to your batteries .

Here is the cheap one I would recomend to my customers that can't afford a good mppt for initial installs.
https://www.ebay.com/itm/WindyNation...edirect=mobile

I had a Windy Nations solar controller similar to this that lasted one year and worked just like the PO's present controller which I have now plus a Victron 75/15.

So you never can tell about the longevity. They are both PWM with float setting

https://www.ebay.com/itm/WindyNation...ss!23455!US!-1

[newhaul]

Originally Posted by thomm225

I had a Windy Nations solar controller similar to this that lasted one year and worked just like the PO's present controller which I have now plus a Victron 75/15.

So you never can tell about the longevity. They are both PWM with float setting

https://www.ebay.com/itm/WindyNation...ss!23455!US!-1

you were lucky I know of many people that have cooked their batteries by use of that pos controller.
The windy nation p30l is settable to the tenth of a volt . The p20l unit you linked to is not nearly as user friendly . The unit that the op shows is factory set with 3 specific profiles all of them wrong. He may get lucky like you did .

[thomm225]

Originally Posted by newhaul

you were lucky I know of many people that have cooked their batteries by use of that pos controller.
The windy nation p30l is settable to the tenth of a volt . The p20l unit you linked to is not nearly as user friendly . The unit that the op shows is factory set with 3 specific profiles all of them wrong. He may get lucky like you did .

I believe his is also adjustable to tenths of volts for float. I have mine at 14.0 when using the boat and just before. 13.2 volts or so in Winter

https://www.amazon.com/Controller-Ba...62348230&psc=1

Victron is still at defaults so 13.8 float

I used one of those $12.00 Chinese controllers for ears that simply charged
your batteries to 14.4 and stayed there. I had it on alligator clips and would disconnect after a few hours at that voltage

[rwoodnz]

Thanks for the feedback all. It's been very useful.
I've ordered a Victron 100/30. That should allow me to double my panels if I decide to later.

[thomm225]

They are nice and even the lights on the case tell you a lot about what is happening...…...along with your battery monitor and your phone

Some of us have noted though that at times the voltage will read a couple tenths low on the Victron which to me is nothing to worry about but seems to be a very serious problem to others