Best Low-Cost Charge Controller?

[sailorchic34]

Sounds like its working sort of, not in mppt mode. If the voltage is not rising above 14.4, maybe it is at float and the indicating light control is wonky. Whats your entering and leaving voltage to the controller?

[Captain Bill]

Originally Posted by sailorchic34

Sounds like its working sort of, not in mppt mode. If the voltage is not rising above 14.4, maybe it is at float and the indicating light control is wonky. Whats your entering and leaving voltage to the controller?

Unfortunately the monitor only shows the incoming amps, not voltage. The outgoing voltage is battery voltage which was 14.4. It does seem to be working to some extent in that it does not seem to be exceeding the acceptance voltage limit of 14.4. The float voltage is set to 13.2 and it eventually does go into float. The vendor says that it will immediately go from acceptance to float if the unit reaches 14.4 volts and cannot sustain 1.5 amps/100 ah going into the battery. The problem is that it should go into acceptance mode well before it gets to 14.4 and it never does. It was a little bit hazy today so I can't say that it should have produced more that 12.3 amps, but that is about all I've ever seen, even on spectacularly clear days. When its been a bit cooler I've seen 12.5 amps, but with my old controller I regularly saw 16 amps. Today wasn't really an ideal day for measuring output as the batteries were too well charged and may not have been able to take more than 7.5 amps. My concern today was more around the batteries being at maximum acceptance voltage and indicating 100% and the unit still being in bulk mode. Since the LED is being flashed by the same microprocessor that contols the charge mode, I think something is amiss. It's not clear to me if this is a hardware or software problem. If this was a software problem it would seem likely that tech support would be seeing a lot of this so I think a hardware problem is more likely.

[noelex 77]

Originally Posted by Captain Bill

The vendor says that it will immediately go from acceptance to float if the unit reaches 14.4 volts and cannot sustain 1.5 amps/100 ah going into the battery.

This is a very good way of determining when to terminate the acceptance stage and drop back to float. To work on a boat it needs two shunts or an interface with the battery monitor. The better solar controllers have this.
The Bluesky unit I think only has provision for 1 shunt and i dont think it will integrate with any of the battery monitors so it does not know the current going into the battery only the total current. This means with any load on ( which is generally all the time on a boat) the feature does not work.

Originally Posted by Captain Bill

The problem is that it should go into acceptance mode well before it gets to 14.4 and it never does.

No this is not correct. If 14.4v is the bulk voltage and 13.2v is the float voltage (these voltages, particularly float are too low for most batteries unfortunately) the battery voltage will rise in the morning as the solar panels put energy into the batteries. This is the bulk stage. When the battery voltage reaches 14.4v the controler will reduce the solar panel output so that the voltage stays at 14.4v (providing there is enough solar) and will not let it get higher. This is the acceptance stage. The controler starts a timer that runs while the batteries are at 14.4v if the voltage drops lower the timer pauses. When the total time at 14.4 reaches at acceptance time ( usually set at 1-2 hours) the controler should drop back to float.

I hope this description of how the charging algorithm works will help you determine if your controler is working as it should do.

[Celestialsailor]

I have a Blue Sky 2512 MPPT controller with 2, 100 watt Grape Solar panels. Seems more efficient than my old Flexcharge 25 on my other boat. I decided not to be cheap in this area since I need it for cruising.

[foggysail]

Time to revisit this thread--

What are the panel open circuit voltages folks are using? I just started looking into solar, just tired of running my generator 2 hours in the morning and another at night to recharge batteries using a Zantrex 50 charger. Heck, fuel savings alone will help pay for solar.

Anybody using the higher voltage panels? Are there problems with controllers for higher voltage panels? Panel cost--- still looking but have not found that $160 panel Chic mentioned here in an earlier post. I have only looked into two so far, a 235 watt panel made by Schott that is physically larger than Suntech's similar panels.

Foggy

[Feral Cement]

They sold out in about a week!

Amazon.com: DM 145w Polycrystalline Solar Panel: Patio, Lawn & Garden

145W for $160 including shipping. OCV on an almost clear day: 20.8 DCV and 21.2 DCV.

Now, advice on where to mount? Somehow, a 7' arch on a 27 foot boat seems out of scale and would probably affect performance. Rail mount? Stern pulpit is already overloaded. Ideas?

Thanks,

John

[foggysail]

So much for $160! OK, I'll bite the higher cost with a higher wattage panel. Mounting! I have a hard top over my aft deck. Mounting for me should be a piece of cake.

[noelex 77]

Originally Posted by foggysail

Time to revisit this thread--

What are the panel open circuit voltages folks are using? I just started looking into solar, just tired of running my generator 2 hours in the morning and another at night to recharge batteries using a Zantrex 50 charger. Heck, fuel savings alone will help pay for solar.

Anybody using the higher voltage panels? Are there problems with controllers for higher voltage panels? Panel cost--- still looking but have not found that $160 panel Chic mentioned here in an earlier post. I have only looked into two so far, a 235 watt panel made by Schott that is physically larger than Suntech's similar panels.

Foggy

Higher voltage panels (or multiple "12" panels in series) require the use of an MPPT controler and won't deliver much if the controler dies ("12v" panels can be connected straight to the battery if the controler fails.). The wire size can be reduced from panels to controler.
Otherwise the results are very much the same as lower voltage panels. Fit the maximum watts in the available space for the minimum cost ( include the regulator and wire cost)

[foggysail]

Originally Posted by noelex 77

Higher voltage panels (or multiple "12" panels in series) require the use of an MPPT controler and won't deliver much if the controler dies ("12v" panels can be connected straight to the battery if the controler fails.). The wire size can be reduced from panels to controler.
Otherwise the results are very much the same as lower voltage panels. Fit the maximum watts in the available space for the minimum cost ( include the regulator and wire cost)

Sure! That is a good point Noelex. Now the lower range panels I see have outputs around 20vdc. Is this the popular low voltage you refer to?

Foggy

[foggysail]

Originally Posted by Feral Cement

They sold out in about a week!

Amazon.com: DM 145w Polycrystalline Solar Panel: Patio, Lawn & Garden

145W for $160 including shipping. OCV on an almost clear day: 20.8 DCV and 21.2 DCV.

Now, advice on where to mount? Somehow, a 7' arch on a 27 foot boat seems out of scale and would probably affect performance. Rail mount? Stern pulpit is already overloaded. Ideas?

Thanks,

John

They were sold out this morning BUT THEY ARE NOW BACK!

Foggy

[noelex 77]

Originally Posted by foggysail

Sure! That is a good point Noelex. Now the lower range panels I see have outputs around 20vdc. Is this the popular low voltage you refer to?

Foggy

A "12v" panel will have a Voc of about 21v and a Vmpp of about 17.5v.
These sort of voltages are necessary to ensure the panel can still charge battery at say 14.7 v when the solar cell temperatures rise etc. This is what I meant by a 12v or low voltage panel.
Higher panel voltages are OK, but an MPPT regulator is needed if the voltages are much higher than listed above

[foggysail]

Thanks Noelex-- I just placed an order for 2 panels from Amazon---$160 each delivered as recommended by many here in the forum. Now I am chasing a controller. There are some very inexpensive pulse width modulated controllers along with more expensive MPPT controllers over at Ebay. They offer a 30 ampere MPPT for less than $90..........maybe that is the way I'll go but have not made a decision. Welcome suggestions--

Foggy

[willardj]

Those panels are nice I have one too. If you can't find them on Amazon you can go to there company link DM 145w solar panel, solar module 145w, 12V Solar Panel The panels are listed as a 2 pack for $240 and $100 for shipping this way but comes out about the same.

As far as MPPT chargers be careful with the cheap ebay models. There are some good one out the starting on the smaller size Morningstar Sunsaver mppt 15a($200 range), and Tristar 45($400 range). Rogue also makes a nice 30a mppt($325 range).

[noelex 77]

Originally Posted by willardj

As far as MPPT chargers be careful with the cheap ebay models. There are some good one out the starting on the smaller size Morningstar Sunsaver mppt 15a($200 range), and Tristar 45($400 range). Rogue also makes a nice 30a mppt($325 range).

I agree if you want MPPT you need to get a reasonable quality controler. Something like the Rogue.
Cheap MPPT controllers don't work well.

[foggysail]

I agree with your folks about cheeeepy ones, and yes I bought a cheepy at $80. I thought about getting a pulse width modulated unit which most likely has a buck converter at its heart but I know these can be noisy therefore went with the $80 ALMPPT30. How good it is remains to be seen, it should get me started though.

I am fed up with running my generator hours/day when on my anchor.

The panels-- I purchased them from Amazon with free delivery for a total cost of $320.

What I did not purchase were the the connector fittings after reading many of the recommendations posted about them. As I type, I don't know how I will make the connections, I presume they have some type of flying leads for the output power. If I find I absolutely need them then I will order some.

Back to MPPT! Over the winter after I get caught up with my many (to many) projects, I intend to take a serious look at MPPT. I believe I can make a device that will work properly. That project is shelved until winter.

More on my solar adventures as the saga continues--

Foggy