MPPT vs PWM

[jsk125]

I have a Rockwood Minilite 2511s with two 200W roof panels and two Lion Lithium batteries and a Victron Shunt.

My problem is the GoPower SB-PWN-30-BT controller. It does not play well with the Lion Lithium batteries (a known problem). I have it on LIFPO, but i get odd errors. Right now an overcharging error. If I open up, turn on fridge and slide outs, it goes away. Close up, and in a few minutes of sun the error returns. I've had some other problems as well.

I'm thinking of moving to an MPPT solar controller - like a Victron 30am. I assume it's just a swap out, and likely someone heading toward the inverter/batteries a fuse already exists.

I'm to play around with the gopower settings per their advice .. reduce the charging voltage.

Anyone have experience with better controllers for lithium?

Finally, I get mixed info on leaving the Lion batteries engaged over the winter (I live in Pennsylvania). I have the heaters on the Lion batteries .. and we have a one month trip to Florida in late January .. I have to pull out the batteries and put them back in. Thoughts? Ok to leave in? I used to take an old 12v flooded and take out my two good flooded batteries - it worked fine. Now I have the lithium.

Thanks in advance for any info

 

[Aussieguy]

I would look at your roof and see how many panels you can fit up there before buying a new controller

once you know what panels you can put on the roof get a MPPT to suit
MPPT can have much higher voltages than PWM so you can more easily put panels in series or series/parallel combos

suppose to be a 20% performance increase

I bought a cheap 50amp controller off Amazon $85.00 ... it even came with a bluetooth dongle
which allowed me to set the voltages
was worth a try and so far it has worked well. 4000miles and no hiccups

whatever controller you get
don't let your panel voltage go over the controllers voltage... include cold temp calculation for voltage

a 50 amp controller can handle a string of panels around 800w
100/50 controller means:
100volts max panels
50amp max output to battery

for approx reference just multiply max amps x charging voltage
50 x 14.2 = 710w of panels
30 x 14.2 = 432w
you can go up a panel 50amp should handle 800w of panels laying down on roof
consult your MPPT documentation for max PV power recommendations

Get a big controller... add panels at leisure ... without need to constantly update controller

 

[Aussieguy]

PS... I very rarely look at the bluetooth any more
I just look at battery and .... "Yup...its charging" that's enough info for average Joe

I got 2.... 340w panels 37v 10amps
they produce all the 12v I need
3 adults camping using all the regular 12v stuff slides lights jacks and stabilizers
NO Inverter usage .... but 12v fridge and furnace

I never turn on my Converter 90% of the time even up in Northern Ohio plenty of sun
200 ah lifepo4 battery

 

[TacomaJoe]

The quick fix would be to switch the controller to sealed/gel profile to lower the charging voltages. I'm thinking that the 14.0 float voltage is getting one of the cells into overvoltage.

I had the issue with my DIY batteries, lowering the voltage allowed the battery to balance the cells, then I could sneak up the voltage using the CUSTOM profile.

It's all voltage at this point, mine is MPPT. Unless you are changing panels, I don't think you'll see a lot of change.

 

[PhilFromMaine]

I have a Rockwood Minilite 2511s with two 200W roof panels and two Lion Lithium batteries and a Victron Shunt.

My problem is the GoPower SB-PWN-30-BT controller. It does not play well with the Lion Lithium batteries (a known problem). I have it on LIFPO, but i get odd errors. Right now an overcharging error. If I open up, turn on fridge and slide outs, it goes away. Close up, and in a few minutes of sun the error returns. I've had some other problems as well.

I'm thinking of moving to an MPPT solar controller - like a Victron 30am. I assume it's just a swap out, and likely someone heading toward the inverter/batteries a fuse already exists.

I'm to play around with the gopower settings per their advice .. reduce the charging voltage.

Anyone have experience with better controllers for lithium?

Finally, I get mixed info on leaving the Lion batteries engaged over the winter (I live in Pennsylvania). I have the heaters on the Lion batteries .. and we have a one month trip to Florida in late January .. I have to pull out the batteries and put them back in. Thoughts? Ok to leave in? I used to take an old 12v flooded and take out my two good flooded batteries - it worked fine. Now I have the lithium.

Thanks in advance for any info

Yes, basically, but you should look at the specs to make sure the new MPPT will work well with your panels output in terms of volts and amps. It is a simple enough process to do as illustrated on many YouTube videos.

 

[Aussieguy]

I tried using the lifepo4 settings on my controller
it would NOT go into 14.2 unless battery had discharged below a certain point

which is totally stupid
switch the charging to user defined and just put the 14.2 charge and 13.6 float
worked much better!

 

[jsk125]

Thanks ....

Aussie ... I have two 200W panels, and won't add any more. I'll fiddle around with the GoPower solar controller and try to fix the overcharging error per the suggestion from GoPower. However, I think I will look at moving to an MPPT controller at some point, or a different PWM controller that plays nice with the Lion Batteries. Renogy perhaps. The issue with GoPower and Lion is something I read about earlier this year when I added a panel and the Lithium batteries. GoPro sent me (for free) and updated controller that is supposed to play nice with lithium batteries .. apparently not with Lion Lithium batteries.

 

[Boomerweps]

I thought the Victron’s were overhyped UNTIL I bought a used one off eBay and worked with it, a SmartSolar 75/15. Then I purchased a 100/30 to replace my similar speced EPEver. I have them both installed in my TT with seperate inputs connected to the 12vdc power. After installing a second pair of 100 watt panels, I copied Aussieguy and shut off my converter. The batteries are only charged with solar.

 

[Aussieguy]

again... if you do swap out to MPPT get one that is maximized for the max string of panels you MAY/COULD/POSSIBLY/MAYBE ONEDAY put up there.

even a ebay one .... second hand is a good choice

Bigger = not needing to swap it again later just to add another panel or two.

50 amp is a good size as most roofs (+19 foot ) can handle between 600-800w
IT will work nicely with the panels and the the wiring you currently have...
don't let the 50amp number fool you.... it is designed to work with a maximum of 50 amps... It does not require/must have always 50amps being produced

the panels and wires may send a lot less throughout the day... clouds, rain, shade etc etc all effect the amps

of course if your roof is small and you can only put 600w of panels then a 30amp controller will be good ...



there will only be maybe 2 -3 hours of FULL panel production even on the best of days

--------------------------------------------------------------
later you can add panels ...if you so choose
without swapping controller again


BTW I got my panels from Facebook (local) no delivery

 

[TitanMike]

Aussie ... I have two 200W panels, and won't add any more. I'll fiddle around with the GoPower solar controller and try to fix the overcharging error per the suggestion from GoPower. However, I think I will look at moving to an MPPT controller at some point, or a different PWM controller that plays nice with the Lion Batteries. Renogy perhaps. The issue with GoPower and Lion is something I read about earlier this year when I added a panel and the Lithium batteries. GoPro sent me (for free) and updated controller that is supposed to play nice with lithium batteries .. apparently not with Lion Lithium batteries.

MPPT would definitely be my choice if you make a change.

PWM controllers only attribute is they are less expensive. They also waste power from the solar panels but that's hardly an attribute.

An MPPT controller also gives one the option to connect the existing panels in series then take advantage of the early sun as well as charging later into the day. Two panels in series will reach the "charging threshold" far quicker than two panels in parallel. Only downside to series connections would be if one parks in the shade but if relying on solar fir charging batteries isn't that counter intuitive?

Right at this minute (7:58AM in PNW) my rooftop panels connected in series with MPPT controller are producing charging current even though we under heavy overcast. PWM controller would still be asleep and may not even wake up if clouds don't clear out.

BTW - If you're absolutely sure you won't add panels to your roof put your money in a Victron Smart MPPT controller that fits your current panel needs. Put the extra money towards a portable solar panel kit for days you might be shaded.

You'll like the bluetooth capability that provides EASY setup and custom charge profile for just about any battery you connect to it

 

[ppine]

No contest. An MTTP will save you the cost of some panels. AussieGuy is right. Plan for the future. Buy a controller that is large enough. Check to make sure it is lithium compatible. I just went with a Renogy 40 amp Rover. It is the third controller I have purchased. The first one was not Li compatible. The second one is on my old trailer.

 

[jsk125]

Update

Update

I bought the Victron MTTP 100/50 with Blue Tooth. I already have the Victron Shunt (which perhaps I can ditch? Or not?) My challenge now is where to install.

In the 2511s the GoPower controllers is installed over the kitchen sink. Easy to get to, and to remove. However, it has two metal plates. The old one and a newer one that fits in the newer, smaller controller they sent me for free.

The wiring from the panels comes through the wall, as well as the wire from the batteries.

I could try to install it within that wall, thus not having to screw with any new rewiring. I can easily cover that hole in the wall with something.

Short of that, I guess I'd have to try to add m or wiring and run clear to the front storage, which I don't know how to do and it seems like a real pain. Likely having to remove the undercarriage materials.

Thoughts? I can likely get some bracing on the wall behind the GoPower hole. The Victron cannot be "nicely" placed on the wall, like the GoPower.

Thanks in advance for any advice.

 

[JimM2109S]

One idea would be to connect (in the space behind the PWM controller) the wires from the solar panels to the wires running to the battery bank. In other words, simply remove the PWM controller from that wiring. The wires already exist and require no rerouting. Be sure to first disconnect the wires from the GoPower controller at the battery bank.

At the battery bank, simply connect the existing wiring from the old PWM controller to the MPPT controller and use new wires to the battery bank. Find an appropriate cover/picture/clock for the old GoPower controller hole.

 

[reidfo]

Update

I bought the Victron MTTP 100/50 with Blue Tooth. I already have the Victron Shunt (which perhaps I can ditch? Or not?) My challenge now is where to install.

In the 2511s the GoPower controllers is installed over the kitchen sink. Easy to get to, and to remove. However, it has two metal plates. The old one and a newer one that fits in the newer, smaller controller they sent me for free.

The wiring from the panels comes through the wall, as well as the wire from the batteries.

I could try to install it within that wall, thus not having to screw with any new rewiring. I can easily cover that hole in the wall with something.

Short of that, I guess I'd have to try to add m or wiring and run clear to the front storage, which I don't know how to do and it seems like a real pain. Likely having to remove the undercarriage materials.

Thoughts? I can likely get some bracing on the wall behind the GoPower hole. The Victron cannot be "nicely" placed on the wall, like the GoPower.

Thanks in advance for any advice.

Victron in my opinion is a good choice. The bluetooth range is pretty awful, but if you're in or near the RV it should be fine. I installed Victron 30A and 50A controllers in my passthrough for two different size and voltage panels (200W and 400W). Each panel has its own shutoff breaker and they go to a bus bar and a Victron snmart shunt. Aside from poor bluetooth I'm really happy with them.

 

[Aussieguy]

X2 What JimM2109s said

disconnect the old PWM and use a GOOD splice and shrink wrap on the wire to join the wires.

find the wires near the battery and use them to go to your new controller
use the biggest wire (buy new) you can fit into the OUTPUT of the MPPT to the battery



100/50 arrange your panel's connections so the voltage is higher and the amps is low
so to keep the amps less than 30...... as the wire is probably only rated for 30amps

50 amp controller.... you can have about 800w of panels
50amp x 14.2v = 710w