Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested :)

solartechtown.com · August 2010

Hey,

I'm currently back in the market again for a new charge controller for my solar power system.

Soon I will be producing 220 Watts (4x 55W Panels - 3.1A ea.) and 12.4A.

Features I'd Like To Have But Budget May Be Too Low For Some:

Prevent Backflow of Current
LCD That Displays Battery Voltage
LCD That Displays Amount of Amps My Solar Panels Are Producing
LCD That Displays Amount of Volts My Solar Panels Are Producing
Prevent Overcharing - of course
Works well in high temperatures: 80°F - 95°F+ (The controller will be in my outside shed)

The one in "bold" I'd really love to have because I can get an idea if there is something wrong with my solar panels without having to hook a digital multimeter up to the terminals directly.

There are so many charge controllers out there, but I was hoping some of you wise guys/ladies here can suggest some controllers you have found to be very reliable.

mike95490 · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

I don't think that ALL comes on a $100 controller. C-12 is likely closest

solartechtown.com · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

mike90045 wrote: »

I don't think that ALL comes on a $100 controller. C-12 is likely closest

Yeah I figured that from quickly looking around the web. But the key features I'd like are in bold and green. I may have to increase my budget, but I'd like to get a few links to some that either meet my budget or a few bucks over.

Where can I find the C-12 charge controller? I Googled it and found results for an air plane lol.

mike95490 · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

http://store.solar-electric.com/c12.html is the link for our host.

Was Trace C-12, rebranded Xantrex C12

Kamala · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

The Xantrex C12 page at NAWS is here. Otherwise, try including the words "charge controller" in your Google search.

solartechtown.com · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

Kamala wrote: »

The Xantrex C12 page at NAWS is here. Otherwise, try including the words "charge controller" in your Google search.

Well I see that charge controller supports systems that produce under 12A, but as you can see in my original post, my system will be producing over 12A, so what's the difference in the C12 and the Xantrex C35?

Is it just the amount of Amps it can control, or is it completely something different?

mike95490 · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

solartechtown.com wrote: »

Well I see that charge controller supports systems that produce under 12A, but as you can see in my original post, my system will be producing over 12A, so what's the difference in the C12 and the Xantrex C35?

Is it just the amount of Amps it can control, or is it completely something different?

Mostly just the size/capacity. Same tech inside, larger heatsink AFIK.

democopy · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

Specialty Concepts Mark 22-12 Flush Mount with Display

mike95490 · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

democopy wrote: »

Specialty Concepts Mark 22-12 Flush Mount with Display

Looks like a simple single stage (not 3 stage ) controller, and would not be suitable for long battery life.

solartechtown.com · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

mike90045 wrote: »

Looks like a simple single stage (not 3 stage ) controller, and would not be suitable for long battery life.

I ended up going with this one: http://www.infinigi.com/morningstar-ps30m-prostar-30-charge-controller-meter-p-827.html

Not sure if it's three stage or not. How exactly do you know (what will it usually be shown/displayed as in the specs), and can you explain the different stages that allows it to have longer battery life that normal charge controllers that do not have 3 staging?

mike95490 · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

The battery FAQ explains how the different modes work, Bulk, Absorb, Float.
I'm glad you picked the Morningstar, and not (to the solar community) the unknown controller. Read the manual, and don't connect the inverter to the Load terminals.

icarus · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

Actually, I have had (and still have, still use on a standby system) a Specialty Concepts controller. Pretty simple, has a nice battery meter in it, as well as a digital volt/ammeter in it. If all you are doing is keeping a small set fully charged it will work fine. You will have to use a genny to eq when you need to, but for the price it has worked fine and seems to have held up well. ~ 8 years so far.

Tony

PS It does have manual temperature correction which for cheap controller is OK, as well as configurable set points.

dwh · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

Do PWM charge controllers even *have* stages?

As I understood it, they are either on or off (PV connected to battery or not).

BB. · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

PWM is short for Pulse Width Modulation...

Imagine a switch between the solar array and the battery bank "turning on and off" or cycling 100's to 1,000's of times a second...

When lots of current is needed as the battery is below 14.5 volts, the switch is ON nearly 100% of each "cycle". When the battery is full and only needs 13.6 volts for float--the switch is ON only a few percent of the time.

So, the battery is basically "averaging" the voltage (acting like a capacitor by storing the current) of the variable duty cycle of the switch.

The current "pulses" are short enough that the battery voltage is not changed very much during the On/Off time.

At least, that is how I imagine most of the PWM controllers work...

-Bill

niel · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

dwh wrote: »

Do PWM charge controllers even *have* stages?

As I understood it, they are either on or off (PV connected to battery or not).

simply stated it lessens the time it is on to hold the voltage as a battery charges. the stages are the specific voltage setpoints a cc goes to when a certain voltage is reached (goes to absorb) or when the current reduces to a certain point (goes to float) otherwise they would just keep reducing in current like the pwm sunsaver series would do and that is like staying in absorb.

dwh · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

They don't reduce current though do they? Don't they just spend less time with the PV connected to the battery? The current is whatever it is.

From what I understood, the better PWMs basically just switch faster (and/or more often?) and so they can keep the battery topped off more precisely.

Cariboocoot · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

dwh wrote: »

Do PWM charge controllers even *have* stages?

As I understood it, they are either on or off (PV connected to battery or not).

Yes they have Bulk, Absorb, and Float stages. At least good ones like the Tristar do. Different set points trigger the programmed switch in function: i.e. it "knows" that when battery Voltage reaches 14.2, for example, to begin Absorb mode. Then it will switch to Float based on either current flow or time. The main difference between PWM and MPPT is the way it handles the current flow; switching on and off as opposed to adjusting the level for a constant flow. (Simple explanation and probably not 100% accurate, but you get the idea.)

Quoting the Tristar'[s description from NAWS own page:
The controller is a three-function controller that provides reliable solar battery charging, load control or diversion regulation.

dwh · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

Okay, if I have this straight what they do is to adjust the on/off cycle frequency and duration based on battery voltage set points.

What still confuses me is how that can be called a "stage".

I can see it on a constant supply, such as an Iota charger (or even the old Shumacher in my camper) which lowers the amperage as the battery voltage rises (or actually I guess, the battery simply absorbs less amperage as its voltage rises) and I can see how an MPPT can do basically the same thing by adjusting the voltage and/or amperage.

But the PWMs don't adjust the amperage or the voltage, they just turn on and off.

Still seems a bit like apples and oranges to me.

Cariboocoot · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

As far as charging the battery is concerned, it works out the same.
During "Bulk" both controllers put out as much current as they can. The MPPT can down convert higher Voltage to more Amperage, but the PWM just "hooks the panels up directly" and gives whatever the array can put out.
When it hits "Absorb" the MPPT can maintain an exact Voltage level (especially the continuous type like the Rogue) varying the current as needed. The PWM starts pulsing at this point; which is the same as varying the current to maintain Voltage except that the variation is ON/OFF.
The Float stage is the same function as Absorb, only at a lower Voltage level.

This is not an engineer's explanation; just a generalized description from some guy who hooks the wires together and makes it work.

mike95490 · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

Cariboocoot wrote: »

As far as charging the battery is concerned, it works out the same.
During "Bulk" both controllers put out as much current as they can. The MPPT can down convert higher Voltage to more Amperage, but the PWM just "hooks the panels up directly" and gives whatever the array can put out.
When it hits "Absorb" the MPPT can maintain an exact Voltage level (especially the continuous type like the Rogue) varying the current as needed. The PWM starts pulsing at this point; which is the same as varying the current to maintain Voltage except that the variation is ON/OFF.
The Float stage is the same function as Absorb, only at a lower Voltage level.

This is not an engineer's explanation; just a generalized description from some guy who hooks the wires together and makes it work.

But it's pretty close to the engineers explanation !

Vary the pulse rate, and you vary the charge rate. MPPT can "watch out" for itself, but if you over amp the PWM, you just quietly fry the MOSFET - transistors usually fail silently.

dwh · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

Hrmm. Lemme toss out some random comments:

Cariboocoot wrote: »

Quoting the Tristar'[s description from NAWS own page:
The controller is a three-function controller that provides reliable solar battery charging, load control or diversion regulation.

Um, right, but this has nothing to do with charging stages. It refers to the three different things the unit can do - charging is just one of the things it can do.

..........

According to the manual, the TriStar 45 PWM is actually a 2 stage + EQ.

For the actual charging of the battery, it seems to just use PWM to adjust the pulse frequency and duration. Once the battery is charged, it does drop the voltage to hold it at a float level.

http://www.affordable-solar.com/admin/product_doc/Doc_TS_Manual_20060425220321.pdf (Page 27)

And here (Page 50 of the manual):

"BATTERY CHARGING / RTS
• Charge algorithm: PMW, constant voltage"

There's my original question - That's isn't really stages is it? It's just constant voltage PWM until the battery is full and then hold it at a float level.

Yea okay, take that and toss in the EQ function and I suppose it could be called a 3-stage charger - but I don't see anything from Morningstar that calls it that.

..........

Specialty Concepts seems to have been around quite a while.

Their products are American Made and their main product, the ASC, has been in production apparently for 24 years and has a 10 year warranty.

They also claim to ship over 100k units per year. I remember looking into this company before and I wouldn't call them "unknown".

http://www.specialtyconcepts.com/special_home.html

..........

In researching this, I ran across this VERY interesting tidbit:

http://www.morningstarcorp.com/en/support/library/8.%20Why%20PWM1.pdf (Page 3)

"1. Ability to recover lost
battery capacity

According to the Battery Council International,
84% of all lead acid-battery failures are due to
sulfation. Sulfation is even more of a problem
in solar systems, since “opportunity charging”
differs significantly from traditional battery
charging. The extended periods of undercharging
common to solar systems causes grid corrosion,
and the battery’s positive plates become coated
with sulfate crystals.

Morningstar’s PWM pulse charging can deter the
formation of sulfate deposits, help overcome the
resistive barrier on the surface of the grids, and
punch through the corrosion at the interface. In
addition to improving charge acceptance and
efficiency, there is strong evidence that this
particular charging can recover capacity that has
been “lost” in a solar battery over time. Some
research results are summarized here.

A 1994 paper by CSIRO, a leading battery
research group in Australia (reference 1),
notes that pulsed-current charging (similar to
Morningstar controllers) “has the ability to
recover the capacity of cycled cells.” The sulfate
crystallization process is slowed, and the inner
corrosion layer becomes thinner and is divided
into islands. The electrical resistance is reduced
and capacity is improved. The paper’s conclusion
is that pulse charging a cycled battery “can evoke
a recovery in battery capacity.”

Another paper, a Sandia National Labs study in
1996 (reference 2, attached), summarizes testing
of a VRLA battery that had “permanently” lost
over 20% of its capacity. Conventional constant
voltage charging could not recover the lost
capacity. Then the battery was charged with a
Morningstar SunSaver controller, and “much of
the battery capacity has been recovered.”"

I'm wondering now if MPPT charge controllers have the same effect? Anyone know?

Cariboocoot · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

Actually I was thinking of mentioning that: some batteries might "prefer" the pulse charging. It is similar to what a "desulphator" does. Mostly I'd think the advantage would be in not applying a steady-state current, giving the plates a "break" and reducing heat & resulting problems. But the fluctuations are so small I'm not sure it would have any practical effect.

Sorry I misread the Morningstar info. But the fact is there's no reason why a PWM controller can't behave as I described. Maybe there's one out there that does? I'm still a bit unclear as to its set points; "Bulk" is essentially just ramping up to the Absorb Voltage level, and could be considered part of the same thing. As in: "Charge to 14.2 Volts, hold for 'X' time, reduce to 13.8 and maintain".

Could we be picking nits as to the difference between "3 stage" Bulk/Absorb/Float and "3 stage" Bulk-Absorb/Float/Equalize?

Further clarification will have to be provided by someone like Solar Guppy or RCinFLA or boB or Lorelec or .... anyone who really understands the design & execution of charge controllers.

I just make 'em work.

P.S.: Obviously since MPPT output is steady, not pulsed it shouldn't have the same benefit described in that paper.

GreenerPower · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

dwh wrote: »

Okay, if I have this straight what they do is to adjust the on/off cycle frequency and duration based on battery voltage set points.

What still confuses me is how that can be called a "stage".

Bulk charging stage - cycling on/off to keep the "average" current constant at bulk charging current set-point.
Absorb stage - cycling on/off to keep battery voltage at absorb voltage set-point.
Float stage - cycling on/off to keep battery at float voltage set-point.

I can see it on a constant supply, such as an Iota charger (or even the old Shumacher in my camper) which lowers the amperage as the battery voltage rises (or actually I guess, the battery simply absorbs less amperage as its voltage rises) and I can see how an MPPT can do basically the same thing by adjusting the voltage and/or amperage.

Analogy is battery as a water tank, MPPT is a constant water hose to the tank. PWM is shuffling buckets of water into the tank.

But the PWMs don't adjust the amperage or the voltage, they just turn on and off.

Still seems a bit like apples and oranges to me.

PWM - on longer -> using large water buckets
...........off longer -> using small water buckets

Since battery just accumulates the charge put into it whether continuously (MPPT) or a bit at a time (PWM). Once "total" charge reaches its capacity, it's "full".

GP

dwh · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

Cariboocoot wrote: »

Actually I was thinking of mentioning that: some batteries might "prefer" the pulse charging. It is similar to what a "desulphator" does. Mostly I'd think the advantage would be in not applying a steady-state current, giving the plates a "break" and reducing heat & resulting problems. But the fluctuations are so small I'm not sure it would have any practical effect."

According to that Morningstar doc there definately is a practical effect. This might also lend a bit of weight to the "do desulfators work?" question that gets asked around here now and again.

Could we be picking nits as to the difference between "3 stage" Bulk/Absorb/Float and "3 stage" Bulk-Absorb/Float/Equalize?

Could be, but Iota treats EQ as separate and not part of "3-stage charging", so that's how I usually think about it. To me it's "whatever number of stages (+ EQ)", since EQ is a maintenance function and not really part of multi-stage charging.

http://www.iotaengineering.com/iq.htm

Morningstar doesn't even mention bulk, just absorb - which makes sense since all it does is connect/disconnect the PV to the battery until the battery reaches the full charge voltage.

(To answer the OP's question about what he bought...I also saw somewhere on the Morningstar site that all their PWM chargers use the same algorithm.)

P.S.: Obviously since MPPT output is steady, not pulsed it shouldn't have the same benefit described in that paper.

Maybe it's time for PWMMPPT charge controllers?

Cariboocoot · August 2010

Re: Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested

dwh wrote: »

Maybe it's time for PWMMPPT charge controllers?

Interesting idea.
Of course it would have to have separate sensing leads (there's some controller out there that already does - can't remember it) from those that feed the (now pulsed) current otherwise the computer would get confused. Maybe it could switch between 50% and 100% available current? Brings up the question of how rapid the pulsing should be too; 1 Hz or 1000 Hz?

Guess we better leave this one to the engineers!

Looking For A Decent Charge Controller With A $100 Budget - Suggestions Requested :)

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