Affordable MPPT Charge Controller

[SV THIRD DAY]

What about those poor souls spending the summer in the Sea of Cortez where it's 90-degs in the boat day and night.....uggggg...the 5% loss seems a little harsh to me.

[whiskthecat]

I'm looking at it from a design perspective and I don't know any other way to word it than I already have. It makes no difference whether its 20 degrees or 100 degrees ambient temperature. A constant 1 degree rise is still a 1 degree rise over the entire life of the battery. Think of it like amp hours. It's degree hours, although 1 degree seems insignificant it really isn't when you consider that it is happening non stop. There is absolutely no reason to not have a proper amount of capacitance to assure that you are not placing unnecessary wear on the battery bank when you don't have too.

A battery bank in the tropics receiving no current ripple from the charger will last longer than one that is having to deal with current ripple. It really is as simple as that. Would you exclude a 5$ component from your engine that reduced the fuel efficiency or the lifespan of the engine by 5%? Of course not. It wouldn't matter how hard you were running the engine in the first place.

[sailnow2011]

So how does this compare to something like the outback power 80 amp mppt?

[whiskthecat]

Well you probably already know all of this but that controller is 3x the capacity for a 12v bank and 5x the price. I have no idea of the internal build quality but the price seems excessive regardless unless you have a very high voltage battery bank to take advantage of that controllers support for 60v output voltage. Otherwise you are better off buying 3x of the cheap controllers and saving the $200.

[socaldmax]

Originally Posted by whiskthecat

I'm looking at it from a design perspective and I don't know any other way to word it than I already have. It makes no difference whether its 20 degrees or 100 degrees ambient temperature. A constant 1 degree rise is still a 1 degree rise over the entire life of the battery. Think of it like amp hours. It's degree hours, although 1 degree seems insignificant it really isn't when you consider that it is happening non stop. There is absolutely no reason to not have a proper amount of capacitance to assure that you are not placing unnecessary wear on the battery bank when you don't have too.

A battery bank in the tropics receiving no current ripple from the charger will last longer than one that is having to deal with current ripple. It really is as simple as that. Would you exclude a 5$ component from your engine that reduced the fuel efficiency or the lifespan of the engine by 5%? Of course not. It wouldn't matter how hard you were running the engine in the first place.

I'm not going to argue over a 1* rise in temp.

However, this entire train of thought is based on watching a video of a unit with the cover off. You're assuming that it has insufficient capacitance and that it's putting out 8A of ripple.

The only way to determine that is to measure it. Unfortunately, my installed unit is 150 mi away and I'm not driving all the way out there just to check that. Until someone sticks a scope probe on one or a calibrated meter and shows me 8A of ripple, I'm not going to sweat it. Even at 20A, I seriously doubt it's generating even half that in AC ripple. I could be wrong, but I can probably slap a $5 cap on it faster than I can get a firmware upgrade from EPSolar.

Even with a $5 cap included, total cost is $107 delivered. Still cheaper than most controllers (and much easier to adjust/more flexible than some much more expensive controllers) and much cheaper and easier than building one from scratch.

[whiskthecat]

The capacitance is hardly an assumption. There are no visible capacitors besides the SMD ceramics and looking at the size of them there is no way there is more than 1000uF there. As for the actual output ripple you are correct I have no way of knowing for sure without hooking a scope to it. The current ripple can get out of control quite quickly because of how low the internal resistance of the battery is. Just some millivolts of output voltage ripple which is present in most buck converters equates to a decent amount of current ripple.

Regardless as you have pointed out it is still preferable to the EPsolar unit if you just slap on some extra capacitance. You certainly can't modify the firmware yourself for the EPsolar.

much cheaper and easier than building one from scratch.

If you don't value your time it might not be cheaper. It's certainly not as fun.

[DeepFrz]

I sure would like to see someone stick a scope on that cheap charge controller to see how well it is doing its MPPT job. Maine Sail, do you still have the crap one you could test?

[irwin37]

Once again I have tried to stay out of this but there are a lot of misconceptions going on here. First I will say I worked as an engineer for 13 years for Solarex and/or BP Solar.

The largest number of capacitors on the board are not on the output (battery side) of the mppt charge controller they are on the input. The reason is simple, the input is basically a switching power supply and during the off cycle (which must happen as there is a transformer or inductor) there would be little or no current being pulled from your PV modules without the capacitors. The caps charge during the off cycle and give up this charge during the on cycle. This creates a continuous draw from the modules which is the only way you can get the full power from the modules.

The capacitance value is determined as a function of switching frequency. Most of these units switch at frequencies of 100K cycles or more which reduces the size of the inductor/transformer as well as the capacitor values needed. If you opened a modern switching power supply you would find there are very few large capacitors in them as they also run at high frequency's and have very little ripple.

I am sure there are other folks who can explain this better then me but I will say a lot of surface mount ceramic caps are considered better than one or two large electrolytic cap in high frequency applications.

[ErikFinn]

Originally Posted by SV THIRD DAY

Bingo...that's standard operating procedure in China.
See the demand for the product you are making for a US company and then steal and cheapen it. Meanwhile knowing that the US company can't afford the fight and that US consumers for the most part don't give a rat's ass about it if they can save $20. It just is what is as bad as it is.

So... Anyone tried one of these..?

Rosh Ce High Efficiency 60a80a Mppt Solar Charge Controller Of Fangpusun Mppt - Buy Mppt Solar Charge Controller,Solar Charge Controller,Pwm Solar Charge Controller Product on Alibaba.com

[whiskthecat]

Originally Posted by irwin37

The largest number of capacitors on the board are not on the output (battery side) of the mppt charge controller they are on the input.

Well, individual capacitors yes. Overall capacitance maybe not. Since the input side is higher voltage the capacitance of each single capacitor is much lower so you need more of them to make up for it. As seen with the 3 large electrolytics in the original post. There are 2 high voltage input capacitors totaling less than 1000uF and one single low voltage output capacitor of 3500uF. So in this case they have allocated more capacitance to the battery output than the input. Obviously there are no markings on the SMD ceramics but considering they are the same package size it's safe to assume a similar situation.

Originally Posted by irwin37

I am sure there are other folks who can explain this better then me but I will say a lot of surface mount ceramic caps are considered better than one or two large electrolytic cap in high frequency applications.

I think you've done a pretty good job explaining. But I might add that an MPPT isn't basically a switching power supply, it fully is one. Just one that has the additional feature of loading down the input to maximize the power it provides. Good points on the high frequency stuff but as always high is a relative term. Ceramics are great in the Mhz range but with high current supplies the higher frequency the greater the switching losses. It's a cost/efficiency trade off. Lower frequency means higher efficiency and more cost (Bigger capacitors and inductors). Higher frequency means more losses and less cost (Smaller capacitors and inductors). No one has had a chance to hook a scope to these but going off the capacitance in the original post and the size of the inductor I would guess it's probably around 200khz.

[Sailorman Ed]

Ok, read thru all of this, sometimes a little confusing as to which controller the comments attribute to. I am not nearly as smart as some of you so looking for your input. The ECO-Worthy seems to have issues based on the MaineSail comments and also on the uTube videos. So a year later, is the Tracer unit still working well? Can I use one for a 265watt / 31v panel ? Ed

[travellerw]

Originally Posted by Sailorman Ed

Ok, read thru all of this, sometimes a little confusing as to which controller the comments attribute to. I am not nearly as smart as some of you so looking for your input. The ECO-Worthy seems to have issues based on the MaineSail comments and also on the uTube videos. So a year later, is the Tracer unit still working well? Can I use one for a 265watt / 31v panel ? Ed

My tracer (2215BN) has been functioning flawless for the 7 months its been on the boat. Its spent the entire summer in the tropics in a cupboard at +40c or so.

A 265watt panel may be a little big for the 2215BN as that panel is is 5w over the maximim ratting of the controller. If I had the controller, I would be tempted to try, but if I was purchasing new, then I would just buy the 30A version. Its only $33 more. I bought mine from AliExpress. Here is a link.

30A MPPT Tracer 3215BN solar charge controller 12V 24V auto switch MPPT epsolar Tracer3215 solar regulator Light and dual timer -in Solar Controllers from Electrical Equipment & Supplies on Aliexpress.com | Alibaba Group

[socaldmax]

Originally Posted by Sailorman Ed

Ok, read thru all of this, sometimes a little confusing as to which controller the comments attribute to. I am not nearly as smart as some of you so looking for your input. The ECO-Worthy seems to have issues based on the MaineSail comments and also on the uTube videos. So a year later, is the Tracer unit still working well? Can I use one for a 265watt / 31v panel ? Ed

Can you elaborate on these problems with the eco-worthy controller?

I've installed 10 of them so far, and none of them has had a single problem, including the one that is installed in my trailer a year ago that I'm intentionally exceeding it's rated capacity by 33%. So far, so good.

[NahanniV]

Originally Posted by socaldmax

Can you elaborate on these problems with the eco-worthy controller?

I've installed 10 of them so far, and none of them has had a single problem, including the one that is installed in my trailer a year ago that I'm intentionally exceeding it's rated capacity by 33%. So far, so good.

Having installed 10 of these perhaps you might be able to answer a question about these controllers ? I asked the company, but did not get an answer.

When will the controller switch from absorption voltage to float voltage ?
I do not see any settings for this or explanation.
Is it time based or current based ?

I think MaineSails main objection to this controller is that the design was stolen (and possibly cheapened) from a US company.

Thanks,
John Middleton.

[socaldmax]

Originally Posted by NahanniV

Having installed 10 of these perhaps you might be able to answer a question about these controllers ? I asked the company, but did not get an answer.

When will the controller switch from absorption voltage to float voltage ?
I do not see any settings for this or explanation.
Is it time based or current based ?

I think MaineSails main objection to this controller is that the design was stolen (and possibly cheapened) from a US company.

Thanks,
John Middleton.

I haven't really sat around to watch them to see when they switched from absorption to float, that's a good question. I'm just guessing, but I *think* it's neither time based or current based. Once the batteries hit the target voltage, it switches over to float. But I'm not positive.

After Halloween, I'll be using my trailers again and I'll try to make it a point to figure out how long it holds absorption before switching to float.