MPPT charge controller options 4xAGM in Serries

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Re: MPPT charge controller options 4xAGM in Serries

Postby APR » Sun Jan 15, 2017 10:03 am

Little Ray wrote:Battery Charging Current @ 57.6V 50 Amps.


Little Ray in another thread... wrote:What are the advantages and disadvantages between using 4x 200Ah or 8x 100Ah AGM for 48v 200Ah?


A 50 amp charge current to a 200 amp battery each days is sticking it to the battery pack. If you want battery longevity, it would typically be suggested that you charge your battery pack at a C10 rate, or to put it another way, your charge amps should be 1/10 of the battery amp hour rating.

What do you expect your daily battery discharge cycle to be? How many amps, and for how long? The Depth of Discharge (DOD) you will subject the batter pack to daily?
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Re: MPPT charge controller options 4xAGM in Serries

Postby Little Ray » Sun Jan 15, 2017 6:08 pm

226.8W / 48v = 4.725A per hr for 12hrs/night, is a starting point but far from concluded.

Yes, the charging current is way to high for Battery Bank.
I wanted to get some feed back on a controller that would handle 50A, because I am weighing countless options.
That said, you are spot on with point.

Putting aside Battery capacity and Charge rate, another open question is Battery type?

I am lead to believe Flooded Lead Acid are cheaper, last longer "can be cycled more" then AGM.
When I look at FLA prices available in Australia, it looks like a mine field for the new customer?
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Re: MPPT charge controller options 4xAGM in Serries

Postby davidg » Sun Jan 15, 2017 8:16 pm

The fact that a MPPT charge controller can output say 50A, 60A or even 80A is not really an issue, when you use a good smart MPPT charge controller system. This is one of the reasons why I have a heavy leaning towards the likes of the MIDnite classic range, when used with a "whizbang junior" it might only output (programmed) the correct amount of current when only charging the batteries, but it can output far more when there is a load such as an inverter drawing power. So if the charge, lets say should be 20A to the batteries but there is 30A load being drawn by the inverter and assuming there is enough solar being generated then the controller can output 50A. This is the benefit of using good, intelligent MPPT charging system with enough Solar PV installed. :mrgreen: 8-)
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Re: MPPT charge controller options 4xAGM in Serries

Postby Little Ray » Mon Jan 16, 2017 6:48 am

Yes, the load outside and during solar hours is being evaluated. The math is simple, but the Battery type can wait. Pretty much all MPPT programmable chargers should have ability to match load, as it is there function. Not sure that everything leads to a particular brand. My best option might well be different.

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Re: MPPT charge controller options 4xAGM in Serries

Postby Little Ray » Tue Jan 17, 2017 4:16 pm

davidg wrote: smart MPPT charge controller system.


Sometimes the features are for certain application, so to test this:

Lets say we have panels that might be around 100 or 150 VOC, so none specific!
We have a nominal 48v system with no inverter, just a none specific fixed 48v DC load without surge current!

Forget about LCD screens, again, none specific, could be using a Multi-meter!

Whether the above is realistic or even real, is irrelevant.
I just want to isolate the question without referring to a single product or solution.

------------------------------------------
The smart MPPT charge controller maximizes the usable out put of the Array
So for the 48v DC system we have a battery that wants charging at %10 of Capacity or 10A (None specific).
During the day our 48v DC load switches on which also requires 10A (None specific).

The Maximum Charge to Bank is limited to 10A, how does the MPPT sense and provide current to a DC Load switching on during the day. With AC Load the process used could be different, this is direct DC Load from Bank.

Looking at this problem with DC only system, it would seem logical to use an MPPT controller to maximize the Arrays usable energy and use basic current limiting on the Bank.

If the bank is charged and the load is off, that energy is lost regardless.

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Re: MPPT charge controller options 4xAGM in Serries

Postby davidg » Tue Jan 17, 2017 9:33 pm

Little Ray wrote:
davidg wrote: smart MPPT charge controller system.

Sometimes the features are for certain application, so to test this:

No can't. It really does depend on the product.

If it can't tell how much charge is going to the battery pack compared to demand then it can't decide how much to output within it's available limits of design or available current.

I mentioned the "Whizbang Junior" this is small CCT and Shunt that is linked to Midnite which has software support internally so it knows exactly how much is going into or out the batteries in realtime and adjusts available current output accordingly.

Other systems may do similar. Midnite Solar for MPPT charge controller to DC battery charging is one the most elegant that really works well, that's why I keep coming back to it.

If an MPPT charge controller regardless of brand cannot tell what the charge rate is actually being supplied to batteries then it will never be able to adjust charge current properly to maintain an accurate rate when other stuff is taking away current that would otherwise go to the batteries.
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Re: MPPT charge controller options 4xAGM in Serries

Postby Little Ray » Thu Jan 19, 2017 2:07 am

That helps, the wizbang was not very descriptive about what it actually did.
I am assuming the Midnight has only one output, AC is of no value in this application!
So the Controller sees the battery state and functions on the total load current including charge!?

Is the Midnite sensing 'connected to inverter for AC loads?'
Can it function with the same performance if the load is 48v connected directly to the Batteries.

Are you aware of the product for 48v DC loads, or just for conventional AC inverter operation?

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Re: MPPT charge controller options 4xAGM in Serries

Postby davidg » Thu Jan 19, 2017 4:55 am

Little Ray wrote:That helps, the wizbang was not very descriptive about what it actually did.
I am assuming the Midnight has only one output, AC is of no value in this application!

MIDnite Solar.

Classic 150 is DC MPPT charger controller.
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