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stmbtwle

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Reply with quote  #11 
In my experience the charging algorithms don't have to match that closely. One charger will simply stop charging and the other will finish up. At least that's what I've observed. If the batteries are low, both chargers are on line. As voltage comes up I can watch the meters and see the amps drop as the charge controller cuts back while the engine alternator or line charger keeps on. If the voltage drops due to the load, the charge controller will kick back on again. Is it perfect? Probably not. Does it work? Very definitely.

If you are having daily outages, you may NEED both systems to recharge your batteries before the next outage. This could be why you're not getting the battery performance you expect; they might not be getting fully charged. Just a thought, I don't see the charging rate in the specs.

I've also observed that if the batteries are charged and a load such as my fridge comes on, the charge controller will pick up the load and the batteries never "see" it.

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Rick H Parker

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Reply with quote  #12 
"One charger will simply stop charging and the other will finish up."

That is because the algorithms are the same, its the set points that have a slight difference.

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Rick H Parker
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stmbtwle

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Reply with quote  #13 
I rather doubt the algorithms are the same, considering the great differences in the type (and age) of the charging systems (one dates to the 1970s, another to the '80s). But they all do work together. The set points do appear to be slightly different.

Anyway, I see no reason why the UPS charger and a solar charge controller cannot be used in parallel.

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marco.rc.santos

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Reply with quote  #14 

Thank you for your comments, this is helping me a lot to build my strategy. You can find below my comments to some replies.

Even at 500w load, your current battery set is only going to last you maybe 14 hours. If you want more time you'll need bigger/more batteries, or find a way to reduce your load. LED lights are highly recommended if you don't already have them. You could get a second set of batteries and parallel them in with the first set, this should about double your run time.

When you say "your battery set" you mean my 16x38Ah that I currently have installed or you already consider that my intention is to have two sets of 16x38Ah? I have a second set that I installed in parallel, but is currently disassembled for testing at the vendor, due to low capacity (some batteries were measuring less than 10.5V, while others were above 12V). All my lights and appliances are high efficiency/low power. What I have installed is already at the minimum possible. 

If it where mine I would open it and hack the charging section
Well, my initial approach of building a charging module out of contactors, relays and LVD didn't work out quite as expected, so I'm trying to have as most as possible off the shelf assembled components, so I won't be hacking the UPS for now. Furthermore, the UPS is still under warranty and it would void it.
 
There are not a lot of 192V charge controllers out there. I did find some on AliExpress and the suppliers do ship to Angola
I just don't know if I trust AliExpress or Alibaba. Also, I'm trying to keep off the chinese direct market for such products, as a small failure due to low quality components could result on a fire, due to the voltages and currents involved. But I think the solution I'll chose will be a 192V charge controller, as it is a direct replacement of what I currently have.
 
Another alternative is to design a new system using the batteries, solar panels you have along with a new inverter and a charge controller the can accept both grid and solar panels.This would lower your electric bill and give you a backup for when the grid goes down.
For now I don't worry about the electric bill, as I pay a fixed monthly amount (that's how it's done here, for now), and if I would want to have the panels charge while there is power from the grid it would increase the complexity of the system. I'm trying to keep it as simple as possible, as long as it does its duty.
Having a new inverter that would accept both grid and solar panels is a good approach, but it would increase the invesment cost a lot if I want to keep the same power output that I currently have.
 
If you are having daily outages, you may NEED both systems to recharge your batteries before the next outage.
That's right. I need the batteries to be charged from the grid when there is power and from the solar panels when there's an outage. 
 
This could be why you're not getting the battery performance you expect; they might not be getting fully charged. Just a thought, I don't see the charging rate in the specs.
It takes around 12h to fully charge a single set of batteries (that is what I currently have installed). Sometimes we have 1 or 2 days without any outage, but still, after the power goes out it only takes about 5h until the UPS is off (~7h if nothing specific is being used at home - those 500W I mentioned before).
 
The charging algorithms must match so that they do not interfere with each other. 
I'm not worried about having two charging sources at the same time, as the panels will only "kick in" once there is an outage; and once the power returns, the panels will be disconnected.

Thanks
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stmbtwle

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Reply with quote  #15 
When you say "your battery set" you mean my 16x38Ah that I currently have installed... 
Yes that was what I meant.  I had forgotten you already had two sets. sorry.

Considering all the batteries are in series and NOT reading the same voltage, I'd suspect some of them are bad.

Hacking the the charging section may seem like a good idea, but if you get something wrong you could ruin the UPS, AND any warranty you may have.  I can't recommend it.

Typically, when are your outages, daytime or night?  If daytime, your solar array can help cover the load, if at night, it's kind of useless unless you're charging batteries during the day. I wouldn't disconnect it when you have power, the charge controller will take care of that when you get it installed. It will bring the batteries up to charge and then go to "float" mode.

I'm not sure I'd worry too much about Chinese hardware. China is fast becoming a world leader in solar and most electronics are made there already.  If you buy it from the US you'll pay twice the price and likely it'll still be made in China, sad to say.


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Solar is like the wind. It may be free, but putting it to work isn't!
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Rick H Parker

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Reply with quote  #16 
"I'm trying to keep off the chinese direct market for such products, as a small failure due to low quality components could result on a fire, due to the voltages and currents involved."

The Chinese have gotten really good at engineering and manufacturing electronics. PWM is very mature technology, it has been around since the 1960s. Anybody can build a good PWM with off the shelf components and public domain circuits. I'm more worried about getting getting taken by scammers that buy defects and sell them at inflated prices then, getting defects direct from Chinese suppliers.

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Rick H Parker
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Rick H Parker

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Reply with quote  #17 
"I'm not worried about having two charging sources at the same time, as the panels will only "kick in" once there is an outage; and once the power returns, the panels will be disconnected."

That would be easy as pie. A relay that switches in sync with the grid.

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Rick H Parker
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Rick H Parker

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Reply with quote  #18 
"Hacking the the charging section may seem like a good idea, but if you get something wrong you could ruin the UPS, AND any warranty you may have. I can't recommend it."

That is why I listed what to do but no specifics on how to do it. If one needs to be told the specifics, one should not attempt it.

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Rick H Parker
Kansas, USA
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marco.rc.santos

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Reply with quote  #19 

Typically my outages are during the day, but sometimes they last several days, so I need to make sure that the charges make the batteries last long enough until the next charging cycle begins.

I'm not sure I'd worry too much about Chinese hardware. China is fast becoming a world leader in solar and most electronics are made there already.  If you buy it from the US you'll pay twice the price and likely it'll still be made in China, sad to say.
Said that, I'm looking into this charge controller.

Is there a chance that the house load makes the UPS demand higher power from the charger than it (or the panels) can supply? In this case what would happen?

Rick H Parker

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Reply with quote  #20 
"Is there a chance that the house load makes the UPS demand higher power from the charger than it (or the panels) can supply? In this case what would happen?"

The same thing that happen when your smaller UPS could not meet the power demand.


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Rick H Parker
Kansas, USA
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