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Old 12-28-2018, 08:14 AM   #29
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Originally Posted by Shermy1987 View Post
Charging with two charge controllers in almost every instance is perfectly OK. The idea that one controller will fight another controller is simply false. This idea comes from a lack of understanding on how a battery charges.

If a battery is in bulk charging stage, voltage varies and current is constant. If the first charger is charging at 13.7 volts. The second charger charges at 13.7 and current is added.

In absorbtion stage you may get some small variations if each charge controller has different parameters for constant voltage.

This goes beyond just two charge controllers. Theoretically you could charge with two charge controllers, your vehicles alternator and your generator. They will all be working. Your alternator won't be switching on and off. Neither will your generator.

Charging with 2 controllers is common in off grid systems. When one solar array has reached a maximum and another is added. Or say you have one array that gets heavily shaded in winter. You add a second array with a separate controller somewhere else where the sun is shining. Some controllers do talk to each other so they operate on the exact same charge algorithm. However this isn't a necessity and successful charging happens with mixed controllers.

If somebody is experiencing their portable charge controller fighting their TV charge controller. I'd like to see what controllers are being used and dig into how this could possibly be happening.
Hi

....errrr ..... not so much. There are lots of threads on why this is a problem.

Once they both hit 13.7V and you get a slightly higher voltage on one (which you will) the current drops. When it drops past the set threshold, the converter will fold back into float mode and stay there.

The same voltage offset = current imbalance problem is an issue even without the fold back. If you want them both to do the job, you need to keep one in slave mode. It stays in constant current mode and simply duplicates the current delivered by the device that is set to 13.7V. If you take a look at how industrial power systems do this, they all work that way.

Bob
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Old 12-28-2018, 11:45 AM   #30
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Originally Posted by uncle_bob View Post
Hi

....errrr ..... not so much. There are lots of threads on why this is a problem.

Once they both hit 13.7V and you get a slightly higher voltage on one (which you will) the current drops. When it drops past the set threshold, the converter will fold back into float mode and stay there.

The same voltage offset = current imbalance problem is an issue even without the fold back. If you want them both to do the job, you need to keep one in slave mode. It stays in constant current mode and simply duplicates the current delivered by the device that is set to 13.7V. If you take a look at how industrial power systems do this, they all work that way.

Bob
Like I said. Provide us the models of controllers that are having the problem you're stating along with the percentage of time lost to reach full charge. It would be great to have a list of these on the thread.

There's lots of assumptions being thrown around. Who's showing the evidence?
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Old 12-29-2018, 10:59 AM   #31
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Hi

Every non-networked non-slaved controller out there has the problem. A list of "controllers with the problem" is simply a list of every controller made. There is no value in listing every controller on the market. The only ones that I know of that can be set up *not* to have the problem are the Victron units when run with a networking controller to slave them together. I'm sure there are others out there, but they have the same gotcha - you need the networking controller and the software in it to get things to work. That runs the price up.

Bob
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Old 12-29-2018, 03:02 PM   #32
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We have 200 watts of solar on the roof, looks like an AM Solar installation, cant tell for sure, weíre the second owners with the solar added by the first owner (thank you whoever you are!) along with group 27 AGMs somehow stuffed into the stock battery box. This provides ample power in most conditions. We also have a portable 100w panel from InstaPark called a Mars-100. I bought it from Amazon 5 or more years ago for a ridiculously low price and used it as our primary recharging source when we had a t@b camper. Now I use it as backup primarily when the AS19 is parked in the shade. The portable panel has its own charge controller and I wired up a female 7-way receptacle such that I can just plug it into the trailer 7-way connector. I bought 50 feet of 10-gauge landscape lighting wire to allow putting the panel in the sun. Iím thinking of buying 50 feet of 6-gauge flexible welding wire to replace the landscape wire but I havenít gotten around to it. As it is, I can still get adequate charge from this setup so replacing the wire hasnít been a priority. I guess Iíd do it if the portable panel was my primary charging source. I did use the 6-gauge welding wire to power the truckís 7-way receptacle for better en route charging but thatís another story. Anyway, my observation is as uncle_bob suggests, charging comes from which ever panel outputs the most power at the moment. With roof-mounted solar Iím not sure if this or the TV charges while towing. I guess it depends on the charge state of the TV battery. The TV regulator sees the combination of the TV and trailer batteries.
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Old 12-31-2018, 05:10 PM   #33
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All I can say is that the solar business my family has ran for 20 years hasn't shown much evidence of this. Installing up to 5 solar controllers is normal practice. When an array exceeds what a single controller can provide, another is installed and so on. Most controllers seem to be limited to about 60 to 80 amps.

People have the most problemsl when they piggy back controllers. This should never be done. The controllers need to be connected directly to a bus bar or the battery. Only quality controllers are ever used (morningstar, outback power etc) and no they don't synchronise with each other.

The only thing that ever happens is one controller will turn off before the other. This is always at a time when absorbtion is almost complete and the current from one array is sufficient to provide maximum allowable amps anyhow. 20 years and hundreds of installs is pretty good evidence to show that many controllers work just fine in tandem.
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Old 01-01-2019, 11:20 AM   #34
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https://www-altestore-com.cdn.amppro...in-parallel%2F

Found this on the alte store site where two controllers are wired in parallel.

(Hope the link worked my first try. If not search alte store two controllers in parallel)

Thanks
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Old 01-01-2019, 02:18 PM   #35
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Originally Posted by Shermy1987 View Post
All I can say is that the solar business my family has ran for 20 years hasn't shown much evidence of this. Installing up to 5 solar controllers is normal practice. When an array exceeds what a single controller can provide, another is installed and so on. Most controllers seem to be limited to about 60 to 80 amps.

People have the most problemsl when they piggy back controllers. This should never be done. The controllers need to be connected directly to a bus bar or the battery. Only quality controllers are ever used (morningstar, outback power etc) and no they don't synchronise with each other.

The only thing that ever happens is one controller will turn off before the other. This is always at a time when absorbtion is almost complete and the current from one array is sufficient to provide maximum allowable amps anyhow. 20 years and hundreds of installs is pretty good evidence to show that many controllers work just fine in tandem.
Hi

Gee..... one shuts down and the other one is the only one supplying current. Sounds a lot like "they stop working together".

The point this happens is when they go out of constant current mode....

Bob
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Old 01-10-2019, 06:17 PM   #36
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Found this real-world video showing what happens hooking two charge controllers together.



https://www.altestore.com/blog/2016/...-parallel/amp/
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Old 01-11-2019, 12:18 AM   #37
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Found this real-world video showing what happens hooking two charge controllers together.



https://www.altestore.com/blog/2016/...-parallel/amp/
Great minds think alike

See post 34

The alte store have a great set of teaching and exploring videos.
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Old 01-11-2019, 07:16 AM   #38
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Wow. Seems to me it would have been easier to rewire the A-Frame connector to the panel side of the controller. Plug your portable panel (without a built-in controller) into the A-Frame and all panels work together seamlessly.
I would love to see some comments on this approach. I have a 27FB and the charge controller is right there under the front bunk not 2 feet from the A-frame plug. I have factory solar on the roof (2 panels -160 watts) with one open port in the roof top Z-amp collector plug. How would adding a third panel (portable) directly to the input side of the charge controller be any different than adding a third panel to the roof?
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Old 01-11-2019, 09:08 AM   #39
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I would love to see some comments on this approach. I have a 27FB and the charge controller is right there under the front bunk not 2 feet from the A-frame plug. I have factory solar on the roof (2 panels -160 watts) with one open port in the roof top Z-amp collector plug. How would adding a third panel (portable) directly to the input side of the charge controller be any different than adding a third panel to the roof?
It would be the same. You would have to make sure the new solar panel matched in voltage and cell number. The wiring and charge controller would also have to be able to handle the combined current of the old panels plus the new panel.
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