Doug/Vamonos
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Multiple charge controllers from one panel to charge different batteries?
Hi. Can I connect more than one charge controller to a panel in order to charge different types and sizes of batteries? What I want to do is set up a
100 watt panel to pos and neg buss bars and then connect four small charge controllers in order to charge my car battery, quad battery, and two optima
boat batteries while I am away. I don't want to charge the batteries in parallel since I don't want them equalizing together. The simple alternative
is to buy four separate solar/battery maintainers, but I have the panel and the charge controllers to try this instead. Thanks.
[Edited on 11-2-2016 by Doug/Vamonos]
[Edited on 11-2-2016 by Doug/Vamonos]
[Edited on 11-2-2016 by Doug/Vamonos]
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mjs
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If the controllers are all PWM then give it a try as those controllers regulate output based on the battery voltage. A MPPT controller tries to
adjust the load that the panel sees to maximize panel output and then to feed the battery the needed charge parameter. Multiple MPPT controllers on
the same panel will probably end up fighting each other and not work very well.
[Edited on 11-2-2016 by mjs]
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BooJumMan
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I agree with above, using PWM controllers should work fine in parallel. They are essentially just smart switches.
In that pre-Google Earth and social media epoch, The Code was adhered to. It was based on a simple verity: if a locale had been transformational for
you, and you had put the hard yards in to get there and to learn it, to know it, why in god�s name would you broadcast the news, thus ruining the
future experience not only for yourself, but for future adventurers?
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Bob and Susan
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why would a mppt controller fight with the others?
the current coming down is what it is...
the controller stops extra current at the controller for the bank you are charging
if you splice the current BEFORE a controller then each controller get "un-cut" current from the panels
the controller shouldn't know what the other controllers are doing
another question is why charge all the batteries in the quad boat and car...just disconnect those ....no connection no loss...batteries in a store
last a long time
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mjs
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Quote: Originally posted by Bob and Susan  | why would a mppt controller fight with the others?
the current coming down is what it is...
the controller stops extra current at the controller for the bank you are charging
if you splice the current BEFORE a controller then each controller get "un-cut" current from the panels
the controller shouldn't know what the other controllers are doing
another question is why charge all the batteries in the quad boat and car...just disconnect those ....no connection no loss...batteries in a store
last a long time |
The current and voltage of a panel can and do vary. If you look at the specs on a solar panel they will usually list STC and NOTC outputs that are
different. Also the maximum voltage (Voc) and current (Isc) as well as the optimal operating current (Imp) and voltage (Vmp). The MPPT controller
varies the load the panel using Ohm's law to obtain the maximum wattage (Imp x Vmp) output of the panel under different conditions and the needed
charging requirements.
With multiple MPPT controllers they are working against each other as one adjusts the other tries to respond by making its own adjustments which the
first unit sees and then tries to adjust for and then the second adjusts and then the first, etc, etc.
The PWM controller only looks at the battery voltage and adjusts the charge parameters based on that. It does not adjust the load the panel sees to
try and maximize the panel output.
[Edited on 11-2-2016 by mjs]
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Bob and Susan
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why wouldn't this work
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Doug/Vamonos
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Good! The worst I can do is burn down the camp. :-)
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willardguy
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to be safe you might want to add diode's between panels and controllers
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Bob and Susan
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why a diode???
and what kind???
...for sure a breaker
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willardguy
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well lets assume the controllers don't have diode protection, what you have is two batteries in parallel...correct? what happens when one bank is
charged and the other isn't? undercharging, shorted batteries, even if the controllers have built in diodes it can't hurt, right?
on edit....of course I could be wrong!
[Edited on 11-3-2016 by willardguy]
[Edited on 11-3-2016 by willardguy]
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willardguy
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1 1/4 amp per side.....hope you have alot of time! 
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willardguy
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yeah nix the inverter idea...but I think what he's after makes sense! four small cheap charge controllers, just keep em isolated!
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willardguy
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| Quote: Originally posted by soulpatch | | Quote: Originally posted by willardguy | | yeah nix the inverter idea...but I think what he's after makes sense! four small cheap charge controllers, just keep em isolated!
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Why nix the inverter idea?
All he'd have to do is leave it on, plug in the charger and he's good to go.
He isn't going to get a whole lot of amperage out of 1 module.
Doesn't have to assemble a busbar, circuit protection, anything.
Plug it in and don't worry about it.
Once they are in float mode it shuts off and the inverter idles.
Me? I wouldn't worry about any of that.... unless you are gone 6 months at a time you are not going to lose much of a charge unless you use really
crappy batteries.
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well okay by me, I just don't see firing up an inverter to run (4) 1 1/4 amp charging circuits for $190 when you could buy (4) 4 or 5 amp charge
controllers for $30 apiece......but thats just me 
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Doug/Vamonos
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Hey Frank. Yes, I like that idea and would have done it (it was my first choice) but I have this fear of leaving my inverter on while I'm gone for
months at a time? Do I worry too much? For an update, my system is (8) 100 watt panels wired in two series at 48 volts, going to an Outback FM80Flex
controller to a bank of six large 105 amp 12 volt gel batteries wired at 12 volts. The inverter is Xantrex Prowatt 2000.
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