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Old 28-01-2022, 18:31   #1
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2 panels, 2 controllers Flooded batteries... all good?

So as I try to get my feet wet in the solar world I need guidance.
Our boat, a Hans Christian Ketch, has very little real estate for solar panels. I will be installing 2X100W Renogy Eclipse panels. Almost certainly one panel will be shaded when the other isn't.
Here is my "plan"
-Each Panel will connect to a separate MPPT Controller
-Both controllers will connect together to the house bank (small)
-Controllers I have selected are Renogy Rover Elites
-One controller will be set to FLA and the other to Sealed The flooded battery setting invokes a "equallization" every 28 days. The sealed setting does not equalize. (I believe)

Is this all sensible or should I reconsider my basic master plan? Is using 2 controllers going to cause issues when they are trying to "read" the batteries state?
Would I be better off sticking with one controller?

Thanks
RG
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Old 29-01-2022, 00:14   #2
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Re: 2 panels, 2 controllers Flooded batteries... all good?

So long as your battery bank is flooded cells your plan will work well. At lower state of charge both controllers will deliver full capacity, at higher state of charge one will hibernate while the other continues to charge according to its programmed profile - no problem.

If your bank is sealed then you will boil off electrolyte during equalization resulting in damaged cells.
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Old 30-01-2022, 02:02   #3
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Re: 2 panels, 2 controllers Flooded batteries... all good?

set both contollers the same correct type. why would you set them different if going to same battery?
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Old 30-01-2022, 17:50   #4
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Re: 2 panels, 2 controllers Flooded batteries... all good?

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Originally Posted by smac999 View Post
set both contollers the same correct type. why would you set them different if going to same battery?
The reason is because unless they are clocked the same, one may perform its 28day "equalize function" and then the other could do it at another time. Would this not be damaging to the batteries by potentially "equalizing" twice in the 28day period? By setting on to LFA and the other to Sealed, only one would equalize every 28 days, otherwise the charge profiles are the same.
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Old 31-01-2022, 09:26   #5
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2 panels, 2 controllers Flooded batteries... all good?

Got an email response from Renogy, does this seem right? I am looking at 20a river elite controllers
Hello Jim,

“Thanks for responding to my email.

It may help to know that since the said controller is not designed to be stacked, they might overcharge your battery when using 2 controllers for the same battery bank. You can check our Rover 100A and 60A if you wish to have a unit that can be paralleled with one another.

Feel free to send us an email if you have any other inquiries.”
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Old 31-01-2022, 12:27   #6
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Re: 2 panels, 2 controllers Flooded batteries... all good?

If you have 100Ah or more of flooded battery bank there is no chance of overcharging with 200W of panel.

If you have 200Ah or more there is no chance of overcharging with 40Amps input from your 2 charge controllers (which would require more than doubling your existing panel capacity),

Methinks they are trying to boost sales.
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Old 31-01-2022, 16:17   #7
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Re: 2 panels, 2 controllers Flooded batteries... all good?

When installing multiple solar panels, especially panels subject to differing amount of shadow, multiple solar controllers will produce a slightly higher yield, as well as adding redundancy, usually for only a small extra cost.

Unfortunately, solar controllers without user control of all of the charging parameters (such as the Renogy Rover Elites) make life difficult. Even with a single controller it is often not possible to select the optimium charge parameters and this is costly in terms of the energy harvested and the life of the batteries.

As you point out, multiple equalisation cycles are not ideal. Selecting the gel setting on one controller will limit the output from one panel, due to the lower bulk voltage. A better option would be to select the AGM setting on one controller. This should also eliminate the equalisation cycle, although the handbook for the Renogy controller is far from clear on this point. The AGM setting keeps the bulk and float voltage identical to the flooded setting, although at 14.6v this is too low for many flooded batteries.

A better option would be select controllers that are more user adjustable such as the Victron models. This would enable the voltage set points and durations to set correctly for each make of battery.
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Old 31-01-2022, 16:21   #8
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Re: 2 panels, 2 controllers Flooded batteries... all good?

Quote:
Originally Posted by markcouz View Post
If you have 100Ah or more of flooded battery bank there is no chance of overcharging with 200W of panel.

If you have 200Ah or more there is no chance of overcharging with 40Amps input from your 2 charge controllers (which would require more than doubling your existing panel capacity),

Methinks they are trying to boost sales.
The house bank can be seriously overcharged with a much smaller input than your post indicates.
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Old 31-01-2022, 19:42   #9
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Re: 2 panels, 2 controllers Flooded batteries... all good?

I asked for more info from Renogy, here is the reply I just received…
“Hi Jim,

Apologies for the confusion.

To clarify, the Rover Elite controller cannot be stacked since the unit was designed to detect that there is another power source that charges the battery. In that case, it will automatically stop charging. Also, since they are both controllers, either the unit that produces the most power will only charge the battery bank, or worst case, both of them will stop working due to the same feature that they have.”
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Old 31-01-2022, 21:19   #10
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Re: 2 panels, 2 controllers Flooded batteries... all good?

I think whoever wrote the reply probably does not understand how their charge algorithm works.

If what they say is true, their controllers would be a poor choice for most boats as multiple charge sources such as the alternator, wind, battery charger etc would also disable the solar output.

Either way, this controller with only a few fixed charging profiles is not a great solution for boats.
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Old 07-02-2022, 08:32   #11
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Re: 2 panels, 2 controllers Flooded batteries... all good?

I didn’t want to invest in a higher price system until I figure out placements and needs… this is my first foray into solar
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