System questions

TVanover · April 2020

I have pieced together a system for our farm that has 4 flexmax80 charge controllers. It is part of an outback 14.7 KW package.

I have 32 6v full river 415 AH batteries tied together in 48v .

I have 12 of 24 365 watt pv panels up running 96V.

I am wondering if I should isolate the 4 battery arrays one to each charger for better operation.

Thoughts?

BB. · April 2020

Welcome to the forum TVA,

I am a little confused... Are you looking to break your 4x parallel strings of batteries, and pull, at least one, and charge with its own FM80?

In general, I am a fan of keeping everything together unless you know you have a weak/bad string and need to do some "corrective" charging on just the one string.

So, towards that end, I suggest measuring/logging the voltage of each battery (under charge/under load/resting, etc.) and look for a battery (or several) that are different from the rest of the bank. A battery that is too low of voltage or too high of voltage vs the rest, can be a sign of problems to come. It could be a bad connection, it could be a bad battery, it could be a low battery being masked by a bad higher voltage battery during charging, etc....

Next, us a DC current clamp meter and measure the charge/discharge current of each string... All strings should be roughly similar in current... A string that has high or low current, or during rest, a string that is "discharging" the other three strings can be an issue (shorted cell in one string, etc.).

If you do not have a DC Current Clamp DMM (Digital multi-meter), I would suggest you get one (really an AC+DC Current Clamp DMM--Not the AC only CC DMM):

https://www.amazon.com/UNI-T-Digital-Current-Capacitance-Multimeter/dp/B0772FYF5M (inexpensive, may be hard to find at the moment)
https://www.amazon.com/gp/product/B019CY4FB4 (mid-priced meter)

I suggest that you do the measurements/debugging first, before thinking of splitting up the bank.

Your thoughts/feedback?

-Bill

TVanover · April 2020

Everything on this system is brand new, spoke to rep yesterday from outback and he gave me the answer. I currently have 2 6 panel arrays being combined to a 1 aw cable and going to a barn 200 feet from the power panel. In the barn I split it back out into individual circuits. with another breaker box. Rep said I can't do that, so for the moment I'll

use a single charge controller of 4
take 3 panels offline
reconfigure to 150 by cabling

the fm80 cannot take over 4000kw and I am apparently spiking them as they cycle through operations

I am new to this with a good deal of electrical mechanical background just need to fit all the pieces together.

We are in process of building house and the power panel will be relocated there when completed and when that happens I'll set out the rest of the arrays and have 4 panel arrays wired independently to the 4 charge controllers.

While 80 amps charge may not be much on the battery array I built for this we are not there all the time and are not consuming much off the batteries so we should be ok as long as we don't go crazy on it when we are there working .

Thanks for your input and ideas!

BB. · April 2020

Yes, you are correct, each controller needs its own properly sized/configured array. You cannot connect 4x MPPT charge controllers to one large array.

Sounds like you are on the correct path.

-Bill

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