Multiple controllers and capacity

Discussion about the MX60 Charge Controller

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magneticanomaly
Forum Member
Posts: 14
Joined: Wed Nov 19, 2008 1:08 pm
My RE system: 2 siemens 75's, 4 Shell 165's, MX60, FX2524, 28 Exide 100A-hr Lexan case 6V batteries from scrapyard, lots of cables and copper bus bars from scrapyard, multi-layer lightning prot syst including spark gaps, arrestors, capacitors, inductors
Location: West Virginia

Multiple controllers and capacity

Post by magneticanomaly » Mon Jun 10, 2019 11:59 am

I am expanding our PV array beyond the capacity of our MX-60 controller. Have an FM-80.

Q 1. Is there any problem with connecting both controllers to the same battery bank?

Q2. I understand both the the FM-80 and MX-60 will down-convert, for instance from a 48VDC array to 24VDC battery bank.. Is the 80A capacity measured at the higher input voltage (lower current) , or at the lower output voltage (higher current)?

THANKS!

pss
Forum Guru
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Joined: Mon Jul 24, 2017 8:40 am
My RE system: 8330 watts in three strings, Flexmax 60 x 3, Radian 8048A, GSLC load center, Mate 3S, Hub 10.3, FN-DC and 900 Amp, 48V Trojan T105-RE battery bank.

Re: Multiple controllers and capacity

Post by pss » Mon Jun 10, 2019 12:10 pm

You can connect multiple charge controllers to a single battery bank. What is important is that your charge controllers essentially have the same charging parameters set (absorb and float voltages, absorb times, wakeup times, etc. If you want the FM80 to be the "lead charger", you could probably set its voltages like 0.5 volts higher than your other charge controller. I have 3 FM60's, all with the same settings to one bank and they work just fine together.

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Kurt Lundquist
Alpha Energy Engineering
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Joined: Tue May 31, 2011 7:23 am
My RE system: VFX3524, Mate3, 200Ah 24V AGM Battery Bank
Location: Arlington, WA

Re: Multiple controllers and capacity

Post by Kurt Lundquist » Mon Jun 10, 2019 12:53 pm

magneticanomaly wrote:Q2. I understand both the the FM-80 and MX-60 will down-convert, for instance from a 48VDC array to 24VDC battery bank.. Is the 80A capacity measured at the higher input voltage (lower current) , or at the lower output voltage (higher current)?
The 80A rating is based on output. The input is rated for max 64 amps. As long as the input does not exceed 145V (150V max) and 64A the controller will buck the higher input voltage to whatever the battery bank needs. It does need at least 2V of greater input voltage vs output voltage to work properly.

-Kurt
Kurt Lundquist
Renewable Energy Project Engineer
http://alphaenergy.us/

magneticanomaly
Forum Member
Posts: 14
Joined: Wed Nov 19, 2008 1:08 pm
My RE system: 2 siemens 75's, 4 Shell 165's, MX60, FX2524, 28 Exide 100A-hr Lexan case 6V batteries from scrapyard, lots of cables and copper bus bars from scrapyard, multi-layer lightning prot syst including spark gaps, arrestors, capacitors, inductors
Location: West Virginia

Re: Multiple controllers and capacity

Post by magneticanomaly » Mon Jun 10, 2019 4:39 pm

Thank you, PSS and Kurt! Just the info i needed. Was on the barn roof drilling my new rails, hopefully in the correct pattern, until it rained.

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