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groingo
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# Posted: 7 May 2014 08:31pm
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That's the question, using mppt power controller can the power output (amps) be set or is is automatic?
Am considering doing a small 500 watt solar, but the controller shows it puts out 60amps which would fry my batteries.... looking for some user advise.
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MtnDon
Member
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# Posted: 7 May 2014 10:00pm - Edited by: MtnDon
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No you can set voltage limits for the absorb, float and equalize charge states but the CC does the thinking for the amps. At least that's how the Outback, Xantrex, Midnight Solar ones I am familiar with work.
But there may not be a problem. Sounds like the MPPT controller can put out a maximum of 60 amps, but that depends on what the input is. More details needed...
PV panels wattage = 500 ?
Look at the panel specs and what is...
Voc
Vmp or Vmax
Isc
Imp or Imax
Also what is the batteries amp-hour capacity?
Voltage? How are they wired together?
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MtnDon
Member
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# Posted: 7 May 2014 10:06pm - Edited by: MtnDon
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Part of the idea behind MPPT is that the CC will Maximize the charge by choosing the voltage and amperage that will charge the batteries fastest. That's all it tries to do when in bulk; puts the voltage just high enough to push the current and maximizes the current flow into the batteries. If the CC has a battery temperature probe/sensor the CC will cut back the current if/when the batteries get too hot.
Matching the panel wattage to the batteries is how to control the theoretical maximum current, that's why the extra info is needed to be of any real help.
You are right in that too high a charge current can ruin batteries, shorten their life.
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groingo
Member
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# Posted: 7 May 2014 10:29pm
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Don, you answered the part I was in doubt on, was to late to call Outback so I thought I'd run it by and see if I was on the right track, looks like I was.
Going to put together the package tomorrow and finally get it done now that my power has been consistantly under 1/2 kwh a day and less for the past year with a fridge going!
Sales people are one thing but actual users are more credible... .thanx!
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MtnDon
Member
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# Posted: 7 May 2014 11:25pm
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If your system is small have a look at the Midnite Solar "The Kid"
midnitesolar.com
I may have bought it if it had been available back when I was doing our system. I don't come anywhere close to using the capacity of the FM60 and the MN The Kid would do what I need for $400.
I like our Outback equipment, but MN has some highly rated stuff too. FWIW MN was started by engineers who left Outback. Outback was started by engineers who left Trace (now Xantrex)
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creeky
Member
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# Posted: 9 May 2014 09:32am
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One thIng: 500 watts of solar will only create 35* amps of power. You have crown 295s if memory serves. 2 or 4? So you should have no worries there.
The good thing about a 60 amp controller is if you decide to expand your battery/panel setup in the future you've got the capacity to increase to 800 watts of panels (at 12 volts).
* watts=voltage amps, so 500 watts = 15v (charge voltage) X amps. Then amps = 35 (more or less)
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