[RE-wrenches] Voltage settings for AGM's in grid tie with back up

[Dave Palumbo]

I am looking for a recommendation for Max Voltage, and how often to attain
this bulk voltage? For the following system: 

.         Trojan 8D AGM battery bank (4 bats for 11kWh rated storage with
900 Watts of PV)

.         Home was previously off gird. We upgraded it to a grid tied net
metered system using OutBack pre-wired FP1-3 (GVFX3524 with FM 80 etc.)

I know with wet cell L-16RE's in a Radian grid back up application we were
told to program an Equalization charge every 60 days which we can do with
that Radian system.

.         Right now we have this system set up as follows:  

FM 80 PV Charge Controller: 

*	GT (Grid Tied enabled)
*	Absorb 28.6 V
*	Absorb time 4 hrs
*	Float 27.0 V
*	End Amps 0 (originally had set at 9A but OutBack senior tech support
person Katee Wood helped us understand the need for -0- when trying to sell)

 

Flex Net DC set to:  Firmware REV 001.001.071

*	Battery Voltage 28.0
*	Return Amps 9.2
*	Parameters met 1 minute
*	94% charge efficiency

 

Mate 2 controller settings: REV 4.2.1

*	AC input USE
*	RE-Float 25.0
*	Absorb 28.2V
*	Absorb time 0.1
*	Float 27.0
*	Float time 0
*	Sell RE Voltage 25.6                         
*	GT Authority Grid Tie
*	Re-bulk 24.0V                

 

After some learning curve selling problems it has now been selling very well
for the past two weeks. But the state of charge is now down to 70% on the
Flex Net (I don't know the accuracy of this as Katee had us disable the FN
DC Advanced Grid Tie Authority feature in the interest of much better
selling performance) and the MAX Voltage has only reached 26.4. The MIN
Voltage is 25.5. They typically are sitting at 25.9 to 26.2 Volts.

 

This customer, having been a good caretaker of wet cell LA's for 15 years is
concerned that we get the settings as good as is possible for efficient
selling but also to foster as long a battery life as is possible.

 

What is the best way to reach an occasional high voltage of say 28.4 (if
that is our target). Is this programmable automatically with this OutBack
setup or do we need to trigger a bulk charge manually?

.         If so. What is the easiest, and or best way, to trigger the bulk
charge?

 

Thanks,

Dave

 

David Palumbo

Independent Power LLC 

462 Solar Way Drive

Hyde Park, VT 05655

www.independentpowerllc.com 

NABCEP Certified PV Installer

Vermont Solar Partner

24 Years Experience, (802) 888-7194 

 

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