[RE-wrenches] Trojan RE Series Tech question

Wed Aug 3 08:56:11 PDT 2011

We have been dropping the absorption setting from 29.2 vdc
to 28.2-4 volts and raised the transition current setting
for the "empty" houses we care for over the winter and have
not seen any odd specific gravity variations and done an EQ
cycle before putting back into service. The water usage
during this setback time has dropped by 80-90%. I was very
surprised and the trips to 10,000 ft elevation can now be
reduced safely. When the client was there over the winter
they had to water every 6-7 weeks.

Dana Orzel

Great Solar Works, Inc

E - dana at solarwork.com

V - 970.626.5253

F - 970.626.4140

C - 970.209.4076

web - www.solarwork.com

"Responsible Technologies for Responsible People since 1988"

Do not ever believe anything, but seriously trust through
action.

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf
Of Allan Sindelar
Sent: Tuesday, August 02, 2011 5:05 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Trojan RE Series Tech question

Dave,
My response is only part of the answer, but may help with
your system setup. Both the SB50 and the FM60 have the
ability to limit the absorption time, although by different
methods. This may serve as a key setting to reduce gassing
and water use when the homeowners are away.

With the SB50, you can adjust the float transition current
to a allow the switch the batteries from acceptance (Blue
Sky's term for absorption) into float sooner. The default
recommendation is 2% of battery capacity per the manual;
perhaps 3% would allow it to transition sooner. The FM60 has
a setting to allow transition to float at a set current -
that is, as long as the voltage is at the bulk/absorption
setpoint (suggesting that the batteries are nearly full),
rather than staying in absorption for the entire timed
absorption period, if the current necessary to maintain
absorption voltage drops below this threshold (of typically
around 2% of battery capacity, or about 44 amps in your
case) the controller will go into float. My understanding is
that this is specifically to reduce daily absorption time
when batteries are lightly cycled, as in this case.

What I don't know is how these two very different
controllers (digital vs. analog, among other differences)
will work as a team together. Other Wrenches may have more
experience. My idea is to set the FTC on the SB50 high so
that it will transition first, allowing the FM80 to regulate
final transition. Maybe instead set the SB50 to a slightly
lower bulk/acceptance setpoint voltage, so that the SB50
drops out a bit sooner and the FM80 completes the daily
charge.
Allan

Allan Sindelar
 <mailto:Allan at positiveenergysolar.com>
Allan at positiveenergysolar.com
NABCEP Certified Photovoltaic Installer
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Positive Energy, Inc.
3201 Calle Marie
Santa Fe, New Mexico 87507
505 424-1112
www.positiveenergysolar.com
<http://www.positiveenergysolar.com/>  

On 8/2/2011 3:49 PM, Dave Palumbo wrote: 

Our go to guy at Trojan, Ron Parades, is evidently gone.
That's what they said at his old phone extension at Trojan.
I left a message for tech support there and have not heard
back as of yet.

Is there another Trojan Tech person to  specifically ask for
now? And is there one on this list helping out as Ron did
previously?

I have a question on the Trojan RE Series charging voltage
settings. I know the specific gravity is lower on this
series and the bulk charge voltage is correspondingly lower
than the old L-16's.

I have an off grid system for a remote home where the client
is only there from June through October. He has 1,560 Watts
of solar and a new battery bank rated at 2,220 AH at 12
volts (12 L-16 RE-2V batteries). 

That is a charge rate in the C/20 range. The homeowner uses
the system reasonable hard when they are there but during
the winter the load is only 15AH per day for a low voltage
security system.

He has previously serviced his Rolls CH-375's (1,400AH with
450 Watts of PV on that system, about a C/33 rate) in
October before leaving for 7 months and has not had a
problem with the battery electrolyte boiling off too much
over that time period. He got 10 years out of the Rolls
batteries using it in this way. The charge voltage for that
system was 14.6  through a Solar Boost 50.

The new system will have 1,110 Watts charging through a Out
Back FM 80 alongside the original array on the Solar Boost
for the total of 1,560 Watts of PV.

I am thinking of charging at 14.6 Bulk with a two hour
absorption time period in the summer  and then changing it
for the 7 month period when the system is lightly used. 

My question is, how low should I set the two charge
controllers for winter/spring use to minimize water
consumption? I'm thinking of 14.2 or 14.3 Volts, with a
reduced absorption time of one hour. 

And what should the float voltage setting be? The batteries
are in a basement that is kept at about 55 degrees. There is
temperature compensation on the battery charging.

Thank you,

David Palumbo

Independent Power LLC 

462 Solar Way Drive

Hyde Park, VT 05655

www.independentpowerllc.com 

NABCEP Certified PV Installer

Vermont Solar Partner

23 Years Experience, (802) 888-7194 

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