[RE-wrenches] Trojan RE Series Tech question

Wed Aug 3 09:37:30 PDT 2011

Alan,

You are correct that on some solar controllers, a current set point, combined with a set time will allow the solar controller to "recognize" end of the absorption-regulation-acceptance phase. Since the energy source is PV, the current available from the PV array varies during the course of the day, which makes the set point difficult to evaluate.
Some digital solar controllers manufacturers will use the PWM duty cycle measurement as an image of the current level to determine when ending the regulation stage. Up to approximately 30A industrial solar series charge controllers like Morningstar Corp using constant voltage PWM would consider that if duty cycle reaches 30% and stay there for 1 hour, they consider the regulation stage completed and move to float charge stage. On larger controller using MPPT will use a different % (as mentioned by Alan) and you can adjust the time.

John
John F. DeBoever
Global Projects Director - Renewable Energy
Trojan Battery Company

12380 Clark Street
Santa Fe Springs, CA 90670
Tel: +1-562-236-3000 Ext. 3139
Cell: +1-514-514-7600 - Time Zone: EST USA (GMT-5)
Fax: +1-562-236-3239
jdeboever at trojanbattery.com<mailto:jdeboever at trojanbattery.com>
NEW WEBSITE - http://www.trojanbatteryre.com/

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From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Dana
Sent: Wednesday, August 03, 2011 11:56 AM
To: Allan at positiveenergysolar.com; 'RE-wrenches'
Subject: Re: [RE-wrenches] Trojan RE Series Tech question

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<mailto:dana at solarwork.com>
V - 970.626.5253
F - 970.626.4140
C - 970.209.4076
web - www.solarwork.com<http://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
Allan at positiveenergysolar.com<mailto: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<http://www.independentpowerllc.com>
NABCEP Certified PV Installer
Vermont Solar Partner
23 Years Experience, (802) 888-7194

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