Hi: This may not be the problem, but I wanted to bring it up as I have heard of a few cases of battery boiling issues with various charge controllers and want to suggest a possible cause.
I'll do this point form. It's easier to describe it that way: 1. Solar charge controllers are programmed to go to bulk charge in the morning. 2. The intensity of the sunlight starts off low in the morning and depending on the weather during the day, the intensity can reach any level between virtually 0% and 100%. 3. The exit criteria for bulk is that the battery voltage reaches the Vbulk/abs volts setting or a bulk/abs timer times out. 4. If the sunlight conditions are just right to keep the charging voltage just below the Vbulk/abs setpoint, the exit from bulk/abs will be the timer. 5. Bulk/Abs timers are usually set for rather a long time, many hours is not uncommon. 6. Given the above, it is possible that the battery stays at gassing voltages for many hours every day at certain times of the year when the sunlight intensity is just right to support that. 7. As a consequence the boiling problem will show up only at particular sites, particular battery/charge controller sizes and particular times of year. Again, I am not suggesting that this is necessarily the cause of battery "boiling" in systems with solar charge controllers, but it could be a reason. 2nd ps. All manufacturers do precise battery voltage/current measurements on the bench with a wide variety of conditions, but we will never be able to simulate the 1000's of conditions that happen on the 1000's of installs out there. With that in mind, on-site battery voltage/current data logging is a very powerful tool when investigating these kinds of issues. JARMO _____________________________________________________________________________________ Jarmo Venalainen | Schneider Electric | Solar Business | CANADA | Training & Development Specialist - Senior Phone: +604-422-2528 | Fax: +604-420-1591 | Mobile: +604-505-0291 Email: [email protected] | Site: www.SEsolar.com | Address: 3700 Gilmore Way, Burnaby, BC V5G4M1 *** Please consider the environment before printing this e-mail From: Drake <[email protected]> To: RE-wrenches <[email protected]>, Date: 11/18/2014 09:15 AM Subject: [RE-wrenches] Suspect MX 60 Sent by: "RE-wrenches" <[email protected]> Hello Wrenches, An MX 60 boiled a 24 volt bank of 4 Trojan L-16 batteries last summer. The batteries all checked out to be in good shape. It is not totally clear that the CC was not set to auto equalize, but the EQ voltage was only set at 31.0 V. The battery bank has been replaced by 8 Full River L-16 AGM batteries. The parameters have all been reset for AGM with EQ disabled. The homeowners are concerned that the charge control may not work, and damage their new battery bank. If there is a problem with the CC, it is very intermittent. Has anyone ever seen an intermittent MX 60? Outback tech support says if we send it in they will update the firmware for $90, and do a 24 hour bench test. It appears that the firmware update will not do anything useful for this off grid system. There are no new boards available for this unit. I'm not sure if the bench test will show up an intermittent problem. Has anyone had this situation before? Would it be better to: Replace the CC Send the CC to Outback Do nothing Thank you, Drake Drake Chamberlin Athens Electric LLC OH License 44810 CO License 3773 NABCEP Certified Solar PV 740-448-7328 http://athens-electric.com/ ______________________________________________________________________ This email has been scanned by the Symantec Email Security.cloud service. ______________________________________________________________________ _______________________________________________ List sponsored by Redwood Alliance List Address: [email protected] Change listserver email address & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://www.mail-archive.com/[email protected]/maillist.html List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out or update participant bios: www.members.re-wrenches.org
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