Friends:
Thanks for the replies. I am going to assume Howie is not eating his batteries during any point of the recharge process. A few respondents are not aware of constraints against watering batteries prior to charging. Here is a typical passage from a battery O&M manual, below. This is from the Deka manual: Distilled or de-ionized water should only be added to batteries while the batteries are on charge and gassing or as soon after recharge as possible. This will prevent overfilling because the electrolyte is at its maximum level during this time. No one has yet provided any evidence, anecdotal or otherwise, to answer the primary question. It is rephrased here: Will adding water to a cell change the specific gravity reading? The implied question is: To get accurate SG readings, do all cells need to be at a consistent fill level? My intuition tells me the answers are yes and yes. If correct, I need to change my maintenance procedure to make sure I am getting accurate SG readings. I am curious enough that I will continue to research this. Here is what is on my agenda: I will continue to monitor this forum in case information from a case study arises. I will contact the engineers at Deka with this question. I have a test set of batteries that I am going to record SG before and after watering. The after watering will include SG readings over a period of time to see how long mixing requires. Thanks to everyone who replied. Battery systems present a level of complexity way beyond regular GT systems and deserve a lot of thought and research-- but then you all know that. William Miller Miller Solar 17395 Oak Road, Atascadero, CA 93422 805-438-5600 www.millersolar.com CA Lic. 773985 *From:* Howie Michaelson [mailto:[email protected]] *Sent:* Tuesday, February 9, 2021 5:13 AM *To:* William Miller; RE-wrenches *Subject:* Re: [RE-wrenches] Battery Specific Gravity versus Electrolyte Level William, It certainly is possible I've missed something, but I've never seen any references to not eating batteries before equalizing. If anything, there is statements saying make sure to check levels before equalizing. I'm not sure why you wouldn't bring levels up before equalizing... Howie Michaelson Sun Catcher NABCEP Certified Solar PV Installer™ Solar Electric & Heat Pumps Systems Sales & Service 802-272-0004 On Tue, Feb 9, 2021, 2:05 AM William Miller <[email protected]> wrote: Friends: Here is a conundrum I have often pondered. Maybe someone can solve this for me: Flooded cell O&M manuals instruct not to top off battery electrolyte levels before equalizing. They also instruct to check SG before adding water. Imagine two identical cells, one low on water, but above the moss-guard, and one at the recommended level. You equalize the array and then check the SG on both. I am imagining that if the cells were equivalent in capacity, they have the same amount of acid. However if one has less water, it has a higher ratio of acid to water, therefore it will read higher in SG. If the above is true, it is not accurate to compare the SG in cells unless the water level is equal, or close to. If you were to add distilled water to the cell that was low, the water would not immediately mix thoroughly. Then to accurately compare SG, you need to wait some time after watering and you would need to be somewhat accurate in keeping all cells at the same water level. How long would this be? Checking SG is but one part of flooded cell maintenance. My monthly procedure is this: 1. Check to see if water is above moss-guard on all cells. (I sometime skip this if I am confident the cells historically do not dry out in one month.) 2. Initiate an EQ charge cycle. 3. Shortly after the EQ cycle, check and record SG in all cells. 4. Re-water batteries to correct level. The above takes long enough. If I have to add water and let it mix before I test SG, the process takes even longer. Nonetheless, I want accurate results. My advice to clients and actions taken are dependent on these readings. Anyone have any wisdom to pour in? I am going to experiment to see what I can learn. William Miller Miller Solar 17395 Oak Road, Atascadero, CA 93422 805-438-5600 www.millersolar.com CA Lic. 773985 _______________________________________________ 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 There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/[email protected]/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
_______________________________________________ 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 There are two list archives for searching. When one doesn't work, try the other: https://www.mail-archive.com/[email protected]/ http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: http://www.re-wrenches.org/etiquette.htm Check out or update participant bios: http://www.members.re-wrenches.org
