Hi Ray, Cold isn't a problem. It reduces capacity and yes they could freeze, but it doesn't shorten life ( I mean besides the freezing part) in fact cooler batteries last longer. But hot is a problem. Those max temps are not the same thing as reduced life from running at a hotter temperature.
As to internal temps, its really hard to do this. IR cameras are pretty good. Temp sensors which stick to the outside of the case's are not as good as ones that bolt to the post. The post is a good thermal conductor vs the plastic case. The glue/stick on ones come loose as we all know and that means less accurate metering. My premise for bring up the temp concern is that with a larger array and smaller battery which equals higher C rates you will have higher internal temps, no way around it. How high, how much/will it shorten the life unclear but probably, how much, ? Let me rephrase it, do you think hotter temperatures are increasing the lifespan of the battery? While on this subject, I've done some quick calcs and with hot areas, its cheaper to add PV for installing daytime AC vs battery life lost due to the heat. We can thank the cheap world of PV for that. And while I've thought about what Allan started this conversion with in regards to sizing batteries. I continue to size my batteries around best life for the battery ( best daily average % DOD). There are many ways to consider the size/cost etc of batteries: For a larger battery (less DOD) you could view it as buying lead futures, longer time between problems, etc. For smaller bank ( higher DOD) my only reason for doing it at this point is a bridge battery to when Li-Ion/other technologies will overtake LA for cost/ease/MX/capabilities. I'd be curious to hear what others think about that last part, jay On Fri, May 22, 2015 at 3:33 PM, Ray Walters <[email protected]> wrote: > I thought I'd post some info on Battery Temp from a few manus: > HUP Solar One: do not exceed 105 F > Full River AGMs: max recommended operating temp 104F > and from Trojan: for every 10C increase in temperature the reaction rate > doubles. Thus, a month of operation at 35C is equivalent to 2 months at > 25C. Heat is the enemy of ALL lead acid batteries. Even small increases > in temperature will have a major influence on battery life. > Their T105 RE battery has a max operating temperature of 113 F > > I think more batteries are hitting high temperatures than we may realize. > This info from Trojan that a battery at 95F (35C) will only last half its > rated life (at 25C) is very concerning. > Once again, thanks Bob and Midnite for giving us a tool to combat over > temperature of batteries. We always knew cold was a problem, now I'm > realizing heat could be just as important. > > R.Ray Walters > CTO, Solarray, Inc > Nabcep Certified PV Installer, > Licensed Master Electrician > Solar Design Engineer303 505-8760 > > On 5/22/2015 3:24 PM, [email protected] wrote: > > I'm very glad to hear Midnite added the high temp disconnect to their > system. They may have saved a life. > > Bob, is battery temp logged, so we could see how often a system quits > charging for high temp, and just what the battery temps are running? > > > > No, but that is on the list as are other things to data log. > > Hopefully the temperature is adjusted higher than it would ever get to > under normal circumstances. > > I could see some future systems wanting to be able to regulate Absorb on > battery temperature mixed with other > parameters some day. Could get REALLY complicated if you wanted to. > We're learning more and more > about what is good for batteries. > > boB > > > > > _______________________________________________ > 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 > > > -- Jay Peltz Peltz Power [email protected]
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