Hi Ray, Good observations...
The reality is that cycle life graphs are not a true representation of the battery's ability to survive in RE applications. The real test would be the IEC 61427 standard as it closely approximates the conditions that batteries will face in RE applications. Have you (or any of the wrenches) had experience with this type of testing? We have done lots of testing and I would be happy to share data with you and the wrenches. Best Regards, Ronald Paredes Technical Product Manager - Renewable Energy Trojan Battery Company 12380 Clark Street Santa Fe Springs, CA 90670 Tel: (562)236-3000 Ext. 3066 Fax: (562)236-3279 rpare...@trojanbattery.com<mailto:rpare...@trojanbattery.com> www.trojanbattery.com<http://www.trojanbattery.com/> Trojan Battery Company - Clean Energy for Life(tm) From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray Walters Sent: Wednesday, July 14, 2010 2:37 PM To: RE-wrenches Subject: Re: [RE-wrenches] Trojan L16 2v vs 6v Kent; Your table shows just what I found as well: too large a battery bank actually isn't as cost effective. Also, based on the Trojan chart, you can see that a regular L16 isn't even as good as golf cart battery, but that the 2 v version doubles the cycle life. (which makes sense, cycle life is primarily a function of plate thickness, and the 2 v version has fewer, but thicker plates.) TO answer your question about making an L16 last longer, I'd say using the 2 v L16 is the answer. I figure roughly 100 80% DOD cycles = one year, so according to that fuzzy math: Exide golf cart < 5 years, a Trojan T105 7 years, a regular L16 6 years, a 2 v L16 10 years HUP 21 years Obviously that's not true for all situations, just a ball park number that has held water in actual field experience here. (i've seen Exides still usable after 10 years, but that's the exception, not the rule.) If the battery bank is not oversized, you will get more bang for your buck as Kent pointed out, but the bank won't last as long as a grossly oversized one. (BTW, a grossly undersized battery that is cycled deeper than 80%, loses lifetime amp hours as well) The bottom line though is to reduce the system's lifetime operating costs, so a smaller, higher quality bank is best. R. Walters r...@solarray.com<mailto:r...@solarray.com> Solar Engineer On Jul 14, 2010, at 3:06 PM, Kent Osterberg wrote: Ronald, Thanks for being so quick to follow up such useful information! Using data extracted from your graph I computed the amphours that the battery should deliver over its lifetime: DOD Cycles LifeTime Amphours 20% 1500 333000 30% 1000 333000 40% 850 377400 50% 680 377400 60% 570 379620 80% 460 408480 I've always tried to design battery systems such that the batteries rarely go below 50% DOD. Looking at this data makes me question that practice. It also makes me wonder about the seven-year warranty. Even with 20% daily discharge it looks like the batteries should be spent in about four years. Any suggestions on how to get seven years of service from a set of L-16s? Kent Osterberg Blue Mountain Solar, Inc. Ronald Paredes wrote: Hello Travis, I apologize for any inconvenience and for not having the data more available. We are currently working on making sure that system designers have easy access to our data. The L16RE-2V battery does have significantly more cycle life than the L16E-AC battery. The "AC" part actually stands for Access and Cleaning. The AC Series batteries were designed for floor scrubbers, sweepers, and aerial work platforms. The RE Series batteries, on the other hand, were specifically designed to meet the challenges of RE applications. I prepared a graph for you and for the rest of the wrenches. Please feel free to contact me if you need additional data. Please let me know if you would like the MS Excel version of the chart. <Mail Attachment.png> Best Regards, Ronald Paredes Technical Product Manager - Renewable Energy Trojan Battery Company 12380 Clark Street Santa Fe Springs, CA 90670 Tel: (562)236-3000 Ext. 3066 Fax: (562)236-3279 rpare...@trojanbattery.com<mailto:rpare...@trojanbattery.com> www.trojanbattery.com<http://www.trojanbattery.com/> Trojan Battery Company - Clean Energy for Life(tm) From: re-wrenches-boun...@lists.re-wrenches.org<mailto:re-wrenches-boun...@lists.re-wrenches.org> [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Travis Creswell Sent: Wednesday, July 14, 2010 12:16 PM To: 'RE-wrenches' Subject: [RE-wrenches] Trojan L16 2v vs 6v Greetings Esteemed Wrenches, I searched the archives and didn't find a specific reference to my question so please accept my apology in advance if this has already been covered. Are the 2v Trojan L16s a much better option than the "standard" (non-re, 370 Ah) L16? Local distributor tells me they are specially formulated for renewable energy. They have a 7yr warranty vs. 6 months for the standard L16 which is pretty attractive. kWh capacity wise they are the same. But I can't find any actual cycle life curves for either battery which is a pretty critical data point in my mind. (would it kill Trojan to publish that on their website????) My cost on the 2v L16 is nearly 50% more than the standard L16 so it's certainly worth doing some homework. It's time to replace a set (3 strings of 4) of L16's that I'm sure have been abused in a full time off grid residence. They won't even make it through the night anymore. I adopted this system several years ago and found a severely sulfated one yr old set of chronically under charged batteries that had replaced a set that they had gotten less than 2yrs out of. Most of the usual suspects....small solar array, both solar and gen charge settings left at the factory defaults, Tri-metric was there but not installed, and customer who didn't pay attention because he didn't have the time. On at least several occasions the customer let the electrolyte level drop to the point where the plates are exposed. I immediately upped the charge settings then over the last 3yrs I've increased the solar to just over 2kW, replaced the tired 8kW generator with 12kW and added a second 4024. All of these upgrades should lead to much a better life for the next set of batteries. If the budget wasn't such a major concern I'd like to get them into a set of HUP's which I still might be able to. A comparable set of HUP's is just over 2x's the money but they offer at least 3 times the life on paper anyway. We've got numerous sets of HUPs out there. Some are approaching 10yrs old but customers take very good care of them. Thanks in advance for any input or suggestions. Best, Travis Creswell Ozark Energy Services This e-mail message and any attachments that accompany it may contain information that is confidential, privileged, or protected from disclosure. It is intended solely for the use of the individual(s) to whom it was intended to be addressed. If you have received this e-mail by mistake, or you are not the intended recipient, any reading, disclosure, copying or other use of this communication is strictly prohibited. If you have received this communication in error, please immediately advise the sender at their phone number listed above, or by electronic mail, and also permanently delete the original and all copies of this e-mail and any attachments from all locations. 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