[RE-wrenches] Cycle Life

[Larry Crutcher, Starlight Solar Power Systems]

Ray,

To question 2: I find Rolls batteries to be outstanding. Our oldest banks are over ten years now and trouble free.  I can say the same about Crown CR-390 batteries if your doing comparisons. Can't say that about Trojan and defiantly not Deka AGM's (run away!).

The 80% DoD thing is a poor way of measuring battery cycle life in RE systems. If your only talking about floor scrubbers, sure, use 80%. But for RE purposes, a 15% to 30% discharge is more realistic. Who discharges to 80% daily? More importantly, who would design such a system? Perhaps 80% DoD is useful for some but I sure wish we had a more realistic standard for the RE world. 
(Did I vociferate?)

Larry
https://www.crownbattery.com/applications/renewable-energy-systems
 
On Dec 18, 2013, at 2:28 PM, Ray Walters <ray at solarray.com> wrote:

Hi;

I was just doing some cost comparisons of different batteries for a customer.  I found that on Rolls website, they've apparently upgrade their cycle life of the S5000 series to 2100 cycles (or more) at 80% DOD.  It has been 1500 cycles at 80% DOD for quite a while, so:
Question 1, what new technology is Rolls now employing in their batteries to boost cycle life by 40% from before?
Question 2, are folks' real world experiences in line with that incredible "best in the business" claim.
Question 3, at what rate of charge and discharge are cycle life tests normally done. Can companies exaggerate their cycle life, by running the tests at 100 hr discharge rate, for instance.
Question 4, Is there any independent confirmation/ testing being done?

Off List replies are fine, for those of you not wanting to publicly share your experiences.

Thanks,

-- 
R.Ray Walters
CTO, Solarray, Inc
Nabcep Certified PV Installer,
Licensed Master Electrician
Solar Design Engineer
303 505-8760