Here's the Rolls chart for cycle life:
http://www.surrette.com/content/agm-faqs?q=node/81&php
The cycle life is considered to be the point before the capacity begins
being reduced.
I'm not seeing anything close to 800 cycles at 80%DOD. It looks like a
typical L16, not over 500 cycles.
Are you using a different chart than what Rolls is posting on their website?
Ray
7 PM, Ron Young wrote:
Hi All,
Not sure where the 4 - 5 strings or more drifted into this
conversation but the setup is basically in two strings of 16 GC
batteries (48v) vs. 8 L-16 batteries in one string that I am
recommending. With 7 year warranty for the Surrettes vs 1 year for the
US Batt.; half the number of cells to water and check - and this is
important as the maintenance on these 4 systems is being done by a
third party who is not always reliably taking care of business; half
the number of connections; half the footprint ...
The only reason I can see someone recommending GC batteries in this
scenario has to do with the company who set the systems up - Xantrex
and their rationale seems to be the easy availability of the GC
batteries e.g. in automotive stores etc. vs the more specialized
distribution of the L-16's. Xantrex want to sell "arrive and drop"
systems that will be sold through mass retailers from what I can see.
The Rolls d.o.d. at 80% shows 800 cycles for the 4000 series batteries
vs. 675 on the U.S. Battery chart but the U.S. battery chart doesn't
differentiate between GC batteries and L-16's or any other type so I
find it a bit suspect.
Ron Young
earthRight Products - Solareagle.com <http://Solareagle.com>
Alternative Energy Solutions ~ Renewable Energy Products
On 2011-09-16, at 1:06 PM, RM You wrote:
forwarded from earth2
Begin forwarded message:
*From: *Ray Walters <r...@solarray.com <mailto:r...@solarray.com>>
*Date: *September 16, 2011 1:03:43 PM PDT
*To: *RE-wrenches <re-wrenches@lists.re-wrenches.org
<mailto:re-wrenches@lists.re-wrenches.org>>
*Subject: **Re: [RE-wrenches] battery cycle life, US Battery
**Reply-To: *RE-wrenches <re-wrenches@lists.re-wrenches.org
<mailto:re-wrenches@lists.re-wrenches.org>>
Larry,
I totally agree, that's a ridiculous # of batteries and strings. If
that's really the case, it seems L16s will still need 4 to 5
strings, which is also crazy. I see only one solution to this
battery bank, and that is the HUP or other large 2 v cell battery.
Comparing golf cart batteries to L16s isn't even on the plate for
good design in this case. For me, HUPs become a no brainer, as soon
as the required amp hours gets into the 1000 AH or higher range.
BTW, don't ever use the 100 hr rate for the Rolls, as they are way
too optimistic. The 20 hr rates are much closer to reality. The
Rolls S-530 becomes a 400 AH battery at the 20 hr rate, also they
list cycles @50% DOD, when everyone else is looking at 80%DOD, be aware.
Here's some quicky math, with costs pulled off the internet:
3 strings of S530s (@24v) would get you 1200 AH for $4200. cycle
life at 80% DOD about 450 to 500 cycles.
HUPs group 25 have 1270 AH and cost $7392, but last 2100 cycles to
80%DOD.
That's about 11.5 cents/ kwh for the life of the battery compared to
about 29.2 cents/ kwh for the Rolls S-530s.
This quicky calculation doesn't even include the extra maintenance
required for watering the L16 type battery, nor the fact that you
will have 4 battery replacements for the same time the HUPs just
have one replacement.
Its very fair to say that the HUPs are more cost effective by about
a 3 to1 ratio.
Ray
Having 6-8 parallel strings of golf cart batteries is a terrible
idea no matter how much better the GC2 may be.
Larry
On Sep 16, 2011, at 10:01 AM, Ray Walters wrote:
The real point is that the Xantrex guy is correct from a scientific
stance. Experimental battery cycle life data shows that some golf
cart batteries (T105) do have more rated cycles to 80%DOD than the
Trojan L16. (750 vs about 600) A really crappy golf cart battery
(some have cycle life below 400 cycles) isn't as good as an L16,
yes. You have to base your decision, and your mouth, on test data
for the batteries considered. Also, you must always compare at 80%
DOD, for an apples to apples comparison. Its usually a clue if a
manu doesn't publish their cycle life data. Of course you must
temper the golf cart vs L16 decision with good paralleling technique.
We use golf cart batteries (never more than 4 strings), jump
straight to the HUPs for larger banks, and skip the L16s all
together. They just don't make sense when you look at the cost/ amp
hr vs their lifespan.
The only time I could see using L16s, was if the battery bank
requirements were beyond 4 strings of golf cart batteries, and the
customer just could not afford the HUPs, or were going to sell the
property soon, and wouldn't appreciate their long term value.
I've spent a lot of time looking at cycle life data, comparing
costs, adding in maintenance and replacement labor, etc..
L16s are serious losers on a $/ kwh operating cost comparison, so
this is a chance to up sell the customer to HUPs (or equivalent) and
make both of you happier in the long run.
Ray Walters
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