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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