[RE-wrenches] battery cycle life, US Battery

[Ray Walters]

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




  On 9/16/2011 10:15 AM, Larry Crutcher, Starlight Solar wrote:
> Hi Ron,
> Have a look back a few months ago to the discussion about multiple 
> battery strings. My synopsis: large, parallel banks are not good; 
> fewer strings are always better. How large a bank are we talking about 
> here?
> Scientist?? That sounds kind of like "Yea, I been a 'lectrician for XX 
> years...", something I have heard hundreds of times. It's just pride 
> saying "Look, I can pee that far too!" when in reality they are 
> clueless about DC power systems. I'm ranting but my point is you 
> should convince your customer that a hands-on, real world experienced 
> professional has a much broader understanding of RE system intricacies 
> than a "scientist".
> Larry
> *From:* Ron Young <mailto:solareagle at solareagle.com>
> *Sent:* Thursday, September 15, 2011 5:11 PM
> *To:* RE-wrenches <mailto:re-wrenches at lists.re-wrenches.org>
> *Subject:* Re: [RE-wrenches] battery cycle life, US Battery
> Hi Larry,
> Client has asked me to compare the cycle life because he is upgrading 
> a large battery bank and has been convinced by a Xantrex "scientist" 
> that golf cart batteries are superior to L-16's even though it 
> involves twice as many batteries, connections, cells, footprint etc. 
> So to convince his purchasing committee he wants to know the 
> difference in cycle life between a U.S.B 208 and a Surrette S-460.
> Ron
>
>
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