>When you do that kind of sizing, do you also adjust for maximum desired
>discharge depth?
that's a bit of a nicety but yes. Allow for only using part of the
battery. If you use a proper deep cycle traction battery then you can
probably use 80% quite safely. Note that amphour capacities vary with
discharge times too, so the four day rate will yield more amphours than the
20 hour rate, which (in turn) is more than at the 5 hour rate.
... A rule of thumb is to size the battery for four days normal use. It is not easy to determine the most economic size, but there is no maximum useful size...
hugh piggott
hugh.piggott@...
Aug 23, 1999 2:04 pm
When you do that kind of sizing, do you also adjust for maximum desired discharge depth? Or just take one day's usage and multiply by 4? Thanks. ron ... From:...
Ron Rosenfeld
ronrosenfeld@...
Aug 23, 1999 3:07 pm
Ron- General rules of thumb apply here. The need for the battery storage is to allow for the complete capture of all the energy that comes from the wind...
Ken Starcher
aeimail@...
Aug 23, 1999 3:07 pm
Hello Ken, ... Can you give me your rationale for these numbers? I've been developing a theory on this subject for the last couple of years and I'd like to...
Ian Woofenden
ianw@...
Aug 23, 1999 5:43 pm
... <snip> ... <snip> ... <snip> ... Tests that repeat the same discharge depth are interesting, but seldom does this happen in actual use. I am curious to...
Mike Fahmie
MPFahmie@...
Aug 23, 1999 7:02 pm
... Yes, that's a good point, Mike. The reality of living with an off-grid system is that cycles vary a lot. But if my theory is correct, it means we could...
Ian Woofenden
ianw@...
Aug 23, 1999 9:35 pm
I think I would do a cost analysis. And that's kind of hard to do since its not so easy to purchase 1/2 of an L16. And you'd also have to factor in the cost...
Ron Rosenfeld
ronrosenfeld@...
Aug 23, 1999 9:35 pm
Hello Ron, ... Right, but when a system design puts you in between two possible bank sizes, the old shallow cycle theory would have you buy more batts and my ...
Ian Woofenden
ianw@...
Aug 24, 1999 1:59 am
Ian, If I remember correctly, at the Trojan seminar we attended the word was that the COST PER AH was lower on deeper cycles (to 50 - 60 % discharge?). I think...
Bob Ellison
ellison@...
Aug 23, 1999 9:36 pm
Hi Bob, ... Yes, this is the conclusion we came to, and the Trojan engineer confirmed it. ... This is self-evident, like saying that money lasts longer if you...
Ian Woofenden
ianw@...
Aug 24, 1999 1:59 am
Thanks for your thoughts. But easier said than done. At least at my stage of analysis. I'm not so interested in sizing the battery bank to capture "all" of...
Ron Rosenfeld
ronrosenfeld@...
Aug 23, 1999 7:44 pm
You might wish to take a look at a taxpayer developed program for expressly the purpose of designing the most cost effective combination of components in a...
Elliott Bayly
elliott@...
Aug 25, 1999 1:03 am
An interesting approach. And a three day supply would be within my budget for this project. But why 80% DOD? It seems to me that the overall costs would be...
Ron Rosenfeld
ronrosenfeld@...
Aug 25, 1999 1:03 am
... that's a bit of a nicety but yes. Allow for only using part of the battery. If you use a proper deep cycle traction battery then you can probably use 80%...
hugh piggott
hugh.piggott@...
Aug 23, 1999 5:43 pm
ron wrote ... It certainly is not easy. With good engine backup, which you hve to use anyway, there is no point in overdoing battery size. Another...
hugh piggott
hugh.piggott@...
Aug 23, 1999 9:35 pm
Ten-twenty times the maximum wind turbine amps -- well the max turbine output is said to be 7.5 kW @ 48V so that's 156.25 amps. X10 is about 1562 amps and X20...
Ron Rosenfeld
ronrosenfeld@...
Aug 24, 1999 2:00 am
... Probably the real goal here is to minimize $$$/year in battery cost. Let us assume that Ians lifetime table is correct. Let us assume that a battery costs...
Mike Fahmie
MPFahmie@...
Aug 24, 1999 2:00 am
... yes ... Mike Bergey suggested in a post a couple of years ago that battery life would be related to total flux in-out, which made sense to me. There are...
Alan Muller
amuller@...
Aug 24, 1999 1:14 pm
... amphours. ... BWC recommend a minimum size of 50kWh for the battery. This would give Amphours equal to about 6.7 times the amp rating (if it actually...
hugh piggott
hugh.piggott@...
Aug 24, 1999 12:55 pm
Hugh, In their prepackaged system, BWC specs a 42 kWh battery bank for the Excel-R, according to literature they sent me. No offense taken as to your...
Ron Rosenfeld
ronrosenfeld@...
Aug 25, 1999 1:03 am
... This prepackaged system has one Trace 5.5 kW inverter. For a similar system with more inverter capacity we would recommend a larger bank of batteries. ...
Mike Bergey
mbergey@...
Aug 26, 1999 2:54 am
Mike, Thanks for that info. I won't complain about longer than expected battery life! As you may know, I'm seriously considering the BWC Excel-R for a home I...
Ron Rosenfeld
ronrosenfeld@...
Aug 26, 1999 2:55 am
... That's true, but under their battery pricelist heading they give the minimum size I quoted earlier - 50kWh. a contradiction. Maybe you should ask BWC. ...
Send Email