Ginormous battery rack [RE-wrenches]

[Andrew Truitt]

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Thank you to everyone!  Lots of great advice as usual.

- Andrew


On 10/2/06, Ezra Auerbach, DragonSun Consulting <ezra at lasqueti.net> wrote:
>
> Hi all,
>
> Sorry for any confusion I may have caused. I do mean apply the
> Capacity divided by five (C/5) charge rate. Which  in these batteries
> (2KS33PS) equals 445 amps. The term "capacity" may cause confusion in
> this dicsussion. Here's why: we normally talk about battery capacity
> at the 72 hour rate (2225 amp hours for this model). This is
> appropriate for the usual rate of residential discharge and we are
> usually looking at storage capacity. However when looking at
> recharging the same battery the appropriate rate to refer to is the
> 20 hour rate. This is because the batteries will be charging faster
> than they were discharged hence more heat will be generated which in
> this case will actually hasten the charging process. The good news,
> is that the 20 hour rating for these batteries is 1766 amp hours
> hence we "only" need an initial charge rate of 353 amps.
>
> That's the problem with ginormous batteries, it takes a lot of
> current to properly recharge them. Most battery manufacturers who
> I've spoken to would like to see the C/5 rate and are thankful if the
> C/10 is a reality. Again for these batteries even the C/10 rate would
> be a charging system capable of 176 amps at 48 Vdc. Not an un-
> achievable charging system with an 8.5 kW array or a couple of large
> wind gennies, a few inverter/chargers or a combination of all. Much
> less than this much charging "umph" will eventually result in
> shortened battery life.
>
> Hope this clarifies.
>
> Ezra
>
>
> On 2-Oct-06, at 8:19 AM, Allan Sindelar wrote:
>
> >
> > Ezra,
> > Minor correction here with large consequences to the question at
> > hand...a
> > C/5 rate is "capacity at a five-hour rate", or 20% of the battery's
> > amp-hour
> > rating, rather than 5%.
> > Allan at Pos Energy
> >
> > ----- Original Message -----
> > From: "Ezra Auerbach, DragonSun Consulting" <ezra at lasqueti.net>
> >>
> >> I totally agree with Drake, your next challenge will be charging
> >> those batteries. You need an on-site ability to apply C5 (5% of the
> >> battery banks amp hour rating at the 20 hour rate).
> >
> >
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-- 
Andrew Truitt
System Designer
Standard Solar Inc.
(301) 296 - 4373
andrewtruitt at standardsolar.com


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