[Power] Charge controller ?

[Kim Quirk]

I would agree with Richard that the off-grid people I work with are still
using the lead-acid flooded batteries because they provide the most number
of cycles for true deep discharging (50% -- we do all our calculations
assuming only 50% discharge and about .88 system efficiency; with an
inverter, the efficiency is more like .77).

I've heard that some of the VLRA batteries have seriously shortened life
expectancy with temperatures other than 70F.

As for smaller charge controllers, I like the Morningstar line of
controllers (http://www.morningstarcorp.com/en/products). The little 4.5A
one, the Sunguard, is in the $30 range. I recommend it to anyone buying
20-50W solar panels to charge a 12V battery (for instance). The Sunkeeper
and SunSaver are the next size up (6-25A), $50-90.

Kim


On Sat, Mar 6, 2010 at 7:01 PM, Richard A. Smith <richard at laptop.org> wrote:

> On 03/06/2010 06:26 PM, Paul Fox wrote:
>
> > smith wrote:
> >   >  when you go into a large %DoD.  If you take a LA battery below 50%
> DoD
> >   >  on a regular basis you will destroy it.  So for 8Ah of juice you
> need a
> >
> > is it this effect that so-called "deep discharge" batteries are
> > better at?
>
> Consumer deep cycle LA batteries aka "Marine" batteries mean that you
> can pull them down on a semi-occasional basis and they won't die
> Opposed to say a car battery where 5 deep cycles and its toast.
>
> A consumer grade deep cycle battery is fine for running your trolling
> motor or your UPS but not in the same league as a LA battery designed
> for alternative power use.  They are designed for discharge use on a
> daily basis.
>
> They are doing pretty fancy things these days with LA.  I see a lot of
> VLRA [1] types when I've been doing searches for capacity pricing.  The
> big big boys however are still flooded cell.
>
> Once LiFePO4 (LFP) batteries come down a bit more in price LA will be a
> thing of the past.  LFP is superior in every category except price.
> Even now if you look at long term life and TCO LFP wins but its still a
> good bit more expensive on the front end.
>
> [1] http://en.wikipedia.org/wiki/VRLA_battery
>
> Funny the wikipedia article doesn't list alternative power under
> applications.
>
> --
> Richard A. Smith  <richard at laptop.org>
> One Laptop per Child
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>



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