Thanks all, this is helpful stuff. We'll see if the batteries are dead or not which would be a real shame since they're only 6 months old... -August
On Wed, Nov 17, 2010 at 7:32 PM, Mick Abraham <m...@abrahamsolar.com> wrote: > Hello, August~ > > Assuming that you don't want to buy a proper (but costly) 48 volt deep > cycle battery charger, here are a few suggestions: > > Find this Craig's List seller in Redwood City: > > http://sfbay.craigslist.org/pen/bfs/2059216588.html > > and ask if they'll rent their 60 volt variable power supply to you for > a couple of days. OR maybe you can beg or borrow a similar DC power > supply closer to home & set it for 60 volts constant voltage. The amps > on this one are tiny...only 5 amps...but maybe that's just what you > need to gradually wake up that battery string. OR: > > ++++++++++++++++++++ > > Connect a string of 120 to 150 PV cells in right polarity to the > battery...with nothing but a fuse or breaker and a watchful eye. As > soon as things come up enough for the Sunny Island to go live, you'd > want to disconnect the PV's then allow the SI to complete the > recharge, since the unbridled PV string would have no voltage > regulation. OR: > > +++++++++++++++++++++++++++ > > The eight units could be temporarily unwired from the Sunny Island > unit, then wired up series/parallel (2s4p) as a 12 volt pack. I advise > that route instead of Ray's suggestion (about charging 12v increments > within the 48v string) because you'll have fewer cell imbalance > problems if you connect series/parallel so every two batts can level > their combined voltage against the other pairs. If all eight units are > wired series/parallel for 12 volt nominal, that pack could handle the > output from a 60 amp 12v charger intended for deep cycle AGM's but if > an automotive type 12v charger is all you can come up with > readily...use that...since you're only trying to bootstrap the system. > > Happy Thanksgiving, > > Mick Abraham, Proprietor > www.abrahamsolar.com > > Voice: 970-731-4675 > > > > On Wed, Nov 17, 2010 at 7:54 PM, August Goers <aug...@luminalt.com> wrote: > > Hi All Battery Friendly Wrenches - > > We have a situation I haven't crossed yet - we have a Sunny Island grid > tied > > battery back system system with a 48 V battery bank consisting of eight 6 > > Volt AGM batteries. The charging breaker feeding the Sunny Island in the > > main electrical panel was shut off by another contractor for about 3 > months > > which caused the Sunny Island to slowly drain the batteries until it > fully > > shutoff in order to protect the batteries. The bank now reads 24 Volts. > > That's low! The Sunny Island is, according to SMA, powered directly from > the > > battery bank and won't even turn on. SMA tech support is recommending > that > > we charge the batteries and then turn the system back on. > > Any ideas about the best way to charge a 48 V battery bank? > > Thanks for your advice, > > -August > > -- > > August Goers > > VP, Engineering > > > > Luminalt Energy Corporation > > 1320 Potrero Avenue > > San Francisco, CA 94110 > > O: 415.641.4000 > > M: 415.559.1525 > > aug...@luminalt.com > > > > _______________________________________________ > > List sponsored by Home Power magazine > > > > List Address: RE-wrenches@lists.re-wrenches.org > > > > Options & settings: > > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > > > List-Archive: > > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > > > List rules & etiquette: > > www.re-wrenches.org/etiquette.htm > > > > Check out participant bios: > > www.members.re-wrenches.org > > > > > > > > > ++++++ > _______________________________________________ > List sponsored by Home Power magazine > > List Address: RE-wrenches@lists.re-wrenches.org > > Options & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out participant bios: > www.members.re-wrenches.org > > -- August Goers VP, Engineering Luminalt Energy Corporation 1320 Potrero Avenue San Francisco, CA 94110 O: 415.641.4000 M: 415.559.1525 aug...@luminalt.com
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