Wrenches I have to agree with Dana, battery imbalance is alway an issue, add in a mid tap load and failure is in your future, l have also seen this done and it never works as you might hope. Jerry
On Tue, Dec 31, 2019, 12:46 PM Dan Fink <danbo...@gmail.com> wrote: > I second everyone. Center-tapping a 24 or 48v battery bank for 12v SEEMS > like it should work just fine, especially for low load infrequent use like > a 12v water pressure pump for a greenhouse, a weather station, etc.. Nope, > I've been a loser every time, with that battery or pair always the first to > go bad. > > Samlex and Victron both make DC-DC converters I have had good luck with; > they are thermally protected and you can stack multiple units for more > amperage. > > Dan Fink > Executive Director, Buckville Energy Consulting > NABCEP PV Associate > NABCEP Certified PV System Inspector > IREC Certified Instructor™ for: > ~ PV Installation Professional > ~ Small Wind Installer > NABCEP Registered Continuing Education Providers > d <dan.f...@greendustrialtraining.com>anbo...@gmail.com > 970-672-4342 > > > > > On Tue, Dec 31, 2019 at 10:57 AM Ray <r...@solarray.com> wrote: > >> Even with battery balancers, battery tapping is still a really bad idea. >> I know, I did it on my own system in the 90s. The DC/DC converters are the >> way to go, but be sure and over size it by a fair amount to handle the >> fridge starting surge. Unfortunately my favorites are no longer available: >> made by Solar Converters in Canada. I've seen them last decades. Iota >> should be good stuff, their chargers have long term reliability. Samlex >> inverters have been around for quite a while too, but I don't have long >> term experience with their converters. >> >> Ray Walters >> Remote Solar >> 303 505-8760 >> >> On 12/31/19 10:05 AM, Dave Angelini Offgrid Solar wrote: >> >> Tapping a battery bank is not a good practice. it will unbalance the >> bank. Much better to add a 24V electronic converter for the 12V loads. Then >> replace the 12V loads when time permits. They will need a spare converter >> so buy 2. Amazon has tons of these converters. Your quote is great BTW. H N >> Y ! >> >> >> >> *Dave Angelini Offgrid Solar >> "we go where powerlines don't" >> http://members.sti.net/offgridsolar/ <http://members.sti.net/offgridsolar/> >> e-mail offgridso...@sti.net <offgridso...@sti.net> >> text 209 813 0060* >> >> On Tue, 31 Dec 2019 11:52:20 -0500, Chris Schaefer >> <ch...@solarandwindfx.com> <ch...@solarandwindfx.com> wrote: >> >> G'day and Happy New Year to All, >> >> Recently came across this offgrid OB FX system. The first part is a 12v >> battery system w/ 2 PV modules, 2 Trojan L16 batteries used to power a >> frig and freezer about 6 years old. The second is a 24v with 3kw of PV, 4 >> Trojan L16's, twin OB FX inverters installed by an HVAC contractor back in >> 2016. This was their first offgrid project. Oh boy, lol. The client would >> like to add more battery capacity to both. My thought here is since we are >> powering only a 12v frig and freezer why not simplify the system by >> creating a single battery bank and then tapping off of the 24v bank using >> proper fusing and creating a 12v buss? Admittedly I live in a 48v world so >> I'm asking our esteemed colleges as to options on how to address this. >> >> Oh yeah, the installer is unresponsive (no surprise there) and they are >> also having firmware issues with an old Mate 3 and would like me to install >> a new Mate 3s but that's another issue I'll tackle when I head out to site. >> >> Thanks All, >> Christopher- >> >> Chris Schaefer's >> <http:www.solarandwindfx.com> >> >> *Tel/Fax 585-229-2083 or Cell 585-748-1870 * >> *5115 South Hill Road ~ Canandaigua New York 14424 **www.solarandwindfx.com >> <http://www.solarandwindfx.com> ~ E-mail: ch...@solarandwindfx.com >> <ch...@solarandwindfx.com>* >> >> >> Thomas Jefferson, the author of our great Constitution, once said, >> "democracy" will cease to exist when you take away from those who are >> willing to work and give to those who would not." >> >> -- >> >> >> >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change listserver email address & >> settings:http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html >> >> List rules & etiquette:www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios:www.members.re-wrenches.org >> >> _______________________________________________ >> List sponsored by Redwood Alliance >> >> List Address: RE-wrenches@lists.re-wrenches.org >> >> Change listserver email address & settings: >> http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org >> >> List-Archive: >> http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html >> >> List rules & etiquette: >> www.re-wrenches.org/etiquette.htm >> >> Check out or update participant bios: >> www.members.re-wrenches.org >> >> _______________________________________________ > List sponsored by Redwood Alliance > > List Address: RE-wrenches@lists.re-wrenches.org > > Change listserver email address & settings: > http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org > > List-Archive: > http://www.mail-archive.com/re-wrenches@lists.re-wrenches.org/maillist.html > > List rules & etiquette: > www.re-wrenches.org/etiquette.htm > > Check out or update participant bios: > www.members.re-wrenches.org > >
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