[RE-wrenches] combining 24v and 12v systems
Ray
ray at solarray.com
Thu Jan 2 18:23:33 EST 2020
How do you insure proper charge voltage to the 12 v set? Never tried
that one.
Ray Walters
Remote Solar
303 505-8760
On 1/2/20 1:37 PM, Chris Worcester wrote:
>
> I would like to add that you don’t need to get rid of the 12 v battery
> bank, but use it for the high amp draw buffer, like a large capacitor.
> Then use the DC to DC converter between the two battery banks. Done
> this for years on multiple off grid systems.
>
> Chris Worcester
>
> Solar Wind Works
>
> NABCEP PV Installation Professional
>
> Office 530-582-4503
>
> Cell 530-448-9692
>
> www.solarwindworks.com
>
> chris at solarwindworks.com
>
> *From:*RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org]
> *On Behalf Of *Tom Duffy
> *Sent:* Wednesday, January 01, 2020 8:55 AM
> *To:* RE-wrenches
> *Subject:* Re: [RE-wrenches] combining 24v and 12v systems
>
> Agree! use a Victron DC to DC Converter
>
> Kind regards
>
> **
>
> *Tom Duffy*
>
> */Senior Solar Design Engineer/*
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> **
>
> *If you don’t have the Time or Money to do it right in the first
> place, how will you get the Time and Money to fix it?*
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> *From:* RE-wrenches <re-wrenches-bounces at lists.re-wrenches.org> *On
> Behalf Of *Allan Sindelar
> *Sent:* Tuesday, December 31, 2019 6:51 PM
> *To:* RE-wrenches <re-wrenches at lists.re-wrenches.org>
> *Subject:* Re: [RE-wrenches] combining 24v and 12v systems
>
> Agreed: no 12v tap. I’ll add (with modest experience, as this doesn’t
> come up as an upgrade very often any more) that Mean Well, despite the
> odd name, proved itself pretty reliable in some early Wattsun tracker
> drives and some other DC-DC applications. Available online; see
> https://www.meanwell-web.com/en-gb/dcdc-converters/
>
> Allan
>
>
> On Dec 31, 2019, at 10:46 AM, Dan Fink <danbob88 at gmail.com
> <mailto:danbob88 at 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 <mailto:dan.fink at greendustrialtraining.com>anbob88 at gmail.com
> <mailto:anbob88 at gmail.com>
>
> 970-672-4342
>
>
> On Tue, Dec 31, 2019 at 10:57 AM Ray <ray at solarray.com
> <mailto:ray at 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/*
>
> *e-mail offgridsolar at sti.net <mailto:offgridsolar at sti.net>*
>
> *text 209 813 0060*
>
> On Tue, 31 Dec 2019 11:52:20 -0500, Chris Schaefer
> <chris at solarandwindfx.com>
> <mailto:chris at 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
> Image removed by sender. <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:
> chris at solarandwindfx.com
> <mailto:chris at solarandwindfx.com>/
>
> /Image removed by sender./
>
> Thomas Jefferson, the author of our great
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> --
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