[RE-wrenches] combining 24v and 12v systems

[Ray]

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> 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: 
>> chris at solarandwindfx.com <mailto:chris at 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."
>>
> -- 
>   
>
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