[RE-wrenches] BACKUP system revival

[Darryl Thayer]

Hello and happy holidays.  About 10 years ago, I had a similar problem with
a similar customer who wanted a similar problem solved.  The Generac auto
transfer switch needed a 12 volt source.  When the grid went down the
generac transfer switch disconnected and waited about 10 to 15 seconds then
started the generator.  The customer wanted shorter outage transfer time. I
used the inverter driving a dedicated load panel picking up the priority
loads.  When the generator started it would, then after 3 minutes, the
inverter would drop out letting the generator carry all loads, and
the inverter would go back to battery charging.  (note: 8 kW for 15 to 20
minutes is only 2.7 kWh, but the battery system has to be fast,  a LiFe at
C/2 requires 16 kWh/ 300 AH@ 48V and a LA at C/6 requires 48 kWh or 1000
AH)  This job also had solar, and it was DC coupled using a charge
controller.  It has been working for  years, but has never had a major
outage.  The generator better be a good clean signal.  also the grid outage
has to be longer than 10 to 15 seconds for the generator to take over, and
the customer wants if the generator on propane runs out of fuel to go to
solar in my case.  Many years ago I had an off grid customer with a 200 amp
service I supplied using two Outback FX and an auto transformer. It
worked for years.  Good luck.

On Sat, Dec 17, 2022 at 10:28 AM Dana Orzel via RE-wrenches <
re-wrenches at lists.re-wrenches.org> wrote:

> Hey All a Cheery Season to you all!
>
>
>
> I inherited a backup system that had “failed”. It was unwired, & poorly
> labeled.
>
>
>
> 1200 AHR AGM Battery – 1 Radian 8KW inverter – 200 amp Generac transfer
> switch – No solar - Feeding a 200 amp house panel.
>
>
>
> First I explained the there were too many loads for an 8KW inverter. It
> could & may overload the 8KW inverter. They said “it had worked fine for 5
> years & they were OK with it as is please get it back up”…
>
> Replaced the existing Eaton transfer switch as the Generac controller was
> shot, with a Generac 200 amp Xfer switch complete with controller &
> transfer switch.
>
> Rewired & had to recharge the 48 volt battery from 20volt back up to full
> with a pair of IOTA chargers in series.
>
>
>
> The original trigger was 3 wires from the Radian to the 12 volt & AUX
> output to the input on the Generac controller. These were disconnected on
> the Generac end. So no clue or labeling there.
>
>
>
> I called Outback & they called it Redneck engineering & send me a few
> articles to read.
>
>
>
> Has anyone configured a backup in this manner?
>
>
>
> All suggestions appreciated, thanks & wishing you all a safe & sane season!
>
>
>
>
>
>
>
> Dana Orzel                              Great Solar Works, Inc.
>
> *C - 208.721.7003                       dana at solarwork.com
> <dana at solarwork.com>*
>
> Idaho Contractor - # 028765         Idaho PV # 028374
>
> www.greatsolarworks.com            www.solarwor.com
>
> *"Responsible Technologies for Responsible People since 1988"  *
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>
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