So help me out with a little more detail please. Example (Dan's configuration
and my current in-progress install): 2 Strings of 8, L-16s for 48V. nom.
Destination: the common pos bus at the bottom of a pair of 125 amp CBs as OCP
for 2, VFX3648s.
Positive battery current path: from each end of both battery string pos
terminals, the next stop would be a (110 amp?) Class T fuse, one for each
cable/string. Then cables from each of these fuses would land on one Bus
(hefty chunk of copper bar stock) mounted on inside of battery box (backed up
with Dan's cement board), combining the outputs of both batt strings. From
this one bus, run 2 cables to the pos bus at the bottom of the 2, 125 Amp CB's
(in this case provided in the OB-DC Flex enclosure, protecting the 3648s.
A little simpler (better?) would be to just bolt the Class T fuses
right to the bus in the battery box, eliminating some cable. Feedback?...and
thanks,
Bill
Feather River Solar Electric
4291 Nelson St.
Taylorsville, CA 95983
530.284.7849 / 6544 fax
----- Original Message -----
From: Dan Fink
To: Allan Sindelar ; RE-wrenches
Sent: Saturday, February 08, 2014 12:05 PM
Subject: Re: [RE-wrenches] DC Fusing/Breakers for Battery Circuits
Allan;
It's a topic much on my mind recently and i will provide a writeup soon. It's
all very well documented. I do have photos, but they don't show the fire damage
to the wooden battery box unfortunately, the client was a bit flustered getting
all the batteries out of there after the incident and when I showed up he had
already demo-ed the box. But the photos of the batteries themselves do tell the
story rather well.
There was another issue also.....his Xantrex power panel was wired with a
'self destruct switch' main battery cutoff. I did not design or install the
panel. But his logical reaction in seeing smoke coming out of his battery box
was to open the main battery disconnect breaker on the panel, which then put
solar 140vdc onto the inverters inputs. Both were zorched by high voltage. He
should have opened the solar breaker first, then the main DC. His homeowner's
unsurance did cover most of it all.
The batteries were 8 years old....end of lifespan situation.
Lessons learned......OCP on parallel battery strings, and cement board liner
in all battery boxes, if they are field built wooden.
Dan Fink,
Executive Director;
Otherpower
Buckville Energy Consulting
Buckville Publications LLC
NABCEP / IREC accredited Continuing Education Providers
970.672.4342
On Fri, Feb 7, 2014 at 10:36 AM, Allan Sindelar
<[email protected]> wrote:
Dan,
Do you have a writeup on that event? Any photos? I have many plywood
battery enclosures in the field.
Thanks,
Allan
Allan Sindelar
[email protected]
NABCEP Certified PV Installation Professional
NABCEP Certified Technical Sales Professional
New Mexico EE98J Journeyman Electrician
Founder, Positive Energy, Inc.
A Certified B CorporationTM
3209 Richards Lane
Santa Fe, New Mexico 87507
505 424-1112 office 780-2738 cell
www.positiveenergysolar.com
On 2/7/2014 10:26 AM, Dan Fink wrote:
Does anyone have any elegant solutions to this? It's really time
consuming and ugly to run big parallel battery string wires *out* of the
battery enclosure to class T fuses, then back into the battery box. It looks
very ugly and DIY, and in conduit adds a few hundred to the install cost just
for labor. The Class T fuses and blocks themselves are not particularly
expensive.
I have been recommending parallel fusing on battery banks of 2x8 L16s and
over now, after a nearly tragic incident with a bad cell that shorted. The
(perfectly legal) wooden battery box made the fire much worse. A pet peeve of
mine.
Dan Fink,
Executive Director;
Otherpower
Buckville Energy Consulting
Buckville Publications LLC
NABCEP / IREC accredited Continuing Education Providers
970.672.4342
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