Remember when? Yeah, yesterday. I get more than a few tightwad, penny
pinchers in our store and no matter what I say they are going to do it
THEIR way.
Quote: "I watch my meter and unhook the panel if it get's to 13 volts"
I'm not kidding.
Another quote: "Life's tough, ...it's even tougher when you are stupid"
Larry
On Dec 2, 2009, at 5:39 AM, Tump wrote:
Here is a good reason to spec out 2 volt cells, all of the
manufactures have
DC input windows that will allow you to remove 2 volts while getting a
replacment.Conversly we have also installed 26/50 volt battery banks
for hi
inrush loads.
Remember when you sized BB w/o charge controllers?
-----Original Message-----
From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of R Ray
Walters
Sent: Tuesday, December 01, 2009 8:20 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] concord batteries, EQUALIZE Them!
Yes, I've had a 48 v system survive a dead cell (Outback inverter),
but 24
or 12 v systems are done. So I guess the Sunnyboy can go down to 42 V?
R. Walters
r...@solarray.com
Solar Engineer
On Dec 1, 2009, at 3:41 PM, Richard L Ratico wrote:
I believe the Sunny Island 5048 can be configured to remain "online"
with up to three cell failures. (Page 90, Sunny Island Manual). Of
course, it is a 48 volt inverter.
Dick Ratico
Solarwind Electric
--- You wrote:
I used to think that one string was optimal; until I had a single
cell
failure take out an entire system for weeks. (try operating a 24 v
system at 22v! ) I now think that 2 parallel strings is optimum, 3
is
OK, and 4 is max. At 4 parallel strings, we start spending more time
looking to make sure all connectors are the same exact length etc. to
insure equal operation. But of course how do you account for varying
internal resistance of the batteries......?? I've done 4 parallel
strings at 144 DC of sealed batteries on an electric vehicle, but we
were very careful with our resistances, I even switched to smaller
wire, on closer strings, and calculated out the exact resistance, so
all strings were theoretically equal. This set actually just died,
but
achieved its manufacturer's predicted cycle life. (B&B battery, 350
cycles to 80% DOD) So if you're careful, 4 strings can work well.
Worst I've seen was 20 golf carts paralleled in a 12 v system, (10
strings) and they didn't pull the main connections from across the
set, just connected to one end. The results were very predictable,
with the furthest batteries being chronically under charged, and the
closest ones being over cycled to a premature death.
Ray Walters
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