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I've set electric vehicle parallel strings up like this too. Once a
month I charge each string separately. At higher charge/ discharge
rates, the problems of unequal batteries increases dramatically.
BTW, single strings are not the magic bullet either; I've had single
strings with equal current through each battery, but some batteries
would be at 15.5 volts, while others next to it would be at 13. The
charge controller shuts off when the sum of the voltages hits the
bulk charge V, but meanwhile some cells are chronically overcharged
or undercharged. (parallel strings no where to be seen)<br>
Manzanita Micro makes a device that shunts current past batteries
that hit full charge in a string. This monitoring of each individual
battery is the state of the art right now for Li+ batteries in EVs.
<br>
I agree, we need much better battery management and safety devices
for solar. Its ridiculous some of the mundane issues we discuss here
sometimes, while hundreds of huge battery packs are just waiting for
one of us to drop a wrench across the terminals, with zero safety to
interrupt it, and its all NEC compliant.<br>
Batteries themselves need to have a current limiting device built
into the positive terminal. Possibly the same device that controls
charge current to it too?<br>
<br>
Dreaming up future BOS equipment,<br>
<br>
Ray Walters<br>
<br>
On 6/2/2011 7:44 PM, <a class="moz-txt-link-abbreviated" href="mailto:dan@foxfire-energy.com">dan@foxfire-energy.com</a> wrote:
<blockquote
cite="mid:20110602184417.720a661d8db719b1f2ad39509c9edaa3.5de8cf490d.wbe@email14.secureserver.net"
type="cite"><span style="font-family: Verdana; color: rgb(0, 0,
0); font-size: 10pt;">
<div>What I like best about Mark's set up (the retired phone co.
dude w/ half a hand), is that he can select individual strings
at random. he can eq an individual string, or top off a few
strings and park them. he can even run strings of T 105s, or
even nicad (individually of course) in the same system as
L-16s and the like.. he just reprograms the chargers (and logs
it). I think he got the design from his days in the Navy.</div>
<div><br>
</div>
<div>So boB, how about a controller that can be user programed
to charge multiple battery configurations with a soft switch?
i.e. Bank A, Bank B...? and while you're at it, maybe a
multiple string DC box? Something with a shunt and a breaker
for each string? A four string set up would be nice.<br>
</div>
<div><br>
</div>
<div>I could use 2% of your first million.</div>
<div><br>
</div>
<div>db<br>
</div>
<div><br>
Dan Brown</div>
</span></blockquote>
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