Equalize charge - SW4024 [RE-wrenches]

[Ray Walters]

Alan,
The T240 has been derated by Trace to 3900 watts, at least according to the
last tech I talked to there. I too have had little luck with the SW series
in EQ mode. I try to size the PV array large enough to EQ the batteries
after bulk charging the system with the generator. 
At 11:41 PM 10/16/00 -0700, you wrote:
>John,
>    RE the EQ: It's [another] design/software weakness in the SW.  If you
>set the generator menu to EQ, the NEXT time the inverter auto-starts the
>generator it will go through the EQ procedure.  That's OK if the generator
>is routinely started by the inverter (which I suppose it will be up in
>Vermont in the winter).  It doesn't work if the array keeps up with the
>load.  The other way is to set the generator menu to EQ, then manually start
>the gennie at the gennie; watch when you reach EQ voltage, then wait X hours
>(according to your preferred EQ time duration) and turn it off.  You can let
>the inverter do the process (which includes bulk charge to EQ setpoint, hold
>for set duration; drop to float) but you still have to watch the process to
>know when to manually shut off the gennie.  Wrenches: I believe that I have
>all this right--any dissent?
>On the pumps: When you say DC250, do you mean T240?  By all means, control
>the T240 on the primary side to avoid phantom loads.  We have done a 3/4hp
>240 well pump with a standard open-coil relay with 24VDC coil voltage
>(Grainger 3X749), letting the control circuit (float switch or pressure
>switch) operate the DC coil; worked great, and even let us series in a DC
>timer (App. Pwr #52-112 with 52-117 step-down resistor).
>The T240 is rated 4.5kW, so whatever the inverter will handle, the T240 will
>too.  If you have trouble (lights flicker, computers crash, etc.) with the
>surge from starting both pumps at once, you could try a second time-delay
>relay (Grainger 4A368 in 24VDC) to control a DC coil AC relay.  Sounds
>complicated, but relays are actually pretty simple and reliable.
>I suspect your client will complain about lights flickering when the pumps
>start.
>By the way, how are you running the hydronic system? A standard AC system
>will kill batteries, it's such an energy hog.  We use all-DC stuff we have
>developed.  Respond if interested...
>
>Allan at Poz E
>-----Original Message-----
>From: John Blittersdorf, Cent. VT Solar & Wind <cvsolar at aol.com>
>To: RE-wrenches at topica.com <RE-wrenches at topica.com>
>Date: Monday, October 16, 2000 7:11 PM
>Subject: Re: Equalize charge - SW4024 [RE-wrenches]
>
>
>>Kurt,
>>   Thanks for the EQ info.  We will try the AUTO mode initialization and
>see
>>what happens.  We have their system metered well so they won't have to
>>babysit watching for it to happen (even though they probably will as they
>>love to watch it run).
>>This system is my flagship off grid job.  It's a new passive solar, energy
>>efficient house with radiant floor heat, solar hot water.  The GC for the
>job
>>was a real perfectionist and everything including the utility room was done
>>looking real sharp.  He is now convinced that solar works so I am hoping
>this
>>will lead to more solar in new homes in this area.  The owners of this
>house
>>are real efficiency nuts so it has been a pleasure to work with them.  I
>have
>>put a lot of extra time into this one at no charge just to have a top notch
>>shining example of my work to show people with money.
>>
>>The EQ problem was the only one with the system.  They also had a problem
>>when the septic pump installed was 240 and we had planned on a 120 vac
>pump.
>>The engineer said that the piping in the mound would have to be changed if
>we
>>went with a 120 pump (GC slipped on this detail- he knew we only had 120)
>We
>>ended up hooking both pumps to one DC250.  Has anyone done this..  Trace
>says
>>that the loads are OK even if both pumps start at the same time (both pumps
>>are 3/4 hp)  We are still waiting to see if the sewer pump shuts off before
>>the well pump all the time.  If so, we can use the pressure switch on the
>>well pump to activate the transformer.  If the flows don't work out right,
>we
>>will have to have the DC250 on all the time.  Hadn't planned on that with
>our
>>load analysis.
>>
>>John
>>CVSolar
>>
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>
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