Tri-Metric program question [RE-wrenches]

Ray Walters walters at taosnet.com
Tue Oct 10 18:16:48 PDT 2006


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Hi Allan;

We've had the same problems. The Trimetric doesn't even read anything 
most of the time due to the shunt location. Solar just passes straight 
thru to the inverter in grid tie operation. A Pentametric can be set up 
with additional shunts on the inverter and solar input, but you're back 
to the same trouble with the charged parameters. What we need is meter 
that has different charged parameters based on the status of the system: 
grid tie  or off grid.
Also, while we're dreaming, a meter that could handle both AC and DC 
inputs, and......ddrum roll please.... wireless.....!   I talked to 
Ralph about this too, but like all of us currently, he's already tapped 
out keeping his current line up running flawlessly (Great Job Ralph) 
While I'm at it, I have to give a shameless plug for his  easy to 
program Windows interface for the Pentametric too. If only the big boys 
at Outback had such a thing instead of the accursed MATE.

Ray

 Allan Sindelar wrote:

>Wrenches,
>We have been including a Tri-Metric monitor with our Outback
>grid-tie-with-battery-backup systems, so that the homeowner has some sort of
>state-of-charge indication during an outage. We have learned to be selective
>about whether to include a Mate as well, as it's not as user-friendly for
>our typical non-technical grid-tie customer.
>
>The issue is that the Tri-Met is fundamentally designed for off-grid use,
>and uses charged-voltage and charged-current parameters to reset the monitor
>on a regular basis. As the PS1 keeps the batteries in float, the Tri-Met can
>develop an accumulated error that is only reset after a grid outage and
>recharge cycle, which could be months at a time. We have seen this happen,
>where the % of full slowly drifts down over days or weeks.
>
>I called Ralph Heise about this, and he had suggestions, but no clear
>answers - in fact he is looking for ideas that have worked too. He suggested
>the following two ideas, which make sense in theory:
>1. Set the charged voltage parameter below the float voltage (far enough
>below to accommodate the effect of hot-weather temperature compensation -
>say 52.4V if float is at 53.6 - and set the charged current setpoint just
>above the float current - 1 or 2A, I would guess. This keeps the monitor
>reading 100% while in float, and the combination of voltage and current
>settings would prevent premature resetting based on voltage-above-float
>alone.
>2. Set the charge efficiency factor unrealistically high - say at 100% - so
>that this keeps the % reading at 100% while in float. This would make the %
>reading slightly high during outage cycling, but it could be easily reset
>each charge cycle.
>
>Has any Wrench out there come up with a good solution? How would you set up
>a TriMet for this application? Or otherwise, how do you address the bigger
>issue of a monitor that is used only during an outage?
>
>Thanks in advance,
>Allan at Positive Energy
>
>  
>


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