Tri-Metric program question [RE-wrenches]

Mick Abraham mick at abrahamsolar.com
Thu Oct 12 07:43:16 PDT 2006


Building on my relay suggestion posted a few daze ago (copied below): if 
the relay was an "on-delay" type, the delay could be set for 12 hours or 
however long a grid powered recharge is calculated to take. When grid 
comes back up, the TM-2020 meter would continue to be powered up and 
running until the time out period occurs. This would totally avoid the 
problem of a reset to 100% occurring as a result of a short term return 
of grid power. Now the question is: are the meter program settings 
permanently non-volatile?

Mick A.

Mick Abraham wrote:
> 
> Here's an off-the-wall idea for Allan's Tri-Metric issue: So long as the 
> 
> grid is up and running, the end user doesn't need any battery state of 
> charge information at all, so: A SPST normally closed relay with a 
> 120vAC coil could interrupt the DC positive going to the meter so long 
> as the grid power is energizing the relay coil. 
> 
> If the grid goes dark, the deadman relay would power up the meter, and 
> the TM-2020 always displays 100% when it's first powered up. TM-2020 
> program settings are retained even with no power to the meter (but I 
> don't know if that's permanent non-volatile memory).
> 
> Here's an advantage: the end user can confirm grid blackout status by 
> noting that the Tri-metric is lit up. Here's a (possibly huge) 
> disadvantage: if the grid comes up briefly then goes back out, this 
> would reset the TM back to 100% which may falsely mislead the end user. 
> Therefore, this suggestion is worth considering if the blackout pattern 
> tends to be off, staying off, then on for a long time. If the balckout 
> pattern tends to be off for awhile, then briefly on, then off again, 
> this suggestion injects a new batch of problems.
> 
> Just thinking outside the box, 
> 
> Mick Abraham
> 
> 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
> > 
> 
> 
> 
> Abraham Solar Equipment
> Pagosa Springs, CO
> www.abrahamsolar.com



Abraham Solar Equipment
Pagosa Springs, CO
www.abrahamsolar.com


- - - -
To send a message: RE-wrenches at topica.com

Archive of previous messages: http://lists.topica.com/lists/RE-wrenches/read

List rules & how to change your email address: www.mrsharkey.com/wrenches/etiquette.php

Check out participant bios: www.mrsharkey.com/wrenches/

Hosted by Home Power magazine

Moderator: michael.welch at homepower.com
--^----------------------------------------------------------------
This email was sent to: michael.welch at homepower.com

EASY UNSUBSCRIBE click here: http://topica.com/u/?bz8Qcs.bz9JC9.bWljaGFl
Or send an email to: RE-wrenches-unsubscribe at topica.com

For Topica's complete suite of email marketing solutions visit:
http://www.topica.com/?p=TEXFOOTER
--^----------------------------------------------------------------





More information about the RE-wrenches mailing list