Detecting and Remedying a Phantom Load on Battery Bank

3 Posts
Dec 11, 2010 02:38 pm
Detecting and Remedying a Phantom Load on Battery Bank

I have a 48V battery bank of 16 Trojan L16s (2 banks of 8 batteries connected in parallel), off-grid, serviced by 3600W solar and 1800W wind.  I monitor the bank with a TriMetric 2020 configured for 48V.  Lately I've been noticing a significant load registering on the system via the TriMetric, as much as 20-25A above what I used to get as system idle current draws.  I've disconnected all load sources, inverters, etc. and still see this phantom load appearing.  Obviously, this is undesirable as it significantly discharges my battery bank each night.  The battery bank isn't in perfect condition (~5 yrs old) and has some weaker cells showing, I've tried equalized the bank, rotating battery positions, reworked terminal connections - all no luck so far.  My two possible conclusions are: 1) a faulty TriMetric that is actually creating this load it is detecting, or 2) the differences in battery cell voltages creates a current draw.  Are either of these conclusions likely?  Is there something else I could be looking at?  Thanks.
 
462 Posts
Dec 11, 2010 09:18 pm
Re: Detecting and Remedying a Phantom Load on Battery Bank

According to the Trimetric instructions, it need to be used in conjunction with a shunt to control the power from the batteries to be correctly monitored. Are you using one? Check here at the AltE product section for details.
 
3 Posts
Dec 11, 2010 10:38 pm
Re: Detecting and Remedying a Phantom Load on Battery Bank

It's installed with the required shunt.  The system has been installed for about 10 years and working fine until the last few months when this "load" started showing up.
 
220 Posts
Dec 12, 2010 09:15 am
Re: Detecting and Remedying a Phantom Load on Battery Bank


 Hi Dave B,

 that's a lot of power to have dissapear and dissipate (use up)!

 sounds real if you are seeing it discharge the battery bank.
My two possible conclusions are: 1) a faulty TriMetric that is actually creating this load it is detecting, or 2) the differences in battery cell voltages creates a current draw.  Are either of these conclusions likely?  Is there something else I could be looking at?  Thanks.

 can't see any way for the trimetric to be involved..that 20 amps has to be used up somehow..ie: to create heat, light or rf/emf wave.

 have you felt the sides of the batteries? none a LOT warmer than the others? maybe take one (48v)string of the battery bank out at a time to try to isolate.

 seeing as you already checked all loads it's time to think about the source side of things.

 can we know more about your wind and solar setup?

 can we get in and check the bridge rectifier of that wind turbine? does the machine seem to be running "lumpy"..(just a knee jerk suspicion here)

cheers, dave
 
462 Posts
Dec 12, 2010 09:59 am
Re: Detecting and Remedying a Phantom Load on Battery Bank

As Dave A. mentions, a little more info would be good. Best to recheck all connections. I would start with the wind. Possible loose connection sending power to ground?...
 
3 Posts
Dec 12, 2010 04:31 pm
Re: Detecting and Remedying a Phantom Load on Battery Bank

Here's a bit more on the overall setup.  There are two solar arrays, each routed through an Outback MX60 charge controller and separate DC breakers/disconnects.  Each charge controller is routed to separate ends of the two series strings of the battery array to balance the charging.  The windmill is a Southwest Windpower Skystream 3.7 wired as 240VAC and backfeeding the mains distribution panel through a Southwest Windpower battery charging relay disconnect.  The power panel is Trace/Xantrex configured with two inverters (a SW4048 and a SW5548), a DC disconnect and and an AC disconnect.  There is an Onan RS12000 generator fed in through the Trace AC Disconnect.

I have gone out and used the DC breakers to remove the solar arrays from the picture during nighttime (to make sure there is not a failed panel diode somewhere) - no impact to the TriMetric readings.  I have also removed the wind turbine and it's battery charging relay by completely unwiring the thing at its entrypoint to the mains panel and it's battery voltage monitoring points - also no impact to the TriMetric readings.  I've also isolated out the inverters (and any such AC load sources) also with no impact.
 
220 Posts
Dec 13, 2010 11:43 am
Re: Detecting and Remedying a Phantom Load on Battery Bank


WOW!

 nice setup you have there dave.

seems you have checked most everything! not too clear if you were able to disconnect the dc side of the inverters or not? (something wacky with one of the sw battery chargers?)

not much help on where to go from here, other than to double and triple check that we actually have a current draw happening with some hand held meters and feeling for things that are too warm.

please keep us updated on what you find.

kind regards, dave
 
462 Posts
Dec 14, 2010 10:30 am
Re: Detecting and Remedying a Phantom Load on Battery Bank

I also agree with Dave, to double check with meters with everything disconnected. It could be just one dead battery drawing from the others. There is another discussion here in the forum about the Trimetric 2020. Do a search above while here in the forum. From what is said, the manual for the trimetric is pretty long and intensive. Is there a battery back up inside the trimetric? If so try removing it and all power to see if it resets. 
 

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