[RE-wrenches] Battery Freezing (was Trace...)

Thu Jan 13 12:19:45 PST 2011

Never underestimate how bad an old system can be.

In the past we have seen systems – including those done by “solar companies” – where part of the battery bank was not even wired in to the system.

From: Kelly Larson 
Sent: Thursday, January 13, 2011 12:57 PM
To: RE-wrenches 
Subject: Re: [RE-wrenches] Battery Freezing (was Trace...)

  "Warning: those old DIY setups quickly become a can of worms, the further you dig into them. Don't assume anything was done right."

...Including checking the polarity of every wire!  Who knows what the color meant to the last guy.   

And don't just mess with a few things and leave it.  That customer is sure to have more problems and you were the last to touch it.  (God forbid if they have an electrical fire.)  Tell them it will take time to fix the mess.   Make yourself a wiring diagram following every wire.   This will take some customer investment, but result in a working system and happy customer.

Blessings,
Kelly

Kelly Larson
Box 104
Piercy, CA 95587
707-223-3209
Electrical Engineer
NABCEP Certified Solar PV Installer
ISPQ Master Trainer
CA C-10 # 868189
SolarKelly at asis.com

"I'd put my money on the sun and solar energy. What a source of power!  I hope we don't have to wait until oil and coal run out before we tackle that."   ~ Thomas Edison

On Dec 29, 2010, at 10:59 AM, R Ray Walters wrote:

  Jay; 

  I've saved a few sets from freezing, different manufacturers' cases are stronger than others. (ie, A Trojan T105 can take more stress than something from Sam's Club.) 
  FIrst I make sure they're less than 5 years old.
  Then, I warm them backup (portable propane heater, very well vented area, no current flow in or out)
  3rd, See if any are leaking
  4th, Charge them with the caps off, monitoring voltage, current, temperature, and bubbling action.

  Jesse;

  Your eyes and health are not worth risking to save those old things; 12 years is a fairly respectable lifespan in a poorly setup system. 
  I think to continue to work with those batteries is inviting danger (everyone's recent explosion stories?)
  All those problems were caused by shorting plates, and other malfunctions, usually only seen in old batteries.

  Batteries only freeze when completely abused. The inverter probably was shutting off all the time from low voltage, and they had DC loads dragging it down even lower.
  The recent string on battery temperature management should be applied in this case too. I've seen poorly designed venting, freeze batteries right next to it, while the batteries on the inside
  were warm.

  I agree with Allan's assessment: this set is toast, and considering this is the worst time of year to not have a good battery set, I'd take care of that lady, and get her into a fresh set, ASAP.
  This is also a chance to do some needed rewiring of the system.
  Warning: those old DIY setups quickly become a can of worms, the further you dig into them. Don't assume anything was done right.

  R. Walters
  ray at solarray.com
  Solar Engineer

  On Dec 29, 2010, at 9:16 AM, jay peltz wrote:

    I'd like to go back to the freezing battery part as I don't live in real freezing territory. 

    How could they actually freeze and not destroy the housing, internal plate structure and in the end work at all?

    thanks,

    jay

      From: re-wrenches-bounces at lists.re-wrenches.org [mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of Allan Sindelar
      Sent: Wednesday, December 29, 2010 10:41 AM
      To: dahlsolar at gmail.com; RE-wrenches
      Subject: Re: [RE-wrenches] Trace inverters undercharging batteries.

      Jesse,
      Don't waste your time on those batteries; they are all toast. Don't replace them with the same; four strings is poor design. Read the article about off-grid batteries in the current Home Power, and then sell the customer a set of 12 (or 24; either one string or two is OK) 2V industrial cells, such as HUPs from Northwest Energy Storage or K-series Surrettes. Size unknown. The existing full bank was 1400 A/hr if the cell cases had black covers, 1600 A/hr if the tops are blue, to give you an idea.

      BP modules from 1998 would have most likely been 12V 75W or 85W, meaning 900-1000 watts; too small an array for that size battery bank if the home is used full-time; OK for a seasonal or weekend cabin.

      Only with new batteries can you even tell what the inverters are doing. My hunch is that the inverters aren't at fault. However, given the poor quality of the original installation, they likely are set to default setpoints, which can charge at a very high rate (about 220A at 28.8V for two if the gennie is big enough) but won't get batteries full (and can't equalize them), as the default setpoints are too low. And I'll bet dollars to doughnuts the default setpoints are in place, as the inverters have been shut down sometime in the last 12 years, losing any original programming settings.

      You might see about getting an experienced off-gridder in your frozen region to work with you. Maybe Darryl could consult now, then make one trip out to set up the system once the new batteries are in. This was the classic late-90s system with a later charge controller upgrade, but if you have never worked with this equipment, you're likely to set it up for a repeat failure years down the road.

      Just read Jamie's post - while his advice is spot on, of course, you need to decide if it's worth your while. I'd be more inclined to try his approach if the battery bank was three years old, not 12. That's a huge amount of time spent, working with acid and an unknown set of hazards, with at best the possibility of a few years' use. I'd suggest that unless it's your father-in-law's cabin, and you value the chance to hang out there for a week, it's not worth your time or the customer's, especially given that you acknowledge having little off-grid experience. 

      Allan

      Allan Sindelar
      Allan at positiveenergysolar.com
      NABCEP Certified Photovoltaic Installer
      EE98J Journeyman Electrician
      Positive Energy, Inc.
      3201 Calle Marie
      Santa Fe, New Mexico 87507
      505 424-1112
      www.positiveenergysolar.com

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