[RE-wrenches] Testing new batteries

Starlight Solar, Larry Crutcher larry at starlightsolar.com
Thu Mar 24 17:12:15 PDT 2011


Benn,

First off, there is never a reason to add acid. The acid/water mixture is very specific and should not be changed.

>From the moment a battery has been activated (electrolyte added), it is in a discharge mode. The sulfuric acid in the electrolyte starts to be absorbed into the plates (electrochemical process) creating lead sulfate. All new batteries need to be initially charged to reverse this. Only then can you get an accurate SG base reading to record in the log book.

New flooded battery charging process:
Start by charging the new battery at a relatively high voltage, about 2.47vpc @ 77 degrees, until the current drops to about 0.5 amps per 100AH capacity. As long as the plates are covered, you do not need to add any water during this process. Turn the voltage up to about 2.6 volts per cell for at least a couple hours. You will notice heavy gassing so make sure they are vented well. Let batteries rest a while and take your SG reading. Only if necessary, add water to the proper level. Long battery life note: Do not discharge new batteries very deep until they have been cycled about 10 to 15 times.

About battery manufacture dates: 
Too often we have received batteries that have set for many months after manufacturing. We return these because the amorphous lead sulfate ions may have formed bonds to the plate that are (or may be) irreversible. This same effect is caused by undercharging a battery for long periods and it usually leads to premature failure. Any flooded battery setting for over 30 days should be fully recharged.

To answer your question about liquid volume, the plates are absorbent. They absorb acid while discharging and the acid is recombined with water when charging. So the level is in constant flux. That is why you should not add water to a discharged battery except to cover the plates; charge it first.

Much more than 2 cents but that's just me.

Larry Crutcher
Starlight Solar Power Systems
www.starlightsolar.com
928-342-9103

  ----- Original Message ----- 
  From: benn kilburn 
  To: Wrenches 
  Sent: Thursday, March 24, 2011 11:12 AM
  Subject: Re: [RE-wrenches] Testing new batteries


  Mick n' Nick,
  Thanks guys.  I shoulda mentioned that the date code says they were mfgrd the 7th week of 2011 and the one exception, the 8th week.  So they haven't been sitting too long.


  I have been in contact with the mfgr, and of course i will take their advice over anyone else's (gotta keep the warranty valid), but you cannot deny the value of the hands-on experience and insight from this list.  They said to add distilled water after the initial charge, which is why i was only "considering" adding acid.  I have asked about adding acid rather than water.  Waiting for reply.....


  Mick, you mentioned that the electrolyte levels may level once all batteries are at equal SOC.  Can you elaborate?  Do the plates become more or less 'absorbent' or does the chemical reaction change the volume of the liquid.  I will watch this closely.


  cheers,
  benn

  DayStar Renewable Energy Inc. 
  benn at daystarsolar.ca
  780-906-7807 
  HAVE A SUNNY DAY 
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