[RE-wrenches] Interstate UL-16 HC problem

Dave Palumbo dave at independentpowerllc.com
Thu Jul 1 03:47:45 PDT 2010


Tom,

 

I have seen many Surrette battery banks of two series strings in parallel
last 10 to 12 years. Also have had a few with three string banks go that
long. All were well designed systems with homeowners providing good
maintenance.

 

Dave

 

From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of The Office
of Tom Duffy
Sent: Wednesday, June 30, 2010 10:56 PM
To: 'RE-wrenches'
Subject: Re: [RE-wrenches] Interstate UL-16 HC problem

 

Jay

 

Higher charge settings, proper absorb times (do the math) and absorb voltage
settings, diligent maintenance and twice yearly good EQs, on a single series
connected, properly sized string, of quality L16s, will yield at least 10 to
12 years. Maybe not on a Deka, Exide or even Interstate which have thinner
plates than Trojan or Surrette. I have seen some 14 year strings in use,
though they were pretty well exhausted.

 

Now I’m only talking about single series banks. There is no hope for
parallel banks without a lot of extra time and work and even then not the
life were talking about here.

 

Remember that 8  400 AH L16s in a 48 volt string is a rather small-small
cabin, for three days autonomy, so proper sizing is a must for good life.
It’s really about cycles because the positive plate is finite and at the
hoped for end to its life there is really no positive plate left. Most of
the batteries out there however will die from sulfation suffocation long
before this end.

 

  Tom Duffy

  Systems Design Engineer



     tom at thesolar.biz

       575-539-2111 X 301

Although no trees were killed in the sending of this message, a large number
of electrons were terribly inconvenienced.

 

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From: re-wrenches-bounces at lists.re-wrenches.org
[mailto:re-wrenches-bounces at lists.re-wrenches.org] On Behalf Of jay peltz
Sent: Wednesday, June 30, 2010 7:20 PM
To: RE-wrenches
Subject: Re: [RE-wrenches] Interstate UL-16 HC problem

 

HI Tom,

 

Are you saying that you are seeing 14 years on a single string of L-16's?

If so I would like to hear your charging  recommendations.

 

thanks,

 

jay

 

peltz power

On Jun 30, 2010, at 9:32 AM, The Office of Tom Duffy wrote:

 

Bob

 

Yes the problem is hard sulfation due to chronically under charging. The
absorb time and voltage is the most critical charge mode for charging
batteries. The default settings on inverters and charge controllers are
always way too short, so they hold the batteries in absorb for a little
while, then go to float, leaving the batteries under charged forever, thus
we get hard sulfation. This is what you have here. Typically two parallel
strings will yield about 6 ½ years of life in a system that is used off
grid. While a single series string will yield 10 to 14 years (properly
maintained) 14 years is not the rule however. 

 

A bit of due diligence is now required to get these back, (and they may not
be worth it). Separate the two strings and give them 62 volts for 10 hours;
you’ll have to watch them so they don’t get too hot. Set the absorb settings
below and give them about three weeks. If there is some improvement in
capacity, another EQ; 61 volts for two hours may just do it. 

 

With the Magnum 48 volt inverter I calculate the absorb time at 5 hours, now
typically the absorb charge should be about 58.8 volts but, most batteries
die because of under charge so I would set the absorb voltage at 59.4. You
may have to update the software for the Magnum control panel to get more
programming flexibility.

 

The MX60 with 6 of the 175s should be set to absorb for as long as possible,
I think the last software version allows 4 hours. I calculated absorb time
with this setup is 19.6 hours which is not possible, so just keep the
controller from going to float for as long as you can.

 

Concord makes a real nice 915 AH 2 volt cell which should give a decade plus
life, for the next bank. I would avoid parallel strings at all cost. If you
feel this is too large a bank then use the 660 AH 2 volt. You can always
call me 575-539-2111 if you have questions. I have been in the battery
business almost 45 years.

 

  Tom Duffy

  Systems Design Engineer

 

     tom at thesolar.biz

       575-539-2111 X 301

Although no trees were killed in the sending of this message, a large number
of electrons were terribly inconvenienced.

 

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