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 ? 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
t...@thesolar.biz
575-539-2111 X 301
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From: re-wrenches-boun...@lists.re-wrenches.org
[mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of bob
Sent: Tuesday, June 29, 2010 4:53 AM
To: 'RE-wrenches'
Subject: [RE-wrenches] Interstate UL-16 HC problem
I have 2 systems that I am trying to correct that another local dealer has
installed.
This one is 2 strings of (8) UL-16 HC Interstate Batteries, 16 batteries
total.
We cannot get the batteries to charge over 1.225 despite discharging them
and generator charging them till everything shut down.
This is a 48 volt system with a Magnum 4448 inverter.
He also has (6) 175 watt Solar World panels on a manual tracker. (spends all
day tracking the sun) He is adding 2 more this summer. The controller is an
MX-60.
I have moved the Magnums settings to 1600 AH battery bank size to allow for
the inverter to have a longer absorb time to help it finish charging and get
to a full battery.
It's not working; we have 1 cell at 1.240 and the rest at 1.225.
These have not been cycled hard if at all, I am going to suggest that he
cycle them several more times to see if anything improves after that
The other system has the same problem with a different inverter! So it's not
inverter related, but I am at a loss.
I have not used Interstates before and want to stay away from them in the
future.
Any other suggestions?
Thanks,
Bob Ellison
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