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-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@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 Im 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. Its 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 t...@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. Confidentiality Notice: This message including any attachments is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender and delete any copies of this message. _____ From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@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; youll have to watch them so they dont 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 Although no trees were killed in the sending of this message, a large number of electrons were terribly inconvenienced.
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