boB, If you build it, it will sell.
I’d love to see a battery distribution box, with separate fusing and disconnects, and maybe shunts, for each string, with large bus bars in it and enclosed in a corrosion resistant box. Oh…and Listed. It would need to come in a variety of sizes, like 250A, 500A, 1000A, and also maybe able to be daisy-chained for really large systems, like up to 100kW at 48VDC Hint..hint… Brian Teitelbaum AEE Solar From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of boB Gudgel Sent: Thursday, June 02, 2011 8:50 PM To: RE-wrenches Subject: Re: [RE-wrenches] 24 volt Battery Bank comparison On 6/2/2011 6:44 PM, d...@foxfire-energy.com<mailto:d...@foxfire-energy.com> wrote: What I like best about Mark's set up (the retired phone co. dude w/ half a hand), is that he can select individual strings at random. he can eq an individual string, or top off a few strings and park them. he can even run strings of T 105s, or even nicad (individually of course) in the same system as L-16s and the like.. he just reprograms the chargers (and logs it). I think he got the design from his days in the Navy. So boB, how about a controller that can be user programed to charge multiple battery configurations with a soft switch? i.e. Bank A, Bank B...? and while you're at it, maybe a multiple string DC box? Something with a shunt and a breaker for each string? A four string set up would be nice. I could use 2% of your first million. db Well, It's not a bad idea ! I'll forward that question off to Robin. I have ran into several that use separate and independent battery banks and switch between them. I'm not sure why they don't just use those L-16 size 2V cells though instead. But as I mentioned before, I think that a battery balancer device would take care of problems with single strings but maybe even parallel strings, as well as the pesky problem of AGM batteries that like to plump when you cook 'em ! (I hate when that happens and one battery gets real hot) Say, maybe a gizmo that goes across each battery (no 2V cells though) to keep each battery in the string at the same voltage. It would have to be cheap, maybe $30. Great discussion. boB Dan Brown Foxfire Energy Corp. Renewable Energy Systems (802)-483-2564 www.Foxfire-Energy.com<http://www.Foxfire-Energy.com> NABCEP #092907-44 -------- Original Message -------- Subject: Re: [RE-wrenches] 24 volt Battery Bank comparison From: boB Gudgel <b...@midnitesolar.com<mailto:b...@midnitesolar.com>> Date: Thu, June 02, 2011 8:56 pm To: RE-wrenches <re-wrenches@lists.re-wrenches.org<mailto:re-wrenches@lists.re-wrenches.org>> Nobody mentioned this in this thread, but it occurs to me that the answer may be made clearer by looking at the Voc of each battery string after so many Amp-Hours (years) of service. i.e., disconnect the strings' parallel connection and measure the individual string voltage after charging them all the best that can be done. This would be making the assumption that the batteries themselves were fairly equal capacity and voltage at installation time. And for whatever reasons, connections, temperatures and everything else discussed here, the strings degrade differently. The older and more worn out batteries should have a lower voltage (Voc) than the less worn out strings. Thus, the better strings may be tending to hold up the worse strings by dumping charge into them when the whole bank is discharging, and wasting energy and battery efficiency. I guess that just large 2V cells are the answer in this case, if at all possible. Thanks for the help on this question ! boB On 6/2/2011 10:42 AM, Tom Elliot wrote: Not surprised at all about the phone company guy. It was a phone company guy who read me the riot act that no one in their right minds would ever parallel battery banks the way PV off-grid systems did and got me to set up my system with separate strings connected independently to buss bars. The battery engineer I talked to years ago at Dynasty not only said the same thing but also said keeping strings separate meant individual string distance from the bars became irrelevant (given correctly sized wire for each string’s parallel connectors). I had a system with 12 100 amphour strings of paired 12v Dynasty AGMs which was rock solid until the day I sold the house. The last time I checked the system before the sale no single battery varied from any other in the system by more than 1/10 volt and the majority were still holding identical voltages. From: d...@foxfire-energy.com<mailto:d...@foxfire-energy.com> Sent: Wednesday, June 01, 2011 4:14 PM To: RE-wrenches<mailto:re-wrenches@lists.re-wrenches.org> Subject: Re: [RE-wrenches] 24 volt Battery Bank comparison Good thread. Thanks. In my experience, it all boils down to the customer. I've seen one temp. set up with like 12 strings (for a concert). but they were recharged and sold individually within a few weeks.. I've also seen a single string (Teledyne aircraft batteries) fail in less than a year.. they were in a brand new airplane tug that was never charged -- ever. (the guy said "I dunno, it just stopped working"). I have one customer who (last I knew) was running 6 strings of mixed aged L-16s going on 8 years. Thing is, he's a retired phone company dude (Who's missing half of his right hand from using one of those pocket pal screwdriver thingys on a key chain in a hot DC rack.. like he'd done hundreds of times before.. but that's another tale). But I do like his set up.. he has each string set up with it's own fused Disco and Trimetric.. Gives him random control over each string. And yes, he keeps a very detailed log, and you can bet that when he takes a battery out of service, it's done. Me? for an average bullet proof off grid system, I shoot for a max of two strings for 24V systems (for the redundancy), and manually reconfigure them every few years. for 48V systems, I shoot for one string of two Volt cells.. thinking that if I loose a cell I can still operate a 46V system until I get a replacement. And Yes, as we all know, there are folks out there that really shouldn't be allowed to operate a popsicle stick. db Dan Brown Foxfire Energy Corp. Renewable Energy Systems (802)-483-2564 www.Foxfire-Energy.com<http://www.Foxfire-Energy.com> NABCEP #092907-44 -------- Original Message -------- Subject: Re: [RE-wrenches] 24 volt Battery Bank comparison From: Michael Welch <michael.we...@re-wrenches.org<mailto:michael.we...@re-wrenches.org>> Date: Wed, June 01, 2011 1:43 pm To: RE-wrenches <re-wrenches@lists.re-wrenches.org<mailto:re-wrenches@lists.re-wrenches.org>> Every now and then I see reference on this list to the need for thermal detection. Here is an interesting, inexpensive piece of equipment that could be used for finding hot (loose or corroded) connections, hot batteries, hot PV cells in modules, and even poorly insulated spots, its original intended purpose: http://www.blackanddecker.com/power-tools/TLD100.aspx I have one and used it for finding uninsulated spaces, but cannot attest to its durability or suitability for the other uses mentioned above. boB Gudgel wrote at 01:00 AM 6/1/2011: >This might be a good reason for an installer to have one of those FLIR (or >similar) thermal imager cameras.  They're a bit on the expensive side, but >could >really be helpful for so many things.  Even just to know if you have left a >nut loose (under load of course) > >boB _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org<mailto:RE-wrenches@lists.re-wrenches.org> Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm<http://www.re-wrenches.org/etiquette.htm> Check out participant bios: www.members.re-wrenches.org<http://www.members.re-wrenches.org> ________________________________ _______________________________________________ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org<mailto:RE-wrenches@lists.re-wrenches.org> Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm<http://www.re-wrenches.org/etiquette.htm> Check out participant bios: www.members.re-wrenches.org<http://www.members.re-wrenches.org> ________________________________ No virus found in this message. 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