interstate gc2s?

nyarelathodepnyarelathodep Solar Expert Posts: 99 ✭✭
So, getting ready to purchase the final components for my system and am considering 4 of the interstate gc2 XHDs (6v, 232 ah)... they are priced similar to the trojans, but claim to have +40-50% of the cycle longevity of the trojans. Don't know how much of that is marketing hype. Does anyone have any testimonies for or against these batteries?

Also, the ones I am looking at (which are conveniently local) only have two posts per... is it ok to attach all the wiring to the same posts? This would be the CC inputs, inverter outputs, and a shunt. The system is 24v, and for now the loads are restricted to sub-400 watts... at this low level of power which is only supplying lights, tv, small sound system, and laptop/phone charging, is it a big deal to ground everything, or can that part be fine without any grounds? The inverter and Cc will have breakers on the negative wires at 15a and 100a respectively.

Comments

  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: interstate gc2s?

    I have not had experience with those particular Interstate batteries, but have not had good experience with Interstate products. The 232 Amp hour capacity suggests they may be made by East Penn and sold through Interstate, in which case they would be fine. Don't believe any claims about greater lifespan over another brand; it isn't possible to change the internal construction so much that it would affect such an increase.

    You seem confused on wiring. Most batteries have only two posts; positive and negative. It is normal to attach charge controller and inverter to the same posts if those are the only connections and there are only one or two battery strings.

    The shunt would go between the negative post and all other connections.

    Circuit breakers/fuse by convention go on the positive side, not the negative. I don't know what you're using for charge controller or inverter, but the inverter over-current protection is usually the larger because it will pull the most current. 15 Amps is not much for either, considering the batteries should have a peak charge rate around 23 Amps and at 24 Volts 15 Amps is only 360 Watts. I presume the 100 Amp is for the inverter: 2400 Watts. Be sure to get the wire size right or it will fry before the fuse does.

    Grounding is not essential for functioning. It is safety measure mainly. With any type of A/V equipment you may find it helps to reduce induced noise.
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: interstate gc2s?

    If you are prone to lightning in your area, I really like to ground bond the DC Battery Negative to Earth Ground (typically an 8-10 foot ground rod driven near the battery bank/power shed on the outside of the foundation. 6 AWG minimum.... If you have over 200 amp fuses/breakers on the battery bus, then going to 4 AWG or larger is probably better (I am sure the NEC has lots of regulations about the sizing of the ground wire).

    On the AC output, if you have a MSW Inverter (modified sine/square wave inverter), you usually cannot ground the neutral. It creates a dead short across the inverter and will let the magic smoke out (MSW inverters typically do not have "galvanic" isolation from DC input to AC output).

    If you have a TSW/PSW (True or Pure sine wave) inverter, you usually can ground the AC "Neutral" or white wire. TSW inverters usually have isolation between the DC input and AC output.

    Again, if you have lightning in the area, surge suppression is a good idea too. In the

    past, our retired moderator said that majority of their lighting damage was on the AC Inverter's output. The DC side (and charge controllers) tended to be less impacted by lighting.

    Ground does several things.

    1) All metal items (electrical boxes, copper plumbing, sinks, gas/propane lines, AC/DC neutrals and returns, etc.) are tied together (typically at the main ground rod to the house) so that if there is a Hot to Metal short circuit, the excess current flows through the grounding and pops the circuit breaker/fuse/etc.

    2) Lightning suppression--You want to get any lightning energy to the ground as soon as possible. You don't want the lighting ground current to come into the home (i.e., solar panel frames/mounting racks/surge suppressor green wire grounds, etc.) to the ground rod beside the foundation.

    3) Natural static electricity. When you have solar arrays on the roof, wind turbine on a tower, etc., you can have static electricity build up (or under a thunderstorm). Draining the buildup to earth ground can prevent electric shock/sparks inside the home.

    4) There are a few appliances that "need" green wire grounding. The most common are AC Florescent Tube fixtures (some need green wire ground to reliably start/turn on) and automatic spark ignition (stoves, water heater, gas space heater, etc.--Need the ground to "sense" when the fire is "burning").

    Not to say that you must earth ground your system... It is a convention and makes for a "more stable/easier to debug/safer" larger power systems. But many folks will run small off grid/RV power systems with floating power. For the most part, it works just fine.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nyarelathodepnyarelathodep Solar Expert Posts: 99 ✭✭
    Re: interstate gc2s?

    Hi coot, thanks for the response sir. To clarify the set up, the inverter is a samlex sa600w and the CC is the classic150. The wire size is all 6awg, from the pv combiner box to the inverter cables. The PV array is currently a pair of 245w Canadian solars (30.1 ov). I was given 4 very heavy Guage short battery interconnects with the "L" block style ends (looks like 2/0, proly overkill, but they were free, so i figure that can't hurt). The 15a breaker was for the inverter and the 100 for the CC, i just happened to have them hanging around (both are the midnight solar ones, the 100 a panel Mount and the 15 a dinn).

    Thanks for the clarification on the post set up. The shunt wiring I'm still a little confused on, but I'm sure when I'm ready to hook that up there is plenty of material on YouTube.

    The interstate gc2 is made by East Penn, according to the salesperson.

    Bill, i live in maine and im told lightning isn't really a problem with a very low strike rate. Still reading through your comments, as always, my thanks.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: interstate gc2s?

    Yep; lots of information on Youtube. So much so there's even the possibility you might find correct information. Absolutely certain you'll find lots that isn't.

    Okay two 245 Watt panels: 490 Watts. On a 24 Volt system that would make about 16 Amps peak. You do not need nor want a 100 Amp breaker on that circuit, and a 15 Amp one would be like to trip immediately. The wire size here only needs to be 12 AWG to handle the current, but larger if a long wire run is involved. If you are planning future expansion, wire for it now and save yourself the trouble of having to change it all later. The 6 AWG can handle 60 Amps without difficulty.

    A 600 Watt inverter (I can't find a reference to SA600, only PST600) on 24 Volts will draw about 25-30 Amps at maximum power; a 15 Amp breaker on that would trip if run up that high. Even at 400 Watts it could pull 19 Amps, depending on how low the battery Voltage is allowed to go. This really needs to be wired with 8 AWG minimum and a 50 Amp fuse.

    In either place that 15 Amp fuse is not likely to last; prepare for disappointment. And if you use the 100 Amp breaker on 6 AWG wire the wire will fry before the breaker trips.

    Shunts go between battery negative and everything else, so that all current flowing to or from the batteries passes through the shunt. That is how things like the WhizBang Jr. keep track of SOC.
  • nyarelathodepnyarelathodep Solar Expert Posts: 99 ✭✭
    Re: interstate gc2s?

    Alright, now I think I'm getting conflicting information on the pv breaker... The folks at midnight and Alt-e told me to go with a 15a breaker for the panels at the combiner box. Are you telling me I need a bigger breaker there, or are we taking about the inverter/CC side?
    The wire sizing selected (6awg) was put in place to allow another 2-4 panels of similar size.

    The SA model is samlex' s "industrial grade" model meant to handle heavier starting loads as found on induction motors, etc. It's peak is 1k, and it's microprocessor design is more efficient than the pst, apparently.
    So regarding the fuse, will any 50a fuse work? Are there DC fuses? And the breaker between the cc and the bank...60a?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: interstate gc2s?
    Alright, now I think I'm getting conflicting information on the pv breaker... The folks at midnight and Alt-e told me to go with a 15a breaker for the panels at the combiner box. Are you telling me I need a bigger breaker there, or are we taking about the inverter/CC side?
    The wire sizing selected (6awg) was put in place to allow another 2-4 panels of similar size.

    The SA model is samlex' s "industrial grade" model meant to handle heavier starting loads as found on induction motors, etc. It's peak is 1k, and it's microprocessor design is more efficient than the pst, apparently.
    So regarding the fuse, will any 50a fuse work? Are there DC fuses? And the breaker between the cc and the bank...60a?

    Okay: combiner box is on the input to the charge controller. With only two panels you don't in fact need one nor any circuit breaker or fuse. Things get different when you have multiple parallel PV connections. In this case you'll have two PV's in series connected to the input of the Classic: no combiner box, no breaker. If you're planning on expansion than each and every parallel PV connection would have a breaker on it in the combiner box and yes it would likely be 15 Amp.

    The output of the charge controller needs over-current protection. Otherwise if something should go wrong inside it the batteries can dump hundreds of Amps through the wire in an instant; far more than any wire you'd use there can take. It is more important to have that protection here than on the PV's.

    I know about Samlex's SA models, but have never seen one rated at 600 Watts. Only 1kW, 1.5kW, 2kW, and 3kW versions (12 & 24 Volt). The 1kW 24 Volt is model SA-1000k-124 and at that power level would draw around 48 Amps at full power and minimum input Voltage. Most of the time 50 Amp would work.

    Yes there are DC fuses/breakers. The reason for this is that it is more difficult to interrupt DC than AC and so any such over-current protection must be rated for the Amps, current type, and Voltage. Our host has quite a range of these things available: http://www.solar-electric.com/installation-parts-and-equipment/midnite/cipr1.html
    Note there are both high Amperage inverter fuses and breakers. Most people choose breakers because they make a handy way to completely shut down the inverter when needed. You can also source Blue Sea battery terminal fuses and switches if they fall within the specs required by the system. Often a local RV/Marine dealer will have them.
  • nyarelathodepnyarelathodep Solar Expert Posts: 99 ✭✭
    Re: interstate gc2s?

    And to clarify the issue of the shunt, the battery negative and the positives from the CC and the inverter (3 wires total) are what must pass through the shunt? For the battery negative, exactly which terminal should this come from?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: interstate gc2s?
    And to clarify the issue of the shunt, the battery negative and the positives from the CC and the inverter (3 wires total) are what must pass through the shunt? For the battery negative, exactly which terminal should this come from?

    No.

    ONLY the negative wiring is connected through the shunt:

    BATT (-) ---SHUNT ---CC & INV (-)
    BATT (+)
    CC & INV (+)
  • nyarelathodepnyarelathodep Solar Expert Posts: 99 ✭✭
    Re: interstate gc2s?

    Ah, thanks for clearing up the breaker issue. I already have the panels in series (i think... took the neg and connected it to the positive of the other, then took the 2 remaining pos and neg of each panel and wired them into the combiner...pos going into the breaker, and neg going into the neg bar.... Did i do that right? ). So, Even though i don't need the breaker and combiner box, is it ok that they are wired through then anyway? Just followed the diagram on the box. The breaker connects toa bar to which the positive 6awg wire is attached which goes into the house, and the negative 6awg is attached to the negative terminal of the neg bar which then goes into the house. Sorry if that seems confusing.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: interstate gc2s?
    Ah, thanks for clearing up the breaker issue. I already have the panels in series (i think... took the neg and connected it to the positive of the other, then took the 2 remaining pos and neg of each panel and wired them into the combiner...pos going into the breaker, and neg going into the neg bar.... Did i do that right? ). So, Even though i don't need the breaker and combiner box, is it ok that they are wired through then anyway? Just followed the diagram on the box. The breaker connects toa bar to which the positive 6awg wire is attached which goes into the house, and the negative 6awg is attached to the negative terminal of the neg bar which then goes into the house. Sorry if that seems confusing.

    That is correct.
    It allows you to add more strings of PV in future (providing you can match the Vmp of the existing string), each with its own breaker.
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    Re: interstate gc2s?

    One additional note regarding an input breaker between the PVs and the CC;

    It is handy to have a CC input breaker, near the CC. Perhaps it could be mounted in the same box as the CC's output breaker.

    When one does the Firmware Update on the Classic, the CC output breaker must be switched off, and back on at the correct time. It is much better to switch the PV input, off first and on last, anytime that the Classic's output breaker needs to be cycled.

    One just needs a switch to perform the PV input interruption, but a breaker (like the MNEPV) is inexpensive, and rated for this service.

    It is also convenient to be able to switch the CC input feed off, when testing, making wiring changes, etc ... IMO. FWIW, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • Dan_Dan_ Solar Expert Posts: 61 ✭✭✭✭
    Re: interstate gc2s?

    I have 8 Interstate GC2s from Costco (208Ah). They have not been fun to deal with. Problem right up front is that Interstates spec sheet for the batteries is confusing and possibly wrong. They spec a very high absorb voltage and claim SG should be 1.285 which its not. If you call support they are totally clueless. They're good batteries to start out on and ruin in a few years time but otherwise I would not recommend them
  • verdigoverdigo Solar Expert Posts: 428 ✭✭
    Re: interstate gc2s?
    Dan_ wrote: »
    I have 8 Interstate GC2s from Costco (208Ah). They have not been fun to deal with. Problem right up front is that Interstates spec sheet for the batteries is confusing and possibly wrong. They spec a very high absorb voltage and claim SG should be 1.285 which its not. If you call support they are totally clueless. They're good batteries to start out on and ruin in a few years time but otherwise I would not recommend them

    I agree although the 232 ah the OP referenced seem to need a pretty high absorb voltage to get any real gains in SG. I follow Interstate's recommendations for charging voltages.

    I operate a garage and sell Interstate batteries on consignment. When the GC2s set on the rack for too long they just pick them up, recharge them, and sell them as new somewhere else.

    When mine die I plan on a single string of larger capacity batteries. Hopefully these will be some revolutionary new thing that last twice as long and half the price.
  • nyarelathodepnyarelathodep Solar Expert Posts: 99 ✭✭
    Re: interstate gc2s?

    Thanks for that little tidbit on the breaker, vic. Timely, as I'm about to wire everything up tomorrow, at long last. I ended up going with a 4 pack of the T-105re batteries at any rate. A final question has popped in my mind though... Does it matter wether the breakers are wired before or after the shunt? In my layout, it makes more sense to wire them after the shunt, if it doesn't make a difference...
  • VicVic Solar Expert Posts: 2,970 ✭✭✭✭
    Re: interstate gc2s?

    nyarelathodep,

    The breakers really belong in the positive input and output to the Classic. The shunt must be in the negative battery lead.

    If you are planning to ever use the WBjr with the Classic, it MUST be in the negative battery lead. And, it is possible that the WB could be damaged if the breaker/s are in the negative lead, as it uses the negative as a return for its power.

    AND, it is customary to find these breakers in the positive leads of these systems, so anyone else looking after your system would probably believe that that is where the breakers must be wired, and any other approach might add confusion.

    FWIW. Have fun with the new system. Opinions, Vic
    Off Grid - Two systems -- 4 SW+ 5548 Inverters, Surrette 4KS25 1280 AH [email protected], 11.1 KW STC PV, 4X MidNite Classic 150 w/ WBjrs, Beta KID on S-530s, MX-60s, MN Bkrs/Boxes.  25 KVA Polyphase Kubota diesel,  Honda Eu6500isa,  Eu3000is-es, Eu2000,  Eu1000 gensets.  Thanks Wind-Sun for this great Forum.
  • nyarelathodepnyarelathodep Solar Expert Posts: 99 ✭✭
    Re: interstate gc2s?

    Ah jeeze, and I knew that too, after Coot set me straight on that. Think I'm overthinking at this point, heh. I do have the whizbang actually. Going to have to order another breaker for the additional pv in, but I'm guessing that's not critical for initial hookup at this time, correct? And what should that be rated at? The two i have now are the 50a (to inverter) and 60a (battery interrupt), 6awg, and 500w of panels (2/ 250w in series 30.1 voc).
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: interstate gc2s?

    If you have a combiner box with breakers (one breaker per panel string), you do not need any more breakers/switches.

    If your array only has one or two parallel strings, you don't need a breaker, but a breaker/switch can be handy for debugging servicing (able to "turnoff" controller without having to pull a connection).

    In general, a breaker should be around 1.56x Isc (panel or array's total Isc)--You should be able to find series fuse/breaker ratings for panels on their spec. sheet.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nyarelathodepnyarelathodep Solar Expert Posts: 99 ✭✭
    Re: interstate gc2s?

    Thanks, bill. Those two panels on series go through a 15a breaker at the combiner box. Just got my package today and the 50a breaker didn't ship yet, unfortunately. But everything else is there. Giving that i really want to hook all this stuff I've been collecting the last 3 months, leaving the inverter un-fused/breakered for a couple days shouldn't be an issue, right? Very minimal load will be drawn off it (less than 100 watts on average). Also, just to clarify, the inverter and CC can be attached to the same battery post, yes?
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: interstate gc2s?
    Just got my package today and the 50a breaker didn't ship yet, unfortunately. But everything else is there. Giving that i really want to hook all this stuff I've been collecting the last 3 months, leaving the inverter un-fused/breakered for a couple days shouldn't be an issue, right? Very minimal load will be drawn off it (less than 100 watts on average). Also, just to clarify, the inverter and CC can be attached to the same battery post, yes?

    Yep, you don't need the breaker until you do. :cry:

    I don't know which inverter you have--A breaker is very nice for turning off the inverter (when not used/servicing).

    If you want to play with the system and do some testing, a missing breaker is probably OK. However, I would not leave the system unattended without a breaker if a fire from an overheated cable will be a problem.

    I used to be pretty carefree in my youth:blush: (fuses/breakers--who needs those). But after many years of seeing every type of failure under the sun (what the heck happen here:confused:)--I try not to leave this stuff to good luck.

    If you have a "larger" battery bank, they can output an amazing amount of current into a dead short (100's to 1,000's of amps)... Like nothing you have seen when dealing with 120/240 VAC power. And you cannot just yank a heavy cable from a bolted connection.

    Will anything bad happen without a breaker--Almost certainly not. But--Is the risk worth the chances.... Only you can answer that question.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • nyarelathodepnyarelathodep Solar Expert Posts: 99 ✭✭
    Re: interstate gc2s?

    Ok, so I've got these battery interconnects that were given to me, 3 total... they are the "L" block connector type and the cable is 4/0 copper...2 of them are 11" long and 1 is 7" long. .. I've read that the interconnects should be the same length, but given the heavy Guage, would these cables be alright to connect my 4 6v batteries together in series (the shorter one in the middle)? Or am I asking for trouble here.
  • softdownsoftdown Solar Expert Posts: 2,403 ✭✭✭✭
    Re: interstate gc2s?
    verdigo wrote: »
    I agree although the 232 ah the OP referenced seem to need a pretty high absorb voltage to get any real gains in SG. I follow Interstate's recommendations for charging voltages.

    I operate a garage and sell Interstate batteries on consignment. When the GC2s set on the rack for too long they just pick them up, recharge them, and sell them as new somewhere else.

    When mine die I plan on a single string of larger capacity batteries. Hopefully these will be some revolutionary new thing that last twice as long and half the price.

    I had this same thought when I bought batteries three years ago. Batteries have resisted great technological change from what I see. Hopefully Elon Musk and/or the US Navy are able to realize a major breakthrough. It is the need for expensive batteries that makes off grid solar so hard to justify economically. It may take decades to break even.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • BB.BB. Super Moderators, Administrators Posts: 29,511 admin
    Re: interstate gc2s?

    For parallel battery strings... The idea is that the total length of the wiring path be the same with each string. So that you have equal total resistance in each parallel string.

    So, you don't need + and - leads to be the same length.

    With batteries, they have very low internal resistance (the ideal battery has zero resistance). If you have one string with 4' of wire and a second string with 6' total of wire length, then the battery with 4' of wiring will have lower resistance and tend to carry more of the current when charging and discharging.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • gww1gww1 Solar Expert Posts: 963 ✭✭
    Re: interstate gc2s?

    nya..........
    If you are connecting four 6 volt batteries in series for a 24 volt battery bank, I belive cable lenth will not be an issue. If two by two for a twelve volt system, you need the cables to be the same.
    Hope this helps
    gww
  • nyarelathodepnyarelathodep Solar Expert Posts: 99 ✭✭
    Re: interstate gc2s?

    That helps alot, gentlemen. Thanks so much for bearing with my many questions, some rather repetitive :/ hopefully, i will be up and running tomorrow!
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