Why won't my cells work in series?

BigD
BigD Registered Users Posts: 9
I have tons of cells to experiment with. I have bus tape, thin tape, and plenty of solder and copper wire. To get higher voltage, I need to arrange the cells in series right? Negative( bottom ) of one cell attached to the positive( top ) of the next cell and so on. Connecting them in parallel would keep voltage the same but increase current right? So I tested two of my 2x2 cells... each put out about .35v in room lighting. When I soldered them together with wire, bottom to top...the voltage dropped to zero, even though each cell, tested separately, still yielded .35v while soldered together. What am I doing wrong? Just wanted to make a battery charger for starters, then some other projects. I guess I need a tutorial in how to properly get these cells to link up right b/c whatever I'm doing now doesn't seem to work :) Thanks in advance for your help, and this looks like a great website, looking forward to learning a lot!

Comments

  • mike95490
    mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    Re: Why won't my cells work in series?
    BigD wrote: »
    To get higher voltage, I need to arrange the cells in series right? Negative( bottom ) of one cell attached to the positive( top ) of the next cell and so on. Connecting them in parallel would keep voltage the same but increase current right?

    About all I can do is confirm this for you. Right.

    Solder will dissolve the metal layer on the cells, the soldering has to be done quickly, with an iron that is as low in temp as possible. Thermal shock on the cell can ruin it too. Have fun, hope you have lots of supplies.

    Mike
    Powerfab top of pole PV mount | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
    || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
    || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

    solar: http://tinyurl.com/LMR-Solar
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  • BigD
    BigD Registered Users Posts: 9
    Re: Why won't my cells work in series?

    Don't worry I have literally several hundred cells to play with and I'm very careful. All the cells were soldered at low temp, and all of them still work when tested separately... just not when I try to measure the voltage by putting the neg. lead at one end and the positive lead at the far end of the string... then it reads 0v. Each individual cell will still read about .35v, but the whole string reads 0. I just don't know why. Maybe bad connectivity... perhaps a conductive pen... higher quality silver solder? Solder paste? Any ideas here? I think I may have to enlist the help of someone who's done it before when I visit home this weekend but if that doesn't happen, please keep suggestions coming, thanks! Maybe if I wired a few in parallel to see if the volts stay the same but the amps go up? Just as an experiment?
  • Kamala
    Kamala Solar Expert Posts: 452 ✭✭
    Re: Why won't my cells work in series?

    The symptoms you describe suggest that your solder connection has failed.
  • BigD
    BigD Registered Users Posts: 9
    Re: Why won't my cells work in series?

    Yeah that's what I'm thinking too... so how best to go about fixing it. I've heard I should use the higher-quality silver solder maybe? And solder paste? Don't even know what that is. I also have bus line and some thinner metal ribbon that came as a set. How do you guys connect your cells and get good contact? My 3 tries with 3 different methods have all yielded failure so far, but like a good tinkerer, I'm just getting started! :)
  • BB.
    BB. Super Moderators, Administrators Posts: 33,431 admin
    Re: Why won't my cells work in series?

    Silver solder is a higher temperature solder--so I don't think it would work for you...

    Have you looked at this thread?

    Anyone build your own panels?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Brock
    Brock Solar Expert Posts: 639 ✭✭✭✭
    Re: Why won't my cells work in series?

    If you have a bunch in series can you test any two right next to one another, if they work move in either direction? Maybe there is one bad joint in the string? If none work in series something is really wrong.

    And your sure you are + on one end then the - from that cells is attached to the + from the next cell correct, in other words + to - to + to - and so on? I you wire them + to + and - to - along the way that will drop the voltage to zero as well.
    3kw solar PV, 4 LiFePO4 100a, xw 6048, Honda eu2000i, iota DLS-54-13, Tesla 3, Leaf, Volt, 4 ton horizontal geothermal, grid tied - Green Bay, WI
  • BigD
    BigD Registered Users Posts: 9
    Re: Why won't my cells work in series?

    Yes I have 2 wired in series and 3 wired in series. All 3, while still soldered together, bottom of one cell to top of the next cell, separately still produce normal voltage. But when I test the string out, meaning one electrode at the first cell, the other electrode at the last cell, I get 0v for some reason. Maybe if I reverse the connections? Top to bottom instead of bottom to top? Shouldn't make any difference whatsoever that I can tell, but who knows? I think maybe I just have a bad connection, it's been a long time since I did much soldering, I think I've lost my touch. I'm going to visit my parents this weekend, and a family friend of ours just happens to be a great electrician, and he's going to help me get my cells working right. Also I bought a few small panels to study, just to make sure I'm doing it right also. Thanks for the suggestions... now, how to make a panel big enough for 48V and a decent amperage to charge a 48v twin-engine electic scooter with about half a dozen big honkin' batteries!
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Why won't my cells work in series?
    BigD wrote: »
    All the cells were soldered at low temp, and all of them still work when tested separately... just not when I try to measure the voltage by putting the neg. lead at one end and the positive lead at the far end of the string... then it reads 0v.

    My first thought was: Continuity test?

    My second thought was: Is there enough *light* hitting the cells to make voltage?
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Why won't my cells work in series?

    dwh,
    he confirmed each individual cell will still output so your first thought is in order. bad connection somewhere.
  • BigD
    BigD Registered Users Posts: 9
    Re: Why won't my cells work in series?

    SOMEone didn't read the post! :) I already DID a continuity test.. all the cells work separately. And ALL the cells work period, producing about .35v on ambient kitchen light. So no, continuity is not a problem, and neither is lighting. I'm just going to keep trying and hopefully this weekend I'll have someone who's done it before help me out, come back and let you know where I went wrong so someone else doesn't repeat my mistakes :)
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Why won't my cells work in series?

    calm down. getting angry at us isn't going to solve anything. there is only so much that could've happened that would have prevented output. if the cells have output individually and continuity is good then there has to be a miswired cell or cells. check that the power of one cell was delivered to the next cell at the proper place.
  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    Re: Why won't my cells work in series?
    BigD wrote: »
    SOMEone didn't read the post! :) I already DID a continuity test.. all the cells work separately. And ALL the cells work period, producing about .35v on ambient kitchen light. So no, continuity is not a problem, and neither is lighting. I'm just going to keep trying and hopefully this weekend I'll have someone who's done it before help me out, come back and let you know where I went wrong so someone else doesn't repeat my mistakes :)


    Sorry, I was unclear.

    I can see that you did test each individual cell...what I was wondering about was if you tested *the entire string* of cells.

    If the string itself doesn't test out as a continuous circuit - then it's broken somewhere along the line.
  • BigD
    BigD Registered Users Posts: 9
    Re: Why won't my cells work in series?

    You guys are touchy lol. Did the smiley face not make it clear I meant the comment jokingly? :) Anyway, yes the cells all work separately, and no the string fails the continuity test. Either I'm connecting them wrong somehow, or there's a bad connection somewhere. How and where do YOU guys all connect your cells?
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Why won't my cells work in series?

    don't know how i missed that, but we do have smilies you can put in that are good enough for somebody as blind as me.
    :p:D:D:D

    cell1+ to cell2-, cell2+ to cell3-, cell3+ to cell4-, etc.
  • BigD
    BigD Registered Users Posts: 9
    Re: Why won't my cells work in series?

    Well I actually started out cell one- to cell2 +... should I have started from cell1+ to cell2- instead? Voltage should flow either way though right? :D
  • GreenerPower
    GreenerPower Solar Expert Posts: 264 ✭✭✭✭✭✭
    Re: Why won't my cells work in series?

    * Check individual cell in the soldered string to see if they all have proper voltage (with you "test" light shining the entire string)
    * Check from one end of the string to the first cell to see if voltage is proper.
    * Move the Volt meter lead from the first cell to 2nd cell and so on, each step, you should see the total voltage goes up by one cell voltage. If not, there is your trouble cell.
    Hope this helps,
    GP
  • BigD
    BigD Registered Users Posts: 9
    Re: Why won't my cells work in series?

    Man I have to repeat myself a lot. There are NO bad cells. Every single cell I've tested separately works just fine and produces about .35v with room lighting. It's only when I try connecting them pos. to neg., that the voltage drops to zero. I must just be getting a bad connection because even when they're connected, if I touch the leads the each cell separately they're still producing .35v. It's just not adding up so there must be a bad connection, I just don't know how to fix it. How do you guys connect your cells?
  • Cariboocoot
    Cariboocoot Banned Posts: 17,615 ✭✭✭
    Re: Why won't my cells work in series?
    BigD wrote: »
    How do you guys connect your cells?

    We don't. We buy commercially-made solar panels. Your experience points out very well why there are limits to do-it-yourself and solar power. Getting a weather-proof seal is another issue.

    Obviously when you're making your connection something is going wrong and actually causing a break in the circuitry instead of a continuation. Some foreign matter or even flux getting in the way.

    Can you just touch the (+) of one to the (-) of another and get a voltage increase? If so, it's the soldering process (which is very delicate). If not ... are you sure they're all the same kind of cell and the polarity is correct?

    Building your own solar panels is a great learning experience. Although usually what you learn is not to do it.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Why won't my cells work in series?
    BigD wrote: »
    Well I actually started out cell one- to cell2 +... should I have started from cell1+ to cell2- instead? Voltage should flow either way though right? :D

    it depends on which end you designate as cell 1, but yes you have it that for series it connects to the next cell's opposite polarity. just like looking at a series of flashlight batteries end to end. i really can't say what the problem might be as i'm not there to see what you did, unfortunately. try wiring leads to one cell so you will get a + and a minus output from it. confirm its output is on the leads. duplicate this so you have 2 of them like this. now place them in series and see if you get double the voltage. if you do, then you can eliminate one of the leads and use just the one to interconnect the cells. hopefully this will reveal what was going wrong in your effort.
  • BigD
    BigD Registered Users Posts: 9
    Re: Why won't my cells work in series?

    Thanks niel, I'll give that a try. And if it still doesn't work, I have a friend who's an electrician who's working on an electric scooter of mine, he'll help me out. And just to hedge my bets a little, I DID order some premade panels too lol :)
  • claychps
    claychps Registered Users Posts: 9
    Re: Why won't my cells work in series?

    Check out this site, might help you !
    http://pyronet.50megs.com/RePower/Homemade%20Solar%20Panels.htm
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Why won't my cells work in series?

    bigd,
    these will make for good experimentation and some lessons learned. if you find out anything then let us know. it will probably be something silly that was overlooked.
  • Just Me
    Just Me Solar Expert Posts: 48
    Re: Why won't my cells work in series?

    Hi All, been lurking for a while and found this thread interesting.

    BigD, don't take any of this as an insult, but we have to start from the beginning to cover all bases.

    I have no idea what your panels are rated at. What are they supposed to put out in direct sunlight?

    First off, does the voltage go up if you shine a light right on the panel? What kind of volt meter are you using and is it on volts and not ma or A and the correct range? If it is over-range, it may go blank. If you can, how about posting a picture or a link to one of your panels showing the solder joints.

    Try this: After you solder the minus wire going to the second panel, put your meter probe to the plus side of the first panel, and the other probe to the solder joint of the wire you just soldered on going to the second panel. It should still read .35V. Now, leaving the probe to the + side of the first panel, go to the other end of that wire and see if it has .35V with it not connected to the second panel. If it's not showing .35V, you sir, have invented a Black Hole here on earth and I offer my services as your manager. :D If it is .35V, solder it to the + of the second panel that you know is putting out .35V, then with your probe on the first panel +, put your other probe on the second panel -. It should read ~.70V. If it doesn't, take up another hobby. :D
    My guess is that probe placement is screwing you up.

    Let us know what you come up with.
  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    Re: Why won't my cells work in series?

    just me,
    he is dealing with cells and not pvs, but the series connections would result in an upping of the voltage in either case and is why he is confused as to what went wrong. it has me wondering too as there is only so much that could've happened and is no douibt something being overlooked and taken for granted i think.
  • jeffkruse
    jeffkruse Solar Expert Posts: 205 ✭✭✭
    Re: Why won't my cells work in series?

    Just a thought. If you are connecting them correctly and you read 0V then try to connect them incorectly and see what happens. Try + to + and - to -. Shouldnt work but who knows.
  • GreenerPower
    GreenerPower Solar Expert Posts: 264 ✭✭✭✭✭✭
    Re: Why won't my cells work in series?
    BigD wrote:
    ...I must just be getting a bad connection because even when they're connected, if I touch the leads the each cell separately they're still producing .35v.
    jeffkruse wrote: »
    Just a thought. If you are connecting them correctly and you read 0V then try to connect them incorectly and see what happens. Try + to + and - to -. Shouldnt work but who knows.

    Measuring each when in a string should tell whether a cell is reversed polarity (the way it is soldered) already.
    GP