Desperately Seeking Normally Closed Latching Contactor (but not that desperate)

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Comments

  • LostinSpaceLostinSpace Registered Users Posts: 27 ✭✭
    I really like this design. One single string.

    I did run into one snag. I don't think the celllog 8s are happy with this config. This config sort of physically and logically locks to 3.2 72AH cells together so that they are seen as one single 3.2 142AH cells. At least from the perspective of the celllog 8s.

    The cellog8 has only a single negative/common lead. There is no way for it to differentiate one single cell. As you wire in each pair of cells ( - to + to - to +, etc) the celllog sees each pair of cells as one cell.

    I think I'm going to need to use individual cell monitors that have discreet negative and positive leads.

    LOL. Is this why you asked if I had already ordered the celllog 8s? LOL. No matter. This project is being viewed as a hobby. It's fun to learn.
    Qty 24 Sharp 153W poly panels, Midnite MNPV6 combiner, Magnum MS-4448-PAE inverter with RC50 remote, Magnum MMP Mini panel, Midnite Classic 150 charge controller, Qty 32 LiFePO4 72AH cells in 2 string 48V array. BMS.
  • karrakkarrak Solar Expert Posts: 214 ✭✭✭
    You are right, strapping the two cells together in parallel makes them into one cell as far as the outside world is concerned. It also means that the voltage of both cells in parallel are the same because they are tied together. Because of this you only need to measure the voltage of each pair of cells. So you wire the cellog 8 up with the minus going to the battery negative, 1 to the first pair of plus terminals, 2 to the second pair of plus terminals and so on.

    The reason I am a little apprehensive about the cellog 8 is that unless an internal modification is made to it as shown below it will slowly unbalance your battery. This picture comes from a thread in the Endless Spheres forum


    Simon
    Off-Grid with LFP (LiFePO4) battery, battery Installed April 2013
    32x90Ah Winston cells 4p8s (24V), 4kW Latronics Inverter, 1160W of Solar Panels, homemade MPPT controller
    Homemade BMS https://github.com/simat/BatteryMonitor
     

  • LostinSpaceLostinSpace Registered Users Posts: 27 ✭✭
    edited August 11 #64
    Got it. I was thinking of ordering individual monitors, but as you say, the cells will always be at the same voltage since they are strapped together, So why bother.

    I think I'll make that patch though. As much as I can tell from the photo and diagram at the other end of your link is that you just jumper D4 to D5. I guess one just ignores that yellow line from D4 to D3 and beyond. Would you concur?
    Qty 24 Sharp 153W poly panels, Midnite MNPV6 combiner, Magnum MS-4448-PAE inverter with RC50 remote, Magnum MMP Mini panel, Midnite Classic 150 charge controller, Qty 32 LiFePO4 72AH cells in 2 string 48V array. BMS.
  • karrakkarrak Solar Expert Posts: 214 ✭✭✭
    Yes, you just need a jumper between D4 and D5.

    A couple of small comments regarding the wiring of your battery. I can't see if you have any spring washers between the bolts and the interconnection straps. I think it is a good idea to have a spring washer and flat washer so that if the bolt does loosen slightly that there is still good pressure between the straps and the battery terminal.

    It is usually good practice to have the fuses/circuit breakers as close to the positive battery terminal as possible or to make sure that the positive and negative cables are kept well apart from each other until the other side of the fuses/circuit breakers. The reason for this is that if the cable insulation is damaged by maybe rats or something else or chemically breaks down and the cables are next to each other or in a common metal conduit, gland or share common metal cable clamps that the cable might short out on the unprotected section.

    I have not seen any cells that look like yours. Do you know who they were manufactured by?

    Simon
    Off-Grid with LFP (LiFePO4) battery, battery Installed April 2013
    32x90Ah Winston cells 4p8s (24V), 4kW Latronics Inverter, 1160W of Solar Panels, homemade MPPT controller
    Homemade BMS https://github.com/simat/BatteryMonitor
     

  • LostinSpaceLostinSpace Registered Users Posts: 27 ✭✭
    1) Nice idea on the spring washers. Good spotting.

    2) That positive battery lead you see goes into the Magnum mini-panel just above (less than 2ft.) That houses the 175A breaker

    3) With the new config I was happy that the + and - cables are now adjacent to one another. And I tie wrapped them together. WHY? Because the Magnum inverter manual suggests it. It says it is less strain on the inverter (it may have been regarding capacitance. I cold check).

    4) The cells came from electric car parts company (same place the balancers came from). I switch to this brand from the calbs at the last minute. They have a higher stated cycle life and I think were a bit cheaper. sales has had them in the wild for about a year with no returns. SO, how much stock do I put in those claims. Not a lot, but the batteries come with cell covers, and have 4 holes at the perimeter of each cell to pass threaded rod through and bind the array together. So I thought what the heck, give them a try. So far so good. They came well balanced from ECPC.

    http://www.electriccarpartscompany.com/New-Energy-72Ah-Aluminum-Encased-Battery


    Qty 24 Sharp 153W poly panels, Midnite MNPV6 combiner, Magnum MS-4448-PAE inverter with RC50 remote, Magnum MMP Mini panel, Midnite Classic 150 charge controller, Qty 32 LiFePO4 72AH cells in 2 string 48V array. BMS.
  • karrakkarrak Solar Expert Posts: 214 ✭✭✭
    I like the fact that the cells are in aluminium cases and nice plastic shells to go around them. Electric Car Parts have cells from quite a few different manufacturers which is good to see. Now we just have to wait to see which perform the best over time.

    Thanks for the information

    Simon
    Off-Grid with LFP (LiFePO4) battery, battery Installed April 2013
    32x90Ah Winston cells 4p8s (24V), 4kW Latronics Inverter, 1160W of Solar Panels, homemade MPPT controller
    Homemade BMS https://github.com/simat/BatteryMonitor
     

  • karrakkarrak Solar Expert Posts: 214 ✭✭✭
    karrak said:
    I agree with you regarding counterfeit products. I don't think the one that I mentioned is a counterfeit. When you look look at the cost of the components that you would need to make a 200A DC SSR the cost seems about right. The company selling this has their own website and specialise in electronic equipment and have been selling on ebay since 2005. I will put my money where my mouth is and buy one of these and run some tests on it.
    The 200A SSR finally arrived and I finally got around to doing some tests on it.


    The one they sent did not have the "mager" brand marking, instead it was branded "MGR". Not an encouraging start.

    I hooked it in line with my inverter and measured the voltage across the switch with my inverted under load. From this I calculated the the On resistance of the switch to be ~2mOhm (.002 Ohms). With no heatsink the SSR is warm to touch with a load of 88A. Around 115A is around the limit without a heatsink. I ran it for several days with no problems.

    The SSR is rated at 60V, next test was to hook it up to 60V (actual test voltage 60.8V) while off for several days. Again it passed this test.

    There is a 400A version of this SSR which should have an On resistance around 1/4 of this SSR.

    Only gripe I have with this SSR is the terminal lugs. I made a copper adapter plate up with one big hole for my cable lug and three smaller holes for the SSR terminals.

    User "jflorey2" on another forum came up with this,
    All Electronics is now selling a TE Connectivity relay (intended for EV's) for $39. 24VDC coil, contacts rated 500 amps 900 volts. (Cat # SOL-205.) Should be enough for almost any battery system.

    This will draw ~14W with the coil voltage at 24V.

    Simon
    Off-Grid with LFP (LiFePO4) battery, battery Installed April 2013
    32x90Ah Winston cells 4p8s (24V), 4kW Latronics Inverter, 1160W of Solar Panels, homemade MPPT controller
    Homemade BMS https://github.com/simat/BatteryMonitor
     

  • LostinSpaceLostinSpace Registered Users Posts: 27 ✭✭
    edited September 18 #69

    karrak said:

    A couple of small comments regarding the wiring of your battery. I can't see if you have any spring washers between the bolts and the interconnection straps. I think it is a good idea to have a spring washer and flat washer so that if the bolt does loosen slightly that there is still good pressure between the straps and the battery terminal.


    I am still looking into adding the spring washers. But I've had the bolts in and out of the cells quite a few times now with all the configuring and re-configuring. There's a bit of friction when tightening and loosing I want to lubricate the bolts next time they're out. In researching this a whole new world of varying opinions about lubing solar battery connections opens up. LOL Do you (or anyone) have a lubricant you can recommend that's worked well for you?

    I found this: https://www.amazon.com/Jet-Lube-Anti-Seize-Lubricant-Conductive-Termination/dp/B009VO2O1Y/ref=sr_1_1?s=instant-video&ie=UTF8&qid=1505692643&sr=8-1&keywords=conductive+lube+for+nuts+and+bolts.

    And this: http://www.sanchem.com/electrical-contact-lubricant.html

    Qty 24 Sharp 153W poly panels, Midnite MNPV6 combiner, Magnum MS-4448-PAE inverter with RC50 remote, Magnum MMP Mini panel, Midnite Classic 150 charge controller, Qty 32 LiFePO4 72AH cells in 2 string 48V array. BMS.
  • bill von novakbill von novak Solar Expert Posts: 711 ✭✭✭✭
     There's a bit of friction when tightening and loosing I want to lubricate the bolts next time they're out. In researching this a whole new world of varying opinions about lubing solar battery connections opens up.

    Why do you want to lubricate?  Friction is good and it keeps your connections tight.  Contamination of contacts is bad; it increases contact resistance and leads to battery heating.
  • LostinSpaceLostinSpace Registered Users Posts: 27 ✭✭
    edited September 18 #71
     There's a bit of friction when tightening and loosing I want to lubricate the bolts next time they're out. In researching this a whole new world of varying opinions about lubing solar battery connections opens up.

    Why do you want to lubricate?  Friction is good and it keeps your connections tight.  Contamination of contacts is bad; it increases contact resistance and leads to battery heating.
    Good point. But in this case the bolts thread into the battery a little "sticky". Neither the bolt nor the threaded receptacle have best finishes (for lack of being able to express this better) and you sort of have to work the bolts in. A touch of conductive lube I think will allow the bolts to turn a little easier. But I'm posting before acting as I don't want to create more problems than I solve. :>

    You can see a photo of the cells earlier in this post.
    Qty 24 Sharp 153W poly panels, Midnite MNPV6 combiner, Magnum MS-4448-PAE inverter with RC50 remote, Magnum MMP Mini panel, Midnite Classic 150 charge controller, Qty 32 LiFePO4 72AH cells in 2 string 48V array. BMS.
  • mike95490mike95490 Solar Expert Posts: 7,307 ✭✭✭✭
    There is a copper loaded connector lube sold by mcmaster carr   Looks to be close to the same thing in the amazon link, copper flake and grease.
    https://www.mcmaster.com/#conductive-grease/=19g4evs

    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
    gen: http://tinyurl.com/LMR-Lister ,

  • karrakkarrak Solar Expert Posts: 214 ✭✭✭
    Here is another option for the grease which is available on Amazon.  This is recommended by someone Mike knows. Looks good to me.

    I didn't put any lubricant on my battery terminals when I put it together but would do so now. I agree you have to be very careful not to get the aluminium from the cathode terminals of the LFP cells binding to the steel bolts which might damage the aluminium thread the next time you remove the bolt . The lubricant would stop this.

    From an electrical conductivity point of view the electrical contact between the screw thread and the terminal is not as important as the contact between the flat part of the cable lugs/interconnectors and the flat surface of the battery terminals. Make sure you mechanically remove any oxidation off the terminals and cable lugs/interconnectors so they are bright and shiny before you assemble the connection.

    Simon

    Off-Grid with LFP (LiFePO4) battery, battery Installed April 2013
    32x90Ah Winston cells 4p8s (24V), 4kW Latronics Inverter, 1160W of Solar Panels, homemade MPPT controller
    Homemade BMS https://github.com/simat/BatteryMonitor
     

  • LostinSpaceLostinSpace Registered Users Posts: 27 ✭✭
    Thanx Simon.
    Qty 24 Sharp 153W poly panels, Midnite MNPV6 combiner, Magnum MS-4448-PAE inverter with RC50 remote, Magnum MMP Mini panel, Midnite Classic 150 charge controller, Qty 32 LiFePO4 72AH cells in 2 string 48V array. BMS.
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