Using a T-fuse without the fuse block?

St8koutSt8kout Registered Users Posts: 33 ✭✭

I read that you should locate inverter fuses close to the battery.

For my small off grid system, (more like an emergency backup), I was looking at the T-fuse for the inverter and is there any reason I can't mount one end directly to the battery post of my Vmax SLA battery without using the fuse block? As big as the T-fuse is, it fits quite nicely using a few washers to lift it up a bit to clear the battery case. From there I just need a short cable run to my battery disconnect switch, then on to the inverter. (I could actually attach the other end of the T-fuse directly to the switch without a cable. I only need to widen the fuse hole a bit.)

So since it's not a flooded lead acid battery, what is the downside of doing this since there are no corrosive/explosive fumes to deal with? (Yeah, I know, SLA's are not fully sealed, but they will not be in an enclosed container.)


Comments

  • Marc KurthMarc Kurth Solar Expert Posts: 1,009 ✭✭✭✭
    edited December 2016 #2
    I am a fan of fuses at the battery/battery bank, sized based on the cable and cumulative peak loads size -  and of course a fused inverter.

    With batteries commonly used in off grid systems, the energy levels are nothing short of fearsome. Heck the typical 2v, 1200ah that I deal with, can go to 9,000 amps on a dead short.  No, I'm not exaggerating! Watching the short circuit tests is pretty awesome actually.

    Did I mention that I really like fuses?
    I always have more questions than answers. That's the nature of life.
  • EstragonEstragon Registered Users Posts: 4,496 ✭✭✭✭✭
    I did it something like that for a few years on my initial small temp system. Kinda mickey mouse but it worked. Obviously the batteries have to be somewhere out of the way to avoid accidents.
    Off-grid.  
    Main daytime system ~4kw panels into 2xMNClassic150 370ah 48v bank 2xOutback 3548 inverter 120v + 240v autotransformer
    Night system ~1kw panels into 1xMNClassic150 700ah 12v bank morningstar 300w inverter
  • HorseflyHorsefly Registered Users Posts: 451 ✭✭✭✭
    edited December 2016 #4
    I'm going to be using one of these:

    http//www.samlexamerica.com/products/ProductDetail.aspx?pid=8

    mounts directly on the positive battery post, and the cable connects to the other post on the fuse holder.  Any reason not to do this? 

    Steve

    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 8S (25.6V), 230Ah Eve LiFePO4 battery in a custom insulated and heated case.
  • softdownsoftdown Solar Expert Posts: 3,673 ✭✭✭✭
    Horsefly said:
    I'm going to be using one of these:

    http://http//www.samlexamerica.com/products/ProductDetail.aspx?pid=8

    mounts directly on the positive battery post, and the cable connects to the other post on the fuse holder.  Any reason not to do this? 

    Steve

    I think you need to discard the first http: as the link does not work.

    Back to OP:
    As for me....I bought a bunch of fuse blocks and a whole lot more fuses. Of course the fuse blocks are nice to have. Having fused power lines put one ahead of many, many solar installs....whether a fuse block is used or not.

    This isn't a car that is going to vibrate over 100,000 miles of road. Whether one needs to take a number of large safety precautions may depend on whether children and guests have access to the battery bank.
    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
  • HorseflyHorsefly Registered Users Posts: 451 ✭✭✭✭
    Sorry. I fixed the link.
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 8S (25.6V), 230Ah Eve LiFePO4 battery in a custom insulated and heated case.
  • softdownsoftdown Solar Expert Posts: 3,673 ✭✭✭✭
    Horsefly said:
    I'm going to be using one of these:

    http//www.samlexamerica.com/products/ProductDetail.aspx?pid=8

    mounts directly on the positive battery post, and the cable connects to the other post on the fuse holder.  Any reason not to do this? 

    Steve

    That fuse looks pretty ideal to me. Our host does not carry it. What kind of price tag is normal for such a fuse?
    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
  • HorseflyHorsefly Registered Users Posts: 451 ✭✭✭✭
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 8S (25.6V), 230Ah Eve LiFePO4 battery in a custom insulated and heated case.
  • westbranchwestbranch Solar Expert Posts: 5,183 ✭✭✭✭
     
    KID #51B  4s 140W to 24V 900Ah C&D AGM
    CL#29032 FW 2126/ 2073/ 2133 175A E-Panel WBjr, 3 x 4s 140W to 24V 900Ah C&D AGM 
    Cotek ST1500W 24V Inverter,OmniCharge 3024,
    2 x Cisco WRT54GL i/c DD-WRT Rtr & Bridge,
    Eu3/2/1000i Gens, 1680W & E-Panel/WBjr to come, CL #647 asleep
    West Chilcotin, BC, Canada
  • HorseflyHorsefly Registered Users Posts: 451 ✭✭✭✭
    That one looks pretty much identical to the one I pointed to, except my link came with a 300A fuse. I think the fuse comes separate for the one you are linking to. Still, not much difference.
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 8S (25.6V), 230Ah Eve LiFePO4 battery in a custom insulated and heated case.
  • mike95490mike95490 Solar Expert Posts: 9,583 ✭✭✭✭✭
    I'd suggest not reaming out the hole of the fuse end, that may disturb the internal element. 
    Unlikely disturbing would increase the rating, but rather decrease it.  Use copper washers (harbor freight has a good cheap kit of many sizes) and SS bolt with lube ( I like the McMaster Carr copper flake conductive lube ) should give you a good connection,  Steel or SS is not very conductive and will heat up under large loads.
    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 ,

  • St8koutSt8kout Registered Users Posts: 33 ✭✭

    You know, I saw those terminal block fuses but since I kept seeing everyone using T-fuses for inverters I thought I should go with those.

    What I didn't like is having to buy/use those T-fuse holder blocks which take up a lot of space and need an extra cable run.

  • HorseflyHorsefly Registered Users Posts: 451 ✭✭✭✭
    edited December 2016 #13
    St8kout said:

    You know, I saw those terminal block fuses but since I kept seeing everyone using T-fuses for inverters I thought I should go with those.

    What I didn't like is having to buy/use those T-fuse holder blocks which take up a lot of space and need an extra cable run.

    Those two reasons (size and extra cable) are the reasons I decided to avoid the ones you are talking about and instead go with the terminal-mounted fuses.
    Off-grid cabin: 6 x Canadian Solar CSK-280M PV panels, Schneider XW-MPPT60-150 Charge Controller, Schneider CSW4024 Inverter/Charger, Schneider SCP, 8S (25.6V), 230Ah Eve LiFePO4 battery in a custom insulated and heated case.
  • WaterWheelWaterWheel Registered Users Posts: 363 ✭✭✭
    With the Blue Seafuse blocks you can find most amp sizes from 30A to 300A on Amazon.       A battery short seriously scares me.       Lots of heat in a short with that many amps.

    Conext XW6848 with PDP, SCP, 80/600 controller, 60/150 controller and Conext battery monitor

    21 SW280 panels on Schletter ground mount

    48v Rolls 6CS 27P

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