200 amp fuse

greenthumb76greenthumb76 Solar Expert Posts: 40
I need to upgrade my cables, and install a 200 amp fuse between my batteries and inverter.

I hope to use
  • my microwave (8.5 amps a/c) or
  • toaster oven (1200 watts) or
  • my bucket heater (1000 watts)
for short periods of time (1 to 10 minutes).

I have a 1500 watt inverter (3000 watt peak).

My question: what is the most economical fuse and holder, that will do the job?

Comments

  • john pjohn p Solar Expert Posts: 814 ✭✭
    Re: 200 amp fuse

    A 1500 w inverter is not going to be happy with any of the 3 items you mentioned. And the problem will be worse if its a MSW inverter rather than a sine wave inverter.. Inverters in general(relatively low cost ones) overheat very quickly with resistave loads
    The start up current needed for a cold element can be as much as 3 times the runnning current.
    As you not give location it hard to give a possible place to purchase a 200a fuse and holder
  • WindsunWindsun Solar Expert Posts: 1,164 ✭✭
    Re: 200 amp fuse

    And rather than a fuse, I would go with a breaker, such as this http://store.solar-electric.com/mndc175.html

    Running what you are, you might be buying a lot of fuses at $20+ each.
  • greenthumb76greenthumb76 Solar Expert Posts: 40
    Re: 200 amp fuse

    umm . . . I can't tell you how poor I am . . . I live like the Amish.

    My question was: what is the most economical fuse and holder, that will do the job?

    All the 'bells and whistles' would be nice (like the link you posted has), but I'm talking about the bare necessities . . .
  • john pjohn p Solar Expert Posts: 814 ✭✭
    Re: 200 amp fuse

    Dear mister very poor living like an Amish with a green thumb, I will tell you how to get a 200 a "fuse" that is a lot less than buying a genuine 200a fuse holder and fuse. but you have to promise not to tell anyone I told you this.. ok?
    Go to an electronics store and buy a 200a shunt.. they do the job very well have good solid mounting base and a large about3/8 " nut and bolt each end to take upto a size #2 cable no problems...
    Only one problem if you do "blow" it you have to throw it away..
    a 200a shunt will withstand about 240a no problems for short time but will blow if current exceeds about 300a:D

    Try asking the site owners here NAWS it should cost about $30.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 200 amp fuse

    200 Amp inverter fuse with holder: $37.50
    http://store.solar-electric.com/fb200ampfuwi.html
    With bolt connectors: $45.00
    http://store.solar-electric.com/fb-200t.html

    NAWS: Always a good place to start. :D
  • john pjohn p Solar Expert Posts: 814 ✭✭
    Re: 200 amp fuse

    wayne from canada the message wasnt for you. , True they were never designed for that purpose but in reality do do the job in some ways better than a "real" fuse, They can also be used at the same time to actually measure the current going into the inverter .. I have done this a few times and have always found they take about 20% over the rating for short times (10 mins)and fail at about 50% over..
    IM using a 100a one on my system between battery and inverter
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: 200 amp fuse

    Sorry to upset you John. I'll delete my message and send it to Greenthumb as private message. I'll remember this lesson for any future help I may have to offer others.
    Cheers.
  • greenthumb76greenthumb76 Solar Expert Posts: 40
    Re: 200 amp fuse

    Thanks for the links and info! I think this should work fine.

    One last question: are the rest of you in agreement with John P?
    A 1500 w inverter is not going to be happy with any of the 3 items you mentioned. And the problem will be worse if its a MSW inverter rather than a sine wave inverter.. Inverters in general(relatively low cost ones) overheat very quickly with resistave loads
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 200 amp fuse

    I'll hazard a guess you have a 1500 Watt MSW 12 Volt inverter. The microwave will not like it, and the inverter will not like the heating elements. Under such heavy loads it is entirely possible to see Voltage drop on the DC side that will send the Amps soaring. There could be enough drop to shut the inverter off, if it senses it only has 10.5 Volts (due to the draw). Use of a PSW inverter will solve the first problem (electronic control of microwave acting up) but not the second. You will be running pretty close to the inverter's peak capacity (ignore the 3 kW surge rating - that's for momentary draw).

    For this kind of continual load, a 2 kW 24 Volt inverter would be a better choice, like this Exeltech: http://store.solar-electric.com/exxp1224vo20.html But it is probably more money than you care to spend ($1,300 and an OB 2524 is nearly $2,000). You could go up in Voltage with this Samlex: http://store.solar-electric.com/sa15wa12vosi1.html Other choices are more $.

    I would not agree to using a shunt as a fuse either, as they are not contained and therefor present a possible fire hazard depending on the mounting circumstances. I know john p has the smarts to avoid this, but 'tis better to err on the side of caution. :D
  • KamalaKamala Solar Expert Posts: 452
    Re: 200 amp fuse
    I would not agree to using a shunt as a fuse either, as they are not contained and therefor present a possible fire hazard depending on the mounting circumstances.

    I agree. And I don't think that the minimal savings are worth it. Wasting a precision resistor designed to measure a Vdrop instead of utilizing a fuse for its intended function seems foolish. To me.:confused:
    I know john p has the smarts to avoid this, but 'tis better to err on the side of caution. :D

    Again, agreed. But not enough smarts to know that a statement like...
    john p wrote: »
    ... but you have to promise not to tell anyone I told you this.. ok?

    is meaningless in an open and public forum such as this.
    K
  • john pjohn p Solar Expert Posts: 814 ✭✭
    Re: 200 amp fuse

    ok all mabe it wasnt a great suggestion .. but it was offered as a viable one .. trust me it does work well.. and when they fail the bits of metal just seem to "disappear" ..
    Greenthumb you have been shown by others there are much cheaper fuses than the first one shown to you I now suggest you use one of them..

    I oly said "dont tell anyone " in jest.. I know everyone can read that,, duh

    WAYNE FROM CANADA.. PLEASE DONT TAKE WHAT I SAID THE MESSAGE WASNT FOR YOU WAYNE AS A REAL STATEMENT IT ALSO WAS IN JEST..

    But all I said about those loads on the inverter are definately FACT. If your 1500 w inverter is MSW it will fail or just stop working trying to use it on such high amp resistave loads..
  • greenthumb76greenthumb76 Solar Expert Posts: 40
    Re: 200 amp fuse

    Darn, darn, darn. I've given up so much already. Thought the bucket heater would be a good solution for my homemade shower setup. :cry:

    And it sure would have been nice to have the convenience of the microwave or toaster oven a few minutes a day.

    Boo hoo

    Well, thanks for saving me the money! Looks like the 4 awg cables and 100 amp fuse I have now will do just fine--for the things I AM able to use.

    I can still thank God that I have lights, music, and heat!
  • john pjohn p Solar Expert Posts: 814 ✭✭
    Re: 200 amp fuse

    Kamala I really thought a man with the experiance you have on these forums you would have been capable of instantly being able to see my saying""but you have to promise not to tell anyone I told you this.. ok? was only said in jest as EVERYBODY knows that there are going to be many many people read that post..

    And to the others if you had given it more thought you would have seen the reasons you gave for not using a shunt as a combined shunt and fuse were wrong.
    Mabe it was because none of you have ever done it that you thought it best just to say the idea was bad.. I accept mabe you just all wanted to err on the side of caution and not have someone do it, But if you do that with everything you not tried nothing new gets tried. And this was not a life or death situation.
    There is nothing wrong with using something designed for one thing then used in a different way..
    During my life have done many things that experts said could not or should not be done and succeeded.
  • greenthumb76greenthumb76 Solar Expert Posts: 40
    Re: 200 amp fuse

    Amen John. Me too.

    Thanks to ALL of you for the suggestions and warnings.

    Now please, stop bickering!! This is MY thread!! ;)
  • greenthumb76greenthumb76 Solar Expert Posts: 40
    Re: 200 amp fuse
    A 1500 w inverter is not going to be happy with any of the 3 items you mentioned. And the problem will be worse if its a MSW inverter rather than a sine wave inverter.. Inverters in general(relatively low cost ones) overheat very quickly with resistive loads

    What about using a 700 watt microwave instead?
  • john pjohn p Solar Expert Posts: 814 ✭✭
    Re: 200 amp fuse

    Green thumb what type of inverter do you have?? MSW (modified squarewave)or SW(true sine wave" ?

    If SW it will work fine providing you have enough batteries to support it..

    If its MSW it will work ok also with one difference it will take twice as long to heat something. this is not a theory it really does.

    WARNING microwave ovens were not designed to work off MSW inverters. So be careful if you do it as mabe thousands of others have done "the correct use police"' dont catch you
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: 200 amp fuse
    What about using a 700 watt microwave instead?

    A "700 Watt" microwave is really 1000 Watts - or more. Do not confuse its "cooking power" with what it actually draws. I have a "700 Watt" unit: running it draws 1080 Watts. Nor does lessening the "cooking power" necessarily result it lower power consumption. I went through several before finding one that had "only" a 300 Watt disparity between draw and cooking power.

    Microwaves aren't resistive loads either; it's their control circuits which may not like the MSW, in addition to using more power. Ugly situation, isn't it? How are you fixed for generator power? A couple minutes' gasoline usage every so often can be a lot cheaper than a solar power set-up capable of handling such loads.
  • greenthumb76greenthumb76 Solar Expert Posts: 40
    Re: 200 amp fuse

    Thanks guys. MSW inverter. No generator. :(
  • john pjohn p Solar Expert Posts: 814 ✭✭
    Re: 200 amp fuse

    I will try to give simple explanation why microwave ovens use more power for longer than when they are on Sinewave(grid) or Sinewave inverter Its not because they are a resistave load its because the mgnetron gets most of its power during the peak of the wave. On a MSW inverter there really is no peak .so a lot of cooking power is wasted.
  • nsaspooknsaspook Solar Expert Posts: 396 ✭✭✭
    Re: 200 amp fuse
    john p wrote: »
    I will try to give simple explanation why microwave ovens use more power for longer than when they are on Sinewave(grid) or Sinewave inverter Its not because they are a resistave load its because the mgnetron gets most of its power during the peak of the wave. On a MSW inverter there really is no peak .so a lot of cooking power is wasted.

    Some of newer "Inverter" microwaves work much better on dirty power.

    They've got other (QA related, I've repaired a few) problems but they seem to work just fine on cheap DC/AC inverter power.

    http://www.google.com/url?sa=t&source=web&cd=3&ved=0CCIQFjAC&url=http%3A%2F%2Fwww.eletrodomesticosforum.com%2Fes%2Fcursos%2Fhorno_microondas%2FInverter.pdf&ei=jrLlTLmFNoOqsAPp9qWyCw&usg=AFQjCNHaXZ3406KSN2LMV4wN8E3ijqpFEg&sig2=40LAMjJjUQDSBz-pOxgDyg
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