Do i need a mosfet for a lipo battery?

Discussion in 'Electric Guns' started by BCB_Airsoft, Aug 12, 2012.

  1. BCB_Airsoft

    BCB_Airsoft New Member

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    I have never used lipo's before. Ive always used the same 9.6v for 1 1/2 years and now im thinking of a lipo. Im planning on getting a 7.4v 1200 mAh battery for my old JG M4 S-System with some minor internal upgrades. My only concern is, will the 7.4v lipo mess up my aeg without a mosfet, or is it completely ok to use it without a mosfet? Thanks. - Adrian
     
  2. theonlyBuster

    theonlyBuster Active Member Lifetime Supporter

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    No, you don't need it. It's just a recommendation.
    I've been using an 11.1v high discharge brick of a Lipo battery for about 2years now with no problems. The mosfet basically minimizes the carbon that builds up on your trigger contacts.

    I choose not to use a mosfet because trigger contacts are only about $5-$10 and if you shoot your airsoft gun properly, they last a few years. So with that said I personally choose not to use one. But others will disagree. But in the end of the day, it's really up to you. Just know and understand the risks before choosing to go with or without it.
     

  3. RCV

    RCV New Member

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    Buster is right. A 7.4 is perfectly fine and a 11.1 is still ok. Your gun may not run a 11.1 for a long time in stock form.

    I've run most of my guns without mosfets on big 11.1s for a long time with no issues. I do, however, clean them of carbon often. A mosfet would eliminate that, but I don't see much of an issue. The mosfet hype is a bit much.
     
  4. alex

    alex New Member

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    not all AEG's are the same. some trigger contacts are more sensitive than others.

    here's an L86 running a 7.4v 20c 2200mAH (no mosfet). it came in with trigger issues.
    [​IMG]

    my son's JG m4 lasted a few months before he lost trigger pull on a 7.4v 25c 1600 mAH (no mosfet). then again, i worked on a KWA m4 that's been running 11.1v 15c 1300mAH (no mosfet) without any trigger issues (failed piston).
     
    Last edited: Aug 12, 2012
  5. BCB_Airsoft

    BCB_Airsoft New Member

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    Vacaville/Fairfield
    @alex thanks, and sorry for the late reply.
     
  6. mvsrocks

    mvsrocks New Member

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    A 7.4v LiPo can be thought as an equivalent to a 9.6v NiMh, with a little higher discharge rate.
     
  7. Giggly_weeds

    Giggly_weeds New Member

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    I use a 7.4v LiPo, and it has been working perfectly for quite some time. I can't attest for a 11.1v, but I think that may be pushing it.
     
  8. naecO.rM

    naecO.rM New Member

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    That was six years ago.
    Is that still true that the mosfet not necessary for Lipo batteries?
    Clean contacts or change microswitch regularly is much cheaper with the same effect on aeg performance.
     
  9. cetane

    cetane Well-Known Member

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    you don’t value your time much do you..? A basic commercially available mosfet is >$25... use your existing trigger contacts before they’re burnt up/out. If you have the skill to change out a set of trigger contacts that are not prewired, you have the necessary skills to install a mosfet, and you won’t have to deal with trigger contacts again... like 1hr labour if you have everything on the bench ready to go in regards to tools and supplies.

    I value my time at about $20/hour. If it costs more than $20/hour for me to get something fixed I do it myself. If it’s less than that I’ll pay someone to do it if it is something I have no want to do
     
  10. Lefse

    Lefse Well-Known Member Supporting Member

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    You can forget using just stock trigger contacts for a high performance setup, they have nowhere near the current handling of a mosfet. Also, if you have decent soldering skill you can make your own mosfet unit for around 10 bucks.
     
  11. naecO.rM

    naecO.rM New Member

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    We have hobby and it's not about time value. Sorry, to tel you, but my time is much more higher than €20 per hour.

    To take off the microswitch from my G36, as example, I have to spend 3minutes.
    Open and clean contacts (sandpapering or with knife ) 2more minutes. And get back 3 minutes more. 3+2+3=8minutes.
    Soldering of new switch is a bit longer, for more 5minutes.

    More important to know if mosfet helps.
    I prefer to put in any necessary things, to keep it's simple and have more space for battery.
     
  12. naecO.rM

    naecO.rM New Member

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    Are you talking about black switcher? Not necessarily to use mosfet with that type of microswitch?
    Or blue?

    220V 16A, which is 3250W.

    [​IMG]
    [​IMG]

    DIY mosfet like that?
    [​IMG]

    What do you mean "high performance"?

    Thanks.
     
  13. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    For a 2S battery, not needed. For a 3S, recommended.
     
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  14. Ben3721

    Ben3721 Active Member

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    The 10 dollar mosfet that you can make on your own typically is the 3034 mosfet with a 2.2k on the drain and a 100 ohm on the gate. Some add a TVS diode too. Simple if you have the right chips and the diagram, not to mention the ability to solder without cooking the fet.
    [​IMG]

    Also just take a 60rps at 400fps dsg or even a 35rps 400fps short stroked ssg and wire it to trigger contacts outside the gearbox and click them together and see what happens. Obviously you'd need a 3 or even 4 cell lipo with a solid discharge rate and AH to give you the amps you'll need. It's very easy to get the amp discharge of a battery, just multiply the AH to the C rating. Then consider the burst rating which you will definitely see during motor start ups when amps spike.

    The whole lipo ready thing is just a gimmick to sell more aegs. Yes a weak stock aeg with a m100 spring on 18:1 gears with a 28 turn ferrite magnet motor on a low discharge lipo wont ruin the contacts, and you might reach 20rps at like 370fps with .20gram bbs. But a upgraded aeg with a m140 on a 13:1 ss4 gears with a 18 turn neodymium motor to get that 35rps at 400fps is going to need that mosfet or you can kiss the remaining dust of your trigger contacts goodbye.
     
    Last edited: Oct 14, 2019
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  15. Lefse

    Lefse Well-Known Member Supporting Member

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    You seem to forget the difference in voltage, 16 amps at 12 volts is a mere 192 watts, a high performance setup can reach twice that in average consumption with amperage spikes reaching triple digits in extreme setups. It's the same reason why high performance car stereos need such ridiculously thick power cables, because the voltage is so low.
     
  16. naecO.rM

    naecO.rM New Member

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    No, 220V 16A is tech spec of microswitch.
    Difficult to burn the microswitch at 12V.
     
    Last edited: Oct 14, 2019
  17. Guges Mk3

    Guges Mk3 Administrator Staff Member Administrator Supporting Member Lifetime Supporter

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    Bet you can do some damage at 12V 100A
     
  18. Lefse

    Lefse Well-Known Member Supporting Member

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    Current is current, regardless of voltage and that switch is made to handle 16A, not more. You can definitely burn that microswitch at 12V, with enough current it can even melt. Send a continous current of say 25A through it at 12V continuously, I guarantee you that it'll get really toasty.
     
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  19. Ben3721

    Ben3721 Active Member

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    The only alternative to a mosfet that can handle high amps is a relay. They are quite large, click and would kinda be like having an external mosfet. There are many relays for 12volts with higher amps like we already use in the hobby. Good luck fitting it in your buttstock, buffer or foregrip... You'd still have to rewire to use one.

    Too many people are afraid of stepping up to lipos and mosfets. It's not that bad. Especially if your good at soldering already.
     
  20. Lefse

    Lefse Well-Known Member Supporting Member

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    I actually had an automotive relay in my old AUG, it worked quite well.
     
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