So I bought a cheap box offline and it fried (I'm sure the little guy is dead) and wanted to know if the IRF510 from RadioShack would work in its place. Not really good with reading the technical sheets, if ya could tell me the max continues amperage that would really help. (Assuming it is capable of being used in this application)
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Do not use that MOSFET, it can only handle about 2A before it gets hot enough to burn out.
The tried-and-true IRLB3034 is a great MOSFET, good for up to about 18A for high reliability and 25A if you are willing a bit of risk.
The tried-and-true IRLB3034 is a great MOSFET, good for up to about 18A for high reliability and 25A if you are willing a bit of risk.
Do you know anything in the 45amp range? I'm really trying to buy local but something like amazon works. Is there any type of store I.e. lows that might sell something like what I need?
Edit: and thanks for the reply mooch, got called all kinds of names trying to ask about this on another forum.
Edit: and thanks for the reply mooch, got called all kinds of names trying to ask about this on another forum.
For high amps, just parallel two or three IRLB3034s. You can just stack them up and use a single 15k resistor for bias. I think you may need some extra resistors to prevent oscillation. I read something about this on reddit.
No problem.
No single MOSFETs for that much current without it costing a LOT of money. @drmarble's recommendation for multiple MOSFETs is probably the best way to go. I really, really recommend not buying them from Amazon though as there are plenty of fakes out there. Best to buy from a modder's parts web site or from another modder.
What kind of batteries are you going to be using for that much current?
Have you confirmed that the wiring and sled in that box can handle that much current?
Would be a shame to have these awesome MOSFETs hooked up and something else couldn't handle the current.
Wouldn't that require higher voltage to open the gate though? Farely new too this but I would think 2.1v through each wouldn't be enough for them to function properly. I think I remember reading something about under loading MOSFETs causing heat. Will keep searching or just shell out thr $$$ for a 40 amp .
No problem.
No single MOSFETs for that much current without it costing a LOT of money. @drmarble's recommendation for multiple MOSFETs is probably the best way to go. I really, really recommend not buying them from Amazon though as there are plenty of fakes out there. Best to buy from a modder's parts web site or from another modder.
What kind of batteries are you going to be using for that much current?
Have you confirmed that the wiring and sled in that box can handle that much current?
Would be a shame to have these awesome MOSFETs hooked up and something else couldn't handle the current.
They are the 26650 efest 3500 mah. (I'm very experienced in mechs but box building is a headache) the actual sled is more or less exactly like the tank crossing's. Don't suppose you could explain the benefits of the parallel MOSFETs? Do they scale max amperage at 1.5x similar to parallel batteries?
Multiple MOSFETs in parallel only need the same voltage as one. They will turn on at slightly different voltage levels, and share current unevenly, but three in parallel should handle 45A nicely and last a long time. Going to only two is a bit risky in my opinion, but I build my stuff to last for decades.
With three MOSFETs, you'll need 2.8V minimum at all times. Drop below that and you could burn out the MOSFETs. The higher the voltage, to a point, the harder they turn on and the cooler they run. If the voltage drops too low they start heating up and can quickly fail.
Parallel mosfets act very much the same as parallel batteries, the load gets split between them so they don't get as hot. That 1.5x scaling is a good worst case you can use for mosfets too. It's often better than that though, 1.2x-1.3x. But, better to assume 1.5x and have a more reliable setup.
The splitting up of your 45A across three mosfets means, on average, each handles 15A. A single IRLB3034 at 45A would produce about 6W of heat and its temperature would rise to about 400°C. Since it can burn out at 175°C, that's a problem.
A single IRLB3034 running at 15A produces about 0.7W of heat, its temperature only rising to about 72°C. Three of them together only produce a bit over 2W of heat. They would be next to each other so they couldn't cool down as quickly as one but I still think the temperature would be under 100°C, even with the uneven sharing of current.
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@drmarble brought up a good point...
If you have multiple mosfets in parallel they are more susceptible to oscillating and frying themselves. Adding a 100 ohm resistor connected directly from each mosfet's gate, and running out to the 15k resistor and the button, will help to supress those oscillations.
If you have multiple mosfets in parallel they are more susceptible to oscillating and frying themselves. Adding a 100 ohm resistor connected directly from each mosfet's gate, and running out to the 15k resistor and the button, will help to supress those oscillations.
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