Help! Having problem with Mosfet/Charger

[fasteddie600]

would these be any good?

Buy MOSFET Transistors IRF3711PBF, N-channel MOSFET Transistor, 110A 20V, 3-Pin TO-220AB International Rectifier IRF3711PBF online from RS for next day delivery.

 

[RicModMaker]

Sparky, I owe you many!!

Thankfully I have a switchable DC bench power supply so set to testing at different voltage.
4.5V I only get 3.2v at atty slowly ramping up
6V I get 5.5V at atty very quick firing.
So looks like these MOSFET has too high a Vgs for parallel battery configuration, @Seedy do you have any with lower Vgs ideally 1.5-2.5V?

Any suggestions which MOSFET's to get? I am going to start looking now

Cheers everyone

Bugger. That's all I've got. Im learning something here. I thought they just turn on and off. Really sorry fella. I owe you the cost of those FETs.

 

[RicModMaker]

sparkyjuice. You are the man of knowledge. What am I looking for in a mosfet that will not do this again?

 

[fasteddie600]

Bugger. That's all I've got. Im learning something here. I thought they just turn on and off. Really sorry fella. I owe you the cost of those FETs.

No worries seedy, it's all a learning curve! I think those MOSFETS would be fine in an 8V build.

@sparkyjuice. You are the man of knowledge. What am I looking for in a mosfet that will not do this again?

I think we are looking for one around the 10mm x 10mm dimension with ideally 50A+ Rating? and Vgs max <3.0V I would think max Vds of 10-20v would ideal. I am only going of what info I can find/remember and an electonics education that fees like a distant memory, hopefully sparky can illuminate us!

 

[RicModMaker]

No worries seedy, it's all a learning curve!



I think we are looking for one around the 10mm x 10mm dimension with ideally 50A+ Rating? and Vgs max <3.0V I would think max Vds of 10-20v would ideal. I am only going of what info I can find/remember and an electonics education that fees like a distant memory, hopefully sparky can illuminate us!

Its hard getting your head around all the specs. I need to get some that work well at 4.2 as well as 8.4. I'll have a dig around and see what I can find out. I do owe you one though for those FETs ;-)

 

[sparkyjuice]

would these be any good?

Buy MOSFET Transistors IRF3711PBF, N-channel MOSFET Transistor, 110A 20V, 3-Pin TO-220AB International Rectifier IRF3711PBF online from RS for next day delivery.

those FETs would work
VGS(th) Gate Threshold Voltage 1.0 ... 3.0 V VDS = VGS, ID = 250µA
but gate voltage I 3v max you would have to set a potential divider resistor network at the fire button to avoid exceeding the 3v max
as I'm not sure how they would handle continuous max voltage but they would fire rapidly
actually scratch that they seem fine as long as 16v not exceeded Seedy

 

[fasteddie600]

those FETs would work
VGS(th) Gate Threshold Voltage 1.0 ... 3.0 V VDS = VGS, ID = 250µA
but gate voltage I 3v max you would have to set a potential divider resistor network at the fire button to avoid exceeding the 3v max
as I'm not sure how they would handle continuous max voltage but they would fire rapidly
actually scratch that they seem fine as long as 16v not exceeded @Seedy

The gate voltage(Vgs) Max I believe refers to the full-on state, i.e. it should give full power anything over 3v which seems ideal so would basically be useless if batteries dropped below 3v.
They should take anything up to 20V as absolute max so plenty safe.

 

[RicModMaker]

The gate voltage(Vgs) Max I believe refers to the full-on state, i.e. it should give full power anything over 3v which seems ideal so would basically be useless if batteries dropped below 3v.
They should take anything up to 20V as absolute max so plenty safe.

So are these ones I've got no good? My head hurts [emoji30]

 

[sparkyjuice]

So are these ones I've got no good? My head hurts [emoji30]

hope you aint got thousands mate, no good for 4v setup
the ones in @fasteddiie600 linky are good

 

[RicModMaker]

hope you aint got thousands mate, no good for 4v setup
the ones in @fasteddy600 linky are good

No, I've not got that many but would you have a look at the specs and tell me where I went wrong pretty please? Thanks fella.
N-Channel MOSFET 80A/55V