hot mosfet

[adam.]

 

[fasteddie600]

Ok, can't quite see what is wired to what with your stealth wiring system!

Is it possible the heat sink on your FET is shorting to the box lid or box?

 

[adam.]

Ok, can't quite see what is wired to what with your stealth wiring system!

Is it possible the heat sink on your FET is shorting to the box lid or box?

Its heat shrinked so it cant be shorting. As it was getting hot i tried with the fet poking out of the box and its still the same.

I built 2 at the same time and they are both doing the same.

This will not defeat me!

 

[adam.]

So today i rewired the whole thing using 2.5mm cable.making sure all the connections were decent. And used a new mosfet. Still a195a one.
Still having the same issue.
The voltage under load is only 2.7v

Any other ideas?

 

[fasteddie600]

So today i rewired the whole thing using 2.5mm cable.making sure all the connections were decent. And used a new mosfet. Still a195a one.
Still having the same issue.
The voltage under load is only 2.7v

Any other ideas?

Hmm, in the absence of a multi-meter this is tricky to diagnose. It would be very useful to know what voltage you are getting at the battery sled, and, Gate on the FET.

I am assuming you are taking the reading from the 510 with a tank-o-meter. That could indicate large battery sag or FET not activating fully.

Next then I guess would be to try linking your switch wires together and if that works, try a new switch.

Can you show us the wiring diagram you are working to?

 

[adam.]

Hmm, in the absence of a multi-meter this is tricky to diagnose. It would be very useful to know what voltage you are getting at the battery sled, and, Gate on the FET.

I am assuming you are taking the reading from the 510 with a tank-o-meter. That could indicate large battery sag or FET not activating fully.

Next then I guess would be to try linking your switch wires together and if that works, try a new switch.

Can you show us the wiring diagram you are working to?

I got myself a multi meter today. I mesured the voltage on the atty fired up.

I have also just wired it up in series and the thing works a treat. Ill leave that one in series but as for the other box i have i still want to run in paralell.

This makes me think the problem is the fet not liking the imput voltage?

 

[fasteddie600]

I got myself a multi meter today. I mesured the voltage on the atty fired up.

I have also just wired it up in series and the thing works a treat. Ill leave that one in series but as for the other box i have i still want to run in paralell.

This makes me think the problem is the fet not liking the imput voltage?

Nice one, a multimeter will be very useful!

Is the other parallel box up and running? If it is, what voltage do you have at the battery sled underload? And what is your gate-to-source and gate-to-drain voltage reading under load?

It certainly sounds like you are not getting sufficient voltage to the FET for some reason, what does the code typed on the FET read?

 

[adam.]

Nice one, a multimeter will be very useful!

Is the other parallel box up and running? If it is, what voltage do you have at the battery sled underload? And what is your gate-to-source and gate-to-drain voltage reading under load?

It certainly sounds like you are not getting sufficient voltage to the FET for some reason, what does the code typed on the FET read?

Its not up and running at the moment. Ill measure them tomorrow.

I hot a reply from the guy at mod maker and he said a few people are having issues with those mosfets at the moment and asked me to try it in series.

So maybe it is just the mosfet after all.

 

[Chegs]

My wooden box just recently decided to try & set me/my house/my desk on fire,4.2V 4000 mah lipo pack and a 0.2 or just under dual coil.The mosfet got hot and destroyed the insulation,mosfet then shorted on the 510 & disconnected the fire switch.The RDA centre pin was glowing as brightly as the coils causing the insulator in the 510 to melt & disconnected the atty.I was desperately trying to remove the lipo to disconnect it,but without burning myself on the hot components and the double-sided tape holding the lipo had decided to get a really powerful grip(probably with the abundance of heat)& I was trying to be gently forceful as I didn't really want to damage the lipo pack.I'm fortunate as the only dead items are the FDV 510 & the bridging resistor,the wooden box will fix with sandpaper & new varnish,the lipo pack has recharged in the same time as it used to before this incident & still chucks out masses of amperage(I have since tested it down to 0.1 ohms)but the mosfet still gets hot enough to heat a small room.I think I'm going to be sourcing some other FET's for the 4.2V boxes as the 8.4V box is still thumping away with the same components as the 4.2V & no hot FET.

 

[adam.]

My wooden box just recently decided to try & set me/my house/my desk on fire,4.2V 4000 mah lipo pack and a 0.2 or just under dual coil.The mosfet got hot and destroyed the insulation,mosfet then shorted on the 510 & disconnected the fire switch.The RDA centre pin was glowing as brightly as the coils causing the insulator in the 510 to melt & disconnected the atty.I was desperately trying to remove the lipo to disconnect it,but without burning myself on the hot components and the double-sided tape holding the lipo had decided to get a really powerful grip(probably with the abundance of heat)& I was trying to be gently forceful as I didn't really want to damage the lipo pack.I'm fortunate as the only dead items are the FDV 510 & the bridging resistor,the wooden box will fix with sandpaper & new varnish,the lipo pack has recharged in the same time as it used to before this incident & still chucks out masses of amperage(I have since tested it down to 0.1 ohms)but the mosfet still gets hot enough to heat a small room.I think I'm going to be sourcing some other FET's for the 4.2V boxes as the 8.4V box is still thumping away with the same components as the 4.2V & no hot FET.

Sounds like it might just be an issue with the fets then. Glad you didnt do yourself any damage in that situation!