Need Some Help Finding the Right MOSFET

[Supercap2F]

Adam,
Do you think this one has protection: http://www.hobbyking.com/hobbyking/store/__23319__Turnigy_nano_tech_1000mah_1S_15C_Round_Cell.html
Dan

 

[Arouse1973]

Adam,
Do you think this one has protection: http://www.hobbyking.com/hobbyking/store/__23319__Turnigy_nano_tech_1000mah_1S_15C_Round_Cell.html
Dan

Not sure Dan to be honest.
Adam

 

[Supercap2F]

Not sure Dan to be honest.
Adam

That's Okay, I can just contact them. I think that it might because they don't have a warning on the ad like they did on the one that had no protection.

One last thing: If it does have protection, it's okay to put them in series right?
Dan

 

[Arouse1973]

Might be best to check with them first, the reviews down the bottom don't give them a good rating for discharge current. They do say you can connect them together to form a bigger pack. But my personal choice would be a qualified pack with leads and a connector.
Adam

 

[Supercap2F]

Might be best to check with them first, the reviews down the bottom don't give them a good rating for discharge current. They do say you can connect them together to form a bigger pack. But my personal choice would be a qualified pack with leads and a connector.
Adam

Okay, Thanks a million Adam!
Dan

 

[Arouse1973]

No probs mate. Just be careful Dan, please!
Adam

 

[Supercap2F]

Well, I contacted Hobby King about the batteries today, and they said that none of their batteries have under voltage protection... Even the ones with two sets of wires.

So I guess I'm back to square one... What do you think would be the best thing to do next? Should I try and design my own, or...

 

[cjdelphi]

Ebay has a lot of over/under voltage circuits on batteries including the protection circuit (ironically costing more than a battery with an ic protecting it lol)


Why we talking about protected batteries anyway? They annoy me lol...


Basically a zener diode in conjunction with the enable pin might simply be enough...

Say a 2v zener in reverse, up to 2v the diode will block but once we hit above 2v/ 3v ... the diode will conduct, i'd send this to the base of an npn to pull the enable high... but i have no idea about the ic you're using eg if it expects > 1v to enable then you're laughing otherwise extra circuitry (transistor) required

 

[Supercap2F]

Basically a zener diode in conjunction with the enable pin might simply be enough...

Say a 2v zener in reverse, up to 2v the diode will block but once we hit above 2v/ 3v ... the diode will conduct, i'd send this to the base of an npn to pull the enable high... but i have no idea about the ic you're using eg if it expects > 1v to enable then you're laughing otherwise extra circuitry (transistor) required

Great idea cjdelphi! The voltage regulator I'm using is a LD39200 (it's datasheet is here). The enable pins high voltage level is 1.2V, but doesn't a zener allow almost all the voltage pass when it breaks down? And if the zener started conducting at, say, 3.3V then it should have plenty of voltage to set the enable pin high, right?
Thanks!!
Dan

 

[cjdelphi]

A resistor in series with the diode? 1kish should do... But it will be tricky though because you wont get much headroom above a volt according to the simulator...

 

[Supercap2F]

You mean like this: battery out ---/\/\/\/-----]<|------ Voltage Regulator enable pin.
..................................................................... R ........... Z
(R being the 10K resistor, and Z the zener)

I did play around with simulating it some, and I did notice that I couldn't get more than a volt of headroom when it was conducting. I thought that might just be me though.. Maybe the best way to go would be a Op-amp comparator circuit? It would add a little bit more complexity, but I would think it might be more reliable.
Dan