First Time Build - Dual MOSFET Dual Parallel LiPo

[Mark Spivey]

Building my first mod. Please chime in if you see where I'm not on the right track or where I could do something better.

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[Mark Spivey]

Slight change in plans... decided to make it a dual mode mod. Now the challenge of getting it all to fit.

 

[Mark Spivey]

 

[Mark Spivey]

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[Dbot87]

Cool

 

[Skreech]

What size coil will you be using?

 

[Mark Spivey]

TBD. It's going to need a lot of mass and not go below 0.22 Ohms. I'm looking at the initial build being a 1.6 Ohms dual coil 28 AWG Kanthal with an ID of 4 mm and 12 wraps each, due to the heat flux.


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[david4500]

Interesting! I'll have to take a look at the data sheets for the dual schottky & fet you're using

 

[Mark Spivey]

Your input would be welcomed!


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[david4500]

Mark, the PLM boards are battery level indicators? Do you have a link to them?

 

[Mark Spivey]

Yes... I will look for a link. As I recall, I got them on eBay from China.


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[Mark Spivey]

https://m.ebay.com/itm/1S-2S-3S-4S-...-Level-LED-Indicator-/192054256404?nav=SEARCH


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[david4500]

rfp30n06le - RDS ON 47 milliohms is too high. You want about 2 milliohms or less.

mbr6045wt - Forward voltage (voltage drop) is at least 0.55V. You could use pfets instead of a rectifier diodes for better performance. http://www.ti.com/lit/an/slva139/slva139.pdf

 

[Mark Spivey]

True... I was willing to accept the voltage drop for the purpose of LiPo pack isolation to individually monitor the cells. I didn’t think about utilizing a P-Type MOSFET. I may do a retrofit after I’m done since I don’t have any of those on hand (and I might need to put a DPST fire button in too, which I also don’t have). My vape budget for the year is exhausted. Thanks for the feedback!


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[Mark Spivey]

I'm thinking the retrofit will include a IPP023N10N5 N-Channel MOSFET and a SQP90P06-07L P-Channel MOSFET. I wasn't able to find any MOSFETs that are more efficient and relatively low cost. This will need to be a 2018 thing since funds are going to be extra tight until mid January.

 

[Mark Spivey]

Putting up a revised drawing. I ran out of room to put everything in the Mod that I wanted. So, I've gone to a three wire LED VM to act as a pilot (Mod on) light reading 0.00, provide a relative voltage (for adjusting) in PWM mode, and actual voltage in unregulated mode when the fire button is pushed. The pilot LED or the LED VM had to be removed from play. Obvious selection for me... Bye bye pilot (on indicator) LED.

 

[Mark Spivey]

A little rough but it will do its job.

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[david4500]

Will you be using fuses like you have shown in your diagram?

 

[Mark Spivey]

Yes, absolutely! They will be between the battery positive (XT-30) connections and the Schottky Diode.


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[Mark Spivey]

Finally finished except the cleaning. Had to replace multiple parts multiple times but finally working as it should. Barely able to fit everything into the housing.

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