Raptor Flip-Top VV Mod with 20A, 120W dc/dc converter...

[Matt Collins]

Mamu - how would you go about adding a built in charger to the circuit?


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[MadmanMacguyver]

Mamu My hat is off to you once again as you build some of the prettiest toys...looks like a Star Trek TOS flip top communicator...

Going to try my hat with one with a twist...You know me and my OVERZEALOUS penchant for safety I'm slapping a protection board in one...

Mamu - how would you go about adding a built in charger to the circuit?


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Matt that is Risky at best internal charging of Li-Ion cells in series requires several considerations...the most important of which is Cell Balance...if the internal charger pushes one batt above max voltage due the the cells being out of balance it will NOT be pretty...look up Li-ion battery fire...the ones they force to go thermal are "usually" done by overcharging them...also the second cell would explode more violently than the first...

 

[Matt Collins]

Yeah, I have looked at the risk end of it now I am looking into power diversion wiring to be able to pull off of each cell individually for the charging circuit

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[MadmanMacguyver]

If you need help Matt give me a holler via PM...I may not get back to ya right away...but I try to help where and when I can...WE ARE ALL IN THIS TOGETHER...also there are threads on that in the modding section...

 

[Little White Cloud]

Mamu My hat is off to you once again as you build some of the prettiest toys...looks like a Star Trek TOS flip top communicator...

Going to try my hat with one with a twist...You know me and my OVERZEALOUS penchant for safety I'm slapping a protection board in one...




Matt that is Risky at best internal charging of Li-Ion cells in series requires several considerations...the most important of which is Cell Balance...if the internal charger pushes one batt above max voltage due the the cells being out of balance it will NOT be pretty...look up Li-ion battery fire...the ones they force to go thermal are "usually" done by overcharging them...also the second cell would explode more violently than the first...

There is no danger in having a recharge port. That's what these pcbs are for. PCB/PCM/Fuel Gauge for 7.2V(7.4V) Lithium Battery Pack

I use the 8 amp board. It is small and will handle 30w with ease. If you intend to go higher than that the 20 amp board should do 80w.

Just do a proper installation and use a quality smart charger for 7.4v.

 

[Matt Collins]

I want to have all of the charging components built in the unit so there is no special charger required that way if I give it to a friend or something all they need is a micro usb cord and wall adapter

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[Little White Cloud]

That is not at all practical. These "pack pcbs" are made for smart chargers that ether plug into the wall or use a constant 12v source. USB ports only provide 5v at 500ma. That is not enough power to properly charge a 7.4v pack no matter what circuitry is used.

 

[Matt Collins]

That is why I am looking into power diversion wiring to get the cells wired to the charging circuit as a 2 cell parallel but still supply power to the actual unit as a 2 cell series setup

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[Alexander Mundy]

That is why I am looking into power diversion wiring to get the cells wired to the charging circuit as a 2 cell parallel but still supply power to the actual unit as a 2 cell series setup

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USB Charging 2 Li-Po Batteries.

 

[Little White Cloud]

USB Charging 2 Li-Po Batteries.

The setup in that link could work but is not near as safe as what I mentioned. If that setup is attempted make sure the switch can handle 10 amps dc at least.

 

[Rapture]

The fuses listed in the parts liar say resettable. But how do you go about resetting them if they trip?


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[Rapture]

Yes, Raptor is working aok.

The only thing I have changed since the initial build is adding a P-FET for full reverse polarity protection.



There are 2 P-FETs I've tested that work aok with Raptor, and also the OKR, for full reverse polarity protection - an smd one and a leaded one. Neither adversely affect the circuit or cause voltage loss and do a great job in protecting the batts and the entire circuit if you inadvertently place the batts in backwards.

Here are the specs for each:
Si7157DP (smd)
Drain to Source Voltage (Vdss) - 20V
Current - Continuous Drain (Id) @ 25°C - 46.5A (Ta)
Rds On (Max) @ Id, Vgs - 1.6 mOhm @ 25A, 10V
Vgs(th) (Max) @ Id - 1.4V @ 250µA
Gate Charge (Qg) @ Vgs - 625nC @ 10V
Input Capacitance (Ciss) @ Vds - 22000pF @ 10V
Power - Max - 6.25W


SUP75P03-07-E3 (leaded)
Drain to Source Voltage (Vdss) - 30V
Current - Continuous Drain (Id) @ 25°C - 75A (Tc)
Rds On (Max) @ Id, Vgs - 7 mOhm @ 30A, 10V
Vgs(th) (Max) @ Id - 3V @ 250µA
Gate Charge (Qg) @ Vgs - 240nC @ 10V
Input Capacitance (Ciss) @ Vds - 9000pF @ 25V
Power - Max - 3.75W
Mounting Type - Through Hole

Both digikey and mouser have the leaded P-FET (SUP75P03-07-E3) in stock and it's a LOT easier to work with and wire than the smd one.

I am using that pfet you have showed here. I did not wire in a led though. Will this pfet still protect me if I put the batteries in backwards and try and fire it. Thanks

 

[Rapture]

The fuses listed in the parts list say resettable. But how do you go about resetting them if they trip?


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[Matt Collins]

They should automatically reset

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[moflicky]

So, it looks like there's been a run on the 20 amp raptor boards, as mouser and digitech both have weeks long backorder times. what are the drawbacks to using the 10amp?

 

[jakl_53]

60 watt capability versus 120 watts.

 

[branflan]

Does the ground pin where the caps and 7.5k resistor are terminated need to be grounded? I've already built my mod and it's functional but I noticed someone on reddit with it grounded.

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[moflicky]

Thanks Jakl - I think I can live with 60 watts. my dna never goes above 22 or so.

 

[rolf]

Does the ground pin where the caps and 7.5k resistor are terminated need to be grounded? I've already built my mod and it's functional but I noticed someone on reddit with it grounded.

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just measured from the ground pin on the right to the ground pin you mentioned ...no resistance...so it must be on the board it selv.
mine is still open and just about finished . so I thought I mesure it real quick ...have funn.

 

[Matt Collins]

Does anybody happen to have any raptor chips they would want to sell?

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