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If you're going to use a high side NMOS driver, you can use any MOSFET really. The driver will provide a 5.4V gate-source voltage so you don't need a low threshold voltage. Go for the lowest on resistance. This one is better; http://www.nxp.com/documents/data_sheet/PSMN1R1-30PL.pdf The best P-channel I've come across for use as a user power switch is this one; http://www.vishay.com/docs/62860/si7157dp.pdf
Good idea, i'll see what I can come up with
David, where did those battery decals come from?
http://www.mouser.com/ProductDetail/Analog-Devices/ADM660ANZ/?qs=sGAEpiMZZMtitjHzVIkrqYThiPHWFX9aAfsE1NTyhUU%3d
I keep snapping legs of my mosfets trying to shoehorn them into a 1590g case with batteries so I made this while I wait for some prototype circuit board to arrive to do it properly(er).
Hi guys Question about using a p channel
Yes, you can. Divide battery voltage by the resistance to get current. Square it and multiply by resistance. Or, you can square voltage and divide by resistance. It's going to be a small number so you'll find that you can use pretty much any wattage rating you want. Like I said, even the tiny 0402 parts with a 1/16W rating will be okay. It's probably an 0805 that fits well, those are 1/8W. The 0603 size is 1/10W.
If the fet is opening/closing the negative feed it is low side?
Input voltage (4.2-3.0) doubled and outputted (8.4-6.0) to drive mosfet gatehttp://www.mouser.com/ProductDetail/Analog-Devices/ADM660ANZ/?qs=sGAEpiMZZMtitjHzVIkrqYThiPHWFX9aAfsE1NTyhUU%3d
How would I go about making an 8.4v REGULATED box mod? ie 8.4v whatever the charge in the battery?Bob
There's two areas where charging rates are limited not including the maximal rate the batteries can tolerate. First is the power connector and supply, secondly is the charger controller chip.There's a good amount of power that a linear charger controller has to dissipate. They work pretty much the same as a linear regulator with current limiting. Like any linear regulator, it has to dissipate the difference in output voltage minus the difference in input voltage times output current. That being the case, that little chip has to dissipate a worst case of 5V input minus 3V output (lowest battery voltage) times the charging rate. So with a 1A rate, that can be as high as 2W, a lot for a small linear regulator.You can get around that limitation by using a charger controller that employs a DC-DC converter. Those conserve power aside from a small loss usually under 10%. In that case, the charger controller can put out much higher currents. There are charger controllers like that, not a wide range of them, but they are available. They tend to be costly in both price and part count. They reguire a larger PCB and have a larger number of supporting parts.The other limitation is the supply and connector. USB mini-B and micro connectors are limited in the amount of current they can handle. You can remove that limitation by using a barrel type DC power connector. The larger ones like the 5.5x2.1mm are rated for up to 6A. Of course you also need an adapter that can support the current demand, not going to be a USB adapter since those typically don't go above 1A. You can find them up to 2A, but you don't want to run one close to its limit if you can avoid it.It should be possible to parallel USB charger controllers, though it would be a rather odd thing to do. Odd as it is, I can't think of any reason why it would cause any functional issues. You would need a separate connector and adapter for each charger or it defeats the purpose due to the limitation of the USB connector. If you try to run 2A or more through a single connector, it will fail at some point, possibly not immediately, but it will fail.
Sorry if this as already been posted but I was on break.Here is plans for a unregulated 18650 box to give a little more details. Hope it helps. I know they sell them but they have the best diagram I have seen so far in regards to wiring.
How would I go about making an 8.4v REGULATED box mod? ie 8.4v whatever the charge in the battery?Quote from: XombyCraft on October 02, 2014, 11:29:59 AMIf you want to keep it at 8.4v all the time, you'd have to use a booster board to force the voltage to stay around 8.4v and be regulated.
If you want to keep it at 8.4v all the time, you'd have to use a booster board to force the voltage to stay around 8.4v and be regulated.
Or... and I kind of doubt anyone would recommend this, you could use a buck board and three lipos in series to regulate a nominal 11.1v down to 8.4v... tricky and potentially lethal.
Oh okay, I thought that one topped out at 6V, according to the data sheet anyway. If it can put out 8.4V without dying, then yes, it can be used for that. In any case, the series battery configuration will deliver the maximal current the module is rated for which can be as high 20A, higher in terms of burst limits. The big advantage with the booster is it's single cell and a lot smaller, but greatly more limited in output current.
Here's a 50watt booster you can run with series batts lil biggums and gets warm @50 watts but if you wood mod it it will be probably be manageable.
That's like the crappiest converter you could build; It's asynchronous (uses a diode rectifier) It has a 65 mOhm internal switch (way too high resistance) It's current mode (less efficient) It uses bulk capacitors (takes up way too much space) It's built on a perf board (maximally lame)Everything opposite of what I would do in building a converter. I'm amazed he even got it to work. Though I've got to hand it to that guy, he makes the most complicated things sound simple. He did it that way to show a booster in the most simple way possible so I understand the motivation, but not good for anything but a paper weight after being used as an educational tool.
