7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by nevermind1534 » Sun Jun 13, 2010 9:55 pm

bacteria's picture will only work for the smaller PTH08080s and PTH08000s, not the 78020 with seven pins. I'll see what I can do and maybe get you a pic in the next few days. You'll need a 2.2mdf ceramic and a 330mdf electrolytic capacitor for the 78020 (go with at least 16V caps for both capacitors). A 7.52k ohm resistor will get you 7.4V, but I'm not sure if 7.52 is an actual value of resistor, so get something close to it (higher resistance will give less voltage, lower resistance will give more voltage). For the 3.3V regulator, you'll need a 100mfd electrolytic capacitor (use at least 16V) and a 1.8k ohm resistor. People do use as high as 2.2k ohms, which I believe puts out 3.1V, so a higher value will work if necessary.
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by lucidPerspective » Sun Jun 13, 2010 10:19 pm

Thanks for that, I'll go grab some components and wait for your godly images :mrgreen: your really helpful! thanks so much! :D
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by blaze3927 » Sun Jun 13, 2010 11:25 pm

i didnt go through a regulator with the 12v china battery (i obviously had to use one for the 3.3v line), however i did have good vetilation and a fan.
the china battery is 3, easy to relocate, and quite sturdy, they've survived well even after of plenty of short circuits etc.
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by lucidPerspective » Mon Jun 14, 2010 12:46 am

I wasn't sure how wise running the 7v-12v N64 on a battery that output's 9v-12.6v was. It's good to know that it's possible, but even so, regulating it down to near 7v will give a boost in battery life :D ..but yea, I'm definitely good with the batteries you suggested this time. Just nearly changed my mind when I saw that 10,000mAh one :mrgreen:
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by samjc3 » Mon Jun 14, 2010 9:48 am

lucidPerspective wrote:I wasn't sure how wise running the 7v-12v N64 on a battery that output's 9v-12.6v was. It's good to know that it's possible, but even so, regulating it down to near 7v will give a boost in battery life :D ..but yea, I'm definitely good with the batteries you suggested this time. Just nearly changed my mind when I saw that 10,000mAh one :mrgreen:
as long as you step down the 3.3v line correctly, you can run the 12v line at anywhere between 6v and 40v (DC). the 12v line simply goes into a 7805. the reason people use 7.4v batts is because its easy/cheap.
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by nevermind1534 » Mon Jun 14, 2010 1:10 pm

How many volts does the psone screen accept?


If you can get the regulator cheap (which you can), I would use it so the cooling doesn't have to be as intense.
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by lucidPerspective » Mon Jun 14, 2010 8:20 pm

I just had a little search, and found that the Official PSone screen needs 5v, and 7.5v. :?: They might have some leeway, but I'm not sure :?:

SO I guess I'll also need to regulate those voltage.. I had completely forgotten, that I'd need those voltages too :facepalm:
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by nevermind1534 » Mon Jun 14, 2010 8:24 pm

lucidPerspective wrote:I just had a little search, and found that the Official PSone screen needs 5v, and 7.5v. :?: They might have some leeway, but I'm not sure :?:

SO I guess I'll also need to regulate those voltage.. I had completely forgotten, that I'd need those voltages too :facepalm:
And get another PTH08000 or 08080 to regulate the 5V :) or just use a less efficient linear regulator
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by lucidPerspective » Mon Jun 14, 2010 8:37 pm

Couldn't I just use PTN78020W's for everything? Cause I think when you order samples you get like 20 :mrgreen:
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by nevermind1534 » Mon Jun 14, 2010 9:22 pm

You're allowed 10 samples per order. I'd still use the 08080s or 08000s for the lower voltages, though, because that's what they're made for, and I think they're a little more efficient, but I can't remember if they do 5V... They might only go up to 4.5V for the output.
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by lucidPerspective » Mon Jun 14, 2010 10:15 pm

The PTN78020's are 96% efficient, while the PTH08000's are 94% efficiant.

The PTH08000's would give me enough volts, the max output is 5.5v. and max input is 14v. so that chip would work, but is 2% less efficient.. it outputs 2.25A max too, which should be enough to power the screen :?: but I can't really see the benefit of using it?
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by timmeh87 » Sat Jun 19, 2010 1:15 am

K I only skimmed but I wanna say two things:

If you have to buy a 12v battery pack, then you are best off just cutting it open and rewiring it into a 7.2v battery pack. We're talking wires versus a 15 dollar regulator plus some other parts. Its just another thing that might not work or that you can blow up. Economically it doesn't make sense other than the fact that you can probably get one for free. Plus you are still losing some power in the regulator. Its like lose-lose.

That said, the original 10000mAh battery pack in OP is made out of 18650 cells, they are 18mm dia. and 65.0mm long. Working from the given dimensions on the picture, the pack is exactly as thick as one of these cells (18mm), one side is exactly as long as 5 cells (90mm), and the last side is as long as two cells plus room for a circuit board. So that's 10 cells in a 5x2 arrangement. Given that the capacity of individual 18650 li-ion cells is 2200 - 2800 mAh (ref: batteryspace), then Id say the pack does hold 10000mAh. It is also suspiciously cheap. like 1/2 price of batteryspace
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by lucidPerspective » Sat Jun 19, 2010 6:25 am

In regards to the 12v batteries.. it's actually 3 x (4.2V 3500mAh) ..I was thinking about the possibility of breaking them up, because then, for the size, they'd be pretty cheap. But then I'm left with a charger I can't use, and a protection circuit that I can't use. Also, each 4.2v cell can go down to 3v safely, so if I had 2 cells as a battery it would start at 8.4v but then go down to 6v.. ..so to get the maximum playtime out of the batteries I'd still have to keep it regulated above 7v. seems more straightforward to me to just get some free samples from ti and regulate it from the start, I only lose like 4% to inefficiency :)

and the 10,000mAh in the first post, they would be a bit of a risk to use, but I have read quite a lot of good things about them on forums around the place.. in fact I don't think I've seen one bad comment about them. It's funny how the cheap price is making me weary, even though them being cheap could be a great thing if they're also great batteries.. ..but for now I think I'll avoid them until I have some spare cash to try them out.

I've gone with the 12v batteries this time, they look a lot more professional than the 10,000mAh one :D ..hopefully they do the trick
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by timmeh87 » Sat Jun 19, 2010 1:38 pm

If you are going to go regulator crazy, then why not get a big 5v reg and strip out all the 7805's. There's like 3 of them in there.

Also I think you are being way too optimistic on your efficiencies, the pth08080 is only 91% efficient off of 12v. The pth78020 is also around 91% efficient with 15V input and 7V output. It can be as low as 40% under some conditions (24v in, 5v out, almost no current). Its important to read beyond the first page in the datasheet.

The reason I feel like 7.2v is a better way to go, is simply cause I've watched a few hundred portables go by, and a lot of them have 7.2v battery packs. Never finished my own portable... lol

Also its hard to say exactly, but depending on your batteries, if you discharge them at a 0.5C rate, you will use 90% of your capacity before the voltage drops below 7.0V. http://img692.imageshack.us/i/liiondischcurve.png/" onclick="window.open(this.href);return false;

If you battery pack is 10,000mAh, then you C rate is around 0.3, so you are good to go.
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Re: 7.4v 10,000mAh LiPo Battery - Can anyone vouch for this?

Post by lucidPerspective » Sat Jun 19, 2010 6:17 pm

Hmm, you make some valid points, I knew that the 12v line went straight into a regulator but I had no idea there was more than 1 in there lol. I'm thinking changing all that will be for round 2 of my N64 portablizing adventures.

If I hack apart the two 12v batteries I'll have, I'll end up with three 8.4v 3500mAh batteries, and looking at the voltage drop before it get's to 7v I guess I wouldn't really need to regulate it, if I'd get like 95% usage over a 1.4v drop. 10,050mAh would be nice too :mrgreen:

But, I think to keep things simple the first time round, I should go the slightly less efficient regulator way, rather than messing around with protection circuits and everything. Would rather my first one worked before I move onto to building the ultimate N64p :mrgreen:
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