Charging system for n64p

[Warrior_Rocker]

ok, ive designed several portable consoles, and im going to try and build one last one that is superb, however i need ideas for the charging circuit, ive decided on a central 12v power system running around 3.5amp's and im using a 4 volt power converter to run the 3.3v line for the cpu (becuase the n64 has a low tolerance to changes in the line, and ive noticed that when starting at a slightly higher voltage as the line dips down to 3ish the cpu can still run), and im tying the 12v directly into the audio/video out put of the console, however, since it is bad to overcharge batteries, and not good to charge them at high amperages, i need a solution, so that when the console is not on, the batteries are charged at a low amperage, and when the console is on, the power input from the charger changes to match?

[*o*]

look here http://saoghal.cywh.com/N64m_Pictures/n64m.html

he has a guide

[Warrior_Rocker]

you cant be serious, ive built three of these things, and this is what im shown?, there has got to be someone who better understands what i mean

[*o*]

huh? Here is a guide to build a charger

last time i try to help you

RPGTKNick:

# Building a Battery Charger
After a while, I got sick of crappy 20mAH AA's running dead in less than a half hour of play. I ordered some 2100mAH NEXTel rechargeables. Just to make sure, I ran the system without charging the batteries; You know how they have that "inherited" charge they get just for being batteries in the first place. It ran good, so I drained the batteries completely playing StarFox with full volume, so I could safely charge them.
Then a problem- how to charge them? I could put 4 of them in my brother's battery charger, and the other 8 on a car-battery charger. But that's way too combersome for normal use. I had been tossing around the idea of an internal problem for a while. So anyway, I eventually made it. What? You want to make one, too? Well, here's what you need:
# A 6v battery charger (for an RC car or something)
# A stereo headphone jack and plug. Go down to RadioShack and get one of those extension cables for headphones. I used the extension from one of those older, larger headphone things. It was much easier to wire, and was better for higher current; I really suggest one of these.

Now onto building it.
Keep in mind, these instructions are purely based off my exact model. It will obviously vary, depending on your parts. But it shouldn't be much different.
# First, let's wire the jack into the battery pack. Drill a hole in your case, put the jack in and glue it, or attach however you want. The cable has 3 wires- Left, Right, and Ground. Whether it's left or right is irrelivent, just keep track of which wire is which. Have the ground run off to both of the negative (-) terminals on the battery packs. Have one other wire go to the positive (+) on one battery pack, and the other wire go to, ironically, the other battery pack. It's pretty Simple.
# Do pretty much the same thing for the plug. Have both negatives (-) go into the same colored wire as that on your jack. My cable had Black, Red, and White. I used Black for a ground, red for the 12v pack, and white for the 6v pack. So the red wire went into the 12v pack inside the N64, and from the 6v adapter into the plug on the charger.
# Now, since you used 2 AC adapters, you'll want them to run off one circuit. This is really easy, simply solder some wires going from the base of the plug you want to plug into the wall (I used the 6v one- it's bigger), and have them go to the corresponding plug on the other charger- holding them both so the plugs are facing the same way. Attach the second pack to the first however you like, making sure no terminals are touching where they shouldn't.
# Plug in your charger (I suggest using a power strip for safety). Test the plug, and see if you're getting appropriate power ratings. You'll often get those higher than the charger says. My 15v says it outputs 15v, but it's actually 22v. My 6v one outputs 11v, but it works, so I'm not arguing. It's supposed to be higher, anyway.
# Make sure all your connections are good, and plug it into the N64. Your power light will probably flash really fast when you plug it in. That's normal. You should probably unplug your battery packs and test them with the charger running, to make sure it's getting power.
That's it. You're done! A Four hour charge is usually sufficient. Just leave it on charge until the batteries start to get hot, or the N64 runs a good amount of time.
Go to the Pictures & Running Games
section to see it in action...if you want to call charging something action.
# An AC adapter, around 15v. A 12v battery charger will work fine, but I used a normal 12v AC adapter.

[sam]

Cough, resistance?

[nos_slived]

Now, you say you've built several, then you say you've built 3, and yet you don't know what to do for a charger.

BTW: Don't sound so sarcastic on your second post when *o* tries helping you.

[*o*]

wow i feel accepted

i have looked around the internet and i can see any guides to make a charger for AA batteries

[gannon]

a not gate, a transistor, and a resistor should be all you need. The only problem I see is making sure the batteries don't overcharge. a 555 can't time that long, and using a transistor to change when the battery voltage reaches a certain level won't work since you'll be pumping dc voltage into them.

[*o*]

is there any way to make a cutoff cicuit for a charger?

[gannon]

I saw a schematic for a simple one, but it didn't have part values. I also have a feeling that it wouldn't work (measured either voltage draw or current draw in the charger circuit and switched at a certain point)

[Warrior_Rocker]

is there any way to make a cutoff cicuit for a charger?

thats more what im looking for, i dont want a simple power adapter bullS*** circuit for connceing to AA batteries, im using LI-ion cells, and can run the system for 2 + hours, however in case some of you didnt know, its bad to charge hi-amp batts w/ excessive amperage
and all i was wondering if anyone had found a easy way to counteract that, not two different chargers, not freaking ducktape-electrical tape mess, im nearing completion of designing the rest, looks like ill just have to figure it out

[gannon]

For li-ion or li-poly you'd need to add a resistor, a potentiometer, and another transistor to my original idea. Still not sure how to do the auto shutoff though.

[bicostp]

How about a relay that trips at a specific level of power?

EDIT: What about using an RC battery and charger? They're designed to cut off when the batteries are charged.

[gannon]

Sorta what you'd need, but since you're pumping dc voltage into the batteries how can you measure the battery voltage by itself
Unless you build some timer the sets a transistor that turns off the dc input so you can measure battery voltage.

[Warrior_Rocker]

well, what i did last time, was build a external charger w/ 2 different chargers inside, one for providing about 15v @ 500ma, and another for about 15v @ 4.5amp, and have the main switch for the unit turn on switch the input from the low amp trans, to the high amp trans, so the batts could be charged while unit was being used, it seemed to do the trick, but i was just trying to see if anyone had a better idea, i thought of a transistor type circuit, but as mentioned, u cant measure voltage w/o the input being shut off..., i guess these are the problems faced when building an entirely custom device?