Building the Mystical N64p: A Chronicle

XFactor · Post by **XFactor** » Mon Mar 20, 2006 7:16 pm

Yeah, the title was for dramatic effect.

Anyways, today I finally got my battery in the mail; which means i have basically recieved all the parts i need (still waiting on 3mm wide angle LEDs from China). I have allocated the following parts for my build:

1.) N64 (currently undergoing a slot relocation, which i will take a picture of to confirm i haven't shorted anything...)
2.) PSone screen (haven't touched)
3.) DC-DC converter (its a TI converter thats been already mounted and wired; this i will also need a confirmation on it soon when i get some pictures)
4.) Battery (4800mAH at 7.4v with PCB circuit)
5.) 22 gauge wire
6.) DPTP switches (4x)
7.) Three 30 packs of Dr. Pepper

As i said before, i have already begun the slot relocation (it's about halfway done). I'll supply pictures of that as well as the DC-DC converter so i can see if i wired it properly.

Neildo_64 · Post by **Neildo_64** » Mon Mar 20, 2006 7:23 pm

Sounds like fun. Can't wait to see some pics. Theres nothing like seeing a new portable. Good Luck!

Just out of curiosity: What are the 4 switches for?

JackFrost22 · Post by **JackFrost22** » Mon Mar 20, 2006 7:48 pm

DPTP don't you mean DPDT Double Throw Double Pull?

XFactor · Post by **XFactor** » Mon Mar 20, 2006 10:24 pm

i can never remember the names of the switches, so i just make something up to compensate

XFactor · Post by **XFactor** » Mon Mar 20, 2006 11:32 pm

So as i've said, i got my battery today..however, i am having some second thoughts as to whether it is enough capacity.

I have a battery that has 4800mAH. I am thinking that with a 25mm fan (running off of 5v) plus the screen plus speakers and a headphone jack, it just won't give me the 3 hours i desire from it. For that reason, i am considering buying another battery of the same type to boost my capacity to 9600mAH. Here is the battery: http://www.batteryspace.com/index.asp?P ... rodID=2326

Could anyone give me a projection as to the burn time of this battery in relation to the overall system i have just outlined? Do i need the extra capacity?

daguuy · Post by **daguuy** » Tue Mar 21, 2006 3:51 pm

4800mah should give you at least 4 hours if you do the LED mod and dc-dc convertor and all that stuff

vskid · Post by **vskid** » Tue Mar 21, 2006 5:56 pm

So will you be able to charge and play at the same time?

XFactor · Post by **XFactor** » Tue Mar 21, 2006 6:49 pm

I haven't figured that out just yet, but that's one thing i've wanted to have in the portable. Either that or the ability to go between battery and wall power (which requires a shottsky, but from what i've heard, they decrease battery life somewhat). I may just end up making a switch that i would have to turn off the N64 entirly in order to switch to one power source or the other.

I lost my solder so i am going to run to Sears to get some more. I'll update later on tonite with photos

Turbo Tax 1.0 · Post by **Turbo Tax 1.0** » Tue Mar 21, 2006 9:47 pm

your using li-polys right? then yes you can charge and play at the same time as long as you have a protection circuit and a smart charger

XFactor · Post by **XFactor** » Tue Mar 21, 2006 10:40 pm

Turbo Tax, how would I go about doing that? I wanted to be able to run the unit on the lithium polymer battery (with PCB of course, i love my hands) as well as on a wall outlet. I have seen a switch that interchanges between battery power and wall power, but i have not heard of a switch that would allow the battery to be charged by the adapter and once the adapter was removed, the unit would switch back to battery power. Maybe the latter is not possible, but if you could provide some clarification and/or some suggestions, that'd be awsome.

Turbo Tax 1.0 · Post by **Turbo Tax 1.0** » Wed Mar 22, 2006 2:53 pm

since you are using lipolys and you will have a protection circuit all you have to do is hook up a charge jack . and you can run the unit while it is plugged in to the charger. if you do not have a charger yet i would reccomend the smart charger from batteryspace that allows you to choose different voltages.

having the pcb and a smartcharger allows you to treat the batteries just as a GBA sp and you can charge and play at the same time and all that jazz. this is another reason i like lipolys

XFactor · Post by **XFactor** » Wed Mar 22, 2006 7:59 pm

I bought the smart charger at the same time that i bought the lithpolys

So basically your saying to take both the positive and the ground from the battery, split them so one pair of lines (both ground and positive) go to the N64 and another line will be on the outside of the unit for charging the battery/powering it?

daguuy · Post by **daguuy** » Wed Mar 22, 2006 8:00 pm

yes, that'll work

XFactor · Post by **XFactor** » Thu Mar 23, 2006 6:57 am

No, by splitting the connection from the battery you allow yourself two seperate wires for each connection; two pairs of both one ground and one positive line. Because you split the line at the battery input, you essentially allow for current to flow into the battery (to charge it) and current to freely flow from the battery on the other line (to the N64). In that way, the N64 is still using the same connection all the time from the battery regardless if it is plugged in or running off of existing battery power. The only difference is that when the battery is plugged into the charger, the battery no longer depends on itself to draw the charge, but instead is used as a "current medium" by the wall outlet to transfer the charge to the main line.

So really, the battery will always supply the needed charge regardless of whether it is plugged in or being charged by the wall outlet. If you really want to get specific on voltage proportions, i'll give you an example. Say you've been running your battery for 3 hours (at 4800mAH and 7.4v, thats roughly 3/4 of the battery spent). At this point, your voltage will begin to decrease to around 7.3-7.2v (bearly within the limit to run your N64 without distortions mind you

). Because your battery's voltage has decreased, the charger will supply more power to suppliment it (that extra .2v or what have you). This is the only time that the voltage would be such that proportionally, it would be different. At any other time, the battery will have the required voltage if properly charged; its just that the current from the wall would flow through it to 1. charge it and 2. power the unit.

I hope that clarifies your question

XFactor · Post by **XFactor** » Thu Mar 23, 2006 6:46 pm

Well the PCB protection circuit on my battery restricts a maximum voltage spike at 8.4v when it is charged (it does this because if a battery were to be excessively charged, it would result in a spike which would essentially blow a lithium polymer up

). However, as i said before, the battery outputs 7.4v because it acts as a medium; the battery's output value does not change except by about a tenth of a volt. Charging adds more capacity to a battery to burn longer; higher voltage is really just a bi-product of excessive charging.

Now as for your concern about the voltage on different chargers; there is no complete answer i can give here except this: Buying a charger that is around or at your battery's selective voltage is a nessecity. For example, my battery runs off of 7.4v; my charger is set to 8.4v in order to charge it. As long as i said before about it not being overcharged (which really the PCB protection circuit eliminates, but it's good not to do it anyway) the battery should be fine within the diffirencial range of a volt between the charger and battery. Mine is this one. it's quite safe and stops charging if it senses dangerous spikes.

Thirdly, the aspect of charging/playing while eliminating the "smartness" of the charger or the battery, in my opinion, is not really a concern. Again, the battery, even when its not hooked up to anything, is merely completing an electrical circuit. When the charger is hooked up to the battery which is connected to the N64, it is merely extending the connection to other parts of the machine. The same amount of power is flowing through, it's just from a different source. HOWEVER, now please note this because it is important, you may want to see the voltage input specs on your DC-DC converter if your using one. I cannot recall the one i am using but it is the norm for all us portable-builderettes

. If there is a spike (a malfunction) from the charger, it will destroy the DC-DC converter which will fry your board (if your battery has a PCB protection circuit, it will virtually prevent this). That scenerio equates to male PMS and/or neighborhood arson

.

Anyways, hope this helps.