Question Wiimote operational voltage range

[ArtieWilek]

Since I still don't have all the materials for my wii portable project, I decided to mod my Wii remote to use a 18650 battery i had laying around from a broken laptop. The battery was about half charge (measuring 3.5v on a multimeter) and so far, the wiimote works flawlessly (no overheating or malfunctioning). I've only tested it for a few hours, but it looks promising

I know most AA battery powered devices can withstand more than 3v by design since batteries can vary voltage with heat, and the device should expect this to happen at some point (think about leaving your wiimote in the sunlight near the window for a long time).

The question is, ¿What could be the maximum possible voltage for normal operation on this thing? ¿Has anyone actually tried running a wiimote on 3.5v or more and documented the results?

I'm thinking on doing some tests and see how it performs on something like 3.7v, so that I can use a charging circuit for 3.7v lithium batteries. If it heats more than it should, i'll have to design a custom circuit to charge it at a set limit

 

[cheese]

Did you ever end up doing those tests? If you find it does need to be limited it may be better to try and put a regulator so you don't have to lose out on capacity

 

[ArtieWilek]

I have modded another controller since I modded this one, and have been using both controllers for about 5 weeks, some days more than others, with the batteries charged at exactly 3.5v

So far no problems in functionality. The nunchuk accessory and all buttons/sensors work just fine.

There is however a small amount of white noise coming from the controller's speaker that comes and goes from time to time, which I think it's caused due to the extra amount of voltage going into the speaker's amplifier, kinda like the noise you get on speakers in a room when using very long non-insulated audio cables.

The sound is barely noticeable to me, I don't really notice it unless the controller is literally next to my ear, in fact for the first week of usage I didn't even notice it untill my GF told me (She is a musician, so her ear is way more developed than mine)

I guess the amplifier part of the PCB just doesn't have very good noise filtering and it becomes noticeable when the voltage is a little bit higher

Oh yeah, and about the battery life... I have literally charged both of them once, and I still have 2 bars left on the home menu, so i'm very happy with the results =D

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By the way, I still haven't implemented a voltage regulator on the controllers, the battery is literally connected directly to the PCB v+ and v-

(Also, as far as I know, using a voltage regulator would decrease the battery life since efficiency is rarely over 70% on cheap small regulators lol. Another reason I didn't want to bother with it)

About the batteries, I charged them with a regular 3.7v battery charger, carefully checking the voltage from time to time, and disconnected them when they reached 3.5v (By design, this battery chargers usually charge up to 4.2 v on 18650 batteries, and i haven't got the guts to test something greater than 3.5v, so be careful if you want to try this)

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Attached some photos for reference.

1. The plastic inside the controllers was cut to make room for the batteries (choppy as hell BTW)
2. A 9v battery connector was soldered to the PCB, and another one to the battery for convenience
3. The plastic covers were dremeled out a little bit to make the batteries fit better (Barely any pressure on the batteries after this part)

Admin note: please edit your posts instead of making multiple posts one after another.

 

[sparklord555]

sorry bro please you are risking damage to any device you plug into the expansion connector
use a 4.2v cell and two diodes to drop the full charge voltage to 3.3v or less
the speaker issue is literally showing the chips being pushed to damage
use a schottky and a silicone didiod in series to drop about 0.9voff the cell and you can use it safely
using anything over 3.3v will eventually cause damage/glitching
but if you offset the chemical voltage by using diodes it can be safe
wiimotes are bad with battery types

 

[sparklord555]

wiimotes are not very tolerant of above 3.3v inputs(risk of fires from overheated chips in some models) they have an internal boost-only regulator for the nunchuck+motionplus that acts up above 3.3v
best use a set of diodes to offset the voltage of the lithium cell from the operational range of 3.0-4.2v to 2.0-3.2v using a c ombo of a silicon 1-3a and a schottky to get ~0.9v lower(0.6v average plus 0.3v average under load)
this allows the battery status indicator to work normally(it only works 2.0-3.0 for standard cells) and also avoids overvoltage issues causing bugs and fire risk
my parents bought a 4x lithium set when they bought a wii (about 1 year after it came out) it used a stupid LDO circuit to cap at 3.3v at anything above that and so it only told you it was dead a few seconds before it cut off
one of the packs finally died (LDO stopped putting out ANY voltage(likely due to the undervolt abuses)) and I did googling to discover the voltage problem in wiimotes and realized the authorized device did need to limit to less than 3.3v to be approved
so I knew about diode drops being fairly fixed under rated loads so I thought "why not just use diodes to offset the operational range of the cell?"
so I swapped the dead LDO pcb for the diodes (3a was all I could grab on short notice) it works flawlessly and looks basically factory(the only telltale sign is the damaged plastic rivets that hold the contacts in place when not clipped to a controller
and it works 100% perfectly and now even shows the status unlike the old version
basically two cheap 1cent diodes is a small price to pay to prevent damaging your controller or odd bugs from not wanting to use primary AA cells
an 18650 is still perfectly fine if you offset the voltage to the 2.0-3.3v max range of the device
I am actually a fan of making all 2-3xaa devices run off an 18650 so I am someday soon gonna glue (probably superglue) an 18650 holder to the back cover of a spare roku remote and use the diode trick and some wired aaa dummy cells to the 18650 holder
and as most devices stop at 2.0v(2.9 with the diodes) you don't even need a protection pcb as long as you pull cells as soon as the device stops running as 2.5 is the point a lithium cell starts getting damaged and you shouldn't hit is as aa/aaa devices are designed to cut off at 1v/cell(2v for a 2x device) to protect for use with nimh cells that are surprisingly still good these days as long as you don't buy one of the 99% "smart" chargers on the market and instead keep them on a trickle charger at a few dozen ma max
honestly I am pissed off that ALL the chargers I can find are either 2 port useless trickle chargers (who has ONLY 2 cells?) or are smart-only and cut off rather than switching to a mode where you get a few ma to "wake" tired or low capacity cells and reach the ACTUAL 100% rather than the 80-90% that pulsed high-current chargers tendt to false trip at
but please DO NOT CONNECT A BARE >3.3v CELL TO A WIIMOTE WITHOUT ADDITIONAL CIRCUITRY