makita phone charger

well I am at it again hacking my tools to do the things that the
manufacturer didn't think I would want

this would be my simple 5v power supply from a 18v Makita battery really any battery over 7
volts will do so the lxt 14.4v will fit right on as well

I decided to build this as when using my blue tooth headphones on the job
my phone has a rather short batter life listing to streaming radio
over my blue tooth headset just uses to many of the power hungry parts
of any phone for it to last mush over 4 hours

so I find I plug my phone in often or I forfeit music if power is not close at hand
this gives me a portable power source that is small compact I can hang from my tool belt
even

and i suspect my 18v 3ah batteries should have plenty of runtime to keep my phone
happy all day


in the following pics you can see my crude assembly
once I get my reprap printer built I will make a nicer
case of for this for now the base of a broken drill seems to work fine

it after all a hack and it had a little tape and hot glue to make
a genuine hack

but as you can see in the first pic there
is a small board with a 5v switching power supply
and the battery connector from the bottom off the drill
comes out separately which should make printing a new
base for this with the reprap easier

in this pic you can see my butchered drill grip/handle
that is my case










this is the schematic and parts for the power supply
on the little tiny board in there this thing can apparently
produce up to 3 amps at 5v but I suspect I will be melting the hot glue at that point

and this is it almost together
the scavenged usb socket has the 2 data pins shorted for charging my android phones
but you could easily add a couple of resistors for your i pod

future upgrades will be a power switch (currently you just pull the battery) a second usb port to run other items such as a spreaker or some thing



so I am taking it with me to the job site tomorrow I'll post back some runtime info
and use details in the next few days


and other than the scavenged drill handle and usb socket

the power supply parts and the per-fa board cost less than $5

My Intro
well to start of I guess I should say I'm just a guy who
tinkers with things, sometimes to much but I have a number years
in various trades in my back ground and well lets just say some of the things you
may read here might solely be driven by the fact that I can be down right cheep.
what can you say I expect to get a reasonable value for my dollar. Anyways on with the
meat and potatoes.


Some background info
lately my cordless tools have been feeling a little under supported I am a electrician
and I use my makita cordless tools all day, but lately I have had a sting of batteries
fail 4 of them all out of warranty recently and 1 that was covered all with the last 3
months. I know you must be asking how many batteries does this guy need, honestly
I can get by with probably 3 but I had 4 after purchasing my tools so
it started there I have now got 9 working batteries and a few bits left over from number 10
but how i got them all could be a whole other blog.

but need less to say once one of the makita lxt batteries goes south they
will never charge on a makita charger again even after you fix the problem.
in each of these batteries there is a small pcb with some memory and a micro-controller
that monitor the state of the battery and the number of charge cycles they have seen.
once the battery has been declared bad by a charger/battery combo there is no way to reverse this.

so we have a problem some time ago when I got my hands on the first dead battery I tracked down my set of tamper torx keys and popped it open had a look and also went googling for info
and ran across a great video on how to take them apart of course this was after I had it apart

This is not my video clip
it just was a good clip of how take them apart and test the cells


thank you
doctorbass for this

and in comments a a couple of months ago there was a comment about using a rc charger
to recharger them after you fix them so I hunted a cheep one down on ebay
and well it works pretty good so after some tinkering I can up with
my current charger which does a couple things the makita one never did
fist off in now has 2 usb ports on the side for charging my phone, my headset or my mp3 player
with out me getting out a wall wart and fining some where to plug that is as well
second it is now a true balance charger unlike the makita which has only
a mid point reference for balancing mine monitors each parallel set of batteries.
it can with the addition of the original banana to alligator leads the rc charger came with I can charger just about any 22v or less tool battery on site if need be.

The charger
ok in side this thing is a 15v laptop power supply that had 2 usb ports on it I figured there there
why not keep them and there is all the necessary connections to power the charger and to connect it to the battery nothing really fancy in there except I was able to keep the cooling fan for the batteries it is how ever running on 15v now but it seems to be quieter that way
we shall see how long it lasts. i used the small yellow connector to pass the balance conection from the battery to the charger as well as switch the fan on

The batteries
in the batteries I removed all the compents from the the pcb other than the connectors
I jumped the smaller terminal to the larger one as the small one is the charge contact
and I wanted to stick with that and i added 4 wires to the cells and a jumper from the positive to the yellow connector and jump pins 6 and 7 together to complete the fan circuit in the charger. all solder connections are done on the underside to make the cover fit back on. There have been a few choice bits removed from the plastic housing and parts to make everything close up nice.

now that all this has been done I have a charger that can charger my refurbished and my untouched batteries though it will not balance the untouched ones it will still charge them with out hurting them if I put one of these refurbish batteries on a normal charger the charger sits there idle as if there is no battery so there is no harm to batteries or chargers is you happen to mix them up .