Monday, January 11, 2010

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 o
ut of warranty recently and 1 that was covered all with the last 3
months. I know yo
u 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 p
roblem.
in each of thes
e 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 gre
at 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 a
fter 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 b
alance charger unlike the makita which has only
a mid point reference for balancing mine monitors each parallel set of batteries.
it can with the add
ition 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 k
eep 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 .

5 comments:

  1. This looks very nice ;) do you have a drawing on your connections?
    I don't understand what you did inside the charger?

    ReplyDelete
  2. how did you connect the RC charger to the makita charger?

    ReplyDelete
  3. Thansks for the interesting charger rebuild. I will have to follow through with one as well. Great Job!

    ReplyDelete
  4. why cant some one just reset or bypass the counter in the battery or the charger ? come on people !

    ReplyDelete
  5. Those Makita batteries use NEC processor chips, which are quite hard to get any useful technical information on. It makes much harder to reverse engineer. I can sniff exchange protocol if anybody needs it...But I see it a lot easier to use hobby grade balancer/charger to reach the objectives.

    ReplyDelete