Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charging

[sam_sam_sam]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

Commenting on your post

I am commenting on your post

I would have to agree with you sometimes however on this charger this is not the case because this charger is also in the garage and it has been acting weird lately sometimes it would not charge M18 batteries sometimes either or if it did not all the way and you can here the switching power supply board is not consistent with the high frequency sound that it normally has or it there and then you can not hear it at all

In fact one of high amperage battery would refuse to charge ( when I first bought these batteries I thought it was because of the charger not being compatible but after having a couple of them refuse to charge even the M12 batteries I realized that it capacitor failure of some type ) at all now that I replace those capacitors it now charges them as well ( I had put the battery that was showing fully charged on the other battery charger that is also in the garage on the table and it charging correctly so that is why I need to check those capacitors )

Plus the charging LED lights were very dim and very hard to see now it is much brighter

But one thing that I have noticed is that 10uf to 100uf capacitors on some switching power supply when they reach 1.00 ESR value seem to have issues working correctly I will leave them in place if they are less than 0.50 ESR

Later on today I will check the UF value of these capacitors and post the results

[CapLeaker]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

Maybe it’s a design error and larger caps should have been used?

[redwire]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

Many people having problems with Milwaukee M12/M18 chargers and tossin' them in the garbage.
They seem to be from some contract manufacturer "professionally made in china" with quality all over the place. Some use Samxon, Jwco, CapXon. I would replace them if I had problems.

It seems to use a TO-220-7 SMPS IC TOP256EN on the primary side which is where the 10uF 50V and 47uF 16V capacitors seem to be. The 10uF is for its power (could be upsized to 22uF) and 47uF for VFB compensation.
But can't see them making a difference for it being finicky about 12V/18V charging modes.

I'm suspicious of the secondary-side having issues? OP's model only has three electrolytics there.

M12-M18, 48-59-1812 (2011)
M12-M18, 48-59-1812 (2015)
M12-M18 Rapid Charger, 48-59-1808 (2015)
M12, 48-59-2401 (2007)
M18, 48-59-1801 (2008)
M12, 48-59-2401 (2016)
UL File E150119, E250134

[sam_sam_sam]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

“ Many people having problems with Milwaukee M12/M18 chargers and tossin' them in the garbage.” or end up on EBay I just bought 3 of them that are not working so let see what wrong with them even if I can not get every one of them to work I need a replacement case for something I want to build for the battery testing machine battery testing jig for the M12 and M18 battery packs

M12-M-18 48-59-1812 (2011) replaced capacitors
M12-M-18 48-59-1812 (2015) replaced capacitors
M12-M-18 Rapid Charger 48-59-1808 (2015 having issues ) might need to be checked the charging LED is very dim but still charging if I have to recap this one I will try the 22uf instead of 10uf and see if it like this value or not and post the results


I know I have one of these or I might have both I very seldom you them but I have them in the car or truck if need to charge the M12 battery I do not have very many M12 high capacity battery packs I have more of the smaller M12 battery packs which do not get used very much
M12 48-59-2401 ( 2007 )
M12 48-59-2401 ( 2016 )
I am not sure if I have the
M18 48-59-2401 ( 2008 )

[CapLeaker]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

sam... put an oscilloscope to the 10uF cap. Usually a 10uF cap with an ESR of like 1 Ohm should not be a problem to work a circuit. All I can think of is that the 10uF cap is grossly undersized. Wouldn't be the first time that caps were backwards installed or wrong caps in wrong places... it does happen, even misprinted circuit boards. If really the ESR on the 10uF makes such a difference, redwire said upsize to 22uF, well maybe even to 47uF! Right now I can't really see how these to caps have anything to do with the charging (secondary) side. Something is here wrong somewhere.

[redwire]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

I wouldn't scope that cap, it's hazardous live on the hot side and sam might have a bad day.
The 10uF 50V caps don't last because they're made in the bowels of guangdong and can't take much of anything for ripple current. 125mA (ESR=1.3R) for a typical part i.e. Panasonic FC EEUFC1H100. I can't find what that Topswitch consumes, and they say in low freq. Eco-mode it needs to store some charge.
Panasonic FC EEUFC1H100 10uF 50V rated 125mA (ESR=1.3R) 22uF 155mA.
Panasonic FR EEUFR1H100 10uF or 22uF 50V rated 250mA (ESR=0.34R)

It might be the use of non-low ESR parts or the diode recovery is bad, that can trash the cap as well, the current having high spikes.

[CapLeaker]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

The 10uF 50V caps don't last because they're made in the bowels of guangdong...

HAHAHA!
Made my day! Thanks redwire as always!

[sam_sam_sam]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

I used KY or KZE and LXZ

[redwire]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

KZE is low ESR (but no 10uF 50V offering).
KY 10uF 50V is ESR 1.5Ω
Your fix doesn't make sense to me - the old cap's ESR was not way out there, or your meter is reading wonky.
What about the other caps? Why those two failed but not the others also doesn't make sense.

Fixing Milwaukee chargers, I would shotgun it - replace all the electrolytics, I think that's 3 on the secondary and 2 on the primary, filter cap is unknown.
So 5 parts, a few bucks.

I saw one putting out 6A in a youtube video and thought the output cap must be cooking hot with so much ripple current, sure it's for an hour say but still overheating.

[sam_sam_sam]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

I have a Blue ESR meter ( it is not a knock off ) so as I know I do not think it has an issue that I am aware of
I have had it for a very long time so if it is having an issue I am not aware of it

One thing to remember is testing them with the tester is not the same thing as the running them under a working load

Unless this circuit is very picky about how the capacitors reacts in this circuit is the only thing I can come up
with

One note when a capacitor is more than double the ESR value of a new one I consider it bad or at least questionable at best ( values from 10uf to 100uf )

The 10uf and the 47uf are the two capacitors that have failed in all three of them that I have repaired the other 3 capacitors were a little higher than a new one but not by much but senses I was having to repair it anyway I changed the other 3 capacitors for good measure

[stj]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

if it's based on a TOPSWITCH device then use 22uf and go for the highest ripple device you can
it's the startup cap, it needs to hold enough current to kickstart the transformer

[Per Hansson]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

What stj said, I would also measure the capacitance of the supposed bad caps and see what they read:
As that is anyway the most important metric for a startup capacitor.

[sam_sam_sam]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

Well this circuit is very interesting because both of the 10uf and 47uf capacitors go to different optic sensors which I find odd for this setup yes it gets it power from the negative side of the TopSwitch and in part of the circuit it has two different diodes that also are in the circuit going to the optic sensors

This is the feedback part of the circuit but I have not seen it done this way before

https://cdn.badcaps-static.com/pdfs/...59f7bcc5f9.pdf
It very similar to the figure number 44 in this data sheet only the part where it shows using two different types of optic sensors

The switching transformer is not the same either because the one in this charger circuit has an extra winding on the primary side of the circuit

I have not compared all of the component values yet

STJ you are correct in the data sheet it does show that there is a 22uf capacitor and a 47uf capacitor where the optic sensors are

CapLeaker you might be right that there might be a design issue with this circuit based on the data sheet

[sam_sam_sam]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

What stj said, I would also measure the capacitance of the supposed bad caps and see what they read:
As that is anyway the most important metric for a startup capacitor.

Okay I checked one set of capacitors

The 10uf checked out at a little bit over 10uf 10.something
The 47uf checked out at a little bit over 47uf 47.something

[sam_sam_sam]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

I have a question for anyone that wants to answer it

If I put a 22uf instead of a 10uf capacitor in the circuit what is the worst thing that can happen to this circuit or what type of malfunction should I look for

The reason I ask is because once I had a charger for a battery pack that had issues with the current output and taking a very long time charging them

A battery charger that I also have that is not for power tools

In the switching regulator circuit I changed the value to a slightly higher UF value and it worked a lot better but in this process I put to big of a value and it would not turn on or the frequency was so high and very loud that you could not leave it that way for very long because it would drive you mad

[stj]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

the startup capacitor charges through a high value resistor from the rectified mains.
once it reaches enough charge it kicks the circuit into oscillation.

a larger cap increases the delay before the psu starts, as it takes longer to charge.
thats not really an issue.

[redwire]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

The Blue ESR Meter works very well, you can check the calibration with a resistor.

It's odd the 10uF cap keeps having a short life.
I would say Milwaukee's CM either forgot a resistor or used a slow diode there, in the feed from the AUX winding. Can you look what the parts are, feeding up to the 10uF cap? It's around 5R resistor and a lower current diode. There is no penalty to upsizing from 10uF->22uF, it's just the aux power filter cap. The TOP256EN does not use the cap for start-up in the usual way.
It runs at 132kHz. I think the use of two opto-couplers, the second is an extra safety shutdown I think.

[stj]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

dont forget to use low esr caps

[CapLeaker]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

Well... today I've read a flyer to one of our box stores. They are selling now cordless tools that are 40V! They also claim that these batteries can be used on 20V tools, switching automatically to the correct voltage. So one battery can be used either on 40V or 20V. Not sure how good they are...

[stj]

Re: Milwaukee Battery Charger M18/M12 Dual battery charger Dead no light during charg

i have seen 80v tools
problem is, it would be cheaper to buy a generator and a 5m extension cable!!!!