Milwaukee M18 dead battery

[julianf]

what battery is it? size and model

M18 5ah

I think that makes it a B5?

 

[123hotchef]

Probably more cost effective to get a new one at that spec. But that's no fun is it.

 

[julianf]

Probably more cost effective to get a new one at that spec. But that's no fun is it.

About £60. And its not even been hammered. I mean its been used regularly, but not that many cycles. Feel a bit hard done by, but, sure, no point in throwing good money after bad.

 

[addjunkie]

About £60. And its not even been hammered. I mean its been used regularly, but not that many cycles. Feel a bit hard done by, but, sure, no point in throwing good money after bad.

They open up quite easily if you drop them on concrete, saves the little torque tools. Guess how I know. Quite surprising how little and short those screws are. Not gripping on much at all.

 

[500e]

All ways worth a call to importers/manifacturers having a polite complain
Suprised what it can do

 

[julianf]

All ways worth a call to importers/manifacturers having a polite complain
Suprised what it can do

It all seems to be handled by a central returns place (who deal with other makes also)

But, yes, i could see if i cant go to the manufacturer, but i also didnt "register" the battery when i bought it - you get one year as standard, and 3 years if you tell them where you live so they can spam you for ever more.

 

[500e]

Just block the spam
2 years warranty for a bit of spam result. , but was it on battery

 

[julianf]

I've got the lid off the battery now.

Multimeter on the various bits of metal comming up from the cells shows voltages stepping up like I'd expect -

3.59
7.21
10.81
14.42
18.02

I mean they're all low, but evenly spaced, so it's not a single dead cell. Ie I think the cells are probably ok.

PCB I'm a bit dubious of.

Looked ok, limited foreign matter etc, but, curiously, the tops of the the ICS are all kind of soft / gooey. Like I can mark them with my finger nail.

Like when things get exposed to solvents, although this hasnt been, but like that. The battery casing is fine, it's just the PCB itself.

I've not opened my good battery for comparison, as I had to drill out the security bump on the torx and I can't be bothered to do that again.

I can't immediately see how to get the cells out. I suspect they're spot welded in anyway but I was wondering about taking them out and sticking them in a stand alone charger that I have that has a cycle mode to check the cell performance.

But, again, I think it's the PCB. The cells all show some voltage and all pretty even but the LEDs that come on when you press the button on the PCB (to show battery power) do nothing at all. Not a glimmer of life from them at all.

 

[julianf]

I think ill gamble a tenner on a new pcb.

Anyone got any idea what this means -

From this item on ali express -

&M18 Replacement PCB Board Charging Protection Circuit Board For Milwaukee Electric Drill 48-11-1815 &M18 18V 1.5 3.0Ah Batteria - AliExpress 44

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

 

[julianf]

...done, ive bought one. Will report back in 3 months when it gets here.

 

[GafferTapeKing]

I have two batteries and left one battery idle for too long, its an M18 5.0A that throws an error light when on the charger.

So I popped it open and measured the cell voltages, four cells had an almost identical voltage.
One cell was 0.4v lower.

I tried feeding the dead cell separately using a bench power supply with adjustable voltage and current limiting.
The low cell would drop back to its lower voltage over about 30 seconds.

Maybe there are differing designs but mine appeared to have spot welds bonding the cells together so I didnt go any further as the chances of reassembly looked slim.

 

[julianf]

Yeah, this one is all spot welded. I got it out of the case in the end.

Im planning on just desoldering the block as-is, and resoldering to the new pcb. I wont mess with the welds at all.

 

[eddie49]

Some Li-ion power tool batteries contain one or two large MOSFET transistors on heatsinks, which cut or enable power to/from the cells. There are no components on the PCB of this Milwaukee battery large enough to switch the 20- to 40- Amps involved, so the board only monitors voltages, and balances and temp-checks the cells. The 20-odd volts should always be present at the outermost two terminals. The PCB will use one of the other terminals to signal the tool to shut down on low voltage, and probably to control the charger too.
It should be possible to charge the battery using a generic ( Radio-Control ) charger, and to test it under load ( 2 x 12v headlamp bulbs ) across the outermost two terminals.

 

[GafferTapeKing]

Curiosity got the better of me, partially because I already the right torx bits out on my desk from earlier

Voltages (left to right)
overall 16.21
4.05
4.05
4.05
0.00
4.05

So Low Volts has become No Volts and the cells are welded in pairs.
Well it looks like a weld but I might stick a small flatblade under the terminal and see if it actually is welded
Would be a bonus if that is just a sprung terminal

 

[Kram]

Jump starting with an unregulated supply is bad, likely to burn them. Use an rc charger... magnets and loose wire to connect up if needed.

Spot welds are easy to pull off, and so far I just soft solder them with great care to reassemble.

 

[ChrisBailey]

The gloop on the ICs might just be from a pick and place pcb fab machine. Sometimes they leave the rubber part holders on when they get reflowed, results in gloopy stuff on IC.
Could also be potting basically to waterproof it.

 

[julianf]

Curiosity got the better of me, partially because I already the right torx bits out on my desk from earlier

Voltages (left to right)
overall 16.21
4.05
4.05
4.05
0.00
4.05

So Low Volts has become No Volts and the cells are welded in pairs.
Well it looks like a weld but I might stick a small flatblade under the terminal and see if it actually is welded
Would be a bonus if that is just a sprung terminal
View attachment 316773

Ive split up a number of 18650 cells, and that is a spot weld.

You can buy specific machines for sticking back on the tabs, but they are over a hundred quid...

If you find an old laptop battery, that will have similar - you may be able to recover a working cell from that with the spot welds in place, and cut the tab further away from the cell itself - then cut the M18 to match - that would then allow you to join the metal work, rather than solder to the cell. So you keep the heat away from the cell.

Just a thought.

 

[GafferTapeKing]

rc charger ?

I fed the two low ones 5v at 200ma, CPC lists the charging voltage as 4.2 so maybe the cells are baked now rather than a bit low.
Maybe I should have looked up a charging voltage before that but I didn't know the cell type.
Hindsight is great.

The specs on them are impressive, peak current of 25A, I can see how these micro jump packs can step up to cranking an engine and still fit in a pencil case.

 

[ukracer]

rc charger ?

I fed the two low ones 5v at 200ma, CPC lists the charging voltage as 4.2 so maybe the cells are baked now rather than a bit low.
Maybe I should have looked up a charging voltage before that but I didn't know the cell type.
Hindsight is great.

The specs on them are impressive, peak current of 25A, I can see how these micro jump packs can step up to cranking an engine and still fit in a pencil case.

Radio Control battery chargers.

 

[ukracer]

Ive split up a number of 18650 cells, and that is a spot weld.

You can buy specific machines for sticking back on the tabs, but they are over a hundred quid...

If you find an old laptop battery, that will have similar - you may be able to recover a working cell from that with the spot welds in place, and cut the tab further away from the cell itself - then cut the M18 to match - that would then allow you to join the metal work, rather than solder to the cell. So you keep the heat away from the cell.

Just a thought.

The best (cheapest) way to solder tabs back on is to use a decent 12 volt Field Soldering iron with massive tip.
None of the 240 volt irons we had would get anywhere near hot enough at the speed you need to keep the heat localised to not damage the cells.

We used to desolder and resolder battery packs when we raced RC to get cells with the most punch . Good cells would be quicker but would drop off a cliff when empty.
Bad packs lasted longer but would be "soft" i.e have no "punch"

But our 12 volt iron was a godsend