M18 battery repair

[JOEPRO]

This is an original 5amp Milwaukee M18 battery which refuses to charge up. Flashing lights on charger. Cells were 0.0v.

It's only a couple of years old and had very little use. I believe I had this problem with this battery before and a chip on the inboard module was very hot.

So I de-soldered the board and will order an aftermarket replacement on ebay.

The cells are grouped in 2x lots of 4. And a pair or 2x.

I would like to get some pixies back into the cells to keep them semi happy when waiting on the replacement board.

Not ideal but using my power supply and adding charge in 3x lots.

I presume 3.7v is a safe bet or might these supposed to be higher V when in groups?

 

[carbonarc]

Your battery has 5 pairs of 18650 cells connected in parallel with each pair having a voltage of 3.7v. The 5 pairs are connected in series to give an output voltage for the battery of 18.5 volts. Try charging at 18.0 volts and after this check output voltage of each cell in case any is faulty.

 

[Ruffian]

Would clamp to the buzz bars and put 3.5v into each pair of cells,

This way can monitor to see if the cells are recovering in pairs rather than a pack.

But would be very cautious with it showing 0v as personally would just be scrapping the pack as not worth the fire risk.

 

[Kram]

This is an original 5amp Milwaukee M18 battery which refuses to charge up. Flashing lights on charger. Cells were 0.0v.

It's only a couple of years old and had very little use. I believe I had this problem with this battery before and a chip on the inboard module was very hot.

So I de-soldered the board and will order an aftermarket replacement on ebay.

The cells are grouped in 2x lots of 4. And a pair or 2x.

I would like to get some pixies back into the cells to keep them semi happy when waiting on the replacement board.

Not ideal but using my power supply and adding charge in 3x lots.

I presume 3.7v is a safe bet or might these supposed to be higher V when in groups?

View attachment 482369


View attachment 482370

That is a massive fire risk the way you are doing it. If you want to mess with battery packs, at minimum, you need a proper lithoum charger supporting atleast 5 cells in series for the common 18/21v packs.

As a pack, with correct balance charging leads, charge and discharge test to find the capacity. That will tell you if its scrap or not.
If some cells have reduced capacity, the entire pack will be limited to that value, so a high chance its not worth bothering with.

 

[JOEPRO]

That is a massive fire risk the way you are doing it. If you want to mess with battery packs, at minimum, you need a proper lithoum charger supporting atleast 5 cells in series for the common 18/21v packs.

As a pack, with correct balance charging leads, charge and discharge test to find the capacity. That will tell you if its scrap or not.
If some cells have reduced capacity, the entire pack will be limited to that value, so a high chance its not worth bothering with.

Can you recommend a proper suitable lithium charger that I can buy please?

I bought one before and tried it today and it does not suit the LI on batteries so useless unfortunately.

 

[JOEPRO]

Re fire risk, I am only charging them when I am there standing beside it incase anything changes I can immediately unplug and toss them outside. It's a managed risk and one I am comfortable with.

Indeed I may set them up outside on an extension lead if the weather would ever improve. That would be the safest way I know.

 

[carbonarc]

 

[JOEPRO]

View attachment 482408

Bought one of those before.

It has all functions except Li Ion not sure if that one is different

 

[Kram]

I'm not sure I would trust a £5 fake Imax B6, but it may do the job if you make up a suitable balance charging lead - Id suggest soldering to the connection strips and insulating well. Uninsulated croc clips are just asking for fire, one will ping off and short it.

I have/use an old genuine Imax B8 (but I am not ripping packs apart, just charging existing packs). I believe there are much better devices around now in a similar price range.

It has all functions except Li Ion not sure if that one is different

It will be under lipo in the menu, you can select the lipo voltage of 3.6 or 3.7v, which changes the end voltage of 4.1v or 4.2v.

Again this is not something I have played with for a while but I belive most li-ion cells are 3.7/4.2v these days.

 

[carbonarc]

Hi JOEPRO. I have this charger model and it is able to safely charge batteries using 18650 Lipo cells. It is also able to check the battery capacity using the discharge function.

 

[JOEPRO]

I'm not sure I would trust a £5 fake Imax B6, but it may do the job if you make up a suitable balance charging lead - Id suggest soldering to the connection strips and insulating well. Uninsulated croc clips are just asking for fire, one will ping off and short it.

I have/use an old genuine Imax B8 (but I am not ripping packs apart, just charging existing packs). I believe there are much better devices around now in a similar price range.


It will be under lipo in the menu, you can select the lipo voltage of 3.6 or 3.7v, which changes the end voltage of 4.1v or 4.2v.

Again this is not something I have played with for a while but I belive most li-ion cells are 3.7/4.2v these days.

Hi JOEPRO. I have this charger model and it is able to safely charge batteries using 18650 Lipo cells. It is also able to check the battery capacity using the discharge function.

Thank you for the replies, it has a LIpo function, no LIon one but if I can use the Lipo to charge this then all good.

I'll likely rig this up outside in a sealed container and that way it mitigates any fire risk inside my garage

 

[carbonarc]

Hi again. I am anticipating that the if you obtain the charger I have mentioned it will be used to verify the condition of you power tool battery cells and not be a substitute for your power tool charger supplier by the battery manufacturer. On the basis that will be for testing for faults it is essential that you are present when it is used. Good luck.

 

[carbonarc]

Sorry it is me again. An interesting feature with imax B6 charger is that has a port that enables a thermocouple to be connected to monitor 18650 cells for temperature. It is also possible set a maximum temperature limit for cell charging and if reached charging is terminated. The thermocouple attaches magnetically to a cell body and should be available at Ebay UK.

 

[julianf]

Surely you only need to get enough charge into them for the Milwaukee charger to accept them?

 

[m_c]

I'm not sure I would trust a £5 fake Imax B6, but it may do the job if you make up a suitable balance charging lead - Id suggest soldering to the connection strips and insulating well. Uninsulated croc clips are just asking for fire, one will ping off and short it.

The £5.39 price is for the power adapter only, not the charger.

I have/use an old genuine Imax B8 (but I am not ripping packs apart, just charging existing packs). I believe there are much better devices around now in a similar price range.


It will be under lipo in the menu, you can select the lipo voltage of 3.6 or 3.7v, which changes the end voltage of 4.1v or 4.2v.

Again this is not something I have played with for a while but I belive most li-ion cells are 3.7/4.2v these days.

LiPo and LiIon use similar charging voltages, so anything that works for a LiPo will be fine with a LiIon, especially since LiPo are the more volatile of the Lithium batteries.

 

[eddie49]

Cells were 0.0v.

If this is true for all 10 cells, and applies when they are not paralleled ( cut nickel strips with a Dremel ) and not connected to the PCB, then the cells are all duff and the battery is scrap.

 

[Turbo]

Good quality li ion cells have a protection circuit built in that stops you running them flat. Its normally set between 2.5 and 3v. Once the cell reaches that level it cuts power output and the battery will show 0v.

A few minutes of charge from a low amp power supply is usually enough to reset the cut off but on some cells you can do it manually.

I use an old nokia phone charger, output only 3.3v 300ma. I've fitted 2 mini croc clips to the wires, marking + and - clearly.

I have some of these fitted with m3 s/s bolts.

https://www.amazon.co.uk/Neosmuk-Ma...2lkZ2V0TmFtZT1zcF9waG9uZV9zZWFyY2hfYXRm&psc=1

Stick one of these on each end of a pair of cells and attach the phone charger clips to them, observing the correct polarity. Charge the cells for a few minutes under supervision. Disconnect the charger regularly and check the voltage. Check the cells temperature, they should not get hot at this low charge rate. I normally keep charging until the voltage is 3.2v.

Move along the battery, charging each pair of cells the same way. Monitor the charged cells voltage, if they quickly drop down below the 3.2v they are likely goosed.

Once all the cells are up to 3.2v its best to let the tool charger finish the charge as it will monitor and balance the cells.

Regularly I find only one pair of cells with low voltage, usually at one end of the battery. In this case I first charge with the Nokia charger and finish it off with my Opus BT-C3100 charger.

https://buy2fix.co.uk/products/opus...Tp0eU1GrWP94AG72yJ5Sz3zkgjZ9hya0aApSkEALw_wcB

I've made up a fake 18650 battery from a wooden dowel with 2 fly leads from the terminal ends with the other end of the wire attached to a pair of magnets.

Connect the magnets to the pair of cells, insert the fake cell into the opus charger and it will charge the batteries as if they are inserted in the charger.

The opus has several other functions including testing cell capacity. Fabulous charger, much better with li ion than the aforementioned Imax B6 which is more useful to those building their own r/c batteries.
There are fake opus chargers out there so buy from a reliable source.

 

[Turbo]

I've never had a cell blow up but I do charge stuff in a home made charging box. It is a steel ammo box lined with flame retardant plastic sheet to prevent any short circuits.

 

[m_c]

Good quality li ion cells have a protection circuit built in that stops you running them flat. Its normally set between 2.5 and 3v. Once the cell reaches that level it cuts power output and the battery will show 0v.

I've never seen a cell with any protection built in, the protection is always external, which in this case, is all on the circuit board.
Lithium batteries can recover voltage quite quickly from totally flat, but how much charge they'll actually accept, and how long they last after being totally flat, are what will ultimately decide if it's worth repairing the pack.

 

[knighty]

I've charged loads of batteries with a bench top power supply, a literally hundreds of 18650 cells with a 20amp psu set to 4v - I built holders to charge 40 cells at once all in parralel, with a little in-line volt/amp meter so I could see if any of the cells I just plugged in were bad...(volt or amp jump up for down) I'd plug them in for a few min and double check non were getting hot... then leave them to charge for 12hours (or 24hours... or 48hours... or whenever I had time to swap the new cells in)

just put them somewhere safe while you do it, so if there is a fire it's contained


mine weren't contained, they were on the bench behind my desk at work

if you're worried about it - somewhere fireproof to charge them (old bbq? metal tin? in middle of concrete floor? etc.) and turn down the amps on the power supply