Maker Pro
Maker Pro

Lithium battery BMS

ajwright

Feb 13, 2023
4
Joined
Feb 13, 2023
Messages
4
I am trying to replace my drill's nicad batteries with Lithium\BMS.
I ordered a bunch of BMS but upon soldering, I get several problems such as the bms is draining a battery(different battery(1-5) on different BMS), or the power out will read 20v but as soon as I give it a load and squeeze the trigger, the voltage drops to 0v(the whole time the battery still reads 20v.

SO... I just bought a new drill of higher watts to speed up the soldering. It is not like I leave the soldering iron on the board and I am sure I am not shorting wires. Being it is hotter than my old solder, will this fry components on the board, or did I indeed get a bunch of lemmons??

TIA.
 

kellys_eye

Jun 25, 2010
6,514
Joined
Jun 25, 2010
Messages
6,514
Are we to accept that you fitted and connected the BMS correctly? The usual source for BMS modules is China and there is a possibility you got yourself a lemon. When ordering such modules from China I always get a 'few' ..... just in case. They aren't that expensive and even if they all work it only means I have a spare or two lying around.
 

ajwright

Feb 13, 2023
4
Joined
Feb 13, 2023
Messages
4
I have done this before. I ordered 5 from the same seller before. I know I shorted one of them and it didn't work so my bad. The other 4 work fine.
I have 1 more drill to convert so I ordered another 5 this time and all 5 have problems(I didn't short anything). I bought a new soldering iron this time. I only touch the boards to melt the solder and that is it so I wonder if that is anything.
 

kellys_eye

Jun 25, 2010
6,514
Joined
Jun 25, 2010
Messages
6,514
It takes a surprisingly large amount of heat to destroy common components these days - they are made for 'submersion' (in some cases) and infra-red reflow (and hotplate) methods. 350degC for 15 seconds(??? - don't quote me). Normal soldering shouldn't affect them at all so it's possibly a case of haviing to look closer at the board itself.

I have seen many SMD boards with the parts badly located during manufacture - check that the parts are all properly 'landed'.
 

ajwright

Feb 13, 2023
4
Joined
Feb 13, 2023
Messages
4
It takes a surprisingly large amount of heat to destroy common components these days - they are made for 'submersion' (in some cases) and infra-red reflow (and hotplate) methods. 350degC for 15 seconds(??? - don't quote me). Normal soldering shouldn't affect them at all so it's possibly a case of haviing to look closer at the board itself.

I have seen many SMD boards with the parts badly located during manufacture - check that the parts are all properly 'landed'.
The new soldering iron I got the higher wattage Weller iron. Being the tips corrode away in minutes of use, I returned it for a lower watt iron. Sorry to say my 1980's commercial Weller soldering iron from work died...

With this last lower watt iron, I am on a roll in that the last few didn't fry the BMS(so far). Maybe the higher temp DID fry the chip...

I just found 190 lithium batteries so I'm set and will be soldering for a while...
Thanks guys.
 

Attachments

  • IMG_20230405_182307015_HDR[1].jpg
    IMG_20230405_182307015_HDR[1].jpg
    367 KB · Views: 4
Top