Lithium battery BMS

[ajwright]

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]

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]

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]

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'.

 

[Bluejets]

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.

Any static protection....... willing to bet not......