New cells higher amps than old ones, will there be issues ?

[randod2236]

Hi guys. New guy here, I have little knowledge when it comes to repairing battery packs for cordless drills.
What concerns me is the AMPS in all this "story".

I have an older(from 2007) 14,4v cordless drill that I got as a gift from grandad.
Battery is almost dead, barely holds up for 1 minute.
But the drill is working fine and I like it, so I would like to repair the battery pack.

I opened the pack and inside I found four "Sanyo l UR18650SA 025A" cells.
I can't find exact specs, some pages say its discharge current is 10A, others say its 18A but cell has mentions of 025A on it.

I was looking trough the store, and I found these **broken link removed**
They have Max Continuous Discharging Current without temperature cut: 20A
But also Max Continuous Discharging Current: 30A (with temperature cutoff circuitry at 80 degrees)

I bolded this for reason I don't understand it, what does this mean ?

Now the main thing.
Lets say this, these Sanyo cells have discharge current of 10A, but Sony VCT5 cell have discharge current of 20A.
If I replace my old cells with these Sony VCT5 cells that have higher discharge current, will that cause any problems ?
Can the drill, or the motor or the board inside the battery pack, can anything burn out ?

 

[Pommie]

Both of those bolded statements start with "max", the drill will take the current it needs and nothing will burn out.

Those are cheap for genuine 18650s. Are you aware that those cells need welding together?

Mike.

 

[rjenkinsgb]

The battery pack may have a temperature sensor built in, connected between one of the battery terminals and a separate terminal.
If it has, just refit that to the same connections - that will allow the tool or charger to shut down if the battery get excessively hot in use.

Otherwise don't worry about it, the cell ratings look fine, just try them.

As Pommie says, the drill will only take the current it needs; higher rated cells will have a longer overall life than cheap low rated ones that may be overloaded any time you put the drill under load.

 

[randod2236]

Thanks a lot everyone, I know about spot welding, I will ask a friend to do it for me since he has the machine for welding.
And thanks for heads up, but I wont order from the websites I posted, I have a local shop, still I will try my best to figure out if its a fake or genuine cell.

 

[Nigel Goodwin]

Both of those bolded statements start with "max", the drill will take the current it needs and nothing will burn out.

Those are cheap for genuine 18650s. Are you aware that those cells need welding together?

You can easily solder them as well - no issues as long as you're reasonably competent at soldering.

We use a spot welder at work, but for speed, no other reason.

 

[randod2236]

I am, soldering is my thing, but I heard that it can potentially damage the cell and that I should never do it.
Is there something I am missing ?

 

[Nigel Goodwin]

I am, soldering is my thing, but I heard that it can potentially damage the cell and that I should never do it.
Is there something I am missing ?

I've highlighted the word you're 'missing'

As with everything, solder it fast and don't over heat it - shouldn't be a problem.

However, if you've got suitable battery spot welder, then obviously use that.

 

[randod2236]

Got it I will go with spot welding on this one just to be sure since I can.

 

[Nigel Goodwin]

Got it I will go with spot welding on this one just to be sure since I can.

It's more fun than soldering as well

 

[randod2236]

If I can ask one more thing to clear it up, what happens if battery is 30A and BMS is 20A ?
Does it even matter that BMS has lower amps ?

 

[Nigel Goodwin]

If I can ask one more thing to clear it up, what happens if battery is 30A and BMS is 20A ?
Does it even matter that BMS has lower amps ?

The BMS should prevent you taking more than 20A from the batteries - that's all. So assuming the batteries are actually higher power, then they will last longer.