I suggest you look on youtube at all the videos of people trying to make them blow up unsuccessfully.
Worst case scenario you end up with a damaged or underperforming cell.
In most cases that surge of charge current will only last a few seconds, not long enough to heat up the cell to the point where it vents.
Obviously not good for lifespan, but still not really dangerous.
Which I why I stated dangerous for the cell and not dangerous for surroundings obviously.
I hope you didn’t scare the new guy off. And to add just a little more fuel, you didn’t consider individual cell voltages dipping under current load as balance between cells happen.
I really hope not.
We like for new guys to learn.
10.43 AM :
Variables :
- The battery itself . Batteries are not created equal .
I purchased some brand new Sanyo unprotected batteries years ago . The first one DIED within 3 months . The 2nd one died some 3 months later . These batteries were purchased for one of my throwers and because I check my batteries I detected the first one being NQR and pulled them from double duty . ( 2 x 18650 )
Obviously this situation has nothing to do with parallel or series ( battery dying ) and could result in reverse polarity .
I have tested a lot of batteries , and my first hobby charger was only capable of a 1A discharge rate , great for testing battery capacity , but not so for stress testing batteries . When I got myself a better hobby charger , well it could do a 5A discharge . Obviously I went a little nuts seeing how batteries performed and it was quite an eye opener .
First ) Voltage sag under load . When you use a battery ( flashlight ) and say discharge it at 1A , there is something called Voltage sag taking place ( Voltage drops under load ) . The greater the load , the greater the voltage sag . Folks flying RC quads have come across the same issue ( high performance quads ) . Anyways the higher the current the greater the voltage sag .
To the point : Not all batteries can sustain high current , some fail ! When the battery fails , the voltage drops so low as to possibly trigger reverse polarity …. This is in effect a short in you battery pack !
This is bad ju-ju … In series or in parallel …
There are just too many VARIABLES for me to bother talking about .
The bottom line is - It matters not if you run series or parallel - nasty stuff can happen in multi battery set ups ( Li-ion ) , especially in high performance flashlights ( high current ) …
Last word : What is high current ?
I have personally witnessed batteries fail from 2 amps to 3 amps when discharged on a hobby charger .
I have seen batteries start off ok , but after 10 minutes just give up and fail .
So never - ever - forget - batteries are not created equal .
As well that universal law - STUFF happens !
Be prepared , test and monitor your multi battery set up … Do not trust to blind luck !