How does soldering battery works?

[Tom is a Door]

I was thinking about saving up some money to solder the leads of a battery and join it with leads from another to boost battery life. I was planning on taking the positive and negative lead wires and stripping them then solder battery 2's positive and negative to the corresponding stripped leads. I will be using same or +/- 0.1 volt different battery. I have never soldered nor do I know jack squat about electronic engineering. So, I was wondering how practical it is and the dangers of it. I wanted to do this on a handheld device with lithium ion battery.

[Zando_]

Heat + Lithium batteries isn't very good. What device?

[RoryDash]

I would take extreme caution having heat near lithium batteries

[TVwazhere]

3 minutes ago, Tom is a Door said:

I was thinking about saving up some money to solder the leads of a battery and join it with leads from another to boost battery life. I was planning on taking the positive and negative lead wires and stripping them then solder battery 2's positive and negative to the corresponding stripped leads. I will be using same or +/- 0.1 volt different battery. I have never soldered nor do I know jack squat about electronic engineering. So, I was wondering how practical it is and the dangers of it. I wanted to do this on a handheld device with lithium ion battery.

Handheld device like a phone or tablet? or something a bit simpler?

 

Side note: My real name is Tom. I am definitely not a Door

[MrMarriarty]

10 minutes ago, Tom is a Door said:

I have never soldered nor do I know jack squat about electronic engineering

Just dont do it man, this could be EXTREMELY dangerous even if you know what your doing... just buy a battery with more milliamps (mA) than your current one if you want the battery to last longer

[Pesukarhu]

If you have two batteries of the same voltage and type (li-ion in your case) you can connect them in parallel quite safely. They will balance on their own. Just make sure you connect them positive to positive and negative to negative. And preferrably have them charged to the same voltage when connecting them together to avoid high current flow.

 

[mariushm]

It's not a good idea to solder wires to batteries. You spot weld metal strips to the terminals of batteries, Spot welding ... an electric charge is released for a very short period of time, where the metals touch they heat and melt and join together creating good connection.

 

for more research see:

 

https://www.eevblog.com/forum/testgear/battery-tag-welder-from-china/

https://www.eevblog.com/forum/reviews/sunkko-709a-spot-welder-teardown/

https://www.eevblog.com/forum/projects/spot-welding-theory-of-operation/

 

Sure if you're careful you can still solder wires to batteries the regular way, trick is using lots of liquid flux and right amount of temperature on tip and short solder times so you don't overheat battery.

[Maxpphire]

Alternatively, you could just tape the wires to the battery via Electrical tape.

[Unimportant]

16 hours ago, mariushm said:

Sure if you're careful you can still solder wires to batteries the regular way, trick is using lots of liquid flux and right amount of temperature on tip and short solder times so you don't overheat battery.

And, before soldering, scratching the coating away so the solder takes immediately. Otherwise you'll be heating the battery way too long as the solder does not take well.