A few days ago my phone's battery died and there are no original batteries available. So, can I use 2 standard 18650 in parallel to get a capacity of 5200mAh by soldering some wires to the battery connector and can I charge them directly with the phone's built in charging circuit.
Probably. Let us know how it goes.
Not likely.
First most cell phone battery is only 3.7V nom which means single cell. This is to make it easier to maintain and charge using a 5V usb source.
Second most cell phone batteries have connections that control charging and monitor current/temperature. It is not two connections but 4 these days. Having no controller on the battery would most likely make it not work, not charge or both.
Don't forget about all those battery stories of being set on fire while charging and using. LiPo can be dangerous if not used correctly. Don't mess with it. Get a replacement battery they are easy to find and inexpensive.
wolframore:
First most cell phone battery is only 3.7V nom which means single cell.
OP plans to use the batteries in parallel. So no problem with the voltage as such.
Your other concerns may be valid, though.
And there's the issue of possibly unequal charge.
Anshul333:
A few days ago my phone's battery died and there are no original batteries available. So, can I use 2 standard 18650 in parallel to get a capacity of 5200mAh by soldering some wires to the battery connector and can I charge them directly with the phone's built in charging circuit.
Probably best to find a forum where hacking around with mobile phones is discussed.
As has been mentioned whether what you are planning will work (and is safe) probably depends on the particular mobile phone, it might not be as simple as just hooking up the battery connections.
Hi,
What model smartphone?
Tom..
duh parallel... it should self balance while parallel but that's the least of his worry.
Cell phone battery packs include a battery protection circuit and a thermistor for temperature sensing. The changing circuit may or may not be happy about charging without getting a plausible reading from the thermistor. Operating a battery pack without temperature sensing and over/undercharge protection increases the risk of bad things happening.
As an aside I'm guessing a cell phone with a couple 18650 batteries taped to the back is going to attract a great deal of attention should one ever try going through security screening with it.