Don't try this at home....

...the results of un-methodical testing on the TP4056 short circuit protection.

So, I thought I ought to do a quick characterisation of the TP4056 module's short circuit protection feature.

• Test 1: touch a 5mm orange LED rated for 20mA across the BAT+ and BAT- terminals. Result: LED goes into thermal runaway and fails. Then fails conduct and voltage stays high across the terminals.
• Test 2: touch a 5730 orange LED rated for 65mA across the terminals. Result orange LED lights and slightly warms, voltage drops to LED forward voltage of 2.2V.
• Test 3: touch an 8 Ohm resistor across the terminals. Result: resistor stays cool, voltage drops to 0V and protection appears to kick in (status LED switches from blue to red).
• Test 4: touch wire across the terminals. Result: blue LED off, red LED on. Voltage drops to 0V. Presumably protection kicked in.
• Test 5: lick skin on the back of my hand and place terminals a couple of mm apart touching saliva. Voltage stays high and flickering red LED turns solid although blue doesn't completely go out. Seems like it's charging.
• Test 6: hold terminals to own tongue DO NOT REPEAT THIS. Result: a bearable tingling feeling on tongue. Voltage stays high at 4.2V. Appears that a tongue doesn't short the circuit sufficiently to trigger the protection feature. I wouldn't be overly concerned about this tingling but I didn't leave it in contact long enough (only a few seconds) to see whether that was just a current-limited pre-charge mode that then may increase at some point.

So, that's enough testing for me to want to continue with a protection circuit for the charger contacts but not to worry about it if I can't make it work.