I don't believe Sony has officially published the amp limits for their batteries. In fact, the company doesn't like the fact that vapers are using their batteries for vaping, period. They are being produced only for OEC power tools which have their own protection circuitry. The fact that Sony VTC batteries are available at all to vapers is due to some of them leaking out into the public domain.
The Sony VTC4 batteries are believed to be 30 amp continuous batteries.
The below calculations demonstrate that the lower you go in ohms the higher the amp requirement becomes. See how your
0.15 ohm coil will draw OVER 20 amps from your battery. You are also putting a lot of faith into a cheap ohm reader in being precisely accurate to the tenth/hundreth of an ohm. Always tend to err on the side of safety when you make your builds by allowing some safety head room.
1.0 ohm = 4.2 amp draw
0.9 ohm = 4.6 amp draw
0.8 ohm = 5.2 amp draw
0.7 ohms = 6 amp draw
0.6 ohms = 7 amp draw
0.5 ohms = 8.4 amp draw
0.4 ohms = 10.5 amp draw
0.3 ohms = 14.0 amp draw
0.2 ohms = 21.0 amp draw
0.1 ohms = 42.0 amp draw
0.0 ohms = dead short = battery goes into thermal runaway
Everyone is free to set their own parameters, and I can only say what mine are.
I try to never exceed 50% of the CDR (continuous discharge rating) of a fully charged battery (4.2v). So with a 20A batteries, that would be 10A. The
Ohm's Law Calculator tells me that a .4 ohm build is as low as I would want to use.
The reason that I place a 50% limit is because as a battery ages the mAh of the battery degrades, as the mAh degrades so does the battery's c rating (amp limit). So down the road, a 20A battery may only be a 10A battery.
The batteries we have can be quite safe if you use the correct batteries and do not abuse them beyond their recommended amp limit. Most battery incidents result from user error or wrong calculations, or ignoring safe battery practices.
Exceedimg a battery's amp limit can cause it to go into thermal runaway. A battery venting in thermal runaway will release extremely hot gas, toxic chemicals, and possibly flames. Once this chemical reaction begins, there is no stopping it. The gas can build up inside a mod, and if there is inadequate venting the mod becomes a little pipe bomb.
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