Bug

Based around a resettable PTC element, the Bug is a high-amp short-circuit protection module that adds dependable safety to mechanical mods.

Designed and manufactured by Atmizone, the Bug houses a carefully-selected, high-amp, resettable polymeric fuse. These fuses do not ‘burn’ like the traditional ones – they use a polymeric element that interrupts the circuit during an over-current condition. The resistance of such an element is dependent on the current and temperature — a short-circuit quickly brings the fuse to a high-resistance state. When the fault is removed, the device cools down fast and reverts back to its low-resistance state.

The Bug is rated for operation up to 7 A at 40 degrees Celsius and has been designed to trip in about a couple hundred milliseconds when hard-shorting a low-resistance mod powered by a high quality IMR battery. The device will also trip within a few seconds when conducting currents above 8 A.

Thanks to its compact size (D=18.3mm, L=~5mm) and no polarity requirements, the Bug can be used with all telescopic mods and quite a few fixed-length mods with extra tube space.

It can be used in the Roller as a replacement of the collapsible spring for:

• added safety,
• extra performance,
• zero maintenance, thanks to its silver-plated top and bottom contacts.

Background Information

Over-currents and short-circuits are almost unavoidable when working with rebuildable atomizers and mechanical mods. Usually caused by bad atomizer resistor set-ups, shorted wires and wrong connections, sustained over-current conditions always lead to battery overheating and, under extreme conditions, battery and equipment damage. Make-break contacts in mechanical mods are among the first components that may show signs of degradation after a sustained, hard short-circuit.

VV/VW mods usually include dedicated over-current protection that acts fast to interrupt current flow if a fault occurs. However, mechanical devices usually score quite low in terms of safety — since they are designed to be simple / rebuildable, they usually come without any protection circuitry at all.

Collapsible springs, which are often used to provide a basic level of short-circuit / overheating safety, are too slow to prevent battery and equipment damage, since they react only after the battery has already overheated. High-drain IMR batteries, which are the de-facto standard for use with mech mods, come with no integrated protection circuit boards. This leaves us with very few options for protecting our gear and minimizing the risks of battery and equipment failure.

Resettable polymeric fuses have been around for quite a while – they provide an easy means of secondary over-current protection, which is fast enough to prevent component and battery damage. These fuses do not ‘burn’ like the traditional ones – they use a polymeric element that interrupts the circuit during an over-current condition.

A characteristic property of polymeric fuses is that the tripping time depends on the current and the ambient temperature. These devices operate with a relatively static resistance and almost linear voltage drop characteristic at currents lower than a threshold current. Above that threshold, the resistance of such a device increases progressively faster with higher current values. Therefore, proper component selection is key to ensuring a good balance of performance and safety. Additionally, since the response of a PTC device depends on the short-circuit current, using a high drain battery with a low internal resistance and high discharge rate actually ensures that the fuse will trip faster.

Important Notes

1. Use high-drain, high quality IMR batteries only.
2. The device will not trip if a short circuit occurs directly in parallel to the poles of your battery, for example due to insulation damage or wrong battery placement.
3. The Bug is not guaranteed to protect you or your equipment under all possible circumstances, since the tripping time depends on many factors, such as the resistance seen by your battery, its discharge rate and mAh capacity, and the ambient temperature. Use common sense and replace your old, damaged, or stressed batteries.
4. Due to its nature, the Bug comes with absolutely no warranty and should be regarded as disposable. Do not attempt to disassemble or repair the device unless you are professionally qualified.
5. The Bug gets warm when it trips. This behaviour is normal and indicates that the device has responded to an over-current or short-circuit.
6. The fuse used in the Bug is resettable. However, it requires a few seconds to cool down after a short-circuit before it can be used again. Expect a slight reduction in performance for a few minutes after a tripping event, even if the device appears to be cool.
7. The performance of the Bug will slowly deteriorate with every trip. Eventually, it may need to be replaced. After many tripping cycles, it might not work at all, or may show a significant voltage drop.
8. If your mod has a significant short-circuit resistance (over 0.2 Ohms), or your battery has a significant internal resistance, the Bug will not respond fast enough since the short-circuit current will be limited by these resistances. Performance testing should only be done using well-maintained, high performance mechanical mods and high quality IMR batteries.
9. The Bug has no polarity. It can be used with all telescopic mods in any orientation, before or after the battery and next to its positive or negative pole. However, it is advised to place it far from your atomizer since its performance depends heavily on the ambient temperature.
10. The right place to install the Bug in a Roller is right between the bottom cap and negative battery terminal, with the grooved/heatsink-like side of the Bug touching the bottom cap disk. The spring and delrin washer should be removed. As usual, voltage drop can be minimized by keeping the retractable tube a bit tight against the battery / bug. This is especially important for low-ohm vaping, since any resistance due to inadequate contact can cause local overheating / increased losses due to the high current.
11. The Bug can be used with a Dingo in 18500 and 18650 modes only. In 18500 mode (T2), the spring and bottom cap washer can be removed, but the bottom cap disk should be carefully adjusted.