3M Jupiter PAPR alternative battery / USB power supply

 

The 3M Jupiter is a battery-powered PAPR (powered air purifying respirator) device that provides filtered air to a helmet/hood, providing protection against particulates and (depending on the filter) other pollutants.

Since original batteries can be expensive, hard to obtain, and require a proprietary (also expensive and hard to obtain) charger, I investigated the possibility of alternative power supplies. Luckily, the interface between the battery and the device is a standardized barrel connector.

ALL OF THE BELOW INFORMATION IS TO MY BEST KNOWLEDGE, AND COMES WITHOUT ANY GUARANTEES. USE AT YOUR OWN RISK. YOU WILL LOSE LOW BATTERY WARNING PROTECTION, AND YOUR AIR SUPPLY WILL FAIL WITHOUT WARNING IF A USB BATTERY PACK TURNS OFF OR IS ACCIDENTALLY UNPLUGGED.

From my measurements, it appears to be a 5.5×2.5 mm barrel jack (i.e. the plug diameter is 5.5 mm, the inner pin diameter is 2.5 mm) with standard polarity: Positive center pin, negative barrel/sleeve. The jack is on the battery, the plug is fixed inside the blower unit. A corresponding plug will fit the original battery, and a 5.6 mm x 2.5 mm jack (Reichelt HK 25) fits the connector inside the blower unit.

The original 8 hour battery is rated at 4.8 volts, measured at 5.2 volts when fully charged. This means the device can be powered with 5 V. The 8h battery is rated ~36 Wh, implying a power consumption of ~4.5 W (less than 1 A), though power draw could be significantly higher during power-up or under heavy load due to aging or obstructed filters. (Note: Single-use, non-rechargeable primary lithium metal batteries with higher voltage ratings exist according to pictures; e.g. the 6 V BAT-22 lithium-metal battery and the 9 V BAT-21. Some data sheets mention a 7.8 V Intrinsically Safe battery but I’ve also seen pictures of 4.8 V IS batteries.)

By cutting the Micro USB end off a high-quality (low resistance) USB-A to Micro-USB cable, and soldering it to the above-mentioned barrel jack, a makeshift adapter can be created that allows powering the PAPR from a USB battery pack or wired power supply. A jack with strain relief should be used and the cable side of the jack should be filled with hot glue after soldering to provide strain relief, mechanical stability, and protection against short circuits. Remember to slide on the cover before soldering!

Inserting the adapter’s plug/socket into the battery well of the blower unit is best done with needle nose pliers, heavy duty tweezers, or a similar tool. Care must be taken to protect the cable against pulling, especially diagonally, as this could damage the connection on the blower unit. An adapter with the shape of an original battery could possibly be 3D-printed. The battery is 95.9 mm wide, 24 mm thick, with the narrower top part 75.5 mm wide and rounded at the top (the rounding doesn’t seem required).

This way, the PAPR can be powered from a USB power supply (untested) or a regular power bank (tested), as long as the power bank provides enough current to devices that do not perform any negotiation (you will likely have to manually turn on the power bank, even if that isn’t necessary with other devices). Since many power banks can be charged while in use, this effectively provides a way to power the PAPR from mains power with battery backup. Note the warning above: When the power bank discharges and is no longer able to supply the necessary current, it will likely cut out abruptly and without any warning. Do not use such a setup in environments where this could be a problem, or where you would not immediately notice the absence of the blower noise!

Finished USB-to-barrel-plug cable

Other notes:

• Extended use of PAPRs may cause dry eyes.
• Unlike other respirators, tight fit is not required due to the slight overpressure created in the helmet, and the system is highly effective: e.g. no trace of cigarette smoke can be detected even directly next to a smoker with the standard A2P filter.
• The A2P filter is A2P3, i.e. it provides the highest level of particle filtration.
• Air leaving the helmet is not effectively filtered.
• The Versaflo M-106 helmet is surprisingly comfortable. Glasses can be worn. The visor/face shield in the this helmet has a EN166B medium energy impact protection rating, comparable to a good pair of protective googles (verify the marking on your visor to make sure yours is the same, as different visor models exist).
• The air next to a busy road smells noticeably fresh when wearing this, making one realize how bad pollution in cities is and that cars with internal combustion engines should probably be banned sooner rather than later.