OK, so a pair of lungs is lighter than the little inflator looked at here, but the Pad-Pal is, by far, the lightest electric sleeping pad inflator in the world. It is doubtful that anything lighter could be made.
The last thing most backpackers want to do at the end of a day’s hike is blow up an inflatable sleeping pad. It isn’t difficult, it isn’t hard, simply onerous. Many will use a pump sack instead of lungs. This can be an awkward process in the confines of a tent. Some hikers reluctantly accept the weight penalty and carry a small battery powered inflator for the job. But that is a true luxury. One ultralight backpacker in the US noticed this gap in the market.
Tyler Reeves, trail name T-Rex, was convinced that he could design and make a truly lightweight electrically powered sleeping pad inflator. It helped that he was majoring in Computer Engineering and could apply his skills and knowledge to the problem. His aim was to mostly utilise cheap and widely available components where possible. Tyler produced a first generation, decided it was too heavy and refined it into a remarkably lightweight 11.5g Pad-Pal that he sprang on the Ultralite Reddit backpacking crowd in summer 2022. There is a short YouTube film he made for this earlier version.
The Pad-Pal began as a side-line project to help fund Tyler’s expensive development of his ultralight Joule Thief and Joule Bandit heat exchanger pots. Immediate weight loss was realised in the early stages of development by doing away completely with any sort of internal battery. Most backpackers out on trail for multi-days are carrying a powerbank. There is therefore little need to have an inflator with its own battery as it can instead be run from that external power source. This immediately meant that his inflator began to approach the weight of a pad’s pump sack and could be considered as a viable alternative by the lightweight backpacker.
“At less than 11g, this easily makes this the lightest electric sleeping pad inflator in the world”
Not content with his first versions of Pad-Pal, Tyler returned to the drawing board (or more accurately, CAD) and continued to refine his design. A slight redesign of the fan duct removed 1.3g and also increased strength. These inflators are, for the most part, 3D printed and there is a little variance in weights as a result. The v4 Pad-Pal shown here weighs 8.3g with another 2.4g for a Winglock Thermarest NeoAir valve adapter. A total of 10.7g. At less than 11g, this easily makes this the lightest electric sleeping pad inflator in the world. It is also very small. The v4 Pad-Pal measures 32mm x 38.5mm.
The Pad-Pal is really, really, light. Much of this reduction in weight stems from good design and the exclusion of extraneous parts, keeping it simple, keeping it bare bones. Each Pad-Pal is composed of just five parts. Three of which are bespoke and two being ‘off-the-shelf’ parts.
- 3D printed rigid fan duct housing. Pad-Pal generations v1-v4 are polycarbonate. Pad-Pal v4.1 duct is HP HR PA11, a type of nylon.
- 3D printed flexible TPU sleeping pad valve adapter.
- Custom Printed Circuit Board (PCB) with Surface Mount Device (SMD). The v4 version of this motor control board introduced a USB-C connector.
- 6x15mm coreless DC 615 micro dc motor with .8mm shaft and micro JST connector. These are made for drones and cheaply available online.
- 31mm 4 blade mini drone propeller with .8mm press fit shaft hole. These are cheaply available online.
Tyler developed a custom PCB that acts as both motor controller and power management system. Ducts and valve adapters are 3D printed using HP printing technology. There is a +/- 0.2g weight variance between units. The special fan ducts were tested to destruction and are surprisingly robust, capable of resisting 58.9kg axial loading force and 15.8kg of radial point loading.
The Pad-Pal has various valve adapters for different makes of inflatable pads. There is a YouTube film showing Thermarest Winglock valve, Big Agnes flat valve, REI Flash Pad flat valve, Exped flat valve, Nemo flat valve and Thermarest Classic twist valve being inflated with the Pad-Pal. Some adapters are straight forward to use; others are a little tricky. If operated incorrectly the Pad-Pal’s consumable motor’s lifespan can be shortened as a result. For example, the pad also needs to be unencumbered, with nothing on top, otherwise the extra weight may be too much for the Pad-Pal to handle. It is possible that some of the more complex shaped valve adapters, such as those for the Nemo, Exped and Sea to Summit, currently printed in TPU on an FDM process, may be changed to an SLS printed process, still made of flexible TPU. The various valve adapters have been shown to be compatible with the pads below, but this is by no means an exhaustive list.
- NeoAir Uberlite
- NeoAir XLite
- NeoAir XTherm
- Exped Synmat UL MW
- Exped Synmat HL Winter MW
- REI Flash Pad
- Big Agnes Rapid SL Insulated 25” x 72”
- Big Agnes Air Core Ultra 50” x 78”
- Q-Core Deluxe
- New Nemo Tensor flat valve
- Nemo Tensor insulated regular
- Sea-to-Summit Etherlight XT insulated
Some beefier, heavier inflatable pads previously required a larger motor to be fitted to the Pad-Pal, this created the Pad-Pal Plus model. However, v4 of the Pad-Pal introduced some changes to how the motor handles heat created during operation which negated the continued requirement for a Plus model. Radiator fins were added to the Pad-Pal’s motor housing and thermal paste added, making it run cooler. The 15 denier ultra-light Thermarest Uberlite sleeping pad could potentially be inflated with an even lighter inflator and Tyler has already been exploring the option of a smaller fan duct housing with smaller motor and motor control board, and a thinner PCB to create an even lighter inflator for that pad.
“The stress on the tiny Pad-Pal motor varies with each make and model of pad“
The Pad-Pal is not without faults. 3D printing components is effective but does not make for the best of aesthetic finishes. The choice of components was deliberate. They are mostly cheap and light. Therein lies a fault, they are also fragile.
There was a deliberate decision to keep the consumable DC motor as light as possible and the micro motor will require replacing at some point. While replacement parts could potentially be included in a ditty bag on trail, it will likely only be those on a multi-month hike that would do this. Maintenance is fairly easy as Tyler wanted the Pad-Pal to be so simple that major components could be repaired or replaceable with just the nailfile on a Victorinox Classic knife. With the introduction of the v4 Pad-Pal the replacement procedure for the motor changed a little and a second video was produced. With v4 Pad-Pals Tyler began including a 3.6g ‘motor replacement kit‘ with each inflator, that included replacement motor, fan blade, Q-tip and thermal paste.
The stress on the tiny Pad-Pal motor varies with each make and model of pad. The designer has measured motor lifespan under load for various pads and Thermarest Winglock pads came out best when full three-minute inflation cycles are required, with an average of 103 cycles (around five hours) before the motor requires replacement. Big Agnes pads have an average of 84 inflation cycles, Nemo and Sea-to-Summit pads 72-76 inflation cycles, Exped 67 inflation cycles and Thermarest Classic Twist valve pads the worst at 51 inflation cycles. That said, the lightweight Thermarest Uberlite only takes a minute to inflate so some 309 inflations might be expected before the motor requires replacement.
As said, the replacement motors are cheap and readily available. There is no great penalty to carrying spares on trail as the tiny motor weighs just 1.8g. It is likely that removing the press-fit propeller during motor replacement also means that it is no longer firmly fitting and should also be replaced. A spare propeller weighs a further 0.4g. A longer-lived micro-brushless motor was experimented with in the design stage however that was more expensive, twice the weight and took longer to assemble.
Exposed circuitry also makes the Pad-Pal susceptible to damp. Waterproofing components would have inevitably led to weight gain and the simple steps of keeping the inflator in a waterproof baggie or ziplock and being careful to keep it dry when in use should be enough to protect it. If it does get wet, it needs to be thoroughly air-dried before attempting to run it.
The fan is exposed within the open-ended fan duct, and care should be taken to ensure no fingers or anything else is within the duct when operating. You can be sure that if such an inflator were produced by a big-player manufacturer, then some sort of guard would be added over the end, with a resultant increase in weight. It is also best to keep a thumb pressed against the control board when removing the cable connector otherwise it can occasionally pop out of its click-fit housing.
The Pad-Pal uses around 250mWa over a three-minute runtime, before shutting down as a precautionary measure to protect itself from heat build-up. It must be disconnected and reconnected to run again. So, between 3-5% of a 10k powerbank over a seven-day hike with seven pad inflations.
The Pad-Pal has a small fan and motor. This is not going to inflate larger inflatable items intended for the beach etc. It has specifically been developed as a minimal inflator for lightweight sleeping pads. Even then, it is best to open the winglock valve on a modern Thermarest so that the Pad-Pal isn’t also attempting to open the one-way valve. Each model of pad has its own little quirks but the inflation method to use a Pad-Pal with a Thermarest Winglock valve pad is as follows:
- Unroll Thermarest pad, ensuring that nothing heavy is on top of it and it is free to inflate unrestricted.
- Attach Pad-Pal with fitted valve adapter to the sleeping pad valve.
- Twist winglock valve to the deflate position.
- Plug cable into Pad-Pal, the other end of cable into powerbank
- There is a lag of two-seconds prior to the Pad-Pal starting and building in speed.
- Inflate pad, pressure will be just short of full inflation.
- With Pad-Pal still connected and running, turn winglock valve to closed position.
- Unplug cable connector from powerbank, then unplug cable connector from Pad-Pal.
- Top-up pad with two or three breaths to desired firmness.
After two minutes the Pad-Pal isn’t really doing much. Leaving it for the full three minutes when it automatically shuts down means I need to put three breaths into my pad for my desired firmness.
Lightweight backpackers have had the option of buying small battery powered inflators for some years now. The smallest and lightest used to be the 83.4g Flextailgear Tiny Pump that measures 53mm x 43mm. The Tiny Pump has now been refined and its replacement is now over 100g. The Tiny Pump 2X got heavier and larger whereas later generations of the Pad-Pal got smaller and lighter. It is also worth noting that the Pad-Pal is significantly quieter than both generations of Flextailgear pump in operation. I would describe the volume as minimal.
“An open source electric sleeping pad inflation device”github
This truly is a gadget for the lightweight backpacking individual prepared to spend a little cash in pursuit of the lightest gear available. Unlike many items of back-packing gear that are deliberately over-specced in order to last many years with a resultant weight penalty, the Pad-Pal sleeping pad inflator incorporates cheap replaceable consumables and is intended to be so light that even the most resolved of ultralight backpackers would consider including it in their gear. Tyler is to be congratulated for dedicating his time and skills to developing, refining and producing this inflator. Production is still in what Tyler refers to as it’s ‘growth stage’ where all profits are being used to double the next unit count for the next batch in order to keep up with demand. You are not obliged to buy a Pad-Pal. For those with 3D printers and the necessary skills, the inflator was made an open-source project and the inventor put design plans and component specifications online for anyone to adopt or adapt. Three Points of the Compass commends this inclusive and laudable action.
Tyler currently sells both Pad-Pals and components direct via reddit’s r/ULgeartrade and that is how Three Points of the Compass purchased the v4 inflator shown here. He is looking to setting up a Shopify online store, but it could be 2023 before that is realised due to his other commitments. The Pad-Pal is small volume production, labour intensive and is currently an expensive purchase, though Tyler is planning future automation of the manufacturing process which should lead to a reduced unit price. Current pricing (October 2022) is $46 (USD) shipped within the US, or $42 (USD) plus shipping to desired country. The Pad-Pal is also available from Mercantile Ultralite in Europe for 50€ plus shipping.