There would seem to be a market for these and having a sterilised one floating about telling me the SG at any time I would like to read it would frankly be brilliant.
I am now on my third brew, using the iSpindle and it is absolutely great, it being so easy to monitor it at a distance. I have always struggled to read with any accuracy an hydrometer and the iSpindel produces such great accuracy.
I would point out a couple of things to be aware of...
The XL PET is slightly narrower at the neck, than further into the body, which means if you trim the pcb to just fit through the neck, it will be loose down in the body - no way around that. I used the V4 PCB, but decided the best way for the calibration to remain stable is to fix weights to get 25deg calibration, is to fix them to the pcb itself and on the same side as the battery. No need for a battery holder [1], stick both the battery and the weights directly to the pcb and all as close to the lower edge of the pcb as is possible. A bit of trial and error is then needed to get the 25deg AND ALSO with the pcb floating horizontally across the narrow width of the pcb. Sticking weights to the inside base of the PET is entirely the wrong thing to do - any change in relationship between PET and pcb, then causes calibration errors.
The lower down the weight in the PET and the more compact the main weights (battery and calibration weights), the more stable the calibration will be. I used that strong sponge double sided tape, to stick both the battery and the weights in place, alongside the battery. For the weights I used 5mm plumbers lead solder.
My pcb is able to move slightly inside the PET, shake it and it will rattle a little, but despite this its calibration allways remains spot on. The thing is, it always drops back down into exactly the same position inside the PET, once in the FV.
[1] The 18650 will likely survive 500 to 800 recharges before it needs to be replaced, the charger is built into the iSpindle. How many of us are likely to hit 500 to 800 homebrewing sessions and even need to replace the battery? One battery charge may even survive two, three or more batches. The battery in an holder will be higher up the pcb than just the battery without the holder, the battery is by far the heaviest component and needs to be as low as possible down the pcb for best stability. I the battery ever does need to be changed, then the iSpindel will need to be recalibrated anyway, whether in a holder or wired direct to the pcb.
In the UK, Torchy is one source of absolutely genuine 18650 cells.
). I've been poking around some of the server options for logging the data and have found them either a bit lacking/limited/frustrating so I've decided to build my own using a Firebase backend. If anyone is interested I'd happily share the build when it's in a fit state, as all feedback is useful! The plan is to make it super easy to deploy on a free firebase instance, then have easy access from anywhere.
