We recently published a paper describing our experience deploying more than 500 I-Buttons for a study of groundwater temperature. The paper describes precision, accuracy, calibration, reliability, etc. The abstract is here:
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1745-6592.2005.00049.x The paper discusses "temperature" i-buttons; there is no info on RH. Hope this is helpful. -Geoff Poole S. LaDeau wrote: > Below is a summary of the responses I received regarding monitoring > temperature in the field. > > Hobo Series (the most positive responses): > HOBO Pro Family RH/Temperature Data Loggers (model # H08-032-08): > http://www.onsetcomp.com/Products/Product_Pages/HOBO_H08/hobo_pro_family_lo > ggers.html > $135-159 > > These loggers are weatherproof, not waterproof. To protect them from the > rain (mainly the RH sensor), you can purchase a Rain > Shield ($25-30). > > The waterproof versions are too expensive so I make my own waterproof > containers. Just take a little plastic containers with a tight fitting > lid, drill a hole in the side, run the cable for the thermometer through > it and seal it with rubber sealant. They work great and are about ½ the > price of the waterproofed versions. > > The RH sensor can become saturated in extremely wet environments but > saturation can be minimized by using the protective cover. We make our > own covers using a 4 inch PVC pipe cap found at the local hardware store. > These basically act as a solar and rain shield, but also protect the > logger. > > built protective covers out of 1 l plastic soda bottles that were open > at the bottom the protected the loggers from rain and dew. > > HOBO PC compatibility, user friendliness and customer service were all > regarded highly. > > Ibuttons: > Look into ibuttons by Maxim/Dallas Semiconductors > (http://www.maxim-ic.com/products/ibutton/ibuttons/thermochron.cfm). The > data loggers look like large watch batteries, but can collect up to 1800 > data points in a single collection...The temp data are only recorded in > 0.5C increments, so if you are looking for something more exact, this may > not be the way to go. I used them in the field and left them outdoors and > unattended for up to three months at a time. Never had a problem and they > are very reasonably priced, too. > > i-buttons are a very inexpensive versatile way to measure long term > temperature fluctuations > > Potential availability/backorder issues > > For just straight temperature tracking you can't beat i-buttons > (www.ibutton.com) they can track temperatures for any interval for long > periods of time (I have them out for a year tracking temperature every 4 > hours) and last about 10 years before the battery dies. Plus they are > incredibly durable. Half of our ibuttons are under the soil surface > company is terrible to deal with but otherwise they have been great > > The support at Embedded Data Systems has been fantastic. > > I've been using ibuttons, but they are not waterproof and various ways of > keeping them dry (placed in plastic bags, painted with liquid electrical > tape, etc) are problematic. However, they are great temperature data > loggers. They cost about 21$ apiece, and the reader is only 5 bucks and > plugs into your computer via a USB port > > Price for temp/RH is currently $95.00 (for 10-100 units). 1 week lag for > order (10 unit) availability. > > > Other recommendations/comments: > I have had good success with ONSET(http://www.onsetcomp.com) temperature > loggers, currently we are using tidbit loggers (around the size of a stack > of 8 quarters and ~120$) for water temperature and air temperature. I > have also used the HOBO (~60$ for logger and ~30 for waterproof case) > logger from onset as well, while these are larger (around the size of a > coffee mug with waterproof case) you can replace the batteries, unlike the > tidbits. If you are in a heavily traveled area and might have alot of > loggers stolen, the cheaper of the two would definately be the HOBOs and > the computer link for the hobo is cheaper versus the optical link for the > tidbit logger. > > I've had good success with Onset Water Temp Pro loggers but NOT the > Tidbit loggers. I've not tried the newer stainless steel loggers now > available. > >
