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Bat Detector Solar Solution

Why your bat detector runs out of power 

Under most circumstances with proper trigger sensitivity settings, the Pettersson D500x records "mostly" bat calls and can run over a month on D-sized batteries.

But there are situations where the ambient ultrasound overlaps with bat calls, and the detector ends up recording undesirable noise. This can be mitigated first with more aggressive settings, but at some point those settings prevent some bat calls from being recorded. The next step is to add larger memory cards. 128 GB can be installed, but frankly is an insane amount of memory needed for normal summer commuting bat activity, with typical deployments really only requiring a small fraction of that capacity.

Adding a large memory capacity, in a noisy environment, will set up the situation where the detector literally runs constantly all night, ultimately leading to a power failure. Instead of a month of run time, the D500x may only run ~5 nights. If rechargeable batteries are used, the run time is typically shorter, and more issues arise due to some rechargeables having less voltage output, leading to nightly monitoring interruptions.


How to add solar to your bat detector

Short of plugging detectors into a wall outlet or hauling around larger capacity batteries, we have discovered a solar solution originally designed for cellular trail cameras which is easily modified to operate a Pettersson D500x. It is about $150 to upgrade each detector. These are the items required:

Cuddleback Dual battery box: This can hold 2- banks of D batteries. Bank 1 can be rechargeable that charge with a matching solar panel. Bank 2 are regular batteries that is the backup. When bank 1 is low, it switches to bank 2. 

Cuddleback PW-3600 solar charger: This charges bank 1 of the battery pack. However, it also contains its own 7500 mHa internal (and user replaceable) battery it recharges first. This capacity is somewhere between a “C” and a “D” cell.  So, the whole system literally has 3 sets of batteries possible, in addition to the solar.  

The D500x will power on and resume recording after a power fail; so it is ideal for use with a solar setup.

Rechargeable Ni-MH D cells, 10,000 mAh capacity: This is for “bank 1” of the Cuddleback Dual Bank battery box:  Bank 2 does not recharge and regular batteries, or batteries with long self life can be used, as in theory these would never be used under normal conditions. 

Replacement cables that connect the solar panel to the battery, or the battery to the D500x: You'll want a few spares handy for when cows eat the cables. Note these are only 2’ long and so some care must be taken to place your acoustic monitoring station where the panel gets direct southern exposure. Both the panel and the battery come with straps+brackets to wrap on trees/poles, etc. Longer cables of any length could be made yourself- keep reading.

Note that the Cuddlebck system uses 1.7mm x 5.5mm DC plugs and the D500x uses 2.5mm plugs with a threaded retainer nut (Switchcraft 761ks12). Therefore an adapter is needed, which so far we haven’t come across. An adapter probably will not have the threaded capture nut, though there are companies that will make a bunch for you (request a quote to make a 1.7mmx5.5mm male to Switchcraft 761ks12 male and whatever length). Or, just obtain a quantity of the 761ks12 plugs yourself from an electronics parts dealer and DIY. See this document for instructions on how to replace one end of the Cuddleback power cable with the proper 2.5mm threaded D500x plug (Switchcraft 761ks12) using simple tools.