The Sniffer has got very special battery-saving software, and so does not draw as much current as a Cornet, yet nevertheless it can become a drag buying batteries, unless you have already taken the plunge and bought a rechargeable one.
A new product has been released which makes everything a bit simpler. They are still as scarce as hens teeth, because every man (and his dog) are trying to get their hands on them, but I just tested a few I received from Hong Kong.
This battery is unique because it has a BUILT-IN CHARGER. You plug in a micro-USB cable, just like you charge your celllphone. There is a socket in the bottom of the battery. There are also 4 green LEDs to tell you how much energy is left in the battery. An amazing piece of miniaturization.
You sacrifice about 20% of the battery capacity to fit in the electronics, but you can still operate your sniffer continuously for two days on every charge, and for most of us the batteries will last a week or so between needing recharges.
So if you have already bought the EBL or Tenergy Lithium batteries, and a charger, then you can continue to enjoy their extra 20% capacity. Those of you with NiMH rechargeables, however, will get a lot more capacity from this new Lithium cell (about twice as much run time).
You can order them from Banggood in Hong Kong, or if you prefer, you can pay considerably more and order them from Amazon (to be shipped from Hong Kong). Actually, Banggood have a US warehouse now, and my first units came in just a few days. But I bought every one they had in the US, so it may take a few days for them to restock I only see the CN warehouse showing stock at the moment.
The batteries have a 420maH capacity, and (amazingly) will recharge in any normal Lithium charger, if you prefer that. However their internal chargers do charge very fast from USB, achieving 80% in just one hour, and full charge in about another 30 minutes.
ps: they will also power other equipment: your Cornet, even smoke alarms...
pps: Banggood is a reliable supplier, well known to the hobbyist market
ppps: The Sniffer does sense the RF noise generated by the charging electronics, and will tick softly if you charge with the sniffer turned on. There is no noise once the charging cable is unplugged
pppps: DO NOT SUBSTITUTE! There are other similar 9V batteries available now which generate RF noise in normal use, and will not work properly on the sniffer. The green ones are particularly bad
I have just received and tested a different brand of battery that is essentially identical with the DUPU. In fact,, I found the quality control better on this brand. I heartily recommend you spend $6.60 to get one of these for your sniffer (while they are still in stock).
They will power a sniffer for about 36 hours continuously, and recharge in 2 hours from any phone-wall-wart.