Hi Bob, that is a good question, I switched over to NI-MH rechargeable batteries a couple of years ago, I start out each hunt with a fresh set and take an extra fresh set with me for back up. A couple of detectors I have used in the past have been battery hogs, so I feel that I am saving money in the long run, with the rechargeable.
As far as which PI machine to get, that is a tough question, a lot depends on what type of hunting you are going to do, weather in fresh water, salt water, in dry sand, wet sand, or inland hunting for nuggets. Another factor is how much do you want to spend, and if you have ever used a PI detector before, I have a Goldquest SS V2, and so far I am very pleased with it's performance to weight ratio, it is light weight and I can use an adapter to run Minelab DD, or compatible coils, it is real hot on gold and from what I experienced in testing, is not to bothered with hot rocks and black mineralized sand.
The areas that I nugget hunt in are not accessible to 4WD's or evan 4 wheelers, so I have to hike in with a hydration backpack, plus a metal detector, swing a coil for 6 hours, then hike back out, a good 10 hour day. I did have an SD 2100 and it is a good PI detector, but the weight became an issue toward the end of the day. PI detectors are expensive, and can get more expensive when you start buying accessories. The best option is to get with a local metal detecting club and talk with some of the guy's on what they are using and how much they have invested in their set up, or maybe find a multi line dealer where you can try a couple of different detectors.
colt
