Nearly 6 years ago, Garrett Electronics introduced a metal detector that would be recognized as one of the milestones in detector design which over the years have included discrimination, ground balance, target ID, the "S-handle" and silent search. The detector which revolutionized not only their line but the industry as a whole was the AT Pro and it offered a wide range of features that provided above-average performance in a waterproof case that allowed hunters to search land an d shallow water sites without requiring multiple detectors. For the first time, a metal detector that offered visual target ID and depth information could be taken in water up to 10' deep without fear of damaging the electronics. A year after the AT Pro was introduced, Garrett brought out another model that used much of the same design but was focused on the electronic prospecting market . . . and it carried the appropriate name of the AT Gold. The performance offered by both of these models along with their use in the popular National Geographic cable TV show, Diggers, has made the AT Pro and AT Gold two of the best-selling detectors around the world. In fact, the last time I was in Europe, nearly half of the detectorists I had the opportunity to meet were using one of these two models (or the AT Pro International).
While the AT models do an excellent job ferreting out lost treasure on land and in the water, the one thing that they all require is power to operate and that comes from the 4 AA batteries held in the pack contained in the rear of the control housing. Batteries have come down in price and can often find packs at the register line when you check out of a discount store at bargain prices, you often get what you pay for. I can tell you from personal experience that there is nothing worse than finally getting to a productive location, recovering a few targets and then watching the detector turn off as the batteries die. Then unless you have another set with you, it's off to a local convenience store to get more and then you are usually paying a premium for what you need. At a recent club hunt we had this very thing happen to a 14-year old that had received an AT Pro for Christmas. The batteries went dead, another club member had some with him that turned out to also be dead and his mother spent $8 at the local gas station for a set to get him up and running again. So where does that leave us? Well, that is the focus of this report I penned for RNB Innovations.
In 2012 I got a call from Joe Cooper who started RNB Innovations and he discussed his vision for products he would be focusing on. He said that while detector technology had increased by leaps and bounds, battery technology used by the various manufacturers had stalled out in the 1980's. Ni-Cad and NiMH batteries were the norm if rechargeable packs were offered at all and the limitations that this technology had included reduced life after numerous recharge cycles, weight similar or in some cases more than conventional batteries and limited run time between charges. What Joe had noticed was that virtually any other rechargeable battery system out there such as those used on power tools, gardening equipment, RC cars and a myriad of other items were of the Lithium-Ion design. What he noticed when he delved into the Li Ion technology was that they offered several advantages over other rechargeable technology. I summarized the benefits Joe shared with me in the report I did on his initial battery system but they are worth repeating here as they cleary show why Li Ion batteries are superior to any other power source. First, they weigh between 25% and 40% less than a comparable Ni-Cad or NiMH battery offering the same stored energy and while ounces may not seem worth mentioning, after swinging a detector for hours in the field, ounces can and will start to feel like pounds. Second, they don't develop a memory which allows them to be “topped off” at any time including on the drive to a site with no impact on the amount of operating time they will provide. Third, they offer a more consistent discharge of power from initial charge which provides for more operating life from a pack. Fourth, they can be fully recharged in a fraction of the time a Ni-Cad or NiMH pack requires and finally, they tend to hold a charge for months meaning you can pick up your detector after winter weather passes and be ready to go without worrying about looking for the charger.
A few years ago I took one of RNB Innovations battery packs to Germany with me for my White's MXT and was able to hunt the entire time I was there without recharging the pack during the entire trip which really amazed me . . . and in fact, I was able to get even more time on the pack when I returned to the States before needing to charge it.
When I heard that Joe had developed a pack for the Garrett AT Pro / AT Gold, I jumped at the chance to see how it would work in my AT Pro. The local club had several members that also used either the AT Pro or AT Gold which provided an opportunity to get additional feedback on the pack and its performance. Garrett's literature for both models says that one should get between 20 and 40 hours on a set of AA batteries but actual operating life is typically in the 20 hour window. Even with buying AA batteries in bulk packages, if you are a serious hunter you can expect to be replacing them every week or two during hunting season and that cost can add up in short order.
The pack I received did not have the RNB Innovations graphics on it but the battery provided the same 2,200 mAh output as the production battery will have. Charging is a snap as it is with the other packs from RNB and it takes less than two hours to take on a full charge even if completely depleted. The pack has been designed to fit the AT Pro / AT Gold exactly so dropping the pack in and securing the cover was all that was required to be up running with the new battery system. I took the AT Pro out for several hunts and never had to recharge the pack. To see how much run time remained, I left it turned on in the house checking it with a few targets every once in a while and it wasn't until the following day that it finally ran out of power. Continuing to test it after a quick recharge netted me about 35 - 40 hours of operation which was considerably more than I had gotten before trying a wide range of AA alkaline and even lithium batteries. Feedback from club members who were AT Pro owners was overwhelmingly positive and everyone that saw the pack asked when they would be available as they wanted to pick one up and ditch the AA replacement cycle. As I mentioned earlier, there is a slight weight advantage with the RNB pack as compared to AA batteries . . . and when you plan on spending hours in the field, any weight you can shed will be welcome as the day wears on!
The one piece of information worth noting is that the battery strength indication on any detector - including the AT Pro and AT Gold - will show a fully-charged pack when using Li Ion batteries up until there are about 30 minutes or so remaining. Then the indication will drop quickly and the detector will power down. This is simply the way Li Ion batteries discharge and is why it is recommended to recharge the pack every few trips or even on the way to / from the hunt site using the car charger. Remember, Li Ion batteries do NOT develop a memory so keeping them fully charged will ensure you are always ready for hours of uninterrupted hunting when you get out in the field.